Commit 50e185b71822c180fccd07826a8dd5e3ec641cc1 | zig

author	Andrew Kelley <andrew@ziglang.org> 2026-01-01 18:10:24-08:00
committer	Andrew Kelley <andrew@ziglang.org> 2026-01-04 00:27:08-08:00
log	50e185b71822c180fccd07826a8dd5e3ec641cc1
tree	a3672f8f94fd038c55155ea141432c926907f802
parent	0362d9f3215e36dd12b5ba47bca8a9cd107b1697

start: tweak allocator choice

Favor DebugAllocator in Debug mode, even when linking libc. Prevent use
of smp_allocator when single_threaded

2 files changed, 13 insertions(+), 21 deletions(-)

lib
- std
  - process
    Environ.zig
  - start.zig

lib/std/process/Environ.zig-14

...	...	@@ -381,20 +381,6 @@ pub fn createMap(env: Environ, allocator: Allocator) CreateMapError!Map {
381	381	try result.put(key, value);
382	382	}
383	383	return result;
384		} else if (builtin.link_libc) {
385		var ptr = env.block;
386		while (ptr[0]) \|line\| : (ptr += 1) {
387		var line_i: usize = 0;
388		while (line[line_i] != 0 and line[line_i] != '=') : (line_i += 1) {}
389		const key = line[0..line_i];
390
391		var end_i: usize = line_i;
392		while (line[end_i] != 0) : (end_i += 1) {}
393		const value = line[line_i + 1 .. end_i];
394
395		try result.put(key, value);
396		}
397		return result;
398	384	} else {
399	385	for (env.block) \|opt_line\| {
400	386	const line = opt_line.?;

lib/std/start.zig+13-7

...	...	@@ -623,7 +623,7 @@ inline fn callMainWithArgs(argc: usize, argv: [][:0]u8, envp: [:null]?[*:0]u8)
623	623	return callMain(argv[0..argc], envp);
624	624	}
625	625
626		fn main(c_argc: c_int, c_argv: [][:0]c_char, c_envp: [:null]?[:0]c_char) callconv(.c) c_int {
	626	fn main(c_argc: c_int, c_argv: [][:0]u8, c_envp: [:null]?[:0]u8) callconv(.c) c_int {
627	627	var env_count: usize = 0;
628	628	while (c_envp[env_count] != null) : (env_count += 1) {}
629	629	const envp = c_envp[0..env_count :null];
...	...	@@ -638,7 +638,7 @@ fn main(c_argc: c_int, c_argv: [][:0]c_char, c_envp: [:null]?[:0]c_char) cal
638	638	return callMainWithArgs(@as(usize, @intCast(c_argc)), @as([][:0]u8, @ptrCast(c_argv)), envp);
639	639	}
640	640
641		fn mainWithoutEnv(c_argc: c_int, c_argv: [][:0]c_char) callconv(.c) c_int {
	641	fn mainWithoutEnv(c_argc: c_int, c_argv: [][:0]u8) callconv(.c) c_int {
642	642	const argv = @as([][:0]u8, @ptrCast(c_argv))[0..@intCast(c_argc)];
643	643	if (@sizeOf(std.Io.Threaded.Argv0) != 0) {
644	644	if (std.Options.debug_threaded_io) \|t\| t.argv0.value = argv[0];
...	...	@@ -649,7 +649,11 @@ fn mainWithoutEnv(c_argc: c_int, c_argv: [][:0]c_char) callconv(.c) c_int {
649	649	/// General error message for a malformed return type
650	650	const bad_main_ret = "expected return type of main to be 'void', '!void', 'noreturn', 'u8', or '!u8'";
651	651
652		const use_debug_allocator = !builtin.link_libc and !native_arch.isWasm() and builtin.mode == .Debug;
	652	const use_debug_allocator = !native_arch.isWasm() and switch (builtin.mode) {
	653	.Debug => true,
	654	.ReleaseSafe => !builtin.link_libc, // Not ideal, but the best we have for now.
	655	.ReleaseFast, .ReleaseSmall => !builtin.link_libc and builtin.single_threaded, // Also not ideal.
	656	};
653	657	var debug_allocator: std.heap.DebugAllocator(.{}) = .init;
654	658
655	659	inline fn callMain(args: std.process.Args.Vector, environ: std.process.Environ.Block) u8 {
...	...	@@ -660,14 +664,16 @@ inline fn callMain(args: std.process.Args.Vector, environ: std.process.Environ.B
660	664	.environ = .{ .block = environ },
661	665	}));
662	666
663		const gpa = if (builtin.link_libc)
664		std.heap.c_allocator
665		else if (native_arch.isWasm())
	667	const gpa = if (native_arch.isWasm())
666	668	std.heap.wasm_allocator
667	669	else if (use_debug_allocator)
668	670	debug_allocator.allocator()
	671	else if (builtin.link_libc)
	672	std.heap.c_allocator
	673	else if (!builtin.single_threaded)
	674	std.heap.smp_allocator
669	675	else
670		std.heap.smp_allocator;
	676	comptime unreachable;
671	677
672	678	defer if (use_debug_allocator) {
673	679	_ = debug_allocator.deinit(); // Leaks do not affect return code.