/*
 * Copyright (c) 2015 Andrew Kelley
 *
 * This file is part of zig, which is MIT licensed.
 * See http://opensource.org/licenses/MIT
 */

#include "analyze.hpp"
#include "parser.hpp"
#include "error.hpp"
#include "zig_llvm.hpp"
#include "os.hpp"
#include "parseh.hpp"
#include "config.h"
#include "ast_render.hpp"

static TypeTableEntry * analyze_expression(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node);
static VariableTableEntry *analyze_variable_declaration(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, TypeTableEntry *expected_type, AstNode *node);
static void resolve_struct_type(CodeGen *g, ImportTableEntry *import, TypeTableEntry *struct_type);
static TypeTableEntry *unwrapped_node_type(AstNode *node);
static TypeTableEntry *analyze_cast_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node);
static TypeTableEntry *analyze_error_literal_expr(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, AstNode *node, Buf *err_name);
static TypeTableEntry *analyze_block_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node);
static TypeTableEntry *resolve_expr_const_val_as_void(CodeGen *g, AstNode *node);
static TypeTableEntry *resolve_expr_const_val_as_fn(CodeGen *g, AstNode *node, FnTableEntry *fn);
static void detect_top_level_decl_deps(CodeGen *g, ImportTableEntry *import, AstNode *node);

static AstNode *first_executing_node(AstNode *node) {
    switch (node->type) {
        case NodeTypeFnCallExpr:
            return first_executing_node(node->data.fn_call_expr.fn_ref_expr);
        case NodeTypeBinOpExpr:
            return first_executing_node(node->data.bin_op_expr.op1);
        case NodeTypeUnwrapErrorExpr:
            return first_executing_node(node->data.unwrap_err_expr.op1);
        case NodeTypeArrayAccessExpr:
            return first_executing_node(node->data.array_access_expr.array_ref_expr);
        case NodeTypeSliceExpr:
            return first_executing_node(node->data.slice_expr.array_ref_expr);
        case NodeTypeFieldAccessExpr:
            return first_executing_node(node->data.field_access_expr.struct_expr);
        case NodeTypeSwitchRange:
            return first_executing_node(node->data.switch_range.start);
        case NodeTypeRoot:
        case NodeTypeRootExportDecl:
        case NodeTypeFnProto:
        case NodeTypeFnDef:
        case NodeTypeFnDecl:
        case NodeTypeParamDecl:
        case NodeTypeBlock:
        case NodeTypeDirective:
        case NodeTypeReturnExpr:
        case NodeTypeVariableDeclaration:
        case NodeTypeTypeDecl:
        case NodeTypeErrorValueDecl:
        case NodeTypeNumberLiteral:
        case NodeTypeStringLiteral:
        case NodeTypeCharLiteral:
        case NodeTypeSymbol:
        case NodeTypePrefixOpExpr:
        case NodeTypeImport:
        case NodeTypeCImport:
        case NodeTypeBoolLiteral:
        case NodeTypeNullLiteral:
        case NodeTypeUndefinedLiteral:
        case NodeTypeIfBoolExpr:
        case NodeTypeIfVarExpr:
        case NodeTypeLabel:
        case NodeTypeGoto:
        case NodeTypeBreak:
        case NodeTypeContinue:
        case NodeTypeAsmExpr:
        case NodeTypeStructDecl:
        case NodeTypeStructField:
        case NodeTypeStructValueField:
        case NodeTypeWhileExpr:
        case NodeTypeForExpr:
        case NodeTypeSwitchExpr:
        case NodeTypeSwitchProng:
        case NodeTypeArrayType:
        case NodeTypeErrorType:
        case NodeTypeTypeLiteral:
        case NodeTypeContainerInitExpr:
            return node;
    }
    zig_unreachable();
}

ErrorMsg *add_node_error(CodeGen *g, AstNode *node, Buf *msg) {
    // if this assert fails, then parseh generated code that
    // failed semantic analysis, which isn't supposed to happen
    assert(!node->owner->c_import_node);

    ErrorMsg *err = err_msg_create_with_line(node->owner->path, node->line, node->column,
            node->owner->source_code, node->owner->line_offsets, msg);

    g->errors.append(err);
    return err;
}

TypeTableEntry *new_type_table_entry(TypeTableEntryId id) {
    TypeTableEntry *entry = allocate<TypeTableEntry>(1);
    entry->arrays_by_size.init(2);
    entry->id = id;

    switch (id) {
        case TypeTableEntryIdInvalid:
        case TypeTableEntryIdMetaType:
        case TypeTableEntryIdVoid:
        case TypeTableEntryIdBool:
        case TypeTableEntryIdUnreachable:
        case TypeTableEntryIdInt:
        case TypeTableEntryIdFloat:
        case TypeTableEntryIdPointer:
        case TypeTableEntryIdArray:
        case TypeTableEntryIdNumLitFloat:
        case TypeTableEntryIdNumLitInt:
        case TypeTableEntryIdMaybe:
        case TypeTableEntryIdFn:
        case TypeTableEntryIdErrorUnion:
        case TypeTableEntryIdPureError:
        case TypeTableEntryIdUndefLit:
        case TypeTableEntryIdTypeDecl:
            // nothing to init
            break;
        case TypeTableEntryIdStruct:
            entry->data.structure.fn_table.init(8);
            break;
        case TypeTableEntryIdEnum:
            entry->data.enumeration.fn_table.init(8);
            break;

    }

    return entry;
}

static int bits_needed_for_unsigned(uint64_t x) {
    if (x <= UINT8_MAX) {
        return 8;
    } else if (x <= UINT16_MAX) {
        return 16;
    } else if (x <= UINT32_MAX) {
        return 32;
    } else {
        return 64;
    }
}

TypeTableEntry *get_smallest_unsigned_int_type(CodeGen *g, uint64_t x) {
    return get_int_type(g, false, bits_needed_for_unsigned(x));
}

TypeTableEntry *get_pointer_to_type(CodeGen *g, TypeTableEntry *child_type, bool is_const) {
    assert(child_type->id != TypeTableEntryIdInvalid);
    TypeTableEntry **parent_pointer = &child_type->pointer_parent[(is_const ? 1 : 0)];
    if (*parent_pointer) {
        return *parent_pointer;
    } else {
        TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdPointer);

        const char *const_str = is_const ? "const " : "";
        buf_resize(&entry->name, 0);
        buf_appendf(&entry->name, "&%s%s", const_str, buf_ptr(&child_type->name));

        TypeTableEntry *canon_child_type = get_underlying_type(child_type);
        assert(canon_child_type->id != TypeTableEntryIdInvalid);

        bool zero_bits;
        if (canon_child_type->size_in_bits == 0) {
            if (canon_child_type->id == TypeTableEntryIdStruct) {
                zero_bits = canon_child_type->data.structure.complete;
            } else if (canon_child_type->id == TypeTableEntryIdEnum) {
                zero_bits = canon_child_type->data.enumeration.complete;
            } else {
                zero_bits = true;
            }
        } else {
            zero_bits = false;
        }

        if (!zero_bits) {
            entry->type_ref = LLVMPointerType(child_type->type_ref, 0);

            entry->size_in_bits = g->pointer_size_bytes * 8;
            entry->align_in_bits = g->pointer_size_bytes * 8;
            assert(child_type->di_type);
            entry->di_type = LLVMZigCreateDebugPointerType(g->dbuilder, child_type->di_type,
                    entry->size_in_bits, entry->align_in_bits, buf_ptr(&entry->name));
        }

        entry->data.pointer.child_type = child_type;
        entry->data.pointer.is_const = is_const;

        *parent_pointer = entry;
        return entry;
    }
}

TypeTableEntry *get_maybe_type(CodeGen *g, TypeTableEntry *child_type) {
    if (child_type->maybe_parent) {
        TypeTableEntry *entry = child_type->maybe_parent;
        return entry;
    } else {
        TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdMaybe);
        assert(child_type->type_ref);
        assert(child_type->di_type);

        buf_resize(&entry->name, 0);
        buf_appendf(&entry->name, "?%s", buf_ptr(&child_type->name));

        if (child_type->id == TypeTableEntryIdPointer) {
            // this is an optimization but also is necessary for calling C
            // functions where all pointers are maybe pointers
            entry->size_in_bits = child_type->size_in_bits;
            entry->align_in_bits = child_type->align_in_bits;
            entry->type_ref = child_type->type_ref;
            entry->di_type = child_type->di_type;
        } else {
            // create a struct with a boolean whether this is the null value
            LLVMTypeRef elem_types[] = {
                child_type->type_ref,
                LLVMInt1Type(),
            };
            entry->type_ref = LLVMStructType(elem_types, 2, false);
            entry->size_in_bits = child_type->size_in_bits + 8;
            entry->align_in_bits = child_type->align_in_bits;


            LLVMZigDIScope *compile_unit_scope = LLVMZigCompileUnitToScope(g->compile_unit);
            LLVMZigDIFile *di_file = nullptr;
            unsigned line = 0;
            entry->di_type = LLVMZigCreateReplaceableCompositeType(g->dbuilder,
                LLVMZigTag_DW_structure_type(), buf_ptr(&entry->name),
                compile_unit_scope, di_file, line);

            LLVMZigDIType *di_element_types[] = {
                LLVMZigCreateDebugMemberType(g->dbuilder, LLVMZigTypeToScope(entry->di_type),
                        "val", di_file, line, child_type->size_in_bits, child_type->align_in_bits, 0, 0,
                        child_type->di_type),
                LLVMZigCreateDebugMemberType(g->dbuilder, LLVMZigTypeToScope(entry->di_type),
                        "maybe", di_file, line, 8, 8, child_type->size_in_bits, 0,
                        child_type->di_type),
            };
            LLVMZigDIType *replacement_di_type = LLVMZigCreateDebugStructType(g->dbuilder,
                    compile_unit_scope,
                    buf_ptr(&entry->name),
                    di_file, line, entry->size_in_bits, entry->align_in_bits, 0,
                    nullptr, di_element_types, 2, 0, nullptr, "");

            LLVMZigReplaceTemporary(g->dbuilder, entry->di_type, replacement_di_type);
            entry->di_type = replacement_di_type;
        }

        entry->data.maybe.child_type = child_type;

        child_type->maybe_parent = entry;
        return entry;
    }
}

static TypeTableEntry *get_error_type(CodeGen *g, TypeTableEntry *child_type) {
    if (child_type->error_parent) {
        return child_type->error_parent;
    } else {
        TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdErrorUnion);
        assert(child_type->type_ref);
        assert(child_type->di_type);

        buf_resize(&entry->name, 0);
        buf_appendf(&entry->name, "%%%s", buf_ptr(&child_type->name));

        entry->data.error.child_type = child_type;

        if (child_type->size_in_bits == 0) {
            entry->type_ref = g->err_tag_type->type_ref;
            entry->size_in_bits = g->err_tag_type->size_in_bits;
            entry->align_in_bits = g->err_tag_type->align_in_bits;
            entry->di_type = g->err_tag_type->di_type;

        } else {
            LLVMTypeRef elem_types[] = {
                g->err_tag_type->type_ref,
                child_type->type_ref,
            };
            entry->type_ref = LLVMStructType(elem_types, 2, false);
            entry->size_in_bits = g->err_tag_type->size_in_bits + child_type->size_in_bits;
            entry->align_in_bits = g->err_tag_type->align_in_bits;

            LLVMZigDIScope *compile_unit_scope = LLVMZigCompileUnitToScope(g->compile_unit);
            LLVMZigDIFile *di_file = nullptr;
            unsigned line = 0;
            entry->di_type = LLVMZigCreateReplaceableCompositeType(g->dbuilder,
                LLVMZigTag_DW_structure_type(), buf_ptr(&entry->name),
                compile_unit_scope, di_file, line);

            LLVMZigDIType *di_element_types[] = {
                LLVMZigCreateDebugMemberType(g->dbuilder, LLVMZigTypeToScope(entry->di_type),
                        "tag", di_file, line, g->err_tag_type->size_in_bits, g->err_tag_type->align_in_bits,
                        0, 0, child_type->di_type),
                LLVMZigCreateDebugMemberType(g->dbuilder, LLVMZigTypeToScope(entry->di_type),
                        "value", di_file, line, child_type->size_in_bits, child_type->align_in_bits,
                        g->err_tag_type->size_in_bits, 0, child_type->di_type),
            };

            LLVMZigDIType *replacement_di_type = LLVMZigCreateDebugStructType(g->dbuilder,
                    compile_unit_scope,
                    buf_ptr(&entry->name),
                    di_file, line, entry->size_in_bits, entry->align_in_bits, 0,
                    nullptr, di_element_types, 2, 0, nullptr, "");

            LLVMZigReplaceTemporary(g->dbuilder, entry->di_type, replacement_di_type);
            entry->di_type = replacement_di_type;
        }

        child_type->error_parent = entry;
        return entry;
    }
}

TypeTableEntry *get_array_type(CodeGen *g, TypeTableEntry *child_type, uint64_t array_size) {
    auto existing_entry = child_type->arrays_by_size.maybe_get(array_size);
    if (existing_entry) {
        TypeTableEntry *entry = existing_entry->value;
        return entry;
    } else {
        TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdArray);
        entry->type_ref = LLVMArrayType(child_type->type_ref, array_size);
        buf_resize(&entry->name, 0);
        buf_appendf(&entry->name, "[%" PRIu64 "]%s", array_size, buf_ptr(&child_type->name));

        entry->size_in_bits = child_type->size_in_bits * array_size;
        entry->align_in_bits = child_type->align_in_bits;

        entry->di_type = LLVMZigCreateDebugArrayType(g->dbuilder, entry->size_in_bits,
                entry->align_in_bits, child_type->di_type, array_size);
        entry->data.array.child_type = child_type;
        entry->data.array.len = array_size;

        child_type->arrays_by_size.put(array_size, entry);
        return entry;
    }
}

static void unknown_size_array_type_common_init(CodeGen *g, TypeTableEntry *child_type,
        bool is_const, TypeTableEntry *entry)
{
    TypeTableEntry *pointer_type = get_pointer_to_type(g, child_type, is_const);

    unsigned element_count = 2;
    entry->size_in_bits = g->pointer_size_bytes * 2 * 8;
    entry->align_in_bits = g->pointer_size_bytes * 8;
    entry->data.structure.is_packed = false;
    entry->data.structure.is_unknown_size_array = true;
    entry->data.structure.src_field_count = element_count;
    entry->data.structure.gen_field_count = element_count;
    entry->data.structure.fields = allocate<TypeStructField>(element_count);
    entry->data.structure.fields[0].name = buf_create_from_str("ptr");
    entry->data.structure.fields[0].type_entry = pointer_type;
    entry->data.structure.fields[0].src_index = 0;
    entry->data.structure.fields[0].gen_index = 0;
    entry->data.structure.fields[1].name = buf_create_from_str("len");
    entry->data.structure.fields[1].type_entry = g->builtin_types.entry_isize;
    entry->data.structure.fields[1].src_index = 1;
    entry->data.structure.fields[1].gen_index = 1;
}

static TypeTableEntry *get_unknown_size_array_type(CodeGen *g, TypeTableEntry *child_type, bool is_const) {
    assert(child_type->id != TypeTableEntryIdInvalid);
    TypeTableEntry **parent_pointer = &child_type->unknown_size_array_parent[(is_const ? 1 : 0)];

    if (*parent_pointer) {
        return *parent_pointer;
    } else if (is_const) {
        TypeTableEntry *var_peer = get_unknown_size_array_type(g, child_type, false);
        TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdStruct);

        buf_resize(&entry->name, 0);
        buf_appendf(&entry->name, "[]const %s", buf_ptr(&child_type->name));

        unknown_size_array_type_common_init(g, child_type, is_const, entry);

        entry->type_ref = var_peer->type_ref;
        entry->di_type = var_peer->di_type;

        *parent_pointer = entry;
        return entry;
    } else {
        TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdStruct);

        buf_resize(&entry->name, 0);
        buf_appendf(&entry->name, "[]%s", buf_ptr(&child_type->name));
        entry->type_ref = LLVMStructCreateNamed(LLVMGetGlobalContext(), buf_ptr(&entry->name));

        TypeTableEntry *pointer_type = get_pointer_to_type(g, child_type, is_const);

        unsigned element_count = 2;
        LLVMTypeRef element_types[] = {
            pointer_type->type_ref,
            g->builtin_types.entry_isize->type_ref,
        };
        LLVMStructSetBody(entry->type_ref, element_types, element_count, false);

        unknown_size_array_type_common_init(g, child_type, is_const, entry);

        LLVMZigDIType *di_element_types[] = {
            pointer_type->di_type,
            g->builtin_types.entry_isize->di_type,
        };
        LLVMZigDIScope *compile_unit_scope = LLVMZigCompileUnitToScope(g->compile_unit);
        entry->di_type = LLVMZigCreateDebugStructType(g->dbuilder, compile_unit_scope,
                buf_ptr(&entry->name), g->dummy_di_file, 0, entry->size_in_bits, entry->align_in_bits, 0,
                nullptr, di_element_types, element_count, 0, nullptr, "");

        *parent_pointer = entry;
        return entry;
    }
}

TypeTableEntry *get_typedecl_type(CodeGen *g, const char *name, TypeTableEntry *child_type) {
    TypeTableEntry *entry = new_type_table_entry(TypeTableEntryIdTypeDecl);

    buf_init_from_str(&entry->name, name);

    entry->type_ref = child_type->type_ref;
    entry->type_ref = child_type->type_ref;
    entry->di_type = child_type->di_type;
    entry->size_in_bits = child_type->size_in_bits;
    entry->align_in_bits = child_type->align_in_bits;

    entry->data.type_decl.child_type = child_type;

    if (child_type->id == TypeTableEntryIdTypeDecl) {
        entry->data.type_decl.canonical_type = child_type->data.type_decl.canonical_type;
    } else {
        entry->data.type_decl.canonical_type = child_type;
    }

    return entry;
}

// accepts ownership of fn_type_id memory
TypeTableEntry *get_fn_type(CodeGen *g, FnTypeId fn_type_id) {
    auto table_entry = g->fn_type_table.maybe_get(fn_type_id);
    if (table_entry) {
        return table_entry->value;
    }

    TypeTableEntry *fn_type = new_type_table_entry(TypeTableEntryIdFn);
    fn_type->data.fn.fn_type_id = fn_type_id;
    fn_type->data.fn.calling_convention = fn_type_id.is_extern ? LLVMCCallConv : LLVMFastCallConv;

    fn_type->size_in_bits = g->pointer_size_bytes * 8;
    fn_type->align_in_bits = g->pointer_size_bytes * 8;

    // populate the name of the type
    buf_resize(&fn_type->name, 0);
    const char *extern_str = fn_type_id.is_extern ? "extern " : "";
    const char *naked_str = fn_type_id.is_naked ? "naked " : "";
    buf_appendf(&fn_type->name, "%s%sfn(", extern_str, naked_str);
    for (int i = 0; i < fn_type_id.param_count; i += 1) {
        FnTypeParamInfo *param_info = &fn_type_id.param_info[i];

        TypeTableEntry *param_type = param_info->type;
        const char *comma = (i == 0) ? "" : ", ";
        const char *noalias_str = param_info->is_noalias ? "noalias " : "";
        buf_appendf(&fn_type->name, "%s%s%s", comma, noalias_str, buf_ptr(&param_type->name));
    }

    if (fn_type_id.is_var_args) {
        const char *comma = (fn_type_id.param_count == 0) ? "" : ", ";
        buf_appendf(&fn_type->name, "%s...", comma);
    }
    buf_appendf(&fn_type->name, ")");
    if (fn_type_id.return_type->id != TypeTableEntryIdVoid) {
        buf_appendf(&fn_type->name, " -> %s", buf_ptr(&fn_type_id.return_type->name));
    }


    // next, loop over the parameters again and compute debug information
    // and codegen information
    bool first_arg_return = handle_is_ptr(fn_type_id.return_type);
    // +1 for maybe making the first argument the return value
    LLVMTypeRef *gen_param_types = allocate<LLVMTypeRef>(1 + fn_type_id.param_count);
    // +1 because 0 is the return type and +1 for maybe making first arg ret val
    LLVMZigDIType **param_di_types = allocate<LLVMZigDIType*>(2 + fn_type_id.param_count);
    param_di_types[0] = fn_type_id.return_type->di_type;
    int gen_param_index = 0;
    TypeTableEntry *gen_return_type;
    if (first_arg_return) {
        TypeTableEntry *gen_type = get_pointer_to_type(g, fn_type_id.return_type, false);
        gen_param_types[gen_param_index] = gen_type->type_ref;
        gen_param_index += 1;
        // after the gen_param_index += 1 because 0 is the return type
        param_di_types[gen_param_index] = gen_type->di_type;
        gen_return_type = g->builtin_types.entry_void;
    } else if (fn_type_id.return_type->size_in_bits == 0) {
        gen_return_type = g->builtin_types.entry_void;
    } else {
        gen_return_type = fn_type_id.return_type;
    }
    fn_type->data.fn.gen_return_type = gen_return_type;

    fn_type->data.fn.gen_param_info = allocate<FnGenParamInfo>(fn_type_id.param_count);
    for (int i = 0; i < fn_type_id.param_count; i += 1) {
        FnTypeParamInfo *src_param_info = &fn_type->data.fn.fn_type_id.param_info[i];
        TypeTableEntry *type_entry = src_param_info->type;
        FnGenParamInfo *gen_param_info = &fn_type->data.fn.gen_param_info[i];

        gen_param_info->src_index = i;
        gen_param_info->gen_index = -1;

        if (type_entry->size_in_bits > 0) {
            TypeTableEntry *gen_type;
            if (handle_is_ptr(type_entry)) {
                gen_type = get_pointer_to_type(g, type_entry, true);
                gen_param_info->is_byval = true;
            } else {
                gen_type = type_entry;
            }
            gen_param_types[gen_param_index] = gen_type->type_ref;
            gen_param_info->gen_index = gen_param_index;

            gen_param_index += 1;

            // after the gen_param_index += 1 because 0 is the return type
            param_di_types[gen_param_index] = gen_type->di_type;
        }
    }

    fn_type->data.fn.gen_param_count = gen_param_index;

    fn_type->data.fn.raw_type_ref = LLVMFunctionType(gen_return_type->type_ref,
            gen_param_types, gen_param_index, fn_type_id.is_var_args);
    fn_type->type_ref = LLVMPointerType(fn_type->data.fn.raw_type_ref, 0);
    LLVMZigDIFile *di_file = nullptr; // TODO if we get a crash maybe this is the culprit
    fn_type->di_type = LLVMZigCreateSubroutineType(g->dbuilder, di_file,
            param_di_types, gen_param_index + 1, 0);

    g->fn_type_table.put(fn_type_id, fn_type);

    return fn_type;
}

static TypeTableEntryId container_to_type(ContainerKind kind) {
    switch (kind) {
        case ContainerKindStruct:
            return TypeTableEntryIdStruct;
        case ContainerKindEnum:
            return TypeTableEntryIdEnum;
    }
    zig_unreachable();
}

TypeTableEntry *get_partial_container_type(CodeGen *g, ImportTableEntry *import,
        ContainerKind kind, AstNode *decl_node, const char *name)
{
    TypeTableEntryId type_id = container_to_type(kind);
    TypeTableEntry *entry = new_type_table_entry(type_id);

    switch (kind) {
        case ContainerKindStruct:
            entry->data.structure.decl_node = decl_node;
            break;
        case ContainerKindEnum:
            entry->data.enumeration.decl_node = decl_node;
            break;
    }

    unsigned line = decl_node ? decl_node->line : 0;

    entry->type_ref = LLVMStructCreateNamed(LLVMGetGlobalContext(), name);
    entry->di_type = LLVMZigCreateReplaceableCompositeType(g->dbuilder,
        LLVMZigTag_DW_structure_type(), name,
        LLVMZigFileToScope(import->di_file), import->di_file, line + 1);

    buf_init_from_str(&entry->name, name);

    return entry;
}


TypeTableEntry *get_underlying_type(TypeTableEntry *type_entry) {
    if (type_entry->id == TypeTableEntryIdTypeDecl) {
        return type_entry->data.type_decl.canonical_type;
    } else {
        return type_entry;
    }
}

// If the node does not have a constant expression value with a metatype, generates an error
// and returns invalid type. Otherwise, returns the type of the constant expression value.
// Must be called after analyze_expression on the same node.
static TypeTableEntry *resolve_type(CodeGen *g, AstNode *node) {
    if (node->type == NodeTypeSymbol && node->data.symbol_expr.override_type_entry) {
        return node->data.symbol_expr.override_type_entry;
    }
    Expr *expr = get_resolved_expr(node);
    assert(expr->type_entry);
    if (expr->type_entry->id == TypeTableEntryIdInvalid) {
        return g->builtin_types.entry_invalid;
    } else if (expr->type_entry->id == TypeTableEntryIdMetaType) {
        // OK
    } else {
        add_node_error(g, node, buf_sprintf("expected type, found expression"));
        return g->builtin_types.entry_invalid;
    }

    ConstExprValue *const_val = &expr->const_val;
    if (!const_val->ok) {
        add_node_error(g, node, buf_sprintf("unable to resolve constant expression"));
        return g->builtin_types.entry_invalid;
    }

    return const_val->data.x_type;
}

// Calls analyze_expression on node, and then resolve_type.
static TypeTableEntry *analyze_type_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    AstNode **node_ptr = node->parent_field;
    analyze_expression(g, import, context, nullptr, *node_ptr);
    return resolve_type(g, *node_ptr);
}

static TypeTableEntry *analyze_fn_proto_type(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node, bool is_naked)
{
    assert(node->type == NodeTypeFnProto);
    AstNodeFnProto *fn_proto = &node->data.fn_proto;

    if (fn_proto->skip) {
        return g->builtin_types.entry_invalid;
    }

    FnTypeId fn_type_id;
    fn_type_id.is_extern = fn_proto->is_extern || (fn_proto->visib_mod == VisibModExport);
    fn_type_id.is_naked = is_naked;
    fn_type_id.param_count = node->data.fn_proto.params.length;
    fn_type_id.param_info = allocate<FnTypeParamInfo>(fn_type_id.param_count);
    fn_type_id.is_var_args = fn_proto->is_var_args;
    fn_type_id.return_type = analyze_type_expr(g, import, import->block_context, node->data.fn_proto.return_type);

    if (fn_type_id.return_type->id == TypeTableEntryIdInvalid) {
        fn_proto->skip = true;
    }

    for (int i = 0; i < fn_type_id.param_count; i += 1) {
        AstNode *child = node->data.fn_proto.params.at(i);
        assert(child->type == NodeTypeParamDecl);
        TypeTableEntry *type_entry = analyze_type_expr(g, import, import->block_context,
                child->data.param_decl.type);
        switch (type_entry->id) {
            case TypeTableEntryIdInvalid:
                fn_proto->skip = true;
                break;
            case TypeTableEntryIdNumLitFloat:
            case TypeTableEntryIdNumLitInt:
            case TypeTableEntryIdUndefLit:
            case TypeTableEntryIdMetaType:
            case TypeTableEntryIdUnreachable:
                fn_proto->skip = true;
                add_node_error(g, child->data.param_decl.type,
                    buf_sprintf("parameter of type '%s' not allowed'", buf_ptr(&type_entry->name)));
                break;
            case TypeTableEntryIdVoid:
            case TypeTableEntryIdBool:
            case TypeTableEntryIdInt:
            case TypeTableEntryIdFloat:
            case TypeTableEntryIdPointer:
            case TypeTableEntryIdArray:
            case TypeTableEntryIdStruct:
            case TypeTableEntryIdMaybe:
            case TypeTableEntryIdErrorUnion:
            case TypeTableEntryIdPureError:
            case TypeTableEntryIdEnum:
            case TypeTableEntryIdFn:
            case TypeTableEntryIdTypeDecl:
                break;
        }
        if (type_entry->id == TypeTableEntryIdInvalid) {
            fn_proto->skip = true;
        }
        FnTypeParamInfo *param_info = &fn_type_id.param_info[i];
        param_info->type = type_entry;
        param_info->is_noalias = child->data.param_decl.is_noalias;
    }

    if (fn_proto->skip) {
        return g->builtin_types.entry_invalid;
    }

    return get_fn_type(g, fn_type_id);
}


static void resolve_function_proto(CodeGen *g, AstNode *node, FnTableEntry *fn_table_entry,
        ImportTableEntry *import)
{
    assert(node->type == NodeTypeFnProto);
    AstNodeFnProto *fn_proto = &node->data.fn_proto;

    if (fn_proto->skip) {
        return;
    }

    bool is_naked = false;
    for (int i = 0; i < fn_proto->directives->length; i += 1) {
        AstNode *directive_node = fn_proto->directives->at(i);
        Buf *name = &directive_node->data.directive.name;

        if (buf_eql_str(name, "attribute")) {
            Buf *attr_name = &directive_node->data.directive.param;
            if (fn_table_entry->fn_def_node) {
                if (buf_eql_str(attr_name, "naked")) {
                    is_naked = true;
                } else if (buf_eql_str(attr_name, "inline")) {
                    fn_table_entry->is_inline = true;
                } else {
                    add_node_error(g, directive_node,
                            buf_sprintf("invalid function attribute: '%s'", buf_ptr(name)));
                }
            } else {
                add_node_error(g, directive_node,
                        buf_sprintf("invalid function attribute: '%s'", buf_ptr(name)));
            }
        } else {
            add_node_error(g, directive_node,
                    buf_sprintf("invalid directive: '%s'", buf_ptr(name)));
        }
    }

    TypeTableEntry *fn_type = analyze_fn_proto_type(g, import, import->block_context, nullptr, node, is_naked);

    if (fn_type->id == TypeTableEntryIdInvalid) {
        fn_proto->skip = true;
        return;
    }

    fn_table_entry->type_entry = fn_type;

    fn_table_entry->fn_value = LLVMAddFunction(g->module, buf_ptr(&fn_table_entry->symbol_name),
            fn_type->data.fn.raw_type_ref);

    if (fn_table_entry->is_inline) {
        LLVMAddFunctionAttr(fn_table_entry->fn_value, LLVMAlwaysInlineAttribute);
    }
    if (fn_type->data.fn.fn_type_id.is_naked) {
        LLVMAddFunctionAttr(fn_table_entry->fn_value, LLVMNakedAttribute);
    }

    LLVMSetLinkage(fn_table_entry->fn_value, fn_table_entry->internal_linkage ?
            LLVMInternalLinkage : LLVMExternalLinkage);

    if (fn_type->data.fn.fn_type_id.return_type->id == TypeTableEntryIdUnreachable) {
        LLVMAddFunctionAttr(fn_table_entry->fn_value, LLVMNoReturnAttribute);
    }
    LLVMSetFunctionCallConv(fn_table_entry->fn_value, fn_type->data.fn.calling_convention);
    if (!fn_table_entry->is_extern) {
        LLVMAddFunctionAttr(fn_table_entry->fn_value, LLVMNoUnwindAttribute);
    }

    // Add debug info.
    unsigned line_number = node->line + 1;
    unsigned scope_line = line_number;
    bool is_definition = fn_table_entry->fn_def_node != nullptr;
    unsigned flags = 0;
    bool is_optimized = g->build_type == CodeGenBuildTypeRelease;
    LLVMZigDISubprogram *subprogram = LLVMZigCreateFunction(g->dbuilder,
        import->block_context->di_scope, buf_ptr(&fn_table_entry->symbol_name), "",
        import->di_file, line_number,
        fn_type->di_type, fn_table_entry->internal_linkage,
        is_definition, scope_line, flags, is_optimized, fn_table_entry->fn_value);
    if (fn_table_entry->fn_def_node) {
        BlockContext *context = new_block_context(fn_table_entry->fn_def_node, import->block_context);
        fn_table_entry->fn_def_node->data.fn_def.block_context = context;
        context->di_scope = LLVMZigSubprogramToScope(subprogram);
    }
}

static void preview_function_labels(CodeGen *g, AstNode *node, FnTableEntry *fn_table_entry) {
    assert(node->type == NodeTypeBlock);

    for (int i = 0; i < node->data.block.statements.length; i += 1) {
        AstNode *label_node = node->data.block.statements.at(i);
        if (label_node->type != NodeTypeLabel)
            continue;

        LabelTableEntry *label_entry = allocate<LabelTableEntry>(1);
        label_entry->label_node = label_node;
        Buf *name = &label_node->data.label.name;
        fn_table_entry->label_table.put(name, label_entry);

        label_node->data.label.label_entry = label_entry;
    }
}

static void resolve_enum_type(CodeGen *g, ImportTableEntry *import, TypeTableEntry *enum_type) {
    // if you change this logic you likely must also change similar logic in parseh.cpp
    assert(enum_type->id == TypeTableEntryIdEnum);

    AstNode *decl_node = enum_type->data.enumeration.decl_node;

    if (enum_type->data.enumeration.embedded_in_current) {
        if (!enum_type->data.enumeration.reported_infinite_err) {
            enum_type->data.enumeration.reported_infinite_err = true;
            add_node_error(g, decl_node, buf_sprintf("enum has infinite size"));
        }
        return;
    }

    if (enum_type->data.enumeration.fields) {
        // we already resolved this type. skip
        return;
    }

    assert(enum_type->di_type);

    uint32_t field_count = decl_node->data.struct_decl.fields.length;

    enum_type->data.enumeration.field_count = field_count;
    enum_type->data.enumeration.fields = allocate<TypeEnumField>(field_count);
    LLVMZigDIEnumerator **di_enumerators = allocate<LLVMZigDIEnumerator*>(field_count);

    // we possibly allocate too much here since gen_field_count can be lower than field_count.
    // the only problem is potential wasted space though.
    LLVMZigDIType **union_inner_di_types = allocate<LLVMZigDIType*>(field_count);

    TypeTableEntry *biggest_union_member = nullptr;
    uint64_t biggest_align_in_bits = 0;
    uint64_t biggest_union_member_size_in_bits = 0;

    // set temporary flag
    enum_type->data.enumeration.embedded_in_current = true;

    int gen_field_index = 0;
    for (uint32_t i = 0; i < field_count; i += 1) {
        AstNode *field_node = decl_node->data.struct_decl.fields.at(i);
        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[i];
        type_enum_field->name = &field_node->data.struct_field.name;
        type_enum_field->type_entry = analyze_type_expr(g, import, import->block_context,
                field_node->data.struct_field.type);
        type_enum_field->value = i;

        di_enumerators[i] = LLVMZigCreateDebugEnumerator(g->dbuilder, buf_ptr(type_enum_field->name), i);

        if (type_enum_field->type_entry->id == TypeTableEntryIdStruct) {
            resolve_struct_type(g, import, type_enum_field->type_entry);
        } else if (type_enum_field->type_entry->id == TypeTableEntryIdEnum) {
            resolve_enum_type(g, import, type_enum_field->type_entry);
        } else if (type_enum_field->type_entry->id == TypeTableEntryIdInvalid) {
            enum_type->data.enumeration.is_invalid = true;
            continue;
        } else if (type_enum_field->type_entry->id == TypeTableEntryIdVoid) {
            continue;
        }

        union_inner_di_types[gen_field_index] = LLVMZigCreateDebugMemberType(g->dbuilder,
                LLVMZigTypeToScope(enum_type->di_type), buf_ptr(type_enum_field->name),
                import->di_file, field_node->line + 1,
                type_enum_field->type_entry->size_in_bits,
                type_enum_field->type_entry->align_in_bits,
                0, 0, type_enum_field->type_entry->di_type);

        biggest_align_in_bits = max(biggest_align_in_bits, type_enum_field->type_entry->align_in_bits);

        if (!biggest_union_member ||
            type_enum_field->type_entry->size_in_bits > biggest_union_member->size_in_bits)
        {
            biggest_union_member = type_enum_field->type_entry;
            biggest_union_member_size_in_bits = biggest_union_member->size_in_bits;
        }

        gen_field_index += 1;
    }

    // unset temporary flag
    enum_type->data.enumeration.embedded_in_current = false;
    enum_type->data.enumeration.complete = true;

    if (!enum_type->data.enumeration.is_invalid) {
        enum_type->data.enumeration.gen_field_count = gen_field_index;

        TypeTableEntry *tag_type_entry = get_smallest_unsigned_int_type(g, field_count);
        enum_type->align_in_bits = tag_type_entry->size_in_bits;
        enum_type->size_in_bits = tag_type_entry->size_in_bits + biggest_union_member_size_in_bits;
        enum_type->data.enumeration.tag_type = tag_type_entry;

        if (biggest_union_member) {
            // create llvm type for union
            LLVMTypeRef union_element_type = biggest_union_member->type_ref;
            LLVMTypeRef union_type_ref = LLVMStructType(&union_element_type, 1, false);

            // create llvm type for root struct
            LLVMTypeRef root_struct_element_types[] = {
                tag_type_entry->type_ref,
                union_type_ref,
            };
            LLVMStructSetBody(enum_type->type_ref, root_struct_element_types, 2, false);

            // create debug type for tag
            LLVMZigDIType *tag_di_type = LLVMZigCreateDebugEnumerationType(g->dbuilder,
                    LLVMZigTypeToScope(enum_type->di_type), "AnonEnum", import->di_file, decl_node->line + 1,
                    tag_type_entry->size_in_bits, tag_type_entry->align_in_bits, di_enumerators, field_count,
                    tag_type_entry->di_type, "");

            // create debug type for union
            LLVMZigDIType *union_di_type = LLVMZigCreateDebugUnionType(g->dbuilder,
                    LLVMZigTypeToScope(enum_type->di_type), "AnonUnion", import->di_file, decl_node->line + 1,
                    biggest_union_member->size_in_bits, biggest_align_in_bits, 0, union_inner_di_types,
                    gen_field_index, 0, "");

            // create debug types for members of root struct
            LLVMZigDIType *tag_member_di_type = LLVMZigCreateDebugMemberType(g->dbuilder,
                    LLVMZigTypeToScope(enum_type->di_type), "tag_field",
                    import->di_file, decl_node->line + 1,
                    tag_type_entry->size_in_bits,
                    tag_type_entry->align_in_bits,
                    0, 0, tag_di_type);
            LLVMZigDIType *union_member_di_type = LLVMZigCreateDebugMemberType(g->dbuilder,
                    LLVMZigTypeToScope(enum_type->di_type), "union_field",
                    import->di_file, decl_node->line + 1,
                    biggest_union_member->size_in_bits,
                    biggest_align_in_bits,
                    tag_type_entry->size_in_bits, 0, union_di_type);

            // create debug type for root struct
            LLVMZigDIType *di_root_members[] = {
                tag_member_di_type,
                union_member_di_type,
            };


            LLVMZigDIType *replacement_di_type = LLVMZigCreateDebugStructType(g->dbuilder,
                    LLVMZigFileToScope(import->di_file),
                    buf_ptr(&decl_node->data.struct_decl.name),
                    import->di_file, decl_node->line + 1, enum_type->size_in_bits, enum_type->align_in_bits, 0,
                    nullptr, di_root_members, 2, 0, nullptr, "");

            LLVMZigReplaceTemporary(g->dbuilder, enum_type->di_type, replacement_di_type);
            enum_type->di_type = replacement_di_type;
        } else {
            // create llvm type for root struct
            enum_type->type_ref = tag_type_entry->type_ref;

            // create debug type for tag
            LLVMZigDIType *tag_di_type = LLVMZigCreateDebugEnumerationType(g->dbuilder,
                    LLVMZigFileToScope(import->di_file), buf_ptr(&decl_node->data.struct_decl.name),
                    import->di_file, decl_node->line + 1,
                    tag_type_entry->size_in_bits, tag_type_entry->align_in_bits, di_enumerators, field_count,
                    tag_type_entry->di_type, "");

            LLVMZigReplaceTemporary(g->dbuilder, enum_type->di_type, tag_di_type);
            enum_type->di_type = tag_di_type;

        }

    }
}

static void resolve_struct_type(CodeGen *g, ImportTableEntry *import, TypeTableEntry *struct_type) {
    // if you change the logic of this function likely you must make a similar change in
    // parseh.cpp
    assert(struct_type->id == TypeTableEntryIdStruct);

    AstNode *decl_node = struct_type->data.structure.decl_node;

    if (struct_type->data.structure.embedded_in_current) {
        if (!struct_type->data.structure.reported_infinite_err) {
            struct_type->data.structure.reported_infinite_err = true;
            add_node_error(g, decl_node,
                    buf_sprintf("struct has infinite size"));
        }
        return;
    }

    if (struct_type->data.structure.fields) {
        // we already resolved this type. skip
        return;
    }


    assert(struct_type->di_type);

    int field_count = decl_node->data.struct_decl.fields.length;

    struct_type->data.structure.src_field_count = field_count;
    struct_type->data.structure.fields = allocate<TypeStructField>(field_count);

    // we possibly allocate too much here since gen_field_count can be lower than field_count.
    // the only problem is potential wasted space though.
    LLVMTypeRef *element_types = allocate<LLVMTypeRef>(field_count);
    LLVMZigDIType **di_element_types = allocate<LLVMZigDIType*>(field_count);

    uint64_t total_size_in_bits = 0;
    uint64_t first_field_align_in_bits = 0;
    uint64_t offset_in_bits = 0;

    // this field should be set to true only during the recursive calls to resolve_struct_type
    struct_type->data.structure.embedded_in_current = true;

    int gen_field_index = 0;
    for (int i = 0; i < field_count; i += 1) {
        AstNode *field_node = decl_node->data.struct_decl.fields.at(i);
        TypeStructField *type_struct_field = &struct_type->data.structure.fields[i];
        type_struct_field->name = &field_node->data.struct_field.name;
        type_struct_field->type_entry = analyze_type_expr(g, import, import->block_context,
                field_node->data.struct_field.type);
        type_struct_field->src_index = i;
        type_struct_field->gen_index = -1;

        if (type_struct_field->type_entry->id == TypeTableEntryIdStruct) {
            resolve_struct_type(g, import, type_struct_field->type_entry);
        } else if (type_struct_field->type_entry->id == TypeTableEntryIdEnum) {
            resolve_enum_type(g, import, type_struct_field->type_entry);
        } else if (type_struct_field->type_entry->id == TypeTableEntryIdInvalid) {
            struct_type->data.structure.is_invalid = true;
            continue;
        } else if (type_struct_field->type_entry->id == TypeTableEntryIdVoid) {
            continue;
        }

        type_struct_field->gen_index = gen_field_index;

        di_element_types[gen_field_index] = LLVMZigCreateDebugMemberType(g->dbuilder,
                LLVMZigTypeToScope(struct_type->di_type), buf_ptr(type_struct_field->name),
                import->di_file, field_node->line + 1,
                type_struct_field->type_entry->size_in_bits,
                type_struct_field->type_entry->align_in_bits,
                offset_in_bits, 0, type_struct_field->type_entry->di_type);

        element_types[gen_field_index] = type_struct_field->type_entry->type_ref;
        assert(di_element_types[gen_field_index]);
        assert(element_types[gen_field_index]);

        total_size_in_bits += type_struct_field->type_entry->size_in_bits;
        if (first_field_align_in_bits == 0) {
            first_field_align_in_bits = type_struct_field->type_entry->align_in_bits;
        }
        offset_in_bits += type_struct_field->type_entry->size_in_bits;

        gen_field_index += 1;
    }
    struct_type->data.structure.embedded_in_current = false;

    struct_type->data.structure.gen_field_count = gen_field_index;
    struct_type->data.structure.complete = true;

    if (!struct_type->data.structure.is_invalid) {

        LLVMStructSetBody(struct_type->type_ref, element_types, gen_field_index, false);

        struct_type->align_in_bits = first_field_align_in_bits;
        struct_type->size_in_bits = total_size_in_bits;

        LLVMZigDIType *replacement_di_type = LLVMZigCreateDebugStructType(g->dbuilder,
                LLVMZigFileToScope(import->di_file),
                buf_ptr(&decl_node->data.struct_decl.name),
                import->di_file, decl_node->line + 1, struct_type->size_in_bits, struct_type->align_in_bits, 0,
                nullptr, di_element_types, gen_field_index, 0, nullptr, "");

        LLVMZigReplaceTemporary(g->dbuilder, struct_type->di_type, replacement_di_type);
        struct_type->di_type = replacement_di_type;
    }
}

static void preview_fn_proto(CodeGen *g, ImportTableEntry *import,
        AstNode *proto_node)
{
    if (proto_node->data.fn_proto.skip) {
        return;
    }
    AstNode *fn_def_node = proto_node->data.fn_proto.fn_def_node;
    AstNode *struct_node = proto_node->data.fn_proto.struct_node;
    bool is_extern = proto_node->data.fn_proto.is_extern;
    TypeTableEntry *struct_type;
    if (struct_node) {
        assert(struct_node->type == NodeTypeStructDecl);
        struct_type = struct_node->data.struct_decl.type_entry;
    } else {
        struct_type = nullptr;
    }

    Buf *proto_name = &proto_node->data.fn_proto.name;

    auto fn_table = struct_type ? &struct_type->data.structure.fn_table : &import->fn_table;

    auto entry = fn_table->maybe_get(proto_name);
    bool skip = false;
    bool is_internal = (proto_node->data.fn_proto.visib_mod != VisibModExport);
    bool is_c_compat = !is_internal || is_extern;
    bool is_pub = (proto_node->data.fn_proto.visib_mod != VisibModPrivate);
    if (entry) {
        add_node_error(g, proto_node,
                buf_sprintf("redefinition of '%s'", buf_ptr(proto_name)));
        proto_node->data.fn_proto.skip = true;
        skip = true;
    }
    if (!is_extern && proto_node->data.fn_proto.is_var_args) {
        add_node_error(g, proto_node,
                buf_sprintf("variadic arguments only allowed in extern functions"));
    }
    if (skip) {
        return;
    }

    FnTableEntry *fn_table_entry = allocate<FnTableEntry>(1);
    fn_table_entry->import_entry = import;
    fn_table_entry->proto_node = proto_node;
    fn_table_entry->fn_def_node = fn_def_node;
    fn_table_entry->internal_linkage = !is_c_compat;
    fn_table_entry->is_extern = is_extern;
    fn_table_entry->label_table.init(8);
    fn_table_entry->member_of_struct = struct_type;

    if (struct_type) {
        buf_resize(&fn_table_entry->symbol_name, 0);
        buf_appendf(&fn_table_entry->symbol_name, "%s_%s",
                buf_ptr(&struct_type->name),
                buf_ptr(proto_name));
    } else {
        buf_init_from_buf(&fn_table_entry->symbol_name, proto_name);
    }

    g->fn_protos.append(fn_table_entry);

    if (!is_extern) {
        g->fn_defs.append(fn_table_entry);
    }

    fn_table->put(proto_name, fn_table_entry);

    if (!struct_type &&
        g->bootstrap_import &&
        import == g->root_import && buf_eql_str(proto_name, "main"))
    {
        g->bootstrap_import->fn_table.put(proto_name, fn_table_entry);
    }

    proto_node->data.fn_proto.fn_table_entry = fn_table_entry;
    resolve_function_proto(g, proto_node, fn_table_entry, import);

    if (fn_def_node) {
        preview_function_labels(g, fn_def_node->data.fn_def.body, fn_table_entry);
    }

    if (is_pub && !struct_type) {
        for (int i = 0; i < import->importers.length; i += 1) {
            ImporterInfo importer = import->importers.at(i);
            auto table_entry = importer.import->fn_table.maybe_get(proto_name);
            if (table_entry) {
                add_node_error(g, importer.source_node,
                    buf_sprintf("import of function '%s' overrides existing definition",
                        buf_ptr(proto_name)));
            } else {
                importer.import->fn_table.put(proto_name, fn_table_entry);
            }
        }
    }
}

static void resolve_error_value_decl(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    assert(node->type == NodeTypeErrorValueDecl);

    ErrorTableEntry *err = allocate<ErrorTableEntry>(1);

    err->value = g->next_error_index;
    g->next_error_index += 1;

    err->decl_node = node;
    buf_init_from_buf(&err->name, &node->data.error_value_decl.name);

    auto existing_entry = import->block_context->error_table.maybe_get(&err->name);
    if (existing_entry) {
        add_node_error(g, node, buf_sprintf("redefinition of error '%s'", buf_ptr(&err->name)));
    } else {
        import->block_context->error_table.put(&err->name, err);
    }

    bool is_pub = (node->data.error_value_decl.visib_mod != VisibModPrivate);
    if (is_pub) {
        for (int i = 0; i < import->importers.length; i += 1) {
            ImporterInfo importer = import->importers.at(i);
            auto table_entry = importer.import->block_context->error_table.maybe_get(&err->name);
            if (table_entry) {
                add_node_error(g, importer.source_node,
                    buf_sprintf("import of error '%s' overrides existing definition",
                        buf_ptr(&err->name)));
            } else {
                importer.import->block_context->error_table.put(&err->name, err);
            }
        }
    }
}

static void resolve_c_import_decl(CodeGen *g, ImportTableEntry *parent_import, AstNode *node) {
    assert(node->type == NodeTypeCImport);

    AstNode *block_node = node->data.c_import.block;

    BlockContext *child_context = new_block_context(node, parent_import->block_context);
    child_context->c_import_buf = buf_alloc();

    TypeTableEntry *resolved_type = analyze_block_expr(g, parent_import, child_context,
            g->builtin_types.entry_void, block_node);

    if (resolved_type->id == TypeTableEntryIdInvalid) {
        return;
    }

    find_libc_path(g);

    ImportTableEntry *child_import = allocate<ImportTableEntry>(1);
    child_import->fn_table.init(32);
    child_import->c_import_node = node;

    ZigList<ErrorMsg *> errors = {0};

    int err;
    if ((err = parse_h_buf(child_import, &errors, child_context->c_import_buf, g, node))) {
        zig_panic("unable to parse h file: %s\n", err_str(err));
    }

    if (errors.length > 0) {
        ErrorMsg *parent_err_msg = add_node_error(g, node, buf_sprintf("C import failed"));
        for (int i = 0; i < errors.length; i += 1) {
            ErrorMsg *err_msg = errors.at(i);
            err_msg_add_note(parent_err_msg, err_msg);
        }
        return;
    }

    if (g->verbose) {
        fprintf(stderr, "\nc_import:\n");
        fprintf(stderr, "-----------\n");
        ast_render(stderr, child_import->root, 4);
    }

    child_import->di_file = parent_import->di_file;
    child_import->block_context = new_block_context(child_import->root, nullptr);
    child_import->importers.append({parent_import, node});

    detect_top_level_decl_deps(g, child_import, child_import->root);
}

static void satisfy_dep(CodeGen *g, AstNode *node) {
    Buf *name = get_resolved_top_level_decl(node)->name;
    if (name) {
        g->unresolved_top_level_decls.maybe_remove(name);
    }
}

static void resolve_top_level_decl(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    switch (node->type) {
        case NodeTypeFnProto:
            preview_fn_proto(g, import, node);
            break;
        case NodeTypeRootExportDecl:
            // handled earlier
            return;
        case NodeTypeStructDecl:
            {
                TypeTableEntry *type_entry = node->data.struct_decl.type_entry;

                // struct/enum member fns will get resolved independently

                switch (node->data.struct_decl.kind) {
                    case ContainerKindStruct:
                        resolve_struct_type(g, import, type_entry);
                        break;
                    case ContainerKindEnum:
                        resolve_enum_type(g, import, type_entry);
                        break;
                }

                break;
            }
        case NodeTypeVariableDeclaration:
            {
                VariableTableEntry *var = analyze_variable_declaration(g, import, import->block_context,
                        nullptr, node);
                g->global_vars.append(var);
                break;
            }
        case NodeTypeTypeDecl:
            {
                AstNode *type_node = node->data.type_decl.child_type;
                Buf *decl_name = &node->data.type_decl.symbol;

                TypeTableEntry *typedecl_type;
                if (node->data.type_decl.override_type) {
                    typedecl_type = node->data.type_decl.override_type;
                } else {
                    TypeTableEntry *child_type = analyze_type_expr(g, import, import->block_context, type_node);
                    if (child_type->id == TypeTableEntryIdInvalid) {
                        typedecl_type = child_type;
                    } else {
                        typedecl_type = get_typedecl_type(g, buf_ptr(decl_name), child_type);
                    }
                }

                import->block_context->type_table.put(decl_name, typedecl_type);

                break;
            }
        case NodeTypeErrorValueDecl:
            resolve_error_value_decl(g, import, node);
            break;
        case NodeTypeImport:
            // nothing to do here
            return;
        case NodeTypeCImport:
            resolve_c_import_decl(g, import, node);
            break;
        case NodeTypeFnDef:
        case NodeTypeDirective:
        case NodeTypeParamDecl:
        case NodeTypeFnDecl:
        case NodeTypeReturnExpr:
        case NodeTypeRoot:
        case NodeTypeBlock:
        case NodeTypeBinOpExpr:
        case NodeTypeUnwrapErrorExpr:
        case NodeTypeFnCallExpr:
        case NodeTypeArrayAccessExpr:
        case NodeTypeSliceExpr:
        case NodeTypeNumberLiteral:
        case NodeTypeStringLiteral:
        case NodeTypeCharLiteral:
        case NodeTypeBoolLiteral:
        case NodeTypeNullLiteral:
        case NodeTypeUndefinedLiteral:
        case NodeTypeSymbol:
        case NodeTypePrefixOpExpr:
        case NodeTypeIfBoolExpr:
        case NodeTypeIfVarExpr:
        case NodeTypeWhileExpr:
        case NodeTypeForExpr:
        case NodeTypeSwitchExpr:
        case NodeTypeSwitchProng:
        case NodeTypeSwitchRange:
        case NodeTypeLabel:
        case NodeTypeGoto:
        case NodeTypeBreak:
        case NodeTypeContinue:
        case NodeTypeAsmExpr:
        case NodeTypeFieldAccessExpr:
        case NodeTypeStructField:
        case NodeTypeStructValueField:
        case NodeTypeContainerInitExpr:
        case NodeTypeArrayType:
        case NodeTypeErrorType:
        case NodeTypeTypeLiteral:
            zig_unreachable();
    }


    satisfy_dep(g, node);
}

static FnTableEntry *get_context_fn_entry(BlockContext *context) {
    assert(context->fn_entry);
    return context->fn_entry;
}

static TypeTableEntry *unwrapped_node_type(AstNode *node) {
    Expr *expr = get_resolved_expr(node);
    if (expr->type_entry->id == TypeTableEntryIdInvalid) {
        return expr->type_entry;
    }
    assert(expr->type_entry->id == TypeTableEntryIdMetaType);
    ConstExprValue *const_val = &expr->const_val;
    assert(const_val->ok);
    return const_val->data.x_type;
}

static TypeTableEntry *get_return_type(BlockContext *context) {
    FnTableEntry *fn_entry = get_context_fn_entry(context);
    AstNode *fn_proto_node = fn_entry->proto_node;
    assert(fn_proto_node->type == NodeTypeFnProto);
    AstNode *return_type_node = fn_proto_node->data.fn_proto.return_type;
    return unwrapped_node_type(return_type_node);
}

static bool type_has_codegen_value(TypeTableEntryId id) {
    switch (id) {
        case TypeTableEntryIdInvalid:
        case TypeTableEntryIdMetaType:
        case TypeTableEntryIdVoid:
        case TypeTableEntryIdUnreachable:
        case TypeTableEntryIdNumLitFloat:
        case TypeTableEntryIdNumLitInt:
        case TypeTableEntryIdUndefLit:
            return false;

        case TypeTableEntryIdBool:
        case TypeTableEntryIdInt:
        case TypeTableEntryIdFloat:
        case TypeTableEntryIdPointer:
        case TypeTableEntryIdArray:
        case TypeTableEntryIdStruct:
        case TypeTableEntryIdMaybe:
        case TypeTableEntryIdErrorUnion:
        case TypeTableEntryIdPureError:
        case TypeTableEntryIdEnum:
        case TypeTableEntryIdFn:
            return true;

        case TypeTableEntryIdTypeDecl:
            zig_unreachable();
    }
}

static void add_global_const_expr(CodeGen *g, Expr *expr) {
    if (expr->const_val.ok &&
        type_has_codegen_value(expr->type_entry->id) &&
        !expr->has_global_const &&
        expr->type_entry->size_in_bits > 0)
    {
        g->global_const_list.append(expr);
        expr->has_global_const = true;
    }
}

static bool num_lit_fits_in_other_type(CodeGen *g, AstNode *literal_node, TypeTableEntry *other_type) {
    if (other_type->id == TypeTableEntryIdInvalid) {
        return false;
    }
    Expr *expr = get_resolved_expr(literal_node);
    ConstExprValue *const_val = &expr->const_val;
    assert(const_val->ok);
    if (other_type->id == TypeTableEntryIdFloat) {
        return true;
    } else if (other_type->id == TypeTableEntryIdInt &&
               const_val->data.x_bignum.kind == BigNumKindInt)
    {
        if (bignum_fits_in_bits(&const_val->data.x_bignum, other_type->size_in_bits,
                    other_type->data.integral.is_signed))
        {
            return true;
        }
    } else if ((other_type->id == TypeTableEntryIdNumLitFloat &&
                const_val->data.x_bignum.kind == BigNumKindFloat) ||
               (other_type->id == TypeTableEntryIdNumLitInt &&
                const_val->data.x_bignum.kind == BigNumKindInt))
    {
        return true;
    }

    const char *num_lit_str = (const_val->data.x_bignum.kind == BigNumKindFloat) ? "float" : "integer";

    add_node_error(g, literal_node,
        buf_sprintf("%s value %s cannot be implicitly casted to type '%s'",
            num_lit_str,
            buf_ptr(bignum_to_buf(&const_val->data.x_bignum)),
            buf_ptr(&other_type->name)));
    return false;
}

static bool types_match_const_cast_only(TypeTableEntry *expected_type, TypeTableEntry *actual_type) {
    if (expected_type == actual_type)
        return true;

    // pointer const
    if (expected_type->id == TypeTableEntryIdPointer &&
        actual_type->id == TypeTableEntryIdPointer &&
        (!actual_type->data.pointer.is_const || expected_type->data.pointer.is_const))
    {
        return types_match_const_cast_only(expected_type->data.pointer.child_type,
                actual_type->data.pointer.child_type);
    }

    // unknown size array const
    if (expected_type->id == TypeTableEntryIdStruct &&
        actual_type->id == TypeTableEntryIdStruct &&
        expected_type->data.structure.is_unknown_size_array &&
        actual_type->data.structure.is_unknown_size_array &&
        (!actual_type->data.structure.fields[0].type_entry->data.pointer.is_const ||
          expected_type->data.structure.fields[0].type_entry->data.pointer.is_const))
    {
        return types_match_const_cast_only(
                expected_type->data.structure.fields[0].type_entry->data.pointer.child_type,
                actual_type->data.structure.fields[0].type_entry->data.pointer.child_type);
    }

    // maybe
    if (expected_type->id == TypeTableEntryIdMaybe &&
        actual_type->id == TypeTableEntryIdMaybe)
    {
        return types_match_const_cast_only(
                expected_type->data.maybe.child_type,
                actual_type->data.maybe.child_type);
    }

    // error
    if (expected_type->id == TypeTableEntryIdErrorUnion &&
        actual_type->id == TypeTableEntryIdErrorUnion)
    {
        return types_match_const_cast_only(
                expected_type->data.error.child_type,
                actual_type->data.error.child_type);
    }

    // fn
    if (expected_type->id == TypeTableEntryIdFn &&
        actual_type->id == TypeTableEntryIdFn)
    {
        if (expected_type->data.fn.fn_type_id.is_extern != actual_type->data.fn.fn_type_id.is_extern) {
            return false;
        }
        if (expected_type->data.fn.fn_type_id.is_naked != actual_type->data.fn.fn_type_id.is_naked) {
            return false;
        }
        if (!types_match_const_cast_only(expected_type->data.fn.fn_type_id.return_type,
            actual_type->data.fn.fn_type_id.return_type))
        {
            return false;
        }
        if (expected_type->data.fn.fn_type_id.param_count != actual_type->data.fn.fn_type_id.param_count) {
            return false;
        }
        for (int i = 0; i < expected_type->data.fn.fn_type_id.param_count; i += 1) {
            // note it's reversed for parameters
            FnTypeParamInfo *actual_param_info = &actual_type->data.fn.fn_type_id.param_info[i];
            FnTypeParamInfo *expected_param_info = &expected_type->data.fn.fn_type_id.param_info[i];

            if (!types_match_const_cast_only(actual_param_info->type, expected_param_info->type)) {
                return false;
            }

            if (expected_param_info->is_noalias != actual_param_info->is_noalias) {
                return false;
            }
        }
        return true;
    }


    return false;
}

static TypeTableEntry *determine_peer_type_compatibility(CodeGen *g, AstNode *parent_source_node,
        AstNode **child_nodes, TypeTableEntry **child_types, int child_count)
{
    TypeTableEntry *prev_type = child_types[0];
    AstNode *prev_node = child_nodes[0];
    if (prev_type->id == TypeTableEntryIdInvalid) {
        return prev_type;
    }
    for (int i = 1; i < child_count; i += 1) {
        TypeTableEntry *cur_type = child_types[i];
        AstNode *cur_node = child_nodes[i];
        if (cur_type->id == TypeTableEntryIdInvalid) {
            return cur_type;
        } else if (types_match_const_cast_only(prev_type, cur_type)) {
            continue;
        } else if (types_match_const_cast_only(cur_type, prev_type)) {
            prev_type = cur_type;
            prev_node = cur_node;
            continue;
        } else if (prev_type->id == TypeTableEntryIdUnreachable) {
            prev_type = cur_type;
            prev_node = cur_node;
        } else if (cur_type->id == TypeTableEntryIdUnreachable) {
            continue;
        } else if (prev_type->id == TypeTableEntryIdInt &&
                   cur_type->id == TypeTableEntryIdInt &&
                   prev_type->data.integral.is_signed == cur_type->data.integral.is_signed)
        {
            if (cur_type->size_in_bits > prev_type->size_in_bits) {
                prev_type = cur_type;
                prev_node = cur_node;
            }
        } else if (prev_type->id == TypeTableEntryIdFloat &&
                   cur_type->id == TypeTableEntryIdFloat)
        {
            if (cur_type->size_in_bits > prev_type->size_in_bits) {
                prev_type = cur_type;
                prev_node = cur_node;
            }
        } else if (prev_type->id == TypeTableEntryIdErrorUnion &&
                   types_match_const_cast_only(prev_type->data.error.child_type, cur_type))
        {
            continue;
        } else if (cur_type->id == TypeTableEntryIdErrorUnion &&
                   types_match_const_cast_only(cur_type->data.error.child_type, prev_type))
        {
            prev_type = cur_type;
            prev_node = cur_node;
            continue;
        } else if (prev_type->id == TypeTableEntryIdNumLitInt ||
                    prev_type->id == TypeTableEntryIdNumLitFloat)
        {
            if (num_lit_fits_in_other_type(g, prev_node, cur_type)) {
                prev_type = cur_type;
                prev_node = cur_node;
                continue;
            } else {
                return g->builtin_types.entry_invalid;
            }
        } else if (cur_type->id == TypeTableEntryIdNumLitInt ||
                   cur_type->id == TypeTableEntryIdNumLitFloat)
        {
            if (num_lit_fits_in_other_type(g, cur_node, prev_type)) {
                continue;
            } else {
                return g->builtin_types.entry_invalid;
            }
        } else {
            add_node_error(g, parent_source_node,
                buf_sprintf("incompatible types: '%s' and '%s'",
                    buf_ptr(&prev_type->name), buf_ptr(&cur_type->name)));

            return g->builtin_types.entry_invalid;
        }
    }
    return prev_type;
}

static bool types_match_with_implicit_cast(CodeGen *g, TypeTableEntry *expected_type,
        TypeTableEntry *actual_type, AstNode *literal_node, bool *reported_err)
{
    if (types_match_const_cast_only(expected_type, actual_type)) {
        return true;
    }

    // implicit conversion from non maybe type to maybe type
    if (expected_type->id == TypeTableEntryIdMaybe &&
        types_match_with_implicit_cast(g, expected_type->data.maybe.child_type, actual_type,
            literal_node, reported_err))
    {
        return true;
    }

    // implicit conversion from error child type to error type
    if (expected_type->id == TypeTableEntryIdErrorUnion &&
        types_match_with_implicit_cast(g, expected_type->data.error.child_type, actual_type,
            literal_node, reported_err))
    {
        return true;
    }

    // implicit conversion from pure error to error union type
    if (expected_type->id == TypeTableEntryIdErrorUnion &&
        actual_type->id == TypeTableEntryIdPureError)
    {
        return true;
    }

    // implicit widening conversion
    if (expected_type->id == TypeTableEntryIdInt &&
        actual_type->id == TypeTableEntryIdInt &&
        expected_type->data.integral.is_signed == actual_type->data.integral.is_signed &&
        expected_type->size_in_bits >= actual_type->size_in_bits)
    {
        return true;
    }

    // implicit constant sized array to unknown size array conversion
    if (expected_type->id == TypeTableEntryIdStruct &&
        expected_type->data.structure.is_unknown_size_array &&
        actual_type->id == TypeTableEntryIdArray &&
        types_match_const_cast_only(
            expected_type->data.structure.fields[0].type_entry->data.pointer.child_type,
            actual_type->data.array.child_type))
    {
        return true;
    }

    // implicit number literal to typed number
    if ((actual_type->id == TypeTableEntryIdNumLitFloat ||
         actual_type->id == TypeTableEntryIdNumLitInt))
    {
        if (num_lit_fits_in_other_type(g, literal_node, expected_type)) {
            return true;
        } else {
            *reported_err = true;
        }
    }


    return false;
}

static AstNode *create_ast_node(CodeGen *g, ImportTableEntry *import, NodeType kind) {
    AstNode *node = allocate<AstNode>(1);
    node->type = kind;
    node->owner = import;
    node->create_index = g->next_node_index;
    g->next_node_index += 1;
    return node;
}

static AstNode *create_ast_type_node(CodeGen *g, ImportTableEntry *import, TypeTableEntry *type_entry) {
    AstNode *node = create_ast_node(g, import, NodeTypeSymbol);
    node->data.symbol_expr.override_type_entry = type_entry;
    return node;
}

static AstNode *create_ast_void_node(CodeGen *g, ImportTableEntry *import, AstNode *source_node) {
    AstNode *node = create_ast_node(g, import, NodeTypeContainerInitExpr);
    node->data.container_init_expr.kind = ContainerInitKindArray;
    node->data.container_init_expr.type = create_ast_type_node(g, import, g->builtin_types.entry_void);
    node->line = source_node->line;
    node->column = source_node->column;
    normalize_parent_ptrs(node);
    return node;
}

static TypeTableEntry *create_and_analyze_cast_node(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, TypeTableEntry *cast_to_type, AstNode *node)
{
    AstNode *new_parent_node = create_ast_node(g, import, NodeTypeFnCallExpr);
    new_parent_node->line = node->line;
    new_parent_node->column = node->column;
    *node->parent_field = new_parent_node;
    new_parent_node->parent_field = node->parent_field;

    new_parent_node->data.fn_call_expr.fn_ref_expr = create_ast_type_node(g, import, cast_to_type);
    new_parent_node->data.fn_call_expr.params.append(node);
    normalize_parent_ptrs(new_parent_node);

    return analyze_expression(g, import, context, cast_to_type, new_parent_node);
}

static TypeTableEntry *resolve_type_compatibility(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, AstNode *node,
        TypeTableEntry *expected_type, TypeTableEntry *actual_type)
{
    if (expected_type == nullptr)
        return actual_type; // anything will do
    if (expected_type == actual_type)
        return expected_type; // match
    if (expected_type->id == TypeTableEntryIdInvalid || actual_type->id == TypeTableEntryIdInvalid)
        return g->builtin_types.entry_invalid;
    if (actual_type->id == TypeTableEntryIdUnreachable)
        return actual_type;

    bool reported_err = false;
    if (types_match_with_implicit_cast(g, expected_type, actual_type, node, &reported_err)) {
        return create_and_analyze_cast_node(g, import, context, expected_type, node);
    }

    if (!reported_err) {
        add_node_error(g, first_executing_node(node),
            buf_sprintf("expected type '%s', got '%s'",
                buf_ptr(&expected_type->name),
                buf_ptr(&actual_type->name)));
    }

    return g->builtin_types.entry_invalid;
}

static TypeTableEntry *resolve_peer_type_compatibility(CodeGen *g, ImportTableEntry *import,
        BlockContext *block_context, AstNode *parent_source_node,
        AstNode **child_nodes, TypeTableEntry **child_types, int child_count)
{
    assert(child_count > 0);

    TypeTableEntry *expected_type = determine_peer_type_compatibility(g, parent_source_node,
            child_nodes, child_types, child_count);

    if (expected_type->id == TypeTableEntryIdInvalid) {
        return expected_type;
    }

    for (int i = 0; i < child_count; i += 1) {
        if (!child_nodes[i]) {
            continue;
        }
        AstNode **child_node = child_nodes[i]->parent_field;
        TypeTableEntry *resolved_type = resolve_type_compatibility(g, import, block_context,
                *child_node, expected_type, child_types[i]);
        Expr *expr = get_resolved_expr(*child_node);
        expr->type_entry = resolved_type;
        add_global_const_expr(g, expr);
    }

    return expected_type;
}

BlockContext *new_block_context(AstNode *node, BlockContext *parent) {
    BlockContext *context = allocate<BlockContext>(1);
    context->node = node;
    context->parent = parent;
    context->variable_table.init(8);
    context->type_table.init(8);
    context->error_table.init(8);

    if (parent) {
        context->parent_loop_node = parent->parent_loop_node;
        context->c_import_buf = parent->c_import_buf;
    }

    if (node && node->type == NodeTypeFnDef) {
        AstNode *fn_proto_node = node->data.fn_def.fn_proto;
        context->fn_entry = fn_proto_node->data.fn_proto.fn_table_entry;
    } else if (parent) {
        context->fn_entry = parent->fn_entry;
    }

    if (context->fn_entry) {
        context->fn_entry->all_block_contexts.append(context);
    }

    return context;
}

static VariableTableEntry *find_local_variable(BlockContext *context, Buf *name) {
    while (context && context->fn_entry) {
        auto entry = context->variable_table.maybe_get(name);
        if (entry != nullptr)
            return entry->value;

        context = context->parent;
    }
    return nullptr;
}

VariableTableEntry *find_variable(BlockContext *context, Buf *name) {
    while (context) {
        auto entry = context->variable_table.maybe_get(name);
        if (entry != nullptr)
            return entry->value;

        context = context->parent;
    }
    return nullptr;
}

TypeTableEntry *find_container(BlockContext *context, Buf *name) {
    while (context) {
        auto entry = context->type_table.maybe_get(name);
        if (entry != nullptr)
            return entry->value;

        context = context->parent;
    }
    return nullptr;
}

static TypeEnumField *get_enum_field(TypeTableEntry *enum_type, Buf *name) {
    for (uint32_t i = 0; i < enum_type->data.enumeration.field_count; i += 1) {
        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[i];
        if (buf_eql_buf(type_enum_field->name, name)) {
            return type_enum_field;
        }
    }
    return nullptr;
}

static TypeTableEntry *analyze_enum_value_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *field_access_node, AstNode *value_node, TypeTableEntry *enum_type, Buf *field_name)
{
    assert(field_access_node->type == NodeTypeFieldAccessExpr);

    TypeEnumField *type_enum_field = get_enum_field(enum_type, field_name);
    field_access_node->data.field_access_expr.type_enum_field = type_enum_field;

    if (type_enum_field) {
        if (value_node) {
            analyze_expression(g, import, context, type_enum_field->type_entry, value_node);

            StructValExprCodeGen *codegen = &field_access_node->data.field_access_expr.resolved_struct_val_expr;
            codegen->type_entry = enum_type;
            codegen->source_node = field_access_node;
            context->struct_val_expr_alloca_list.append(codegen);
        } else if (type_enum_field->type_entry->id != TypeTableEntryIdVoid) {
            add_node_error(g, field_access_node,
                buf_sprintf("enum value '%s.%s' requires parameter of type '%s'",
                    buf_ptr(&enum_type->name),
                    buf_ptr(field_name),
                    buf_ptr(&type_enum_field->type_entry->name)));
        } else {
            Expr *expr = get_resolved_expr(field_access_node);
            expr->const_val.ok = true;
            expr->const_val.data.x_enum.tag = type_enum_field->value;
            expr->const_val.data.x_enum.payload = nullptr;
        }
    } else {
        add_node_error(g, field_access_node,
            buf_sprintf("no member named '%s' in '%s'", buf_ptr(field_name),
                buf_ptr(&enum_type->name)));
    }
    return enum_type;
}

static TypeStructField *find_struct_type_field(TypeTableEntry *type_entry, Buf *name) {
    assert(type_entry->id == TypeTableEntryIdStruct);
    for (uint32_t i = 0; i < type_entry->data.structure.src_field_count; i += 1) {
        TypeStructField *field = &type_entry->data.structure.fields[i];
        if (buf_eql_buf(field->name, name)) {
            return field;
        }
    }
    return nullptr;
}

static const char *err_container_init_syntax_name(ContainerInitKind kind) {
    switch (kind) {
        case ContainerInitKindStruct:
            return "struct";
        case ContainerInitKindArray:
            return "array";
    }
    zig_unreachable();
}

static TypeTableEntry *analyze_container_init_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    assert(node->type == NodeTypeContainerInitExpr);

    AstNodeContainerInitExpr *container_init_expr = &node->data.container_init_expr;

    ContainerInitKind kind = container_init_expr->kind;

    TypeTableEntry *container_type = analyze_type_expr(g, import, context, container_init_expr->type);

    if (container_type->id == TypeTableEntryIdInvalid) {
        return container_type;
    } else if (container_type->id == TypeTableEntryIdStruct &&
               !container_type->data.structure.is_unknown_size_array &&
               kind == ContainerInitKindStruct)
    {
        StructValExprCodeGen *codegen = &container_init_expr->resolved_struct_val_expr;
        codegen->type_entry = container_type;
        codegen->source_node = node;
        context->struct_val_expr_alloca_list.append(codegen);


        int expr_field_count = container_init_expr->entries.length;
        int actual_field_count = container_type->data.structure.src_field_count;

        int *field_use_counts = allocate<int>(actual_field_count);
        ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
        const_val->ok = true;
        const_val->data.x_struct.fields = allocate<ConstExprValue*>(actual_field_count);
        for (int i = 0; i < expr_field_count; i += 1) {
            AstNode *val_field_node = container_init_expr->entries.at(i);
            assert(val_field_node->type == NodeTypeStructValueField);

            val_field_node->block_context = context;

            TypeStructField *type_field = find_struct_type_field(container_type,
                    &val_field_node->data.struct_val_field.name);

            if (!type_field) {
                add_node_error(g, val_field_node,
                    buf_sprintf("no member named '%s' in '%s'",
                        buf_ptr(&val_field_node->data.struct_val_field.name), buf_ptr(&container_type->name)));
                continue;
            }

            int field_index = type_field->src_index;
            field_use_counts[field_index] += 1;
            if (field_use_counts[field_index] > 1) {
                add_node_error(g, val_field_node, buf_sprintf("duplicate field"));
                continue;
            }

            val_field_node->data.struct_val_field.type_struct_field = type_field;

            analyze_expression(g, import, context, type_field->type_entry,
                    val_field_node->data.struct_val_field.expr);

            if (const_val->ok) {
                ConstExprValue *field_val =
                    &get_resolved_expr(val_field_node->data.struct_val_field.expr)->const_val;
                if (field_val->ok) {
                    const_val->data.x_struct.fields[field_index] = field_val;
                } else {
                    const_val->ok = false;
                }
            }
        }

        for (int i = 0; i < actual_field_count; i += 1) {
            if (field_use_counts[i] == 0) {
                add_node_error(g, node,
                    buf_sprintf("missing field: '%s'", buf_ptr(container_type->data.structure.fields[i].name)));
            }
        }
        return container_type;
    } else if (container_type->id == TypeTableEntryIdStruct &&
               container_type->data.structure.is_unknown_size_array &&
               kind == ContainerInitKindArray)
    {
        int elem_count = container_init_expr->entries.length;

        TypeTableEntry *pointer_type = container_type->data.structure.fields[0].type_entry;
        assert(pointer_type->id == TypeTableEntryIdPointer);
        TypeTableEntry *child_type = pointer_type->data.pointer.child_type;

        ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
        const_val->ok = true;
        const_val->data.x_array.fields = allocate<ConstExprValue*>(elem_count);

        for (int i = 0; i < elem_count; i += 1) {
            AstNode **elem_node = &container_init_expr->entries.at(i);
            analyze_expression(g, import, context, child_type, *elem_node);

            if (const_val->ok) {
                ConstExprValue *elem_const_val = &get_resolved_expr(*elem_node)->const_val;
                if (elem_const_val->ok) {
                    const_val->data.x_array.fields[i] = elem_const_val;
                } else {
                    const_val->ok = false;
                }
            }
        }

        TypeTableEntry *fixed_size_array_type = get_array_type(g, child_type, elem_count);

        StructValExprCodeGen *codegen = &container_init_expr->resolved_struct_val_expr;
        codegen->type_entry = fixed_size_array_type;
        codegen->source_node = node;
        context->struct_val_expr_alloca_list.append(codegen);

        return fixed_size_array_type;
    } else if (container_type->id == TypeTableEntryIdArray) {
        zig_panic("TODO array container init");
        return container_type;
    } else if (container_type->id == TypeTableEntryIdEnum) {
        zig_panic("TODO enum container init");
        return container_type;
    } else if (container_type->id == TypeTableEntryIdVoid) {
        if (container_init_expr->entries.length != 0) {
            add_node_error(g, node, buf_sprintf("void expression expects no arguments"));
            return g->builtin_types.entry_invalid;
        } else {
            return resolve_expr_const_val_as_void(g, node);
        }
    } else if (container_type->id == TypeTableEntryIdUnreachable) {
        if (container_init_expr->entries.length != 0) {
            add_node_error(g, node, buf_sprintf("unreachable expression expects no arguments"));
            return g->builtin_types.entry_invalid;
        } else {
            return container_type;
        }
    } else {
        add_node_error(g, node,
            buf_sprintf("type '%s' does not support %s initialization syntax",
                buf_ptr(&container_type->name), err_container_init_syntax_name(kind)));
        return g->builtin_types.entry_invalid;
    }
}

static TypeTableEntry *analyze_field_access_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    assert(node->type == NodeTypeFieldAccessExpr);

    AstNode *struct_expr_node = node->data.field_access_expr.struct_expr;
    TypeTableEntry *struct_type = analyze_expression(g, import, context, nullptr, struct_expr_node);
    Buf *field_name = &node->data.field_access_expr.field_name;

    if (struct_type->id == TypeTableEntryIdStruct || (struct_type->id == TypeTableEntryIdPointer &&
         struct_type->data.pointer.child_type->id == TypeTableEntryIdStruct))
    {
        TypeTableEntry *bare_struct_type = (struct_type->id == TypeTableEntryIdStruct) ?
            struct_type : struct_type->data.pointer.child_type;

        node->data.field_access_expr.type_struct_field = find_struct_type_field(bare_struct_type, field_name);
        if (node->data.field_access_expr.type_struct_field) {
            return node->data.field_access_expr.type_struct_field->type_entry;
        } else {
            add_node_error(g, node,
                buf_sprintf("no member named '%s' in '%s'", buf_ptr(field_name), buf_ptr(&struct_type->name)));
            return g->builtin_types.entry_invalid;
        }
    } else if (struct_type->id == TypeTableEntryIdArray) {
        if (buf_eql_str(field_name, "len")) {
            return g->builtin_types.entry_isize;
        } else if (buf_eql_str(field_name, "ptr")) {
            // TODO determine whether the pointer should be const
            return get_pointer_to_type(g, struct_type->data.array.child_type, false);
        } else {
            add_node_error(g, node,
                buf_sprintf("no member named '%s' in '%s'", buf_ptr(field_name),
                    buf_ptr(&struct_type->name)));
            return g->builtin_types.entry_invalid;
        }
    } else if (struct_type->id == TypeTableEntryIdMetaType) {
        TypeTableEntry *child_type = resolve_type(g, struct_expr_node);

        if (child_type->id == TypeTableEntryIdInvalid) {
            return g->builtin_types.entry_invalid;
        } else if (child_type->id == TypeTableEntryIdEnum) {
            return analyze_enum_value_expr(g, import, context, node, nullptr, child_type, field_name);
        } else if (child_type->id == TypeTableEntryIdStruct) {
            auto entry = child_type->data.structure.fn_table.maybe_get(field_name);
            if (entry) {
                return resolve_expr_const_val_as_fn(g, node, entry->value);
            } else {
                add_node_error(g, node,
                    buf_sprintf("struct '%s' has no function called '%s'",
                        buf_ptr(&child_type->name), buf_ptr(field_name)));
                return g->builtin_types.entry_invalid;
            }
        } else if (child_type->id == TypeTableEntryIdPureError) {
            return analyze_error_literal_expr(g, import, context, node, field_name);
        } else {
            add_node_error(g, node,
                buf_sprintf("type '%s' does not support field access", buf_ptr(&struct_type->name)));
            return g->builtin_types.entry_invalid;
        }
    } else {
        if (struct_type->id != TypeTableEntryIdInvalid) {
            add_node_error(g, node,
                buf_sprintf("type '%s' does not support field access", buf_ptr(&struct_type->name)));
        }
        return g->builtin_types.entry_invalid;
    }
}

static TypeTableEntry *analyze_slice_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    assert(node->type == NodeTypeSliceExpr);

    TypeTableEntry *array_type = analyze_expression(g, import, context, nullptr,
            node->data.slice_expr.array_ref_expr);

    TypeTableEntry *return_type;

    if (array_type->id == TypeTableEntryIdInvalid) {
        return_type = g->builtin_types.entry_invalid;
    } else if (array_type->id == TypeTableEntryIdArray) {
        return_type = get_unknown_size_array_type(g, array_type->data.array.child_type,
                node->data.slice_expr.is_const);
    } else if (array_type->id == TypeTableEntryIdPointer) {
        return_type = get_unknown_size_array_type(g, array_type->data.pointer.child_type,
                node->data.slice_expr.is_const);
    } else if (array_type->id == TypeTableEntryIdStruct &&
               array_type->data.structure.is_unknown_size_array)
    {
        return_type = get_unknown_size_array_type(g,
                array_type->data.structure.fields[0].type_entry->data.pointer.child_type,
                node->data.slice_expr.is_const);
    } else {
        add_node_error(g, node,
            buf_sprintf("slice of non-array type '%s'", buf_ptr(&array_type->name)));
        return_type = g->builtin_types.entry_invalid;
    }

    if (return_type->id != TypeTableEntryIdInvalid) {
        node->data.slice_expr.resolved_struct_val_expr.type_entry = return_type;
        node->data.slice_expr.resolved_struct_val_expr.source_node = node;
        context->struct_val_expr_alloca_list.append(&node->data.slice_expr.resolved_struct_val_expr);
    }

    analyze_expression(g, import, context, g->builtin_types.entry_isize, node->data.slice_expr.start);

    if (node->data.slice_expr.end) {
        analyze_expression(g, import, context, g->builtin_types.entry_isize, node->data.slice_expr.end);
    }

    return return_type;
}

static TypeTableEntry *analyze_array_access_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    TypeTableEntry *array_type = analyze_expression(g, import, context, nullptr,
            node->data.array_access_expr.array_ref_expr);

    TypeTableEntry *return_type;

    if (array_type->id == TypeTableEntryIdInvalid) {
        return_type = g->builtin_types.entry_invalid;
    } else if (array_type->id == TypeTableEntryIdArray) {
        return_type = array_type->data.array.child_type;
    } else if (array_type->id == TypeTableEntryIdPointer) {
        return_type = array_type->data.pointer.child_type;
    } else if (array_type->id == TypeTableEntryIdStruct &&
               array_type->data.structure.is_unknown_size_array)
    {
        return_type = array_type->data.structure.fields[0].type_entry->data.pointer.child_type;
    } else {
        add_node_error(g, node,
                buf_sprintf("array access of non-array type '%s'", buf_ptr(&array_type->name)));
        return_type = g->builtin_types.entry_invalid;
    }

    analyze_expression(g, import, context, g->builtin_types.entry_isize, node->data.array_access_expr.subscript);

    return return_type;
}

static TypeTableEntry *resolve_expr_const_val_as_void(CodeGen *g, AstNode *node) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    return g->builtin_types.entry_void;
}

static TypeTableEntry *resolve_expr_const_val_as_type(CodeGen *g, AstNode *node, TypeTableEntry *type) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    expr->const_val.data.x_type = type;
    return g->builtin_types.entry_type;
}

static TypeTableEntry *resolve_expr_const_val_as_other_expr(CodeGen *g, AstNode *node, AstNode *other) {
    Expr *expr = get_resolved_expr(node);
    Expr *other_expr = get_resolved_expr(other);
    expr->const_val = other_expr->const_val;
    return other_expr->type_entry;
}

static TypeTableEntry *resolve_expr_const_val_as_fn(CodeGen *g, AstNode *node, FnTableEntry *fn) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    expr->const_val.data.x_fn = fn;
    return fn->type_entry;
}

static TypeTableEntry *resolve_expr_const_val_as_err(CodeGen *g, AstNode *node, ErrorTableEntry *err) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    expr->const_val.data.x_err.err = err;
    return g->builtin_types.entry_pure_error;
}

static TypeTableEntry *resolve_expr_const_val_as_bool(CodeGen *g, AstNode *node, bool value) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    expr->const_val.data.x_bool = value;
    return g->builtin_types.entry_bool;
}

static TypeTableEntry *resolve_expr_const_val_as_null(CodeGen *g, AstNode *node, TypeTableEntry *type) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    expr->const_val.data.x_maybe = nullptr;
    return type;
}

static TypeTableEntry *resolve_expr_const_val_as_c_string_lit(CodeGen *g, AstNode *node, Buf *str) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;

    int len_with_null = buf_len(str) + 1;
    expr->const_val.data.x_ptr.ptr = allocate<ConstExprValue*>(len_with_null);
    expr->const_val.data.x_ptr.len = len_with_null;

    ConstExprValue *all_chars = allocate<ConstExprValue>(len_with_null);
    for (int i = 0; i < buf_len(str); i += 1) {
        ConstExprValue *this_char = &all_chars[i];
        this_char->ok = true;
        bignum_init_unsigned(&this_char->data.x_bignum, buf_ptr(str)[i]);
        expr->const_val.data.x_ptr.ptr[i] = this_char;
    }

    ConstExprValue *null_char = &all_chars[len_with_null - 1];
    null_char->ok = true;
    bignum_init_unsigned(&null_char->data.x_bignum, 0);
    expr->const_val.data.x_ptr.ptr[len_with_null - 1] = null_char;

    return get_pointer_to_type(g, g->builtin_types.entry_u8, true);
}

static TypeTableEntry *resolve_expr_const_val_as_string_lit(CodeGen *g, AstNode *node, Buf *str) {
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;
    expr->const_val.data.x_array.fields = allocate<ConstExprValue*>(buf_len(str));

    ConstExprValue *all_chars = allocate<ConstExprValue>(buf_len(str));
    for (int i = 0; i < buf_len(str); i += 1) {
        ConstExprValue *this_char = &all_chars[i];
        this_char->ok = true;
        bignum_init_unsigned(&this_char->data.x_bignum, buf_ptr(str)[i]);
        expr->const_val.data.x_array.fields[i] = this_char;
    }
    return get_array_type(g, g->builtin_types.entry_u8, buf_len(str));
}


static TypeTableEntry *resolve_expr_const_val_as_unsigned_num_lit(CodeGen *g, AstNode *node,
        TypeTableEntry *expected_type, uint64_t x)
{
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;

    bignum_init_unsigned(&expr->const_val.data.x_bignum, x);
    return g->builtin_types.entry_num_lit_int;
}

static TypeTableEntry *resolve_expr_const_val_as_float_num_lit(CodeGen *g, AstNode *node,
        TypeTableEntry *expected_type, double x)
{
    Expr *expr = get_resolved_expr(node);
    expr->const_val.ok = true;

    bignum_init_float(&expr->const_val.data.x_bignum, x);

    if (expected_type) {
        num_lit_fits_in_other_type(g, node, expected_type);
        return expected_type;
    } else {
        return g->builtin_types.entry_num_lit_float;
    }
}

static TypeTableEntry *resolve_expr_const_val_as_bignum_op(CodeGen *g, AstNode *node,
        bool (*bignum_fn)(BigNum *, BigNum *, BigNum *), AstNode *op1, AstNode *op2,
        TypeTableEntry *resolved_type)
{
    ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
    ConstExprValue *op1_val = &get_resolved_expr(op1)->const_val;
    ConstExprValue *op2_val = &get_resolved_expr(op2)->const_val;

    const_val->ok = true;

    if (bignum_fn(&const_val->data.x_bignum, &op1_val->data.x_bignum, &op2_val->data.x_bignum)) {
        add_node_error(g, node,
            buf_sprintf("value cannot be represented in any integer type"));
    } else {
        num_lit_fits_in_other_type(g, node, resolved_type);
    }

    return resolved_type;
}

static TypeTableEntry *analyze_error_literal_expr(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, AstNode *node, Buf *err_name)
{
    auto err_table_entry = import->block_context->error_table.maybe_get(err_name);

    if (err_table_entry) {
        return resolve_expr_const_val_as_err(g, node, err_table_entry->value);
    }

    add_node_error(g, node,
            buf_sprintf("use of undeclared error value '%s'", buf_ptr(err_name)));

    return get_error_type(g, g->builtin_types.entry_void);
}


static TypeTableEntry *analyze_symbol_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    if (node->data.symbol_expr.override_type_entry) {
        return resolve_expr_const_val_as_type(g, node, node->data.symbol_expr.override_type_entry);
    }

    Buf *variable_name = &node->data.symbol_expr.symbol;

    auto primitive_table_entry = g->primitive_type_table.maybe_get(variable_name);
    if (primitive_table_entry) {
        return resolve_expr_const_val_as_type(g, node, primitive_table_entry->value);
    }

    VariableTableEntry *var = find_variable(context, variable_name);
    if (var) {
        node->data.symbol_expr.variable = var;
        if (var->is_const) {
            AstNode *decl_node = var->decl_node;
            if (decl_node->type == NodeTypeVariableDeclaration) {
                AstNode *expr_node = decl_node->data.variable_declaration.expr;
                ConstExprValue *other_const_val = &get_resolved_expr(expr_node)->const_val;
                if (other_const_val->ok) {
                    return resolve_expr_const_val_as_other_expr(g, node, expr_node);
                }
            }
        }
        return var->type;
    }

    TypeTableEntry *container_type = find_container(context, variable_name);
    if (container_type) {
        return resolve_expr_const_val_as_type(g, node, container_type);
    }

    auto fn_table_entry = import->fn_table.maybe_get(variable_name);
    if (fn_table_entry) {
        node->data.symbol_expr.fn_entry = fn_table_entry->value;
        return resolve_expr_const_val_as_fn(g, node, fn_table_entry->value);
    }

    add_node_error(g, node, buf_sprintf("use of undeclared identifier '%s'", buf_ptr(variable_name)));
    return g->builtin_types.entry_invalid;
}

static TypeTableEntry *analyze_variable_name(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node, Buf *variable_name)
{
    VariableTableEntry *var = find_variable(context, variable_name);
    if (var) {
        return var->type;
    } else {
        add_node_error(g, node,
                buf_sprintf("use of undeclared identifier '%s'", buf_ptr(variable_name)));
        return g->builtin_types.entry_invalid;
    }
}

static bool is_op_allowed(TypeTableEntry *type, BinOpType op) {
    switch (op) {
        case BinOpTypeAssign:
            return true;
        case BinOpTypeAssignTimes:
        case BinOpTypeAssignDiv:
        case BinOpTypeAssignMod:
            return type->id == TypeTableEntryIdInt || type->id == TypeTableEntryIdFloat;
        case BinOpTypeAssignPlus:
        case BinOpTypeAssignMinus:
            return type->id == TypeTableEntryIdInt ||
                   type->id == TypeTableEntryIdFloat ||
                   type->id == TypeTableEntryIdPointer;
        case BinOpTypeAssignBitShiftLeft:
        case BinOpTypeAssignBitShiftRight:
        case BinOpTypeAssignBitAnd:
        case BinOpTypeAssignBitXor:
        case BinOpTypeAssignBitOr:
            return type->id == TypeTableEntryIdInt;
        case BinOpTypeAssignBoolAnd:
        case BinOpTypeAssignBoolOr:
            return type->id == TypeTableEntryIdBool;

        case BinOpTypeInvalid:
        case BinOpTypeBoolOr:
        case BinOpTypeBoolAnd:
        case BinOpTypeCmpEq:
        case BinOpTypeCmpNotEq:
        case BinOpTypeCmpLessThan:
        case BinOpTypeCmpGreaterThan:
        case BinOpTypeCmpLessOrEq:
        case BinOpTypeCmpGreaterOrEq:
        case BinOpTypeBinOr:
        case BinOpTypeBinXor:
        case BinOpTypeBinAnd:
        case BinOpTypeBitShiftLeft:
        case BinOpTypeBitShiftRight:
        case BinOpTypeAdd:
        case BinOpTypeSub:
        case BinOpTypeMult:
        case BinOpTypeDiv:
        case BinOpTypeMod:
        case BinOpTypeUnwrapMaybe:
        case BinOpTypeStrCat:
            zig_unreachable();
    }
    zig_unreachable();
}

enum LValPurpose {
    LValPurposeAssign,
    LValPurposeAddressOf,
};

static TypeTableEntry *analyze_lvalue(CodeGen *g, ImportTableEntry *import, BlockContext *block_context,
        AstNode *lhs_node, LValPurpose purpose, bool is_ptr_const)
{
    TypeTableEntry *expected_rhs_type = nullptr;
    lhs_node->block_context = block_context;
    if (lhs_node->type == NodeTypeSymbol) {
        Buf *name = &lhs_node->data.symbol_expr.symbol;
        if (purpose == LValPurposeAddressOf) {
            expected_rhs_type = analyze_symbol_expr(g, import, block_context, nullptr, lhs_node);
        } else {
            VariableTableEntry *var = find_variable(block_context, name);
            if (var) {
                if (var->is_const) {
                    add_node_error(g, lhs_node, buf_sprintf("cannot assign to constant"));
                    expected_rhs_type = g->builtin_types.entry_invalid;
                } else {
                    expected_rhs_type = var->type;
                }
            } else {
                add_node_error(g, lhs_node,
                        buf_sprintf("use of undeclared identifier '%s'", buf_ptr(name)));
                expected_rhs_type = g->builtin_types.entry_invalid;
            }
        }
    } else if (lhs_node->type == NodeTypeArrayAccessExpr) {
        expected_rhs_type = analyze_array_access_expr(g, import, block_context, lhs_node);
    } else if (lhs_node->type == NodeTypeFieldAccessExpr) {
        expected_rhs_type = analyze_field_access_expr(g, import, block_context, lhs_node);
    } else if (lhs_node->type == NodeTypePrefixOpExpr &&
            lhs_node->data.prefix_op_expr.prefix_op == PrefixOpDereference)
    {
        assert(purpose == LValPurposeAssign);
        AstNode *target_node = lhs_node->data.prefix_op_expr.primary_expr;
        TypeTableEntry *type_entry = analyze_expression(g, import, block_context, nullptr, target_node);
        if (type_entry->id == TypeTableEntryIdInvalid) {
            expected_rhs_type = type_entry;
        } else if (type_entry->id == TypeTableEntryIdPointer) {
            expected_rhs_type = type_entry->data.pointer.child_type;
        } else {
            add_node_error(g, target_node,
                buf_sprintf("indirection requires pointer operand ('%s' invalid)",
                    buf_ptr(&type_entry->name)));
            expected_rhs_type = g->builtin_types.entry_invalid;
        }
    } else {
        if (purpose == LValPurposeAssign) {
            add_node_error(g, lhs_node, buf_sprintf("invalid assignment target"));
            expected_rhs_type = g->builtin_types.entry_invalid;
        } else if (purpose == LValPurposeAddressOf) {
            TypeTableEntry *type_entry = analyze_expression(g, import, block_context, nullptr, lhs_node);
            if (type_entry->id == TypeTableEntryIdInvalid) {
                expected_rhs_type = g->builtin_types.entry_invalid;
            } else if (type_entry->id == TypeTableEntryIdMetaType) {
                expected_rhs_type = type_entry;
            } else {
                add_node_error(g, lhs_node, buf_sprintf("invalid addressof target"));
                expected_rhs_type = g->builtin_types.entry_invalid;
            }
        }
    }
    assert(expected_rhs_type);
    return expected_rhs_type;
}

static bool eval_bool_bin_op_bool(bool a, BinOpType bin_op, bool b) {
    if (bin_op == BinOpTypeBoolOr) {
        return a || b;
    } else if (bin_op == BinOpTypeBoolAnd) {
        return a && b;
    } else {
        zig_unreachable();
    }
}

static TypeTableEntry *analyze_bool_bin_op_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    assert(node->type == NodeTypeBinOpExpr);
    BinOpType bin_op_type = node->data.bin_op_expr.bin_op;

    AstNode *op1 = node->data.bin_op_expr.op1;
    AstNode *op2 = node->data.bin_op_expr.op2;
    TypeTableEntry *op1_type = analyze_expression(g, import, context, nullptr, op1);
    TypeTableEntry *op2_type = analyze_expression(g, import, context, nullptr, op2);

    AstNode *op_nodes[] = {op1, op2};
    TypeTableEntry *op_types[] = {op1_type, op2_type};

    TypeTableEntry *resolved_type = resolve_peer_type_compatibility(g, import, context, node,
            op_nodes, op_types, 2);

    if (resolved_type->id == TypeTableEntryIdInvalid) {
        return g->builtin_types.entry_invalid;
    }

    ConstExprValue *op1_val = &get_resolved_expr(op1)->const_val;
    ConstExprValue *op2_val = &get_resolved_expr(op2)->const_val;
    if (!op1_val->ok || !op2_val->ok) {
        return g->builtin_types.entry_bool;
    }

    bool answer;
    if (resolved_type->id == TypeTableEntryIdNumLitFloat ||
        resolved_type->id == TypeTableEntryIdNumLitInt ||
        resolved_type->id == TypeTableEntryIdFloat ||
        resolved_type->id == TypeTableEntryIdInt)
    {
        bool (*bignum_cmp)(BigNum *, BigNum *);
        if (bin_op_type == BinOpTypeCmpEq) {
            bignum_cmp = bignum_cmp_eq;
        } else if (bin_op_type == BinOpTypeCmpNotEq) {
            bignum_cmp = bignum_cmp_neq;
        } else if (bin_op_type == BinOpTypeCmpLessThan) {
            bignum_cmp = bignum_cmp_lt;
        } else if (bin_op_type == BinOpTypeCmpGreaterThan) {
            bignum_cmp = bignum_cmp_gt;
        } else if (bin_op_type == BinOpTypeCmpLessOrEq) {
            bignum_cmp = bignum_cmp_lte;
        } else if (bin_op_type == BinOpTypeCmpGreaterOrEq) {
            bignum_cmp = bignum_cmp_gte;
        } else {
            zig_unreachable();
        }

        answer = bignum_cmp(&op1_val->data.x_bignum, &op2_val->data.x_bignum);

    } else if (resolved_type->id == TypeTableEntryIdEnum) {
        ConstEnumValue *enum1 = &op1_val->data.x_enum;
        ConstEnumValue *enum2 = &op2_val->data.x_enum;
        bool are_equal = false;
        if (enum1->tag == enum2->tag) {
            TypeEnumField *enum_field = &op1_type->data.enumeration.fields[enum1->tag];
            if (enum_field->type_entry->size_in_bits > 0) {
                zig_panic("TODO const expr analyze enum special value for equality");
            } else {
                are_equal = true;
            }
        }
        if (bin_op_type == BinOpTypeCmpEq) {
            answer = are_equal;
        } else if (bin_op_type == BinOpTypeCmpNotEq) {
            answer = !are_equal;
        } else {
            zig_unreachable();
        }
    } else {
        zig_unreachable();
    }

    return resolve_expr_const_val_as_bool(g, node, answer);
}

static TypeTableEntry *analyze_logic_bin_op_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    assert(node->type == NodeTypeBinOpExpr);
    BinOpType bin_op_type = node->data.bin_op_expr.bin_op;

    AstNode *op1 = node->data.bin_op_expr.op1;
    AstNode *op2 = node->data.bin_op_expr.op2;
    TypeTableEntry *op1_type = analyze_expression(g, import, context, g->builtin_types.entry_bool, op1);
    TypeTableEntry *op2_type = analyze_expression(g, import, context, g->builtin_types.entry_bool, op2);

    if (op1_type->id == TypeTableEntryIdInvalid ||
        op2_type->id == TypeTableEntryIdInvalid)
    {
        return g->builtin_types.entry_invalid;
    }

    ConstExprValue *op1_val = &get_resolved_expr(op1)->const_val;
    ConstExprValue *op2_val = &get_resolved_expr(op2)->const_val;
    if (!op1_val->ok || !op2_val->ok) {
        return g->builtin_types.entry_bool;
    }

    bool answer = eval_bool_bin_op_bool(op1_val->data.x_bool, bin_op_type, op2_val->data.x_bool);
    return resolve_expr_const_val_as_bool(g, node, answer);
}

static TypeTableEntry *analyze_bin_op_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    BinOpType bin_op_type = node->data.bin_op_expr.bin_op;
    switch (bin_op_type) {
        case BinOpTypeAssign:
        case BinOpTypeAssignTimes:
        case BinOpTypeAssignDiv:
        case BinOpTypeAssignMod:
        case BinOpTypeAssignPlus:
        case BinOpTypeAssignMinus:
        case BinOpTypeAssignBitShiftLeft:
        case BinOpTypeAssignBitShiftRight:
        case BinOpTypeAssignBitAnd:
        case BinOpTypeAssignBitXor:
        case BinOpTypeAssignBitOr:
        case BinOpTypeAssignBoolAnd:
        case BinOpTypeAssignBoolOr:
            {
                AstNode *lhs_node = node->data.bin_op_expr.op1;

                TypeTableEntry *expected_rhs_type = analyze_lvalue(g, import, context, lhs_node,
                        LValPurposeAssign, false);
                if (!is_op_allowed(expected_rhs_type, node->data.bin_op_expr.bin_op)) {
                    if (expected_rhs_type->id != TypeTableEntryIdInvalid) {
                        add_node_error(g, lhs_node,
                            buf_sprintf("operator not allowed for type '%s'",
                                buf_ptr(&expected_rhs_type->name)));
                    }
                }

                analyze_expression(g, import, context, expected_rhs_type, node->data.bin_op_expr.op2);
                return g->builtin_types.entry_void;
            }
        case BinOpTypeBoolOr:
        case BinOpTypeBoolAnd:
            return analyze_logic_bin_op_expr(g, import, context, node);
        case BinOpTypeCmpEq:
        case BinOpTypeCmpNotEq:
        case BinOpTypeCmpLessThan:
        case BinOpTypeCmpGreaterThan:
        case BinOpTypeCmpLessOrEq:
        case BinOpTypeCmpGreaterOrEq:
            return analyze_bool_bin_op_expr(g, import, context, node);
        case BinOpTypeBinOr:
        case BinOpTypeBinXor:
        case BinOpTypeBinAnd:
        case BinOpTypeBitShiftLeft:
        case BinOpTypeBitShiftRight:
        case BinOpTypeAdd:
        case BinOpTypeSub:
        case BinOpTypeMult:
        case BinOpTypeDiv:
        case BinOpTypeMod:
            {
                AstNode *op1 = node->data.bin_op_expr.op1;
                AstNode *op2 = node->data.bin_op_expr.op2;
                TypeTableEntry *lhs_type = analyze_expression(g, import, context, expected_type, op1);
                TypeTableEntry *rhs_type = analyze_expression(g, import, context, expected_type, op2);

                AstNode *op_nodes[] = {op1, op2};
                TypeTableEntry *op_types[] = {lhs_type, rhs_type};

                TypeTableEntry *resolved_type = resolve_peer_type_compatibility(g, import, context, node,
                        op_nodes, op_types, 2);

                if (resolved_type->id == TypeTableEntryIdInvalid) {
                    return resolved_type;
                }

                ConstExprValue *op1_val = &get_resolved_expr(op1)->const_val;
                ConstExprValue *op2_val = &get_resolved_expr(op2)->const_val;
                if (!op1_val->ok || !op2_val->ok) {
                    return resolved_type;
                }

                if (bin_op_type == BinOpTypeAdd) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_add, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeSub) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_sub, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeMult) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_mul, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeDiv) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_div, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeMod) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_mod, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeBinOr) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_or, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeBinAnd) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_and, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeBinXor) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_xor, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeBitShiftLeft) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_shl, op1, op2, resolved_type);
                } else if (bin_op_type == BinOpTypeBitShiftRight) {
                    return resolve_expr_const_val_as_bignum_op(g, node, bignum_shr, op1, op2, resolved_type);
                } else {
                    zig_unreachable();
                }
            }
        case BinOpTypeUnwrapMaybe:
            {
                AstNode *op1 = node->data.bin_op_expr.op1;
                AstNode *op2 = node->data.bin_op_expr.op2;
                TypeTableEntry *lhs_type = analyze_expression(g, import, context, nullptr, op1);

                if (lhs_type->id == TypeTableEntryIdInvalid) {
                    return lhs_type;
                } else if (lhs_type->id == TypeTableEntryIdMaybe) {
                    TypeTableEntry *child_type = lhs_type->data.maybe.child_type;
                    analyze_expression(g, import, context, child_type, op2);
                    return child_type;
                } else {
                    add_node_error(g, op1,
                        buf_sprintf("expected maybe type, got '%s'",
                            buf_ptr(&lhs_type->name)));
                    return g->builtin_types.entry_invalid;
                }
            }
        case BinOpTypeStrCat:
            {
                AstNode **op1 = node->data.bin_op_expr.op1->parent_field;
                AstNode **op2 = node->data.bin_op_expr.op2->parent_field;

                TypeTableEntry *str_type = get_unknown_size_array_type(g, g->builtin_types.entry_u8, true);

                TypeTableEntry *op1_type = analyze_expression(g, import, context, str_type, *op1);
                TypeTableEntry *op2_type = analyze_expression(g, import, context, str_type, *op2);

                if (op1_type->id == TypeTableEntryIdInvalid ||
                    op2_type->id == TypeTableEntryIdInvalid)
                {
                    return g->builtin_types.entry_invalid;
                }

                ConstExprValue *op1_val = &get_resolved_expr(*op1)->const_val;
                ConstExprValue *op2_val = &get_resolved_expr(*op2)->const_val;

                AstNode *bad_node;
                if (!op1_val->ok) {
                    bad_node = *op1;
                } else if (!op2_val->ok) {
                    bad_node = *op2;
                } else {
                    bad_node = nullptr;
                }
                if (bad_node) {
                    add_node_error(g, bad_node, buf_sprintf("string concatenation requires constant expression"));
                    return g->builtin_types.entry_invalid;
                }
                ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
                const_val->ok = true;

                ConstExprValue *all_fields = allocate<ConstExprValue>(2);
                ConstExprValue *ptr_field = &all_fields[0];
                ConstExprValue *len_field = &all_fields[1];

                const_val->data.x_struct.fields = allocate<ConstExprValue*>(2);
                const_val->data.x_struct.fields[0] = ptr_field;
                const_val->data.x_struct.fields[1] = len_field;

                len_field->ok = true;
                uint64_t op1_len = op1_val->data.x_struct.fields[1]->data.x_bignum.data.x_uint;
                uint64_t op2_len = op2_val->data.x_struct.fields[1]->data.x_bignum.data.x_uint;
                uint64_t len = op1_len + op2_len;
                bignum_init_unsigned(&len_field->data.x_bignum, len);

                ptr_field->ok = true;
                ptr_field->data.x_ptr.ptr = allocate<ConstExprValue*>(len);
                ptr_field->data.x_ptr.len = len;

                uint64_t i = 0;
                for (uint64_t op1_i = 0; op1_i < op1_len; op1_i += 1, i += 1) {
                    ptr_field->data.x_ptr.ptr[i] = op1_val->data.x_struct.fields[0]->data.x_ptr.ptr[op1_i];
                }
                for (uint64_t op2_i = 0; op2_i < op2_len; op2_i += 1, i += 1) {
                    ptr_field->data.x_ptr.ptr[i] = op2_val->data.x_struct.fields[0]->data.x_ptr.ptr[op2_i];
                }

                return str_type;
            }
        case BinOpTypeInvalid:
            zig_unreachable();
    }
    zig_unreachable();
}

// Set name to nullptr to make the variable anonymous (not visible to programmer).
static VariableTableEntry *add_local_var(CodeGen *g, AstNode *source_node, BlockContext *context,
        Buf *name, TypeTableEntry *type_entry, bool is_const)
{
    VariableTableEntry *variable_entry = allocate<VariableTableEntry>(1);
    variable_entry->type = type_entry;

    if (name) {
        buf_init_from_buf(&variable_entry->name, name);
        VariableTableEntry *existing_var;

        if (context->fn_entry) {
            existing_var = find_local_variable(context, name);
        } else {
            existing_var = find_variable(context, name);
        }

        if (existing_var) {
            add_node_error(g, source_node, buf_sprintf("redeclaration of variable '%s'", buf_ptr(name)));
            variable_entry->type = g->builtin_types.entry_invalid;
        } else {
            auto primitive_table_entry = g->primitive_type_table.maybe_get(name);
            TypeTableEntry *type;
            if (primitive_table_entry) {
                type = primitive_table_entry->value;
            } else {
                type = find_container(context, name);
            }
            if (type) {
                add_node_error(g, source_node, buf_sprintf("variable shadows type '%s'", buf_ptr(&type->name)));
                variable_entry->type = g->builtin_types.entry_invalid;
            }
        }

        context->variable_table.put(&variable_entry->name, variable_entry);
        context->variable_list.append(variable_entry);
    } else {
        buf_init_from_str(&variable_entry->name, "_anon");
        context->variable_list.append(variable_entry);
    }

    variable_entry->is_const = is_const;
    variable_entry->is_ptr = true;
    variable_entry->decl_node = source_node;

    return variable_entry;
}

static TypeTableEntry *analyze_unwrap_error_expr(CodeGen *g, ImportTableEntry *import,
        BlockContext *parent_context, TypeTableEntry *expected_type, AstNode *node)
{
    AstNode *op1 = node->data.unwrap_err_expr.op1;
    AstNode *op2 = node->data.unwrap_err_expr.op2;
    AstNode *var_node = node->data.unwrap_err_expr.symbol;

    TypeTableEntry *lhs_type = analyze_expression(g, import, parent_context, nullptr, op1);
    if (lhs_type->id == TypeTableEntryIdInvalid) {
        return lhs_type;
    } else if (lhs_type->id == TypeTableEntryIdErrorUnion) {
        TypeTableEntry *child_type = lhs_type->data.error.child_type;
        BlockContext *child_context;
        if (var_node) {
            child_context = new_block_context(node, parent_context);
            var_node->block_context = child_context;
            Buf *var_name = &var_node->data.symbol_expr.symbol;
            node->data.unwrap_err_expr.var = add_local_var(g, var_node, child_context, var_name,
                    g->builtin_types.entry_pure_error, true);
        } else {
            child_context = parent_context;
        }

        analyze_expression(g, import, child_context, child_type, op2);
        return child_type;
    } else {
        add_node_error(g, op1,
            buf_sprintf("expected error type, got '%s'", buf_ptr(&lhs_type->name)));
        return g->builtin_types.entry_invalid;
    }
}


static VariableTableEntry *analyze_variable_declaration_raw(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, AstNode *source_node,
        AstNodeVariableDeclaration *variable_declaration,
        bool expr_is_maybe)
{
    bool is_const = variable_declaration->is_const;
    bool is_export = (variable_declaration->visib_mod == VisibModExport);
    bool is_extern = variable_declaration->is_extern;

    TypeTableEntry *explicit_type = nullptr;
    if (variable_declaration->type != nullptr) {
        explicit_type = analyze_type_expr(g, import, context, variable_declaration->type);
        if (explicit_type->id == TypeTableEntryIdUnreachable) {
            add_node_error(g, variable_declaration->type,
                buf_sprintf("variable of type 'unreachable' not allowed"));
            explicit_type = g->builtin_types.entry_invalid;
        }
    }

    TypeTableEntry *implicit_type = nullptr;
    if (variable_declaration->expr) {
        implicit_type = analyze_expression(g, import, context, explicit_type, variable_declaration->expr);
        if (implicit_type->id == TypeTableEntryIdInvalid) {
            // ignore the poison value
        } else if (expr_is_maybe) {
            if (implicit_type->id == TypeTableEntryIdMaybe) {
                implicit_type = implicit_type->data.maybe.child_type;
            } else {
                add_node_error(g, variable_declaration->expr, buf_sprintf("expected maybe type"));
                implicit_type = g->builtin_types.entry_invalid;
            }
        } else if (implicit_type->id == TypeTableEntryIdUnreachable) {
            add_node_error(g, source_node,
                buf_sprintf("variable initialization is unreachable"));
            implicit_type = g->builtin_types.entry_invalid;
        } else if ((!is_const || is_export) &&
                (implicit_type->id == TypeTableEntryIdNumLitFloat ||
                 implicit_type->id == TypeTableEntryIdNumLitInt))
        {
            add_node_error(g, source_node, buf_sprintf("unable to infer variable type"));
            implicit_type = g->builtin_types.entry_invalid;
        } else if (implicit_type->id == TypeTableEntryIdMetaType && !is_const) {
            add_node_error(g, source_node, buf_sprintf("variable of type 'type' must be constant"));
            implicit_type = g->builtin_types.entry_invalid;
        }
        if (implicit_type->id != TypeTableEntryIdInvalid && !context->fn_entry) {
            ConstExprValue *const_val = &get_resolved_expr(variable_declaration->expr)->const_val;
            if (!const_val->ok) {
                add_node_error(g, first_executing_node(variable_declaration->expr),
                        buf_sprintf("global variable initializer requires constant expression"));
            }
        }
    } else if (!is_extern) {
        add_node_error(g, source_node, buf_sprintf("variables must be initialized"));
        implicit_type = g->builtin_types.entry_invalid;
    }

    TypeTableEntry *type = explicit_type != nullptr ? explicit_type : implicit_type;
    assert(type != nullptr); // should have been caught by the parser

    VariableTableEntry *var = add_local_var(g, source_node, context,
            &variable_declaration->symbol, type, is_const);

    variable_declaration->variable = var;


    bool is_pub = (variable_declaration->visib_mod != VisibModPrivate);
    if (is_pub) {
        for (int i = 0; i < import->importers.length; i += 1) {
            ImporterInfo importer = import->importers.at(i);
            auto table_entry = importer.import->block_context->variable_table.maybe_get(&var->name);
            if (table_entry) {
                add_node_error(g, importer.source_node,
                    buf_sprintf("import of variable '%s' overrides existing definition",
                        buf_ptr(&var->name)));
            } else {
                importer.import->block_context->variable_table.put(&var->name, var);
            }
        }
    }

    return var;
}

static VariableTableEntry *analyze_variable_declaration(CodeGen *g, ImportTableEntry *import,
        BlockContext *context, TypeTableEntry *expected_type, AstNode *node)
{
    AstNodeVariableDeclaration *variable_declaration = &node->data.variable_declaration;
    return analyze_variable_declaration_raw(g, import, context, node, variable_declaration, false);
}

static TypeTableEntry *analyze_null_literal_expr(CodeGen *g, ImportTableEntry *import,
        BlockContext *block_context, TypeTableEntry *expected_type, AstNode *node)
{
    assert(node->type == NodeTypeNullLiteral);

    if (!expected_type) {
        add_node_error(g, node,
                buf_sprintf("unable to determine null type"));
        return g->builtin_types.entry_invalid;
    }

    assert(expected_type->id == TypeTableEntryIdMaybe);

    node->data.null_literal.resolved_struct_val_expr.type_entry = expected_type;
    node->data.null_literal.resolved_struct_val_expr.source_node = node;
    block_context->struct_val_expr_alloca_list.append(&node->data.null_literal.resolved_struct_val_expr);

    return resolve_expr_const_val_as_null(g, node, expected_type);
}

static TypeTableEntry *analyze_undefined_literal_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    Expr *expr = get_resolved_expr(node);
    ConstExprValue *const_val = &expr->const_val;

    const_val->ok = true;
    const_val->undef = true;

    return expected_type ? expected_type : g->builtin_types.entry_undef;
}


static TypeTableEntry *analyze_number_literal_expr(CodeGen *g, ImportTableEntry *import,
        BlockContext *block_context, TypeTableEntry *expected_type, AstNode *node)
{
    if (node->data.number_literal.overflow) {
        add_node_error(g, node, buf_sprintf("number literal too large to be represented in any type"));
        return g->builtin_types.entry_invalid;
    }

    if (node->data.number_literal.kind == NumLitUInt) {
        return resolve_expr_const_val_as_unsigned_num_lit(g, node,
                expected_type, node->data.number_literal.data.x_uint);
    } else if (node->data.number_literal.kind == NumLitFloat) {
        return resolve_expr_const_val_as_float_num_lit(g, node,
                expected_type, node->data.number_literal.data.x_float);
    } else {
        zig_unreachable();
    }
}

static TypeTableEntry *analyze_array_type(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    AstNode *size_node = node->data.array_type.size;

    TypeTableEntry *child_type = analyze_type_expr(g, import, context, node->data.array_type.child_type);

    if (child_type->id == TypeTableEntryIdUnreachable) {
        add_node_error(g, node, buf_create_from_str("array of unreachable not allowed"));
        return g->builtin_types.entry_invalid;
    } else if (child_type->id == TypeTableEntryIdInvalid) {
        return g->builtin_types.entry_invalid;
    }

    if (size_node) {
        TypeTableEntry *size_type = analyze_expression(g, import, context,
                g->builtin_types.entry_isize, size_node);
        if (size_type->id == TypeTableEntryIdInvalid) {
            return g->builtin_types.entry_invalid;
        }

        ConstExprValue *const_val = &get_resolved_expr(size_node)->const_val;
        if (const_val->ok) {
            if (const_val->data.x_bignum.is_negative) {
                add_node_error(g, size_node,
                    buf_sprintf("array size %s is negative",
                        buf_ptr(bignum_to_buf(&const_val->data.x_bignum))));
                return g->builtin_types.entry_invalid;
            } else {
                return resolve_expr_const_val_as_type(g, node,
                        get_array_type(g, child_type, const_val->data.x_bignum.data.x_uint));
            }
        } else {
            return resolve_expr_const_val_as_type(g, node,
                    get_unknown_size_array_type(g, child_type, node->data.array_type.is_const));
        }
    } else {
        return resolve_expr_const_val_as_type(g, node,
                get_unknown_size_array_type(g, child_type, node->data.array_type.is_const));
    }
}

static TypeTableEntry *analyze_fn_proto_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    TypeTableEntry *type_entry = analyze_fn_proto_type(g, import, context, expected_type, node, false);

    if (type_entry->id == TypeTableEntryIdInvalid) {
        return type_entry;
    }

    return resolve_expr_const_val_as_type(g, node, type_entry);
}

static TypeTableEntry *analyze_while_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    assert(node->type == NodeTypeWhileExpr);

    AstNode *condition_node = node->data.while_expr.condition;
    AstNode *while_body_node = node->data.while_expr.body;

    TypeTableEntry *condition_type = analyze_expression(g, import, context,
            g->builtin_types.entry_bool, condition_node);

    BlockContext *child_context = new_block_context(node, context);
    child_context->parent_loop_node = node;
    node->data.while_expr.block_context = child_context;

    analyze_expression(g, import, child_context, g->builtin_types.entry_void, while_body_node);


    TypeTableEntry *expr_return_type = g->builtin_types.entry_void;

    if (condition_type->id == TypeTableEntryIdInvalid) {
        expr_return_type = g->builtin_types.entry_invalid;
    } else {
        // if the condition is a simple constant expression and there are no break statements
        // then the return type is unreachable
        ConstExprValue *const_val = &get_resolved_expr(condition_node)->const_val;
        if (const_val->ok) {
            if (const_val->data.x_bool) {
                node->data.while_expr.condition_always_true = true;
                if (!node->data.while_expr.contains_break) {
                    expr_return_type = g->builtin_types.entry_unreachable;
                }
            }
        }
    }

    return expr_return_type;
}

static TypeTableEntry *analyze_for_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    assert(node->type == NodeTypeForExpr);

    AstNode *array_node = node->data.for_expr.array_expr;
    TypeTableEntry *array_type = analyze_expression(g, import, context, nullptr, array_node);
    TypeTableEntry *child_type;
    if (array_type->id == TypeTableEntryIdInvalid) {
        child_type = array_type;
    } else if (array_type->id == TypeTableEntryIdArray) {
        child_type = array_type->data.array.child_type;
    } else if (array_type->id == TypeTableEntryIdStruct &&
               array_type->data.structure.is_unknown_size_array)
    {
        TypeTableEntry *pointer_type = array_type->data.structure.fields[0].type_entry;
        assert(pointer_type->id == TypeTableEntryIdPointer);
        child_type = pointer_type->data.pointer.child_type;
    } else {
        add_node_error(g, node,
            buf_sprintf("iteration over non array type '%s'", buf_ptr(&array_type->name)));
        child_type = g->builtin_types.entry_invalid;
    }

    BlockContext *child_context = new_block_context(node, context);

    AstNode *elem_var_node = node->data.for_expr.elem_node;
    elem_var_node->block_context = child_context;
    Buf *elem_var_name = &elem_var_node->data.symbol_expr.symbol;
    node->data.for_expr.elem_var = add_local_var(g, elem_var_node, child_context, elem_var_name, child_type, true);

    AstNode *index_var_node = node->data.for_expr.index_node;
    if (index_var_node) {
        Buf *index_var_name = &index_var_node->data.symbol_expr.symbol;
        index_var_node->block_context = child_context;
        node->data.for_expr.index_var = add_local_var(g, index_var_node, child_context, index_var_name,
                g->builtin_types.entry_isize, true);
    } else {
        node->data.for_expr.index_var = add_local_var(g, node, child_context, nullptr,
                g->builtin_types.entry_isize, true);
    }

    AstNode *for_body_node = node->data.for_expr.body;
    analyze_expression(g, import, child_context, g->builtin_types.entry_void, for_body_node);


    return g->builtin_types.entry_void;
}

static TypeTableEntry *analyze_break_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    assert(node->type == NodeTypeBreak);

    AstNode *loop_node = context->parent_loop_node;
    if (loop_node) {
        assert(loop_node->type == NodeTypeWhileExpr);
        loop_node->data.while_expr.contains_break = true;
    } else {
        add_node_error(g, node, buf_sprintf("'break' expression outside loop"));
    }
    return g->builtin_types.entry_unreachable;
}

static TypeTableEntry *analyze_continue_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    if (!context->parent_loop_node) {
        add_node_error(g, node, buf_sprintf("'continue' expression outside loop"));
    }
    return g->builtin_types.entry_unreachable;
}

static TypeTableEntry *analyze_if_then_else(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *then_block, AstNode *else_node, AstNode *parent_node)
{
    TypeTableEntry *then_type = analyze_expression(g, import, context, expected_type, then_block);

    TypeTableEntry *else_type;
    if (else_node) {
        else_type = analyze_expression(g, import, context, expected_type, else_node);
    } else {
        else_type = resolve_type_compatibility(g, import, context, parent_node, expected_type,
                g->builtin_types.entry_void);
    }


    if (expected_type) {
        return (then_type->id == TypeTableEntryIdUnreachable) ? else_type : then_type;
    } else {
        AstNode *op_nodes[] = {then_block, else_node};
        TypeTableEntry *op_types[] = {then_type, else_type};
        return resolve_peer_type_compatibility(g, import, context, parent_node, op_nodes, op_types, 2);
    }
}

static TypeTableEntry *analyze_if_bool_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    analyze_expression(g, import, context, g->builtin_types.entry_bool, node->data.if_bool_expr.condition);

    return analyze_if_then_else(g, import, context, expected_type,
            node->data.if_bool_expr.then_block,
            node->data.if_bool_expr.else_node,
            node);
}

static TypeTableEntry *analyze_if_var_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    assert(node->type == NodeTypeIfVarExpr);

    BlockContext *child_context = new_block_context(node, context);

    analyze_variable_declaration_raw(g, import, child_context, node, &node->data.if_var_expr.var_decl, true);

    return analyze_if_then_else(g, import, child_context, expected_type,
            node->data.if_var_expr.then_block, node->data.if_var_expr.else_node, node);
}

static TypeTableEntry *analyze_min_max_value(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node, const char *err_format, bool is_max)
{
    assert(node->type == NodeTypeFnCallExpr);
    assert(node->data.fn_call_expr.params.length == 1);

    AstNode *type_node = node->data.fn_call_expr.params.at(0);
    TypeTableEntry *type_entry = analyze_type_expr(g, import, context, type_node);
    if (type_entry->id == TypeTableEntryIdInvalid) {
        return g->builtin_types.entry_invalid;
    } else if (type_entry->id == TypeTableEntryIdInt) {
        ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
        const_val->ok = true;
        if (is_max) {
            if (type_entry->data.integral.is_signed) {
                int64_t val;
                if (type_entry->size_in_bits == 64) {
                    val = INT64_MAX;
                } else if (type_entry->size_in_bits == 32) {
                    val = INT32_MAX;
                } else if (type_entry->size_in_bits == 16) {
                    val = INT16_MAX;
                } else if (type_entry->size_in_bits == 8) {
                    val = INT8_MAX;
                } else {
                    zig_unreachable();
                }
                bignum_init_signed(&const_val->data.x_bignum, val);
            } else {
                uint64_t val;
                if (type_entry->size_in_bits == 64) {
                    val = UINT64_MAX;
                } else if (type_entry->size_in_bits == 32) {
                    val = UINT32_MAX;
                } else if (type_entry->size_in_bits == 16) {
                    val = UINT16_MAX;
                } else if (type_entry->size_in_bits == 8) {
                    val = UINT8_MAX;
                } else {
                    zig_unreachable();
                }
                bignum_init_unsigned(&const_val->data.x_bignum, val);
            }
        } else {
            if (type_entry->data.integral.is_signed) {
                int64_t val;
                if (type_entry->size_in_bits == 64) {
                    val = INT64_MIN;
                } else if (type_entry->size_in_bits == 32) {
                    val = INT32_MIN;
                } else if (type_entry->size_in_bits == 16) {
                    val = INT16_MIN;
                } else if (type_entry->size_in_bits == 8) {
                    val = INT8_MIN;
                } else {
                    zig_unreachable();
                }
                bignum_init_signed(&const_val->data.x_bignum, val);
            } else {
                bignum_init_unsigned(&const_val->data.x_bignum, 0);
            }
        }
        return type_entry;
    } else if (type_entry->id == TypeTableEntryIdFloat) {
        zig_panic("TODO analyze_min_max_value float");
        return type_entry;
    } else if (type_entry->id == TypeTableEntryIdBool) {
        return resolve_expr_const_val_as_bool(g, node, is_max);
    } else {
        add_node_error(g, node,
                buf_sprintf(err_format, buf_ptr(&type_entry->name)));
        return g->builtin_types.entry_invalid;
    }
}

static void eval_const_expr_implicit_cast(CodeGen *g, AstNode *node, AstNode *expr_node) {
    assert(node->type == NodeTypeFnCallExpr);
    ConstExprValue *other_val = &get_resolved_expr(expr_node)->const_val;
    ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
    if (!other_val->ok) {
        return;
    }
    assert(other_val != const_val);
    switch (node->data.fn_call_expr.cast_op) {
        case CastOpNoCast:
            zig_unreachable();
        case CastOpNoop:
        case CastOpIntWidenOrShorten:
        case CastOpPointerReinterpret:
            *const_val = *other_val;
            break;
        case CastOpPtrToInt:
        case CastOpIntToPtr:
            // can't do it
            break;
        case CastOpToUnknownSizeArray:
            {
                TypeTableEntry *other_type = get_resolved_expr(expr_node)->type_entry;
                assert(other_type->id == TypeTableEntryIdArray);

                ConstExprValue *all_fields = allocate<ConstExprValue>(2);
                ConstExprValue *ptr_field = &all_fields[0];
                ConstExprValue *len_field = &all_fields[1];

                const_val->data.x_struct.fields = allocate<ConstExprValue*>(2);
                const_val->data.x_struct.fields[0] = ptr_field;
                const_val->data.x_struct.fields[1] = len_field;

                ptr_field->ok = true;
                ptr_field->data.x_ptr.ptr = other_val->data.x_array.fields;
                ptr_field->data.x_ptr.len = other_type->data.array.len;

                len_field->ok = true;
                bignum_init_unsigned(&len_field->data.x_bignum, other_type->data.array.len);

                const_val->ok = true;
                break;
            }
        case CastOpMaybeWrap:
            const_val->data.x_maybe = other_val;
            const_val->ok = true;
            break;
        case CastOpErrorWrap:
            const_val->data.x_err.err = nullptr;
            const_val->data.x_err.payload = other_val;
            const_val->ok = true;
            break;
        case CastOpPureErrorWrap:
            const_val->data.x_err.err = other_val->data.x_err.err;
            const_val->ok = true;
            break;
        case CastOpErrToInt:
            {
                uint64_t value = other_val->data.x_err.err ? other_val->data.x_err.err->value : 0;
                bignum_init_unsigned(&const_val->data.x_bignum, value);
                const_val->ok = true;
                break;
            }
    }
}

static TypeTableEntry *analyze_cast_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        AstNode *node)
{
    assert(node->type == NodeTypeFnCallExpr);

    AstNode *fn_ref_expr = node->data.fn_call_expr.fn_ref_expr;
    int actual_param_count = node->data.fn_call_expr.params.length;

    if (actual_param_count != 1) {
        add_node_error(g, fn_ref_expr, buf_sprintf("cast expression expects exactly one parameter"));
        return g->builtin_types.entry_invalid;
    }

    AstNode *expr_node = node->data.fn_call_expr.params.at(0);
    TypeTableEntry *wanted_type = resolve_type(g, fn_ref_expr);
    TypeTableEntry *actual_type = analyze_expression(g, import, context, nullptr, expr_node);

    if (wanted_type->id == TypeTableEntryIdInvalid ||
        actual_type->id == TypeTableEntryIdInvalid)
    {
        return g->builtin_types.entry_invalid;
    }

    // explicit match or non-const to const
    if (types_match_const_cast_only(wanted_type, actual_type)) {
        node->data.fn_call_expr.cast_op = CastOpNoop;
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }

    // explicit cast from pointer to isize or usize
    if ((wanted_type == g->builtin_types.entry_isize || wanted_type == g->builtin_types.entry_usize) &&
        actual_type->id == TypeTableEntryIdPointer)
    {
        node->data.fn_call_expr.cast_op = CastOpPtrToInt;
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }


    // explicit cast from isize or usize to pointer
    if (wanted_type->id == TypeTableEntryIdPointer &&
        (actual_type == g->builtin_types.entry_isize || actual_type == g->builtin_types.entry_usize))
    {
        node->data.fn_call_expr.cast_op = CastOpIntToPtr;
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }

    // explicit cast from any int to any other int
    if (wanted_type->id == TypeTableEntryIdInt &&
        actual_type->id == TypeTableEntryIdInt)
    {
        node->data.fn_call_expr.cast_op = CastOpIntWidenOrShorten;
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }

    // explicit cast from fixed size array to unknown size array
    if (wanted_type->id == TypeTableEntryIdStruct &&
        wanted_type->data.structure.is_unknown_size_array &&
        actual_type->id == TypeTableEntryIdArray &&
        types_match_const_cast_only(
            wanted_type->data.structure.fields[0].type_entry->data.pointer.child_type,
            actual_type->data.array.child_type))
    {
        node->data.fn_call_expr.cast_op = CastOpToUnknownSizeArray;
        context->cast_alloca_list.append(node);
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }

    // explicit cast from pointer to another pointer
    if (actual_type->id == TypeTableEntryIdPointer &&
        wanted_type->id == TypeTableEntryIdPointer)
    {
        node->data.fn_call_expr.cast_op = CastOpPointerReinterpret;
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }

    // explicit cast from child type of maybe type to maybe type
    if (wanted_type->id == TypeTableEntryIdMaybe) {
        if (types_match_const_cast_only(wanted_type->data.maybe.child_type, actual_type)) {
            node->data.fn_call_expr.cast_op = CastOpMaybeWrap;
            context->cast_alloca_list.append(node);
            eval_const_expr_implicit_cast(g, node, expr_node);
            return wanted_type;
        } else if (actual_type->id == TypeTableEntryIdNumLitInt ||
                   actual_type->id == TypeTableEntryIdNumLitFloat)
        {
            if (num_lit_fits_in_other_type(g, expr_node, wanted_type->data.maybe.child_type)) {
                node->data.fn_call_expr.cast_op = CastOpMaybeWrap;
                context->cast_alloca_list.append(node);
                eval_const_expr_implicit_cast(g, node, expr_node);
                return wanted_type;
            } else {
                return g->builtin_types.entry_invalid;
            }
        }
    }

    // explicit cast from child type of error type to error type
    if (wanted_type->id == TypeTableEntryIdErrorUnion) {
        if (types_match_const_cast_only(wanted_type->data.error.child_type, actual_type)) {
            node->data.fn_call_expr.cast_op = CastOpErrorWrap;
            context->cast_alloca_list.append(node);
            eval_const_expr_implicit_cast(g, node, expr_node);
            return wanted_type;
        } else if (actual_type->id == TypeTableEntryIdNumLitInt ||
                   actual_type->id == TypeTableEntryIdNumLitFloat)
        {
            if (num_lit_fits_in_other_type(g, expr_node, wanted_type->data.error.child_type)) {
                node->data.fn_call_expr.cast_op = CastOpErrorWrap;
                context->cast_alloca_list.append(node);
                eval_const_expr_implicit_cast(g, node, expr_node);
                return wanted_type;
            } else {
                return g->builtin_types.entry_invalid;
            }
        }
    }

    // explicit cast from pure error to error union type
    if (wanted_type->id == TypeTableEntryIdErrorUnion &&
        actual_type->id == TypeTableEntryIdPureError)
    {
        node->data.fn_call_expr.cast_op = CastOpPureErrorWrap;
        eval_const_expr_implicit_cast(g, node, expr_node);
        return wanted_type;
    }

    // explicit cast from number literal to another type
    if (actual_type->id == TypeTableEntryIdNumLitFloat ||
        actual_type->id == TypeTableEntryIdNumLitInt)
    {
        if (num_lit_fits_in_other_type(g, expr_node, wanted_type)) {
            node->data.fn_call_expr.cast_op = CastOpNoop;
            eval_const_expr_implicit_cast(g, node, expr_node);
            return wanted_type;
        } else {
            return g->builtin_types.entry_invalid;
        }
    }

    // explicit cast from %void to integer type which can fit it
    bool actual_type_is_void_err = actual_type->id == TypeTableEntryIdErrorUnion &&
        actual_type->data.error.child_type->size_in_bits == 0;
    bool actual_type_is_pure_err = actual_type->id == TypeTableEntryIdPureError;
    if ((actual_type_is_void_err || actual_type_is_pure_err) &&
        wanted_type->id == TypeTableEntryIdInt)
    {
        BigNum bn;
        bignum_init_unsigned(&bn, g->error_value_count);
        if (bignum_fits_in_bits(&bn, wanted_type->size_in_bits, wanted_type->data.integral.is_signed)) {
            node->data.fn_call_expr.cast_op = CastOpErrToInt;
            eval_const_expr_implicit_cast(g, node, expr_node);
            return wanted_type;
        } else {
            add_node_error(g, node,
                    buf_sprintf("too many error values to fit in '%s'", buf_ptr(&wanted_type->name)));
            return g->builtin_types.entry_invalid;
        }
    }

    add_node_error(g, node,
        buf_sprintf("invalid cast from type '%s' to '%s'",
            buf_ptr(&actual_type->name),
            buf_ptr(&wanted_type->name)));
    return g->builtin_types.entry_invalid;
}

static TypeTableEntry *analyze_builtin_fn_call_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    assert(node->type == NodeTypeFnCallExpr);

    AstNode *fn_ref_expr = node->data.fn_call_expr.fn_ref_expr;
    Buf *name = &fn_ref_expr->data.symbol_expr.symbol;

    auto entry = g->builtin_fn_table.maybe_get(name);

    if (!entry) {
        add_node_error(g, node,
                buf_sprintf("invalid builtin function: '%s'", buf_ptr(name)));
        return g->builtin_types.entry_invalid;
    }

    BuiltinFnEntry *builtin_fn = entry->value;
    int actual_param_count = node->data.fn_call_expr.params.length;

    node->data.fn_call_expr.builtin_fn = builtin_fn;

    if (builtin_fn->param_count != actual_param_count) {
        add_node_error(g, node,
                buf_sprintf("expected %d arguments, got %d",
                    builtin_fn->param_count, actual_param_count));
        return g->builtin_types.entry_invalid;
    }

    switch (builtin_fn->id) {
        case BuiltinFnIdInvalid:
            zig_unreachable();
        case BuiltinFnIdAddWithOverflow:
        case BuiltinFnIdSubWithOverflow:
        case BuiltinFnIdMulWithOverflow:
            {
                AstNode *type_node = node->data.fn_call_expr.params.at(0);
                TypeTableEntry *int_type = analyze_type_expr(g, import, context, type_node);
                if (int_type->id == TypeTableEntryIdInvalid) {
                    return g->builtin_types.entry_bool;
                } else if (int_type->id == TypeTableEntryIdInt) {
                    AstNode *op1_node = node->data.fn_call_expr.params.at(1);
                    AstNode *op2_node = node->data.fn_call_expr.params.at(2);
                    AstNode *result_node = node->data.fn_call_expr.params.at(3);

                    analyze_expression(g, import, context, int_type, op1_node);
                    analyze_expression(g, import, context, int_type, op2_node);
                    analyze_expression(g, import, context, get_pointer_to_type(g, int_type, false),
                            result_node);
                } else {
                    add_node_error(g, type_node,
                        buf_sprintf("expected integer type, got '%s'", buf_ptr(&int_type->name)));
                }

                // TODO constant expression evaluation

                return g->builtin_types.entry_bool;
            }
        case BuiltinFnIdMemcpy:
            {
                AstNode *dest_node = node->data.fn_call_expr.params.at(0);
                AstNode *src_node = node->data.fn_call_expr.params.at(1);
                AstNode *len_node = node->data.fn_call_expr.params.at(2);
                TypeTableEntry *dest_type = analyze_expression(g, import, context, nullptr, dest_node);
                TypeTableEntry *src_type = analyze_expression(g, import, context, nullptr, src_node);
                analyze_expression(g, import, context, builtin_fn->param_types[2], len_node);

                if (dest_type->id != TypeTableEntryIdInvalid &&
                    dest_type->id != TypeTableEntryIdPointer)
                {
                    add_node_error(g, dest_node,
                            buf_sprintf("expected pointer argument, got '%s'", buf_ptr(&dest_type->name)));
                }

                if (src_type->id != TypeTableEntryIdInvalid &&
                    src_type->id != TypeTableEntryIdPointer)
                {
                    add_node_error(g, src_node,
                            buf_sprintf("expected pointer argument, got '%s'", buf_ptr(&src_type->name)));
                }

                if (dest_type->id == TypeTableEntryIdPointer &&
                    src_type->id == TypeTableEntryIdPointer)
                {
                    uint64_t dest_align_bits = dest_type->data.pointer.child_type->align_in_bits;
                    uint64_t src_align_bits = src_type->data.pointer.child_type->align_in_bits;
                    if (dest_align_bits != src_align_bits) {
                        add_node_error(g, dest_node, buf_sprintf(
                            "misaligned memcpy, '%s' has alignment '%" PRIu64 ", '%s' has alignment %" PRIu64,
                                    buf_ptr(&dest_type->name), dest_align_bits / 8,
                                    buf_ptr(&src_type->name), src_align_bits / 8));
                    }
                }

                return builtin_fn->return_type;
            }
        case BuiltinFnIdMemset:
            {
                AstNode *dest_node = node->data.fn_call_expr.params.at(0);
                AstNode *char_node = node->data.fn_call_expr.params.at(1);
                AstNode *len_node = node->data.fn_call_expr.params.at(2);
                TypeTableEntry *dest_type = analyze_expression(g, import, context, nullptr, dest_node);
                analyze_expression(g, import, context, builtin_fn->param_types[1], char_node);
                analyze_expression(g, import, context, builtin_fn->param_types[2], len_node);

                if (dest_type->id != TypeTableEntryIdInvalid &&
                    dest_type->id != TypeTableEntryIdPointer)
                {
                    add_node_error(g, dest_node,
                            buf_sprintf("expected pointer argument, got '%s'", buf_ptr(&dest_type->name)));
                }

                return builtin_fn->return_type;
            }
        case BuiltinFnIdSizeof:
            {
                AstNode *type_node = node->data.fn_call_expr.params.at(0);
                TypeTableEntry *type_entry = analyze_type_expr(g, import, context, type_node);
                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return g->builtin_types.entry_invalid;
                } else if (type_entry->id == TypeTableEntryIdUnreachable) {
                    add_node_error(g, first_executing_node(type_node),
                            buf_sprintf("no size available for type '%s'", buf_ptr(&type_entry->name)));
                    return g->builtin_types.entry_invalid;
                } else {
                    uint64_t size_in_bytes = type_entry->size_in_bits / 8;
                    return resolve_expr_const_val_as_unsigned_num_lit(g, node, expected_type, size_in_bytes);
                }
            }
        case BuiltinFnIdMaxValue:
            return analyze_min_max_value(g, import, context, node,
                    "no max value available for type '%s'", true);
        case BuiltinFnIdMinValue:
            return analyze_min_max_value(g, import, context, node,
                    "no min value available for type '%s'", false);
        case BuiltinFnIdMemberCount:
            {
                AstNode *type_node = node->data.fn_call_expr.params.at(0);
                TypeTableEntry *type_entry = analyze_type_expr(g, import, context, type_node);

                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return type_entry;
                } else if (type_entry->id == TypeTableEntryIdEnum) {
                    uint64_t value_count = type_entry->data.enumeration.field_count;
                    return resolve_expr_const_val_as_unsigned_num_lit(g, node, expected_type, value_count);
                } else {
                    add_node_error(g, node,
                            buf_sprintf("no value count available for type '%s'", buf_ptr(&type_entry->name)));
                    return g->builtin_types.entry_invalid;
                }
            }
        case BuiltinFnIdTypeof:
            {
                AstNode *expr_node = node->data.fn_call_expr.params.at(0);
                TypeTableEntry *type_entry = analyze_expression(g, import, context, nullptr, expr_node);

                switch (type_entry->id) {
                    case TypeTableEntryIdInvalid:
                        return type_entry;
                    case TypeTableEntryIdNumLitFloat:
                    case TypeTableEntryIdNumLitInt:
                    case TypeTableEntryIdUndefLit:
                        add_node_error(g, expr_node,
                                buf_sprintf("type '%s' not eligible for @typeof", buf_ptr(&type_entry->name)));
                        return g->builtin_types.entry_invalid;
                    case TypeTableEntryIdMetaType:
                    case TypeTableEntryIdVoid:
                    case TypeTableEntryIdBool:
                    case TypeTableEntryIdUnreachable:
                    case TypeTableEntryIdInt:
                    case TypeTableEntryIdFloat:
                    case TypeTableEntryIdPointer:
                    case TypeTableEntryIdArray:
                    case TypeTableEntryIdStruct:
                    case TypeTableEntryIdMaybe:
                    case TypeTableEntryIdErrorUnion:
                    case TypeTableEntryIdPureError:
                    case TypeTableEntryIdEnum:
                    case TypeTableEntryIdFn:
                    case TypeTableEntryIdTypeDecl:
                        return resolve_expr_const_val_as_type(g, node, type_entry);
                }
            }
        case BuiltinFnIdCInclude:
            {
                if (!context->c_import_buf) {
                    add_node_error(g, node, buf_sprintf("@c_include valid only in c_import blocks"));
                    return g->builtin_types.entry_invalid;
                }

                AstNode **str_node = node->data.fn_call_expr.params.at(0)->parent_field;
                TypeTableEntry *str_type = get_unknown_size_array_type(g, g->builtin_types.entry_u8, true);
                TypeTableEntry *resolved_type = analyze_expression(g, import, context, str_type, *str_node);

                if (resolved_type->id == TypeTableEntryIdInvalid) {
                    return resolved_type;
                }

                ConstExprValue *const_str_val = &get_resolved_expr(*str_node)->const_val;

                if (!const_str_val->ok) {
                    add_node_error(g, *str_node, buf_sprintf("@c_include requires constant expression"));
                    return g->builtin_types.entry_void;
                }

                buf_appendf(context->c_import_buf, "#include <");
                ConstExprValue *ptr_field = const_str_val->data.x_struct.fields[0];
                uint64_t len = ptr_field->data.x_ptr.len;
                for (uint64_t i = 0; i < len; i += 1) {
                    ConstExprValue *char_val = ptr_field->data.x_ptr.ptr[i];
                    uint64_t big_c = char_val->data.x_bignum.data.x_uint;
                    assert(big_c <= UINT8_MAX);
                    uint8_t c = big_c;
                    buf_appendf(context->c_import_buf, "%c", c);
                }
                buf_appendf(context->c_import_buf, ">\n");

                return g->builtin_types.entry_void;
            }
        case BuiltinFnIdCDefine:
            zig_panic("TODO");
        case BuiltinFnIdCUndef:
            zig_panic("TODO");

    }
    zig_unreachable();
}

static TypeTableEntry *analyze_fn_call_ptr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node, TypeTableEntry *fn_type, TypeTableEntry *struct_type)
{
    assert(node->type == NodeTypeFnCallExpr);

    // count parameters
    int src_param_count = fn_type->data.fn.fn_type_id.param_count;
    int actual_param_count = node->data.fn_call_expr.params.length;

    if (struct_type) {
        actual_param_count += 1;
    }

    if (fn_type->data.fn.fn_type_id.is_var_args) {
        if (actual_param_count < src_param_count) {
            add_node_error(g, node,
                buf_sprintf("expected at least %d arguments, got %d", src_param_count, actual_param_count));
        }
    } else if (src_param_count != actual_param_count) {
        add_node_error(g, node,
                buf_sprintf("expected %d arguments, got %d", src_param_count, actual_param_count));
    }

    // analyze each parameter. in the case of a method, we already analyzed the
    // first parameter in order to figure out which struct we were calling a method on.
    for (int i = 0; i < node->data.fn_call_expr.params.length; i += 1) {
        AstNode *child = node->data.fn_call_expr.params.at(i);
        // determine the expected type for each parameter
        TypeTableEntry *expected_param_type = nullptr;
        int fn_proto_i = i + (struct_type ? 1 : 0);
        if (fn_proto_i < src_param_count) {
            expected_param_type = fn_type->data.fn.fn_type_id.param_info[fn_proto_i].type;
        }
        analyze_expression(g, import, context, expected_param_type, child);
    }

    TypeTableEntry *return_type = fn_type->data.fn.fn_type_id.return_type;

    if (return_type->id == TypeTableEntryIdInvalid) {
        return return_type;
    }

    if (handle_is_ptr(return_type)) {
        context->cast_alloca_list.append(node);
    }

    return return_type;
}

static TypeTableEntry *analyze_fn_call_raw(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node, FnTableEntry *fn_table_entry, TypeTableEntry *struct_type)
{
    assert(node->type == NodeTypeFnCallExpr);

    node->data.fn_call_expr.fn_entry = fn_table_entry;

    return analyze_fn_call_ptr(g, import, context, expected_type, node, fn_table_entry->type_entry, struct_type);

}

static TypeTableEntry *analyze_fn_call_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    AstNode *fn_ref_expr = node->data.fn_call_expr.fn_ref_expr;

    if (node->data.fn_call_expr.is_builtin) {
        return analyze_builtin_fn_call_expr(g, import, context, expected_type, node);
    }

    if (fn_ref_expr->type == NodeTypeFieldAccessExpr) {
        fn_ref_expr->block_context = context;
        AstNode *first_param_expr = fn_ref_expr->data.field_access_expr.struct_expr;
        TypeTableEntry *struct_type = analyze_expression(g, import, context, nullptr, first_param_expr);
        Buf *name = &fn_ref_expr->data.field_access_expr.field_name;
        if (struct_type->id == TypeTableEntryIdStruct ||
            (struct_type->id == TypeTableEntryIdPointer &&
            struct_type->data.pointer.child_type->id == TypeTableEntryIdStruct))
        {
            TypeTableEntry *bare_struct_type = (struct_type->id == TypeTableEntryIdStruct) ?
                struct_type : struct_type->data.pointer.child_type;

            auto table_entry = bare_struct_type->data.structure.fn_table.maybe_get(name);
            if (table_entry) {
                return analyze_fn_call_raw(g, import, context, expected_type, node,
                        table_entry->value, bare_struct_type);
            } else {
                add_node_error(g, fn_ref_expr,
                        buf_sprintf("no function named '%s' in '%s'",
                            buf_ptr(name), buf_ptr(&bare_struct_type->name)));
                // still analyze the parameters, even though we don't know what to expect
                for (int i = 0; i < node->data.fn_call_expr.params.length; i += 1) {
                    AstNode *child = node->data.fn_call_expr.params.at(i);
                    analyze_expression(g, import, context, nullptr, child);
                }

                return g->builtin_types.entry_invalid;
            }
        } else if (struct_type->id == TypeTableEntryIdInvalid) {
            return struct_type;
        } else if (struct_type->id == TypeTableEntryIdMetaType) {
            TypeTableEntry *child_type = resolve_type(g, first_param_expr);

            if (child_type->id == TypeTableEntryIdInvalid) {
                return g->builtin_types.entry_invalid;
            } else if (child_type->id == TypeTableEntryIdEnum) {
                Buf *field_name = &fn_ref_expr->data.field_access_expr.field_name;
                int param_count = node->data.fn_call_expr.params.length;
                if (param_count > 1) {
                    add_node_error(g, first_executing_node(node->data.fn_call_expr.params.at(1)),
                            buf_sprintf("enum values accept only one parameter"));
                    return child_type;
                } else {
                    AstNode *value_node;
                    if (param_count == 1) {
                        value_node = node->data.fn_call_expr.params.at(0);
                    } else {
                        value_node = nullptr;
                    }

                    return analyze_enum_value_expr(g, import, context, fn_ref_expr, value_node,
                            child_type, field_name);
                }
            } else if (child_type->id == TypeTableEntryIdStruct) {
                Buf *field_name = &fn_ref_expr->data.field_access_expr.field_name;
                auto entry = child_type->data.structure.fn_table.maybe_get(field_name);
                if (entry) {
                    return analyze_fn_call_raw(g, import, context, expected_type, node,
                            entry->value, nullptr);
                } else {
                    add_node_error(g, node,
                        buf_sprintf("struct '%s' has no function called '%s'",
                            buf_ptr(&child_type->name), buf_ptr(field_name)));
                    return g->builtin_types.entry_invalid;
                }
            } else {
                add_node_error(g, first_param_expr, buf_sprintf("member reference base type not struct or enum"));
                return g->builtin_types.entry_invalid;
            }
        } else {
            add_node_error(g, first_param_expr, buf_sprintf("member reference base type not struct or enum"));
            return g->builtin_types.entry_invalid;
        }
    }

    TypeTableEntry *invoke_type_entry = analyze_expression(g, import, context, nullptr, fn_ref_expr);
    if (invoke_type_entry->id == TypeTableEntryIdInvalid) {
        return g->builtin_types.entry_invalid;
    }

    // use constant expression evaluator to figure out the function at compile time.
    // otherwise we treat this as a function pointer.
    ConstExprValue *const_val = &get_resolved_expr(fn_ref_expr)->const_val;

    if (const_val->ok) {
        if (invoke_type_entry->id == TypeTableEntryIdMetaType) {
            return analyze_cast_expr(g, import, context, node);
        } else if (invoke_type_entry->id == TypeTableEntryIdFn) {
            return analyze_fn_call_raw(g, import, context, expected_type, node, const_val->data.x_fn, nullptr);
        } else {
            add_node_error(g, fn_ref_expr,
                buf_sprintf("type '%s' not a function", buf_ptr(&invoke_type_entry->name)));
            return g->builtin_types.entry_invalid;
        }
    }

    // function pointer
    if (invoke_type_entry->id == TypeTableEntryIdFn) {
        return analyze_fn_call_ptr(g, import, context, expected_type, node, invoke_type_entry, nullptr);
    } else {
        add_node_error(g, fn_ref_expr,
            buf_sprintf("type '%s' not a function", buf_ptr(&invoke_type_entry->name)));
        return g->builtin_types.entry_invalid;
    }
}

static TypeTableEntry *analyze_prefix_op_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    PrefixOp prefix_op = node->data.prefix_op_expr.prefix_op;
    AstNode *expr_node = node->data.prefix_op_expr.primary_expr;
    switch (prefix_op) {
        case PrefixOpInvalid:
            zig_unreachable();
        case PrefixOpBoolNot:
            {
                TypeTableEntry *type_entry = analyze_expression(g, import, context, g->builtin_types.entry_bool,
                        expr_node);
                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return g->builtin_types.entry_bool;
                }

                ConstExprValue *target_const_val = &get_resolved_expr(expr_node)->const_val;
                if (!target_const_val->ok) {
                    return g->builtin_types.entry_bool;
                }

                bool answer = !target_const_val->data.x_bool;
                return resolve_expr_const_val_as_bool(g, node, answer);
            }
        case PrefixOpBinNot:
            {
                TypeTableEntry *expr_type = analyze_expression(g, import, context, expected_type,
                        expr_node);
                if (expr_type->id == TypeTableEntryIdInvalid) {
                    return expr_type;
                } else if (expr_type->id == TypeTableEntryIdInt ||
                           expr_type->id == TypeTableEntryIdNumLitInt)
                {
                    return expr_type;
                } else {
                    add_node_error(g, expr_node, buf_sprintf("invalid binary not type: '%s'",
                            buf_ptr(&expr_type->name)));
                    return g->builtin_types.entry_invalid;
                }
                // TODO const expr eval
            }
        case PrefixOpNegation:
            {
                TypeTableEntry *expr_type = analyze_expression(g, import, context, expected_type,
                        expr_node);
                if (expr_type->id == TypeTableEntryIdInvalid) {
                    return expr_type;
                } else if ((expr_type->id == TypeTableEntryIdInt &&
                            expr_type->data.integral.is_signed) ||
                            expr_type->id == TypeTableEntryIdFloat ||
                            expr_type->id == TypeTableEntryIdNumLitInt ||
                            expr_type->id == TypeTableEntryIdNumLitFloat)
                {
                    ConstExprValue *target_const_val = &get_resolved_expr(expr_node)->const_val;
                    if (!target_const_val->ok) {
                        return expr_type;
                    }
                    ConstExprValue *const_val = &get_resolved_expr(node)->const_val;
                    const_val->ok = true;
                    bignum_negate(&const_val->data.x_bignum, &target_const_val->data.x_bignum);
                    return expr_type;
                } else {
                    add_node_error(g, node, buf_sprintf("invalid negation type: '%s'",
                            buf_ptr(&expr_type->name)));
                    return g->builtin_types.entry_invalid;
                }
            }
        case PrefixOpAddressOf:
        case PrefixOpConstAddressOf:
            {
                bool is_const = (prefix_op == PrefixOpConstAddressOf);

                TypeTableEntry *child_type = analyze_lvalue(g, import, context,
                        expr_node, LValPurposeAddressOf, is_const);

                if (child_type->id == TypeTableEntryIdInvalid) {
                    return g->builtin_types.entry_invalid;
                } else if (child_type->id == TypeTableEntryIdMetaType) {
                    TypeTableEntry *meta_type = analyze_type_expr(g, import, context, expr_node);
                    if (meta_type->id == TypeTableEntryIdInvalid) {
                        return g->builtin_types.entry_invalid;
                    } else if (meta_type->id == TypeTableEntryIdUnreachable) {
                        add_node_error(g, node, buf_create_from_str("pointer to unreachable not allowed"));
                        return g->builtin_types.entry_invalid;
                    } else {
                        return resolve_expr_const_val_as_type(g, node,
                                get_pointer_to_type(g, meta_type, is_const));
                    }
                } else if (child_type->id == TypeTableEntryIdNumLitInt ||
                           child_type->id == TypeTableEntryIdNumLitFloat)
                {
                    add_node_error(g, expr_node,
                        buf_sprintf("unable to get address of type '%s'", buf_ptr(&child_type->name)));
                    return g->builtin_types.entry_invalid;
                } else {
                    return get_pointer_to_type(g, child_type, is_const);
                }
            }
        case PrefixOpDereference:
            {
                TypeTableEntry *type_entry = analyze_expression(g, import, context, nullptr, expr_node);
                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return type_entry;
                } else if (type_entry->id == TypeTableEntryIdPointer) {
                    return type_entry->data.pointer.child_type;
                } else {
                    add_node_error(g, expr_node,
                        buf_sprintf("indirection requires pointer operand ('%s' invalid)",
                            buf_ptr(&type_entry->name)));
                    return g->builtin_types.entry_invalid;
                }
            }
        case PrefixOpMaybe:
            {
                TypeTableEntry *type_entry = analyze_expression(g, import, context, nullptr, expr_node);

                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return type_entry;
                } else if (type_entry->id == TypeTableEntryIdMetaType) {
                    TypeTableEntry *meta_type = resolve_type(g, expr_node);
                    if (meta_type->id == TypeTableEntryIdInvalid) {
                        return g->builtin_types.entry_invalid;
                    } else if (meta_type->id == TypeTableEntryIdUnreachable) {
                        add_node_error(g, node, buf_create_from_str("unable to wrap unreachable in maybe type"));
                        return g->builtin_types.entry_invalid;
                    } else {
                        return resolve_expr_const_val_as_type(g, node, get_maybe_type(g, meta_type));
                    }
                } else if (type_entry->id == TypeTableEntryIdUnreachable) {
                    add_node_error(g, expr_node, buf_sprintf("unable to wrap unreachable in maybe type"));
                    return g->builtin_types.entry_invalid;
                } else {
                    // TODO eval const expr
                    return get_maybe_type(g, type_entry);
                }
            }
        case PrefixOpError:
            {
                TypeTableEntry *type_entry = analyze_expression(g, import, context, nullptr, expr_node);

                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return type_entry;
                } else if (type_entry->id == TypeTableEntryIdMetaType) {
                    TypeTableEntry *meta_type = resolve_type(g, expr_node);
                    if (meta_type->id == TypeTableEntryIdInvalid) {
                        return meta_type;
                    } else if (meta_type->id == TypeTableEntryIdUnreachable) {
                        add_node_error(g, node, buf_create_from_str("unable to wrap unreachable in error type"));
                        return g->builtin_types.entry_invalid;
                    } else {
                        return resolve_expr_const_val_as_type(g, node, get_error_type(g, meta_type));
                    }
                } else if (type_entry->id == TypeTableEntryIdUnreachable) {
                    add_node_error(g, expr_node, buf_sprintf("unable to wrap unreachable in error type"));
                    return g->builtin_types.entry_invalid;
                } else {
                    // TODO eval const expr
                    return get_error_type(g, type_entry);
                }

            }
        case PrefixOpUnwrapError:
            {
                TypeTableEntry *type_entry = analyze_expression(g, import, context, nullptr, expr_node);

                if (type_entry->id == TypeTableEntryIdInvalid) {
                    return type_entry;
                } else if (type_entry->id == TypeTableEntryIdErrorUnion) {
                    return type_entry->data.error.child_type;
                } else {
                    add_node_error(g, expr_node,
                        buf_sprintf("expected error type, got '%s'", buf_ptr(&type_entry->name)));
                    return g->builtin_types.entry_invalid;
                }
            }
    }
    zig_unreachable();
}

static TypeTableEntry *analyze_switch_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    AstNode *expr_node = node->data.switch_expr.expr;
    TypeTableEntry *expr_type = analyze_expression(g, import, context, nullptr, expr_node);

    if (expected_type == nullptr) {
        zig_panic("TODO resolve peer compatibility of switch prongs");
    }

    if (expr_type->id == TypeTableEntryIdInvalid) {
        return expr_type;
    } else if (expr_type->id == TypeTableEntryIdUnreachable) {
        add_node_error(g, first_executing_node(expr_node),
                buf_sprintf("switch on unreachable expression not allowed"));
        return g->builtin_types.entry_invalid;
    } else {
        AstNode *else_prong = nullptr;
        for (int prong_i = 0; prong_i < node->data.switch_expr.prongs.length; prong_i += 1) {
            AstNode *prong_node = node->data.switch_expr.prongs.at(prong_i);

            TypeTableEntry *var_type;
            if (prong_node->data.switch_prong.items.length == 0) {
                if (else_prong) {
                    add_node_error(g, prong_node, buf_sprintf("multiple else prongs in switch expression"));
                } else {
                    else_prong = prong_node;
                }
                var_type = expr_type;
            } else {
                for (int item_i = 0; item_i < prong_node->data.switch_prong.items.length; item_i += 1) {
                    AstNode *item_node = prong_node->data.switch_prong.items.at(item_i);
                    if (item_node->type == NodeTypeSwitchRange) {
                        zig_panic("TODO range in switch statement");
                    }
                    analyze_expression(g, import, context, expr_type, item_node);
                    ConstExprValue *const_val = &get_resolved_expr(item_node)->const_val;
                    if (!const_val->ok) {
                        add_node_error(g, item_node, buf_sprintf("unable to resolve constant expression"));
                    }
                }
                var_type = expr_type;
            }

            BlockContext *child_context = new_block_context(node, context);
            prong_node->data.switch_prong.block_context = child_context;
            AstNode *var_node = prong_node->data.switch_prong.var_symbol;
            if (var_node) {
                assert(var_node->type == NodeTypeSymbol);
                Buf *var_name = &var_node->data.symbol_expr.symbol;
                var_node->block_context = child_context;
                prong_node->data.switch_prong.var = add_local_var(g, var_node, child_context, var_name,
                        var_type, true);
            }

            analyze_expression(g, import, child_context, expected_type,
                    prong_node->data.switch_prong.expr);
        }
    }
    return expected_type;
}

static TypeTableEntry *analyze_return_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    if (!context->fn_entry) {
        add_node_error(g, node, buf_sprintf("return expression outside function definition"));
        return g->builtin_types.entry_invalid;
    }

    if (!node->data.return_expr.expr) {
        node->data.return_expr.expr = create_ast_void_node(g, import, node);
        normalize_parent_ptrs(node);
    }

    TypeTableEntry *expected_return_type = get_return_type(context);

    switch (node->data.return_expr.kind) {
        case ReturnKindUnconditional:
            {
                analyze_expression(g, import, context, expected_return_type, node->data.return_expr.expr);

                return g->builtin_types.entry_unreachable;
            }
        case ReturnKindError:
            {
                TypeTableEntry *expected_err_type;
                if (expected_type) {
                    expected_err_type = get_error_type(g, expected_type);
                } else {
                    expected_err_type = nullptr;
                }
                TypeTableEntry *resolved_type = analyze_expression(g, import, context, expected_err_type,
                        node->data.return_expr.expr);
                if (resolved_type->id == TypeTableEntryIdInvalid) {
                    return resolved_type;
                } else if (resolved_type->id == TypeTableEntryIdErrorUnion) {
                    return resolved_type->data.error.child_type;
                } else {
                    add_node_error(g, node->data.return_expr.expr,
                        buf_sprintf("expected error type, got '%s'", buf_ptr(&resolved_type->name)));
                    return g->builtin_types.entry_invalid;
                }
            }
        case ReturnKindMaybe:
            zig_panic("TODO");
    }
}

static TypeTableEntry *analyze_string_literal_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    if (node->data.string_literal.c) {
        return resolve_expr_const_val_as_c_string_lit(g, node, &node->data.string_literal.buf);
    } else {
        return resolve_expr_const_val_as_string_lit(g, node, &node->data.string_literal.buf);
    }
}

static TypeTableEntry *analyze_block_expr(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    BlockContext *child_context = new_block_context(node, context);
    node->data.block.block_context = child_context;
    TypeTableEntry *return_type = g->builtin_types.entry_void;

    for (int i = 0; i < node->data.block.statements.length; i += 1) {
        AstNode *child = node->data.block.statements.at(i);
        if (child->type == NodeTypeLabel) {
            child->block_context = child_context;
            LabelTableEntry *label_entry = child->data.label.label_entry;
            assert(label_entry);
            label_entry->entered_from_fallthrough = (return_type->id != TypeTableEntryIdUnreachable);
            return_type = g->builtin_types.entry_void;
            continue;
        }
        if (return_type->id == TypeTableEntryIdUnreachable) {
            if (is_node_void_expr(child)) {
                // {unreachable;void;void} is allowed.
                // ignore void statements once we enter unreachable land.
                analyze_expression(g, import, context, g->builtin_types.entry_void, child);
                continue;
            }
            add_node_error(g, first_executing_node(child), buf_sprintf("unreachable code"));
            break;
        }
        bool is_last = (i == node->data.block.statements.length - 1);
        TypeTableEntry *passed_expected_type = is_last ? expected_type : nullptr;
        return_type = analyze_expression(g, import, child_context, passed_expected_type, child);
        if (!is_last) {
            if (return_type->id == TypeTableEntryIdMetaType) {
                add_node_error(g, child, buf_sprintf("expected expression, found type"));
            } else if (return_type->id == TypeTableEntryIdErrorUnion) {
                add_node_error(g, child, buf_sprintf("statement ignores error value"));
            }
        }
    }
    return return_type;
}

// When you call analyze_expression, the node you pass might no longer be the child node
// you thought it was due to implicit casting rewriting the AST.
static TypeTableEntry *analyze_expression(CodeGen *g, ImportTableEntry *import, BlockContext *context,
        TypeTableEntry *expected_type, AstNode *node)
{
    TypeTableEntry *return_type = nullptr;
    switch (node->type) {
        case NodeTypeBlock:
            return_type = analyze_block_expr(g, import, context, expected_type, node);
            break;

        case NodeTypeReturnExpr:
            return_type = analyze_return_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeVariableDeclaration:
            analyze_variable_declaration(g, import, context, expected_type, node);
            return_type = g->builtin_types.entry_void;
            break;
        case NodeTypeGoto:
            {
                FnTableEntry *fn_table_entry = get_context_fn_entry(context);
                auto table_entry = fn_table_entry->label_table.maybe_get(&node->data.goto_expr.name);
                if (table_entry) {
                    node->data.goto_expr.label_entry = table_entry->value;
                    table_entry->value->used = true;
                } else {
                    add_node_error(g, node,
                            buf_sprintf("use of undeclared label '%s'", buf_ptr(&node->data.goto_expr.name)));
                }
                return_type = g->builtin_types.entry_unreachable;
                break;
            }
        case NodeTypeBreak:
            return_type = analyze_break_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeContinue:
            return_type = analyze_continue_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeAsmExpr:
            {
                node->data.asm_expr.return_count = 0;
                return_type = g->builtin_types.entry_void;
                for (int i = 0; i < node->data.asm_expr.output_list.length; i += 1) {
                    AsmOutput *asm_output = node->data.asm_expr.output_list.at(i);
                    if (asm_output->return_type) {
                        node->data.asm_expr.return_count += 1;
                        return_type = analyze_type_expr(g, import, context, asm_output->return_type);
                        if (node->data.asm_expr.return_count > 1) {
                            add_node_error(g, node,
                                buf_sprintf("inline assembly allows up to one output value"));
                            break;
                        }
                    } else {
                        analyze_variable_name(g, import, context, node, &asm_output->variable_name);
                    }
                }
                for (int i = 0; i < node->data.asm_expr.input_list.length; i += 1) {
                    AsmInput *asm_input = node->data.asm_expr.input_list.at(i);
                    analyze_expression(g, import, context, nullptr, asm_input->expr);
                }

                break;
            }
        case NodeTypeBinOpExpr:
            return_type = analyze_bin_op_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeUnwrapErrorExpr:
            return_type = analyze_unwrap_error_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeFnCallExpr:
            return_type = analyze_fn_call_expr(g, import, context, expected_type, node);
            break;

        case NodeTypeArrayAccessExpr:
            // for reading array access; assignment handled elsewhere
            return_type = analyze_array_access_expr(g, import, context, node);
            break;
        case NodeTypeSliceExpr:
            return_type = analyze_slice_expr(g, import, context, node);
            break;
        case NodeTypeFieldAccessExpr:
            return_type = analyze_field_access_expr(g, import, context, node);
            break;
        case NodeTypeContainerInitExpr:
            return_type = analyze_container_init_expr(g, import, context, node);
            break;
        case NodeTypeNumberLiteral:
            return_type = analyze_number_literal_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeStringLiteral:
            return_type = analyze_string_literal_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeCharLiteral:
            return_type = resolve_expr_const_val_as_unsigned_num_lit(g, node, expected_type,
                    node->data.char_literal.value);
            break;
        case NodeTypeBoolLiteral:
            return_type = resolve_expr_const_val_as_bool(g, node, node->data.bool_literal.value);
            break;
        case NodeTypeNullLiteral:
            return_type = analyze_null_literal_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeUndefinedLiteral:
            return_type = analyze_undefined_literal_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeSymbol:
            return_type = analyze_symbol_expr(g, import, context, expected_type, node);
            break;
        case NodeTypePrefixOpExpr:
            return_type = analyze_prefix_op_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeIfBoolExpr:
            return_type = analyze_if_bool_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeIfVarExpr:
            return_type = analyze_if_var_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeWhileExpr:
            return_type = analyze_while_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeForExpr:
            return_type = analyze_for_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeArrayType:
            return_type = analyze_array_type(g, import, context, expected_type, node);
            break;
        case NodeTypeFnProto:
            return_type = analyze_fn_proto_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeErrorType:
            return_type = resolve_expr_const_val_as_type(g, node, g->builtin_types.entry_pure_error);
            break;
        case NodeTypeTypeLiteral:
            return_type = resolve_expr_const_val_as_type(g, node, g->builtin_types.entry_type);
            break;
        case NodeTypeSwitchExpr:
            return_type = analyze_switch_expr(g, import, context, expected_type, node);
            break;
        case NodeTypeSwitchProng:
        case NodeTypeSwitchRange:
        case NodeTypeDirective:
        case NodeTypeFnDecl:
        case NodeTypeParamDecl:
        case NodeTypeRoot:
        case NodeTypeRootExportDecl:
        case NodeTypeFnDef:
        case NodeTypeImport:
        case NodeTypeCImport:
        case NodeTypeLabel:
        case NodeTypeStructDecl:
        case NodeTypeStructField:
        case NodeTypeStructValueField:
        case NodeTypeErrorValueDecl:
        case NodeTypeTypeDecl:
            zig_unreachable();
    }
    assert(return_type);
    // resolve_type_compatibility might do implicit cast which means node is now a child
    // of the actual node that we want to return the type of.
    //AstNode **field = node->parent_field;
    TypeTableEntry *resolved_type = resolve_type_compatibility(g, import, context, node,
            expected_type, return_type);

    Expr *expr = get_resolved_expr(node);
    expr->type_entry = return_type;
    node->block_context = context;

    add_global_const_expr(g, expr);

    return resolved_type;
}

static void analyze_top_level_fn_def(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    assert(node->type == NodeTypeFnDef);

    AstNode *fn_proto_node = node->data.fn_def.fn_proto;
    assert(fn_proto_node->type == NodeTypeFnProto);

    if (fn_proto_node->data.fn_proto.skip) {
        // we detected an error with this function definition which prevents us
        // from further analyzing it.
        return;
    }

    BlockContext *context = node->data.fn_def.block_context;

    FnTableEntry *fn_table_entry = fn_proto_node->data.fn_proto.fn_table_entry;
    TypeTableEntry *fn_type = fn_table_entry->type_entry;
    AstNodeFnProto *fn_proto = &fn_proto_node->data.fn_proto;
    for (int i = 0; i < fn_proto->params.length; i += 1) {
        AstNode *param_decl_node = fn_proto->params.at(i);
        assert(param_decl_node->type == NodeTypeParamDecl);

        // define local variables for parameters
        AstNodeParamDecl *param_decl = &param_decl_node->data.param_decl;
        TypeTableEntry *type = unwrapped_node_type(param_decl->type);

        if (param_decl->is_noalias && type->id != TypeTableEntryIdPointer) {
            add_node_error(g, param_decl_node,
                buf_sprintf("noalias on non-pointer parameter"));
        }

        if (fn_type->data.fn.fn_type_id.is_extern && type->id == TypeTableEntryIdStruct) {
            add_node_error(g, param_decl_node,
                buf_sprintf("byvalue struct parameters not yet supported on extern functions"));
        }

        if (buf_len(&param_decl->name) == 0) {
            add_node_error(g, param_decl_node, buf_sprintf("missing parameter name"));
        }

        VariableTableEntry *var = add_local_var(g, param_decl_node, context, &param_decl->name, type, true);
        var->src_arg_index = i;
        param_decl_node->data.param_decl.variable = var;

        var->gen_arg_index = fn_type->data.fn.gen_param_info[i].gen_index;
    }

    TypeTableEntry *expected_type = fn_type->data.fn.fn_type_id.return_type;
    TypeTableEntry *block_return_type = analyze_expression(g, import, context, expected_type, node->data.fn_def.body);

    node->data.fn_def.implicit_return_type = block_return_type;

    {
        auto it = fn_table_entry->label_table.entry_iterator();
        for (;;) {
            auto *entry = it.next();
            if (!entry)
                break;

            LabelTableEntry *label_entry = entry->value;
            if (!label_entry->used) {
                add_node_error(g, label_entry->label_node,
                    buf_sprintf("label '%s' defined but not used",
                        buf_ptr(&label_entry->label_node->data.label.name)));
            }
        }
    }
}

static void analyze_top_level_decl(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    switch (node->type) {
        case NodeTypeFnDef:
            analyze_top_level_fn_def(g, import, node);
            break;
        case NodeTypeStructDecl:
            {
                for (int i = 0; i < node->data.struct_decl.fns.length; i += 1) {
                    AstNode *fn_def_node = node->data.struct_decl.fns.at(i);
                    analyze_top_level_fn_def(g, import, fn_def_node);
                }
                break;
            }
        case NodeTypeRootExportDecl:
        case NodeTypeImport:
        case NodeTypeCImport:
        case NodeTypeVariableDeclaration:
        case NodeTypeErrorValueDecl:
        case NodeTypeFnProto:
        case NodeTypeTypeDecl:
            // already took care of these
            break;
        case NodeTypeDirective:
        case NodeTypeParamDecl:
        case NodeTypeFnDecl:
        case NodeTypeReturnExpr:
        case NodeTypeRoot:
        case NodeTypeBlock:
        case NodeTypeBinOpExpr:
        case NodeTypeUnwrapErrorExpr:
        case NodeTypeFnCallExpr:
        case NodeTypeArrayAccessExpr:
        case NodeTypeSliceExpr:
        case NodeTypeNumberLiteral:
        case NodeTypeStringLiteral:
        case NodeTypeCharLiteral:
        case NodeTypeBoolLiteral:
        case NodeTypeNullLiteral:
        case NodeTypeUndefinedLiteral:
        case NodeTypeSymbol:
        case NodeTypePrefixOpExpr:
        case NodeTypeIfBoolExpr:
        case NodeTypeIfVarExpr:
        case NodeTypeWhileExpr:
        case NodeTypeForExpr:
        case NodeTypeSwitchExpr:
        case NodeTypeSwitchProng:
        case NodeTypeSwitchRange:
        case NodeTypeLabel:
        case NodeTypeGoto:
        case NodeTypeBreak:
        case NodeTypeContinue:
        case NodeTypeAsmExpr:
        case NodeTypeFieldAccessExpr:
        case NodeTypeStructField:
        case NodeTypeStructValueField:
        case NodeTypeContainerInitExpr:
        case NodeTypeArrayType:
        case NodeTypeErrorType:
        case NodeTypeTypeLiteral:
            zig_unreachable();
    }
}

static void collect_expr_decl_deps(CodeGen *g, ImportTableEntry *import, AstNode *node,
        TopLevelDecl *decl_node)
{
    switch (node->type) {
        case NodeTypeNumberLiteral:
        case NodeTypeStringLiteral:
        case NodeTypeCharLiteral:
        case NodeTypeBoolLiteral:
        case NodeTypeNullLiteral:
        case NodeTypeUndefinedLiteral:
        case NodeTypeGoto:
        case NodeTypeBreak:
        case NodeTypeContinue:
        case NodeTypeErrorValueDecl:
        case NodeTypeErrorType:
        case NodeTypeTypeLiteral:
            // no dependencies on other top level declarations
            break;
        case NodeTypeSymbol:
            {
                if (node->data.symbol_expr.override_type_entry) {
                    break;
                }
                Buf *name = &node->data.symbol_expr.symbol;
                auto table_entry = g->primitive_type_table.maybe_get(name);
                if (!table_entry) {
                    table_entry = import->block_context->type_table.maybe_get(name);
                }
                if (!table_entry) {
                    decl_node->deps.put(name, node);
                }
                break;
            }
        case NodeTypeBinOpExpr:
            collect_expr_decl_deps(g, import, node->data.bin_op_expr.op1, decl_node);
            collect_expr_decl_deps(g, import, node->data.bin_op_expr.op2, decl_node);
            break;
        case NodeTypeUnwrapErrorExpr:
            collect_expr_decl_deps(g, import, node->data.unwrap_err_expr.op1, decl_node);
            collect_expr_decl_deps(g, import, node->data.unwrap_err_expr.op2, decl_node);
            break;
        case NodeTypeReturnExpr:
            collect_expr_decl_deps(g, import, node->data.return_expr.expr, decl_node);
            break;
        case NodeTypePrefixOpExpr:
            collect_expr_decl_deps(g, import, node->data.prefix_op_expr.primary_expr, decl_node);
            break;
        case NodeTypeFnCallExpr:
            collect_expr_decl_deps(g, import, node->data.fn_call_expr.fn_ref_expr, decl_node);
            for (int i = 0; i < node->data.fn_call_expr.params.length; i += 1) {
                AstNode *arg_node = node->data.fn_call_expr.params.at(i);
                collect_expr_decl_deps(g, import, arg_node, decl_node);
            }
            break;
        case NodeTypeArrayAccessExpr:
            collect_expr_decl_deps(g, import, node->data.array_access_expr.array_ref_expr, decl_node);
            collect_expr_decl_deps(g, import, node->data.array_access_expr.subscript, decl_node);
            break;
        case NodeTypeSliceExpr:
            collect_expr_decl_deps(g, import, node->data.slice_expr.array_ref_expr, decl_node);
            collect_expr_decl_deps(g, import, node->data.slice_expr.start, decl_node);
            if (node->data.slice_expr.end) {
                collect_expr_decl_deps(g, import, node->data.slice_expr.end, decl_node);
            }
            break;
        case NodeTypeFieldAccessExpr:
            collect_expr_decl_deps(g, import, node->data.field_access_expr.struct_expr, decl_node);
            break;
        case NodeTypeIfBoolExpr:
            collect_expr_decl_deps(g, import, node->data.if_bool_expr.condition, decl_node);
            collect_expr_decl_deps(g, import, node->data.if_bool_expr.then_block, decl_node);
            if (node->data.if_bool_expr.else_node) {
                collect_expr_decl_deps(g, import, node->data.if_bool_expr.else_node, decl_node);
            }
            break;
        case NodeTypeIfVarExpr:
            if (node->data.if_var_expr.var_decl.type) {
                collect_expr_decl_deps(g, import, node->data.if_var_expr.var_decl.type, decl_node);
            }
            if (node->data.if_var_expr.var_decl.expr) {
                collect_expr_decl_deps(g, import, node->data.if_var_expr.var_decl.expr, decl_node);
            }
            collect_expr_decl_deps(g, import, node->data.if_var_expr.then_block, decl_node);
            if (node->data.if_bool_expr.else_node) {
                collect_expr_decl_deps(g, import, node->data.if_var_expr.else_node, decl_node);
            }
            break;
        case NodeTypeWhileExpr:
            collect_expr_decl_deps(g, import, node->data.while_expr.condition, decl_node);
            collect_expr_decl_deps(g, import, node->data.while_expr.body, decl_node);
            break;
        case NodeTypeForExpr:
            collect_expr_decl_deps(g, import, node->data.for_expr.array_expr, decl_node);
            collect_expr_decl_deps(g, import, node->data.for_expr.body, decl_node);
            break;
        case NodeTypeBlock:
            for (int i = 0; i < node->data.block.statements.length; i += 1) {
                AstNode *stmt = node->data.block.statements.at(i);
                collect_expr_decl_deps(g, import, stmt, decl_node);
            }
            break;
        case NodeTypeAsmExpr:
            for (int i = 0; i < node->data.asm_expr.output_list.length; i += 1) {
                AsmOutput *asm_output = node->data.asm_expr.output_list.at(i);
                if (asm_output->return_type) {
                    collect_expr_decl_deps(g, import, asm_output->return_type, decl_node);
                } else {
                    decl_node->deps.put(&asm_output->variable_name, node);
                }
            }
            for (int i = 0; i < node->data.asm_expr.input_list.length; i += 1) {
                AsmInput *asm_input = node->data.asm_expr.input_list.at(i);
                collect_expr_decl_deps(g, import, asm_input->expr, decl_node);
            }
            break;
        case NodeTypeContainerInitExpr:
            collect_expr_decl_deps(g, import, node->data.container_init_expr.type, decl_node);
            for (int i = 0; i < node->data.container_init_expr.entries.length; i += 1) {
                AstNode *child_node = node->data.container_init_expr.entries.at(i);
                collect_expr_decl_deps(g, import, child_node, decl_node);
            }
            break;
        case NodeTypeStructValueField:
            collect_expr_decl_deps(g, import, node->data.struct_val_field.expr, decl_node);
            break;
        case NodeTypeArrayType:
            if (node->data.array_type.size) {
                collect_expr_decl_deps(g, import, node->data.array_type.size, decl_node);
            }
            collect_expr_decl_deps(g, import, node->data.array_type.child_type, decl_node);
            break;
        case NodeTypeSwitchExpr:
            collect_expr_decl_deps(g, import, node->data.switch_expr.expr, decl_node);
            for (int i = 0; i < node->data.switch_expr.prongs.length; i += 1) {
                AstNode *prong = node->data.switch_expr.prongs.at(i);
                collect_expr_decl_deps(g, import, prong, decl_node);
            }
            break;
        case NodeTypeSwitchProng:
            for (int i = 0; i < node->data.switch_prong.items.length; i += 1) {
                AstNode *child = node->data.switch_prong.items.at(i);
                collect_expr_decl_deps(g, import, child, decl_node);
            }
            collect_expr_decl_deps(g, import, node->data.switch_prong.expr, decl_node);
            break;
        case NodeTypeSwitchRange:
            collect_expr_decl_deps(g, import, node->data.switch_range.start, decl_node);
            collect_expr_decl_deps(g, import, node->data.switch_range.end, decl_node);
            break;
        case NodeTypeFnProto:
            // remember that fn proto node is used for function definitions as well
            // as types
            for (int i = 0; i < node->data.fn_proto.params.length; i += 1) {
                AstNode *param = node->data.fn_proto.params.at(i);
                collect_expr_decl_deps(g, import, param, decl_node);
            }
            collect_expr_decl_deps(g, import, node->data.fn_proto.return_type, decl_node);
            break;
        case NodeTypeParamDecl:
            collect_expr_decl_deps(g, import, node->data.param_decl.type, decl_node);
            break;
        case NodeTypeTypeDecl:
            collect_expr_decl_deps(g, import, node->data.type_decl.child_type, decl_node);
            break;
        case NodeTypeVariableDeclaration:
        case NodeTypeRootExportDecl:
        case NodeTypeFnDef:
        case NodeTypeRoot:
        case NodeTypeFnDecl:
        case NodeTypeDirective:
        case NodeTypeImport:
        case NodeTypeCImport:
        case NodeTypeLabel:
        case NodeTypeStructDecl:
        case NodeTypeStructField:
            zig_unreachable();
    }
}

static void detect_top_level_decl_deps(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    switch (node->type) {
        case NodeTypeRoot:
            for (int i = 0; i < import->root->data.root.top_level_decls.length; i += 1) {
                AstNode *child = import->root->data.root.top_level_decls.at(i);
                detect_top_level_decl_deps(g, import, child);
            }
            break;
        case NodeTypeStructDecl:
            {
                Buf *name = &node->data.struct_decl.name;
                auto table_entry = g->primitive_type_table.maybe_get(name);
                if (!table_entry) {
                    table_entry = import->block_context->type_table.maybe_get(name);
                }
                if (table_entry) {
                    node->data.struct_decl.type_entry = table_entry->value;
                    add_node_error(g, node, buf_sprintf("redefinition of '%s'", buf_ptr(name)));
                } else {
                    TypeTableEntry *entry;
                    if (node->data.struct_decl.type_entry) {
                        entry = node->data.struct_decl.type_entry;
                    } else {
                        entry = get_partial_container_type(g, import,
                                node->data.struct_decl.kind, node, buf_ptr(name));
                    }

                    import->block_context->type_table.put(&entry->name, entry);
                    node->data.struct_decl.type_entry = entry;

                    bool is_pub = (node->data.struct_decl.visib_mod != VisibModPrivate);
                    if (is_pub) {
                        for (int i = 0; i < import->importers.length; i += 1) {
                            ImporterInfo importer = import->importers.at(i);
                            auto table_entry = importer.import->block_context->type_table.maybe_get(&entry->name);
                            if (table_entry) {
                                add_node_error(g, importer.source_node,
                                    buf_sprintf("import of type '%s' overrides existing definition",
                                        buf_ptr(&entry->name)));
                            } else {
                                importer.import->block_context->type_table.put(&entry->name, entry);
                            }
                        }
                    }
                }

                // determine which other top level declarations this struct depends on.
                TopLevelDecl *decl_node = &node->data.struct_decl.top_level_decl;
                decl_node->deps.init(1);
                for (int i = 0; i < node->data.struct_decl.fields.length; i += 1) {
                    AstNode *field_node = node->data.struct_decl.fields.at(i);
                    AstNode *type_node = field_node->data.struct_field.type;
                    collect_expr_decl_deps(g, import, type_node, decl_node);
                }
                decl_node->name = name;
                decl_node->import = import;
                if (decl_node->deps.size() > 0) {
                    g->unresolved_top_level_decls.put(name, node);
                } else {
                    resolve_top_level_decl(g, import, node);
                }

                // handle the member function definitions independently
                for (int i = 0; i < node->data.struct_decl.fns.length; i += 1) {
                    AstNode *fn_def_node = node->data.struct_decl.fns.at(i);
                    AstNode *fn_proto_node = fn_def_node->data.fn_def.fn_proto;
                    fn_proto_node->data.fn_proto.struct_node = node;
                    detect_top_level_decl_deps(g, import, fn_def_node);
                }

                break;
            }
        case NodeTypeFnDef:
            node->data.fn_def.fn_proto->data.fn_proto.fn_def_node = node;
            detect_top_level_decl_deps(g, import, node->data.fn_def.fn_proto);
            break;
        case NodeTypeVariableDeclaration:
            {
                // determine which other top level declarations this variable declaration depends on.
                TopLevelDecl *decl_node = &node->data.variable_declaration.top_level_decl;
                decl_node->deps.init(1);
                if (node->data.variable_declaration.type) {
                    collect_expr_decl_deps(g, import, node->data.variable_declaration.type, decl_node);
                }
                if (node->data.variable_declaration.expr) {
                    collect_expr_decl_deps(g, import, node->data.variable_declaration.expr, decl_node);
                }
                Buf *name = &node->data.variable_declaration.symbol;
                decl_node->name = name;
                decl_node->import = import;
                if (decl_node->deps.size() > 0) {
                    g->unresolved_top_level_decls.put(name, node);
                } else {
                    resolve_top_level_decl(g, import, node);
                }
                break;
            }
        case NodeTypeTypeDecl:
            {
                // determine which other top level declarations this variable declaration depends on.
                TopLevelDecl *decl_node = &node->data.type_decl.top_level_decl;
                decl_node->deps.init(1);
                collect_expr_decl_deps(g, import, node, decl_node);

                Buf *name = &node->data.type_decl.symbol;
                decl_node->name = name;
                decl_node->import = import;
                if (decl_node->deps.size() > 0) {
                    g->unresolved_top_level_decls.put(name, node);
                } else {
                    resolve_top_level_decl(g, import, node);
                }
                break;
            }
        case NodeTypeFnProto:
            {
                // if the name is missing, we immediately announce an error
                Buf *name = &node->data.fn_proto.name;
                if (buf_len(name) == 0) {
                    node->data.fn_proto.skip = true;
                    add_node_error(g, node, buf_sprintf("missing function name"));
                    break;
                }


                // determine which other top level declarations this function prototype depends on.
                TopLevelDecl *decl_node = &node->data.fn_proto.top_level_decl;
                decl_node->deps.init(1);

                collect_expr_decl_deps(g, import, node, decl_node);

                decl_node->name = name;
                decl_node->import = import;
                if (decl_node->deps.size() > 0) {
                    g->unresolved_top_level_decls.put(name, node);
                } else {
                    resolve_top_level_decl(g, import, node);
                }
                break;
            }
        case NodeTypeRootExportDecl:
            resolve_top_level_decl(g, import, node);
            break;
        case NodeTypeImport:
            // already taken care of
            break;
        case NodeTypeCImport:
            {
                TopLevelDecl *decl_node = &node->data.c_import.top_level_decl;
                decl_node->deps.init(1);
                collect_expr_decl_deps(g, import, node->data.c_import.block, decl_node);

                decl_node->name = buf_sprintf("c_import_%" PRIu32, node->create_index);
                decl_node->import = import;
                if (decl_node->deps.size() > 0) {
                    g->unresolved_top_level_decls.put(decl_node->name, node);
                } else {
                    resolve_top_level_decl(g, import, node);
                }
                break;
            }
        case NodeTypeErrorValueDecl:
            // error value declarations do not depend on other top level decls
            resolve_top_level_decl(g, import, node);
            break;
        case NodeTypeDirective:
        case NodeTypeParamDecl:
        case NodeTypeFnDecl:
        case NodeTypeReturnExpr:
        case NodeTypeBlock:
        case NodeTypeBinOpExpr:
        case NodeTypeUnwrapErrorExpr:
        case NodeTypeFnCallExpr:
        case NodeTypeArrayAccessExpr:
        case NodeTypeSliceExpr:
        case NodeTypeNumberLiteral:
        case NodeTypeStringLiteral:
        case NodeTypeCharLiteral:
        case NodeTypeBoolLiteral:
        case NodeTypeNullLiteral:
        case NodeTypeUndefinedLiteral:
        case NodeTypeSymbol:
        case NodeTypePrefixOpExpr:
        case NodeTypeIfBoolExpr:
        case NodeTypeIfVarExpr:
        case NodeTypeWhileExpr:
        case NodeTypeForExpr:
        case NodeTypeSwitchExpr:
        case NodeTypeSwitchProng:
        case NodeTypeSwitchRange:
        case NodeTypeLabel:
        case NodeTypeGoto:
        case NodeTypeBreak:
        case NodeTypeContinue:
        case NodeTypeAsmExpr:
        case NodeTypeFieldAccessExpr:
        case NodeTypeStructField:
        case NodeTypeContainerInitExpr:
        case NodeTypeStructValueField:
        case NodeTypeArrayType:
        case NodeTypeErrorType:
        case NodeTypeTypeLiteral:
            zig_unreachable();
    }
}

static void recursive_resolve_decl(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    auto it = get_resolved_top_level_decl(node)->deps.entry_iterator();
    for (;;) {
        auto *entry = it.next();
        if (!entry)
            break;

        auto unresolved_entry = g->unresolved_top_level_decls.maybe_get(entry->key);
        if (!unresolved_entry) {
            continue;
        }

        AstNode *child_node = unresolved_entry->value;

        if (get_resolved_top_level_decl(child_node)->in_current_deps) {
            // dependency loop. we'll let the fact that it's not in the respective
            // table cause an error in resolve_top_level_decl.
            continue;
        }

        // set temporary flag
        TopLevelDecl *top_level_decl = get_resolved_top_level_decl(child_node);
        top_level_decl->in_current_deps = true;

        recursive_resolve_decl(g, top_level_decl->import, child_node);

        // unset temporary flag
        top_level_decl->in_current_deps = false;
    }

    resolve_top_level_decl(g, import, node);
}

static void resolve_top_level_declarations_root(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    assert(node->type == NodeTypeRoot);

    while (g->unresolved_top_level_decls.size() > 0) {
        // for the sake of determinism, find the element with the lowest
        // insert index and resolve that one.
        AstNode *decl_node = nullptr;
        auto it = g->unresolved_top_level_decls.entry_iterator();
        for (;;) {
            auto *entry = it.next();
            if (!entry)
                break;

            AstNode *this_node = entry->value;
            if (!decl_node || this_node->create_index < decl_node->create_index) {
                decl_node = this_node;
            }

        }
        // set temporary flag
        TopLevelDecl *top_level_decl = get_resolved_top_level_decl(decl_node);
        top_level_decl->in_current_deps = true;

        recursive_resolve_decl(g, top_level_decl->import, decl_node);

        // unset temporary flag
        top_level_decl->in_current_deps = false;
    }
}

static void analyze_top_level_decls_root(CodeGen *g, ImportTableEntry *import, AstNode *node) {
    assert(node->type == NodeTypeRoot);

    for (int i = 0; i < node->data.root.top_level_decls.length; i += 1) {
        AstNode *child = node->data.root.top_level_decls.at(i);
        analyze_top_level_decl(g, import, child);
    }
}

void semantic_analyze(CodeGen *g) {
    {
        auto it = g->import_table.entry_iterator();
        for (;;) {
            auto *entry = it.next();
            if (!entry)
                break;

            ImportTableEntry *import = entry->value;

            for (int i = 0; i < import->root->data.root.top_level_decls.length; i += 1) {
                AstNode *child = import->root->data.root.top_level_decls.at(i);
                if (child->type == NodeTypeImport) {
                    for (int i = 0; i < child->data.import.directives->length; i += 1) {
                        AstNode *directive_node = child->data.import.directives->at(i);
                        Buf *name = &directive_node->data.directive.name;
                        add_node_error(g, directive_node,
                                buf_sprintf("invalid directive: '%s'", buf_ptr(name)));
                    }

                    ImportTableEntry *target_import = child->data.import.import;
                    assert(target_import);

                    target_import->importers.append({import, child});
                } else if (child->type == NodeTypeErrorValueDecl) {
                    g->error_value_count += 1;
                }
            }
        }
    }

    {
        g->err_tag_type = get_smallest_unsigned_int_type(g, g->error_value_count);

        g->builtin_types.entry_pure_error->type_ref = g->err_tag_type->type_ref;
        g->builtin_types.entry_pure_error->size_in_bits = g->err_tag_type->size_in_bits;
        g->builtin_types.entry_pure_error->align_in_bits = g->err_tag_type->align_in_bits;
        g->builtin_types.entry_pure_error->di_type = g->err_tag_type->di_type;
    }

    {
        auto it = g->import_table.entry_iterator();
        for (;;) {
            auto *entry = it.next();
            if (!entry)
                break;

            ImportTableEntry *import = entry->value;

            detect_top_level_decl_deps(g, import, import->root);
        }
    }

    assert(g->error_value_count == g->next_error_index);

    {
        auto it = g->import_table.entry_iterator();
        for (;;) {
            auto *entry = it.next();
            if (!entry)
                break;

            ImportTableEntry *import = entry->value;
            resolve_top_level_declarations_root(g, import, import->root);
        }
    }
    {
        auto it = g->import_table.entry_iterator();
        for (;;) {
            auto *entry = it.next();
            if (!entry)
                break;

            ImportTableEntry *import = entry->value;
            analyze_top_level_decls_root(g, import, import->root);
        }
    }
}

Expr *get_resolved_expr(AstNode *node) {
    switch (node->type) {
        case NodeTypeReturnExpr:
            return &node->data.return_expr.resolved_expr;
        case NodeTypeBinOpExpr:
            return &node->data.bin_op_expr.resolved_expr;
        case NodeTypeUnwrapErrorExpr:
            return &node->data.unwrap_err_expr.resolved_expr;
        case NodeTypePrefixOpExpr:
            return &node->data.prefix_op_expr.resolved_expr;
        case NodeTypeFnCallExpr:
            return &node->data.fn_call_expr.resolved_expr;
        case NodeTypeArrayAccessExpr:
            return &node->data.array_access_expr.resolved_expr;
        case NodeTypeSliceExpr:
            return &node->data.slice_expr.resolved_expr;
        case NodeTypeFieldAccessExpr:
            return &node->data.field_access_expr.resolved_expr;
        case NodeTypeIfBoolExpr:
            return &node->data.if_bool_expr.resolved_expr;
        case NodeTypeIfVarExpr:
            return &node->data.if_var_expr.resolved_expr;
        case NodeTypeWhileExpr:
            return &node->data.while_expr.resolved_expr;
        case NodeTypeForExpr:
            return &node->data.for_expr.resolved_expr;
        case NodeTypeAsmExpr:
            return &node->data.asm_expr.resolved_expr;
        case NodeTypeContainerInitExpr:
            return &node->data.container_init_expr.resolved_expr;
        case NodeTypeNumberLiteral:
            return &node->data.number_literal.resolved_expr;
        case NodeTypeStringLiteral:
            return &node->data.string_literal.resolved_expr;
        case NodeTypeBlock:
            return &node->data.block.resolved_expr;
        case NodeTypeSymbol:
            return &node->data.symbol_expr.resolved_expr;
        case NodeTypeVariableDeclaration:
            return &node->data.variable_declaration.resolved_expr;
        case NodeTypeCharLiteral:
            return &node->data.char_literal.resolved_expr;
        case NodeTypeBoolLiteral:
            return &node->data.bool_literal.resolved_expr;
        case NodeTypeNullLiteral:
            return &node->data.null_literal.resolved_expr;
        case NodeTypeUndefinedLiteral:
            return &node->data.undefined_literal.resolved_expr;
        case NodeTypeGoto:
            return &node->data.goto_expr.resolved_expr;
        case NodeTypeBreak:
            return &node->data.break_expr.resolved_expr;
        case NodeTypeContinue:
            return &node->data.continue_expr.resolved_expr;
        case NodeTypeLabel:
            return &node->data.label.resolved_expr;
        case NodeTypeArrayType:
            return &node->data.array_type.resolved_expr;
        case NodeTypeErrorType:
            return &node->data.error_type.resolved_expr;
        case NodeTypeTypeLiteral:
            return &node->data.type_literal.resolved_expr;
        case NodeTypeSwitchExpr:
            return &node->data.switch_expr.resolved_expr;
        case NodeTypeFnProto:
            return &node->data.fn_proto.resolved_expr;
        case NodeTypeSwitchProng:
        case NodeTypeSwitchRange:
        case NodeTypeRoot:
        case NodeTypeRootExportDecl:
        case NodeTypeFnDef:
        case NodeTypeFnDecl:
        case NodeTypeParamDecl:
        case NodeTypeDirective:
        case NodeTypeImport:
        case NodeTypeCImport:
        case NodeTypeStructDecl:
        case NodeTypeStructField:
        case NodeTypeStructValueField:
        case NodeTypeErrorValueDecl:
        case NodeTypeTypeDecl:
            zig_unreachable();
    }
    zig_unreachable();
}

TopLevelDecl *get_resolved_top_level_decl(AstNode *node) {
    switch (node->type) {
        case NodeTypeVariableDeclaration:
            return &node->data.variable_declaration.top_level_decl;
        case NodeTypeFnProto:
            return &node->data.fn_proto.top_level_decl;
        case NodeTypeStructDecl:
            return &node->data.struct_decl.top_level_decl;
        case NodeTypeErrorValueDecl:
            return &node->data.error_value_decl.top_level_decl;
        case NodeTypeCImport:
            return &node->data.c_import.top_level_decl;
        case NodeTypeTypeDecl:
            return &node->data.type_decl.top_level_decl;
        case NodeTypeNumberLiteral:
        case NodeTypeReturnExpr:
        case NodeTypeBinOpExpr:
        case NodeTypeUnwrapErrorExpr:
        case NodeTypePrefixOpExpr:
        case NodeTypeFnCallExpr:
        case NodeTypeArrayAccessExpr:
        case NodeTypeSliceExpr:
        case NodeTypeFieldAccessExpr:
        case NodeTypeIfBoolExpr:
        case NodeTypeIfVarExpr:
        case NodeTypeWhileExpr:
        case NodeTypeForExpr:
        case NodeTypeSwitchExpr:
        case NodeTypeSwitchProng:
        case NodeTypeSwitchRange:
        case NodeTypeAsmExpr:
        case NodeTypeContainerInitExpr:
        case NodeTypeRoot:
        case NodeTypeRootExportDecl:
        case NodeTypeFnDef:
        case NodeTypeFnDecl:
        case NodeTypeParamDecl:
        case NodeTypeBlock:
        case NodeTypeDirective:
        case NodeTypeStringLiteral:
        case NodeTypeCharLiteral:
        case NodeTypeSymbol:
        case NodeTypeImport:
        case NodeTypeBoolLiteral:
        case NodeTypeNullLiteral:
        case NodeTypeUndefinedLiteral:
        case NodeTypeLabel:
        case NodeTypeGoto:
        case NodeTypeBreak:
        case NodeTypeContinue:
        case NodeTypeStructField:
        case NodeTypeStructValueField:
        case NodeTypeArrayType:
        case NodeTypeErrorType:
        case NodeTypeTypeLiteral:
            zig_unreachable();
    }
    zig_unreachable();
}

bool is_node_void_expr(AstNode *node) {
    if (node->type == NodeTypeContainerInitExpr &&
        node->data.container_init_expr.kind == ContainerInitKindArray)
    {
        AstNode *type_node = node->data.container_init_expr.type;
        if (type_node->type == NodeTypeSymbol &&
            buf_eql_str(&type_node->data.symbol_expr.symbol, "void"))
        {
            return true;
        }
    }

    return false;
}

TypeTableEntry **get_int_type_ptr(CodeGen *g, bool is_signed, int size_in_bits) {
    int index;
    if (size_in_bits == 8) {
        index = 0;
    } else if (size_in_bits == 16) {
        index = 1;
    } else if (size_in_bits == 32) {
        index = 2;
    } else if (size_in_bits == 64) {
        index = 3;
    } else {
        zig_unreachable();
    }
    return &g->builtin_types.entry_int[is_signed ? 0 : 1][index];
}

TypeTableEntry *get_int_type(CodeGen *g, bool is_signed, int size_in_bits) {
    return *get_int_type_ptr(g, is_signed, size_in_bits);
}

TypeTableEntry **get_c_int_type_ptr(CodeGen *g, CIntType c_int_type) {
    return &g->builtin_types.entry_c_int[c_int_type];
}

TypeTableEntry *get_c_int_type(CodeGen *g, CIntType c_int_type) {
    return *get_c_int_type_ptr(g, c_int_type);
}

bool handle_is_ptr(TypeTableEntry *type_entry) {
    switch (type_entry->id) {
        case TypeTableEntryIdInvalid:
        case TypeTableEntryIdMetaType:
        case TypeTableEntryIdNumLitFloat:
        case TypeTableEntryIdNumLitInt:
        case TypeTableEntryIdUndefLit:
             zig_unreachable();
        case TypeTableEntryIdUnreachable:
        case TypeTableEntryIdVoid:
        case TypeTableEntryIdBool:
        case TypeTableEntryIdInt:
        case TypeTableEntryIdFloat:
        case TypeTableEntryIdPointer:
        case TypeTableEntryIdPureError:
        case TypeTableEntryIdFn:
             return false;
        case TypeTableEntryIdArray:
        case TypeTableEntryIdStruct:
             return true;
        case TypeTableEntryIdErrorUnion:
             return type_entry->data.error.child_type->size_in_bits > 0;
        case TypeTableEntryIdEnum:
             return type_entry->data.enumeration.gen_field_count != 0;
        case TypeTableEntryIdMaybe:
             return type_entry->data.maybe.child_type->id != TypeTableEntryIdPointer;
        case TypeTableEntryIdTypeDecl:
             return handle_is_ptr(type_entry->data.type_decl.canonical_type);
    }
    zig_unreachable();
}

void find_libc_path(CodeGen *g) {
    if (!g->libc_path || buf_len(g->libc_path) == 0) {
        g->libc_path = buf_create_from_str(ZIG_LIBC_DIR);
        if (!g->libc_path || buf_len(g->libc_path) == 0) {
            // later we can handle this better by reporting an error via the normal mechanism
            zig_panic("Unable to determine libc path. You can use `--libc-path`");
        }
    }
    if (!g->libc_lib_path) {
        g->libc_lib_path = buf_alloc();
        os_path_join(g->libc_path, buf_create_from_str("lib"), g->libc_lib_path);
    }
    if (!g->libc_include_path) {
        g->libc_include_path = buf_alloc();
        os_path_join(g->libc_path, buf_create_from_str("include"), g->libc_include_path);
    }
}

static uint32_t hash_ptr(void *ptr) {
    uint64_t x = (uint64_t)(uintptr_t)(ptr);
    uint32_t a = x >> 32;
    uint32_t b = x & 0xffffffff;
    return a ^ b;
}

uint32_t fn_type_id_hash(FnTypeId id) {
    uint32_t result = 0;
    result += id.is_extern ? 3349388391 : 0;
    result += id.is_naked ? 608688877 : 0;
    result += id.is_var_args ? 1931444534 : 0;
    result += hash_ptr(id.return_type);
    result += id.param_count;
    for (int i = 0; i < id.param_count; i += 1) {
        FnTypeParamInfo *info = &id.param_info[i];
        result += info->is_noalias ? 892356923 : 0;
        result += hash_ptr(info->type);
    }
    return result;
}

bool fn_type_id_eql(FnTypeId a, FnTypeId b) {
    if (a.is_extern != b.is_extern ||
        a.is_naked != b.is_naked ||
        a.return_type != b.return_type ||
        a.is_var_args != b.is_var_args ||
        a.param_count != b.param_count)
    {
        return false;
    }
    for (int i = 0; i < a.param_count; i += 1) {
        FnTypeParamInfo *a_param_info = &a.param_info[i];
        FnTypeParamInfo *b_param_info = &b.param_info[i];

        if (a_param_info->type != b_param_info->type) {
            return false;
        }

        if (a_param_info->is_noalias != b_param_info->is_noalias) {
            return false;
        }
    }
    return true;
}