track all TODO comments in BRANCH_TODO file

Before merging, do this for every item in the file:
 * solve the issue, or
 * convert the task to a github issue and update the comment
   to link to the issue (and remove "TODO" text from the comment).
Then delete the file.

Related: #363

BRANCH_TODO

@@ -0,0 +1,51 @@
+ * refactor 2 CObject fields to use CSourceFile 
+ * integrate code model and have_frame_pointer to main() and c objects
+ * integrate target features into building C source files
+ * integrate target features into building assembly code
+ * handle .d files from c objects
+ * glibc .so files
+ * support rpaths in ELF linker code
+ * build & link against compiler-rt
+ * build & link againstn freestanding libc
+ * add CLI support for a way to pass extra flags to c source files
+ * implement the workaround for using LLVM to detect native CPU features
+ * self-host main.cpp
+ * capture lld stdout/stderr better
+ * musl
+ * mingw-w64
+ * port the stage1 os.cpp code that raises the open fd limit
+ * use global zig-cache dir for crt files
+ * `zig translate-c`
+ * make sure zig cc works
+   - using it as a preprocessor (-E)
+   - @breakpoint(); // TODO the first arg is empty string right? skip past that.
+   - try building some software
+ * MachO LLD linking
+ * COFF LLD linking
+ * WASM LLD linking
+ * implement proper parsing of LLD stderr/stdout and exposing compile errors
+ * implement proper parsing of clang stderr/stdout and exposing compile errors
+ * implement proper compile errors for failing to build glibc crt files and shared libs
+ * skip LLD caching when bin directory is not in the cache (so we don't put `id.txt` into the cwd)
+ * self-host link.cpp and building libcs (#4313 and #4314). using the `zig cc` command will set a flag indicating a preference for the llvm backend, which will include linking with LLD. At least for now. If zig's self-hosted linker ever gets on par with the likes of ld and lld, we can make it always be used even for zig cc.
+ * improve the stage2 tests to support testing with LLVM extensions enabled
+ * multi-thread building C objects
+ * support cross compiling stage2 with `zig build`
+ * implement emit-h in stage2
+ * implement -fno-emit-bin
+ * audit the base cache hash
+ * implement serialization/deserialization of incremental compilation metadata
+ * incremental compilation - implement detection of which source files changed
+ * improve the cache hash logic for c objects with respect to extra flags and file parameters
+ * LLVM codegen backend: put a sub-arch in the triple in some cases
+ * rework libc_installation.zig abstraction to use std.log instead of taking a stderr stream
+ * implement an LLVM backend for stage2
+ * implement outputting dynamic libraries in self-hosted linker
+ * implement outputting static libraries (archive files) in self-hosted linker
+ * support linking against object files in self-hosted linker
+ * avoid invoking lld when it's just 1 object file (the `zig cc -c` case)
+ * `zig fmt --check` should output to stdout not stderr.
+ * main.zig: If there was an argsAllocZ we could avoid this allocation
+ * improve robustness of response file parsing
+ * there are a couple panic("TODO") in clang options parsing
+ * std.testing needs improvement to support exposing directory path for its tmp dir (look for "bogus")

lib/std/child_process.zig

@@ -213,7 +213,7 @@ pub const ChildProcess = struct {
         const stdout_in = child.stdout.?.inStream();
         const stderr_in = child.stderr.?.inStream();
 
-        // TODO need to poll to read these streams to prevent a deadlock (or rely on evented I/O).
+        // TODO https://github.com/ziglang/zig/issues/6343
         const stdout = try stdout_in.readAllAlloc(args.allocator, args.max_output_bytes);
         errdefer args.allocator.free(stdout);
         const stderr = try stderr_in.readAllAlloc(args.allocator, args.max_output_bytes);
@@ -485,7 +485,7 @@ pub const ChildProcess = struct {
         const any_ignore = (self.stdin_behavior == StdIo.Ignore or self.stdout_behavior == StdIo.Ignore or self.stderr_behavior == StdIo.Ignore);
 
         const nul_handle = if (any_ignore)
-            // "\Device\Null" or "\??\NUL"
+        // "\Device\Null" or "\??\NUL"
             windows.OpenFile(&[_]u16{ '\\', 'D', 'e', 'v', 'i', 'c', 'e', '\\', 'N', 'u', 'l', 'l' }, .{
                 .access_mask = windows.GENERIC_READ | windows.SYNCHRONIZE,
                 .share_access = windows.FILE_SHARE_READ,

src-self-hosted/Compilation.zig

@@ -695,7 +695,6 @@ pub fn update(self: *Compilation) !void {
     defer tracy.end();
 
     // For compiling C objects, we rely on the cache hash system to avoid duplicating work.
-    // TODO Look into caching this data in memory to improve performance.
     // Add a WorkItem for each C object.
     try self.work_queue.ensureUnusedCapacity(self.c_object_table.items().len);
     for (self.c_object_table.items()) |entry| {
@@ -1052,8 +1051,7 @@ fn updateCObject(comp: *Compilation, c_object: *CObject) !void {
             switch (term) {
                 .Exited => |code| {
                     if (code != 0) {
-                        // TODO make std.process.exit and std.ChildProcess exit code have the same type
-                        // and forward it here. Currently it is u32 vs u8.
+                        // TODO https://github.com/ziglang/zig/issues/6342
                         std.process.exit(1);
                     }
                 },
@@ -1069,7 +1067,7 @@ fn updateCObject(comp: *Compilation, c_object: *CObject) !void {
             const stdout_reader = child.stdout.?.reader();
             const stderr_reader = child.stderr.?.reader();
 
-            // TODO Need to poll to read these streams to prevent a deadlock (or rely on evented I/O).
+            // TODO https://github.com/ziglang/zig/issues/6343
             const stdout = try stdout_reader.readAllAlloc(arena, std.math.maxInt(u32));
             const stderr = try stderr_reader.readAllAlloc(arena, 10 * 1024 * 1024);
 
@@ -1100,7 +1098,7 @@ fn updateCObject(comp: *Compilation, c_object: *CObject) !void {
         const o_sub_path = try std.fs.path.join(arena, &[_][]const u8{ "o", &digest });
         var o_dir = try comp.zig_cache_directory.handle.makeOpenPath(o_sub_path, .{});
         defer o_dir.close();
-        // TODO Add renameat capabilities to the std lib in a higher layer than the posix layer.
+        // TODO https://github.com/ziglang/zig/issues/6344
         const tmp_basename = std.fs.path.basename(out_obj_path);
         try std.os.renameat(zig_cache_tmp_dir.fd, tmp_basename, o_dir.fd, o_basename);
 

src-self-hosted/glibc.zig

@@ -270,7 +270,7 @@ pub fn buildCRTFile(comp: *Compilation, crt_file: CRTFile) !void {
                 "-g",
                 "-Wa,--noexecstack",
             });
-            return build_libc_object(comp, "crti.o", &[1]Compilation.CSourceFile{
+            return build_crt_file(comp, "crti.o", &[1]Compilation.CSourceFile{
                 .{
                     .src_path = try start_asm_path(comp, arena, "crti.S"),
                     .extra_flags = args.items,
@@ -288,7 +288,7 @@ pub fn buildCRTFile(comp: *Compilation, crt_file: CRTFile) !void {
                 "-g",
                 "-Wa,--noexecstack",
             });
-            return build_libc_object(comp, "crtn.o", &[1]Compilation.CSourceFile{
+            return build_crt_file(comp, "crtn.o", &[1]Compilation.CSourceFile{
                 .{
                     .src_path = try start_asm_path(comp, arena, "crtn.S"),
                     .extra_flags = args.items,
@@ -339,7 +339,7 @@ pub fn buildCRTFile(comp: *Compilation, crt_file: CRTFile) !void {
                     .extra_flags = args.items,
                 };
             };
-            return build_libc_object(comp, "Scrt1.o", &[_]Compilation.CSourceFile{ start_os, abi_note_o });
+            return build_crt_file(comp, "Scrt1.o", &[_]Compilation.CSourceFile{ start_os, abi_note_o });
         },
         .libc_nonshared_a => {
             return error.Unimplemented; // TODO
@@ -585,7 +585,7 @@ fn lib_path(comp: *Compilation, arena: *Allocator, sub_path: []const u8) ![]cons
     return path.join(arena, &[_][]const u8{ comp.zig_lib_directory.path.?, sub_path });
 }
 
-fn build_libc_object(
+fn build_crt_file(
     comp: *Compilation,
     basename: []const u8,
     c_source_files: []const Compilation.CSourceFile,
@@ -649,7 +649,6 @@ fn build_libc_object(
     else
         try comp.gpa.dupe(u8, basename);
 
-    // TODO obtain a lock on the artifact and put that in crt_files as well.
     comp.crt_files.putAssumeCapacityNoClobber(basename, .{
         .full_object_path = artifact_path,
         .lock = sub_compilation.bin_file.toOwnedLock(),

src-self-hosted/libc_installation.zig

@@ -11,7 +11,7 @@ const is_gnu = Target.current.isGnu();
 
 usingnamespace @import("windows_sdk.zig");
 
-// TODO Rework this abstraction to use std.log instead of taking a stderr stream.
+// TODO https://github.com/ziglang/zig/issues/6345
 
 /// See the render function implementation for documentation of the fields.
 pub const LibCInstallation = struct {

src-self-hosted/main.zig

@@ -1615,7 +1615,7 @@ pub const info_zen =
 
 extern "c" fn ZigClang_main(argc: c_int, argv: [*:null]?[*:0]u8) c_int;
 
-/// TODO make it so the return value can be !noreturn
+/// TODO https://github.com/ziglang/zig/issues/3257
 fn punt_to_clang(arena: *Allocator, args: []const []const u8) error{OutOfMemory} {
     if (!build_options.have_llvm)
         fatal("`zig cc` and `zig c++` unavailable: compiler not built with LLVM extensions enabled", .{});