From 08eb19456b319cc5b0c287773d52850f12f2bcb5 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Thu, 11 Feb 2016 16:15:08 -0700
Subject: [PATCH] add compile error for missing enumeration value in switch

---
 src/analyze.cpp    | 25 +++++++++++++++++++++++++
 test/run_tests.cpp | 17 +++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/src/analyze.cpp b/src/analyze.cpp
index 8d1091392..02056c1be 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -4241,6 +4241,8 @@ static TypeTableEntry *analyze_builtin_fn_call_expr(CodeGen *g, ImportTableEntry
                     return resolve_expr_const_val_as_bool(g, node, g->is_release_build, true);
                 } else if (buf_eql_str(&var_name, "is_test")) {
                     return resolve_expr_const_val_as_bool(g, node, g->is_test_build, true);
+                } else if (buf_eql_str(&var_name, "os")) {
+                    zig_panic("TODO");
                 } else {
                     add_node_error(g, *str_node,
                         buf_sprintf("unrecognized compile variable: '%s'", buf_ptr(&var_name)));
@@ -4650,6 +4652,11 @@ static TypeTableEntry *analyze_switch_expr(CodeGen *g, ImportTableEntry *import,
                 buf_sprintf("switch on unreachable expression not allowed"));
         return g->builtin_types.entry_invalid;
     } else {
+        int *field_use_counts = nullptr;
+        if (expr_type->id == TypeTableEntryIdEnum) {
+            field_use_counts = allocate<int>(expr_type->data.enumeration.field_count);
+        }
+
         AstNode *else_prong = nullptr;
         for (int prong_i = 0; prong_i < prong_count; prong_i += 1) {
             AstNode *prong_node = node->data.switch_expr.prongs.at(prong_i);
@@ -4686,6 +4693,14 @@ static TypeTableEntry *analyze_switch_expr(CodeGen *g, ImportTableEntry *import,
                                 if (type_enum_field->type_entry != var_type) {
                                     all_agree_on_var_type = false;
                                 }
+                                uint32_t field_index = type_enum_field->value;
+                                assert(field_use_counts);
+                                field_use_counts[field_index] += 1;
+                                if (field_use_counts[field_index] > 1) {
+                                    add_node_error(g, item_node,
+                                        buf_sprintf("duplicate switch value: '%s'",
+                                            buf_ptr(type_enum_field->name)));
+                                }
                             } else {
                                 add_node_error(g, item_node,
                                         buf_sprintf("enum '%s' has no field '%s'",
@@ -4729,6 +4744,16 @@ static TypeTableEntry *analyze_switch_expr(CodeGen *g, ImportTableEntry *import,
                     prong_node->data.switch_prong.expr);
             peer_nodes[prong_i] = prong_node->data.switch_prong.expr;
         }
+
+        if (expr_type->id == TypeTableEntryIdEnum && !else_prong) {
+            for (uint32_t i = 0; i < expr_type->data.enumeration.field_count; i += 1) {
+                if (field_use_counts[i] == 0) {
+                    add_node_error(g, node,
+                        buf_sprintf("enumeration value '%s' not handled in switch",
+                            buf_ptr(expr_type->data.enumeration.fields[i].name)));
+                }
+            }
+        }
     }
     return resolve_peer_type_compatibility(g, import, context, node, peer_nodes, peer_types, prong_count);
 }
diff --git a/test/run_tests.cpp b/test/run_tests.cpp
index 333813419..b372473ee 100644
--- a/test/run_tests.cpp
+++ b/test/run_tests.cpp
@@ -1760,6 +1760,23 @@ const float_x = f32(1.0) / f32(0.0);
             ".tmp_source.zig:3:25: error: division by zero is undefined",
             ".tmp_source.zig:4:22: error: division by zero is undefined",
             ".tmp_source.zig:5:26: error: division by zero is undefined");
+
+
+    add_compile_fail_case("missing switch prong", R"SOURCE(
+enum Number {
+    One,
+    Two,
+    Three,
+    Four,
+}
+fn f(n: Number) -> i32 {
+    switch (n) {
+        One => 1,
+        Two => 2,
+        Three => 3,
+    }
+}
+    )SOURCE", 1, ".tmp_source.zig:9:5: error: enumeration value 'Four' not handled in switch");
 }
 
 //////////////////////////////////////////////////////////////////////////////