From cd8fdd252d9ffd5bfb772cef49e4c79041872d38 Mon Sep 17 00:00:00 2001 From: Matthew Lugg Date: Sat, 15 Nov 2025 09:45:22 +0000 Subject: [PATCH] build.zig: use `Step.UpdateSourceFiles` for `zig1.wasm` We were already using this for `stage1/zig.h`, but `stage1/zig1.wasm` was being modified directly by the `wasm-opt` command. That's a bad idea because it forces the build system to assume that `wasm-opt` has side effects, so it is re-run every time you run `zig build update-zig1`, i.e. it does not interact with the cache system correctly. It is much better to create non-side-effecting `Run` steps (using `addOutput*Arg`) where possible so that the build system has a more correct understanding of the step graph. --- build.zig | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/build.zig b/build.zig index 6a707621fc..fbcdd7539e 100644 --- a/build.zig +++ b/build.zig @@ -678,14 +678,14 @@ fn addWasiUpdateStep(b: *std.Build, version: [:0]const u8) !void { }); run_opt.addArtifactArg(exe); run_opt.addArg("-o"); - run_opt.addFileArg(b.path("stage1/zig1.wasm")); + const optimized_wasm = run_opt.addOutputFileArg("zig1.wasm"); - const copy_zig_h = b.addUpdateSourceFiles(); - copy_zig_h.addCopyFileToSource(b.path("lib/zig.h"), "stage1/zig.h"); + const update_zig1 = b.addUpdateSourceFiles(); + update_zig1.addCopyFileToSource(optimized_wasm, "stage1/zig1.wasm"); + update_zig1.addCopyFileToSource(b.path("lib/zig.h"), "stage1/zig.h"); const update_zig1_step = b.step("update-zig1", "Update stage1/zig1.wasm"); - update_zig1_step.dependOn(&run_opt.step); - update_zig1_step.dependOn(©_zig_h.step); + update_zig1_step.dependOn(&update_zig1.step); } const AddCompilerModOptions = struct {