feat(cmd): GOOS-aware headers, audit battery shapes and semicolon spacing

Assisted-by: GLM 5.3 Flash

cmd/gasm/asmhdr.go

@@ -27,7 +27,10 @@ import (
 // GOROOT assembly includes it, and a standalone assembler has no compiler
 // to have produced it, so gasm generates the equivalent itself: the package
 // the .s file lives in is parsed and type-checked here, with the target
-// architecture's own sizes, and the same defines are written out.
+// architecture's own sizes, and the same defines are written out.  The
+// type-checking GOOS is selected by the caller: a GOOS-specific file
+// (sys_darwin_arm64.s) needs its platform's defines, which a header from
+// the ambient GOOS silently omits.
 //
 // The emitter mirrors cmd/compile's dumpasmhdr exactly: constants come out
 // as "const_NAME", struct entries as "NAME__size" followed by the fields in
@@ -67,11 +70,15 @@ func goAsmHeaderResolved(asmDir string, dirs []string) bool {
 	return false
 }
 
-// generateGoAsmHeader type-checks the Go package in pkgDir for goarch,
-// writes its go_asm.h equivalent into dir, and returns dir.  The caller
-// owns the directory and its removal.
-func generateGoAsmHeader(pkgDir, goarch, dir string) (string, error) {
-	imp := newSourceImporter(goarch)
+// generateGoAsmHeader type-checks the Go package in pkgDir for goos and
+// goarch, writes its go_asm.h equivalent into dir, and returns dir.  An
+// empty goos means the ambient one.  The caller owns the directory and its
+// removal.
+func generateGoAsmHeader(pkgDir, goos, goarch, dir string) (string, error) {
+	if goos == "" {
+		goos = build.Default.GOOS
+	}
+	imp := newSourceImporter(goos, goarch)
 	if imp.sizes == nil {
 		return "", fmt.Errorf("go_asm.h: unknown GOARCH %q", goarch)
 	}
@@ -89,7 +96,7 @@ func generateGoAsmHeader(pkgDir, goarch, dir string) (string, error) {
 	}
 
 	var b strings.Builder
-	fmt.Fprintf(&b, "// generated by gasm from package %s (GOARCH %s)\n\n", bp.Name, goarch)
+	fmt.Fprintf(&b, "// generated by gasm from package %s (GOOS %s, GOARCH %s)\n\n", bp.Name, goos, goarch)
 	// Files in the build's own order and declarations in source order: the
 	// same walk the compiler's reader makes, so the header reads the same
 	// way the toolchain's does.  Order carries no meaning to the assembler
@@ -203,13 +210,14 @@ type sourceImporter struct {
 	pkgs  map[string]*types.Package
 }
 
-// newSourceImporter returns the importer for one target architecture.
+// newSourceImporter returns the importer for one target GOOS and GOARCH.
 // Cgo is disabled so the file set is deterministic and independent of the
 // host's C toolchain: cgo-tagged files drop out of the build exactly as
 // they do from a CGO_ENABLED=0 build, whose assembly is what gasm targets.
-func newSourceImporter(goarch string) *sourceImporter {
+func newSourceImporter(goos, goarch string) *sourceImporter {
 	ctxt := new(build.Context)
 	*ctxt = build.Default
+	ctxt.GOOS = goos
 	ctxt.GOARCH = goarch
 	ctxt.CgoEnabled = false
 	return &sourceImporter{
@@ -291,7 +299,7 @@ func (im *sourceImporter) checkPackage(bp *build.Package, files []*ast.File) (*t
 // type-check must not be re-checked once per file.
 type asmhdrCache struct {
 	root string
-	dirs map[string]string // "pkgDir\x00goarch" -> directory holding go_asm.h
+	dirs map[string]string // "pkgDir\x00goos\x00goarch" -> directory holding go_asm.h
 	errs map[string]error
 }
 
@@ -304,17 +312,22 @@ func newAsmhdrCache() (*asmhdrCache, error) {
 }
 
 // dirFor returns the directory holding the generated go_asm.h for pkgDir
-// and goarch, generating it on first use.
-func (c *asmhdrCache) dirFor(pkgDir, goarch string) (string, error) {
-	key := pkgDir + "\x00" + goarch
+// under goos and goarch, generating it on first use.  An empty goos means
+// the ambient one, resolved here so that one package cannot generate twice
+// under an explicit and an implicit spelling of the same GOOS.
+func (c *asmhdrCache) dirFor(pkgDir, goos, goarch string) (string, error) {
+	if goos == "" {
+		goos = build.Default.GOOS
+	}
+	key := pkgDir + "\x00" + goos + "\x00" + goarch
 	if dir, ok := c.dirs[key]; ok {
 		return dir, nil
 	}
 	if err, ok := c.errs[key]; ok {
 		return "", err
 	}
-	dir := filepath.Join(c.root, fmt.Sprintf("h%d_%s", len(c.dirs), goarch))
-	if _, err := generateGoAsmHeader(pkgDir, goarch, dir); err != nil {
+	dir := filepath.Join(c.root, fmt.Sprintf("h%d_%s_%s", len(c.dirs), goos, goarch))
+	if _, err := generateGoAsmHeader(pkgDir, goos, goarch, dir); err != nil {
 		c.errs[key] = err
 		return "", err
 	}
@@ -327,10 +340,10 @@ func (c *asmhdrCache) close() { os.RemoveAll(c.root) }
 
 // ensureGoAsmHeader prepares the include directory a file that includes
 // go_asm.h needs: the generated header for the package in path's directory,
-// for the file's target architecture.  It reports a usage error when the
-// architecture cannot be determined, and passes through the generator's
-// diagnostics, which name the package.
-func ensureGoAsmHeader(path string, target arch.Arch, cache *asmhdrCache) (string, func(), error) {
+// for the file's target GOOS and architecture.  It reports a usage error
+// when the architecture cannot be determined, and passes through the
+// generator's diagnostics, which name the package.
+func ensureGoAsmHeader(path string, target arch.Arch, goos string, cache *asmhdrCache) (string, func(), error) {
 	if path == "-" {
 		return "", nil, errors.New("cannot generate go_asm.h for standard input (no package directory)")
 	}
@@ -338,14 +351,14 @@ func ensureGoAsmHeader(path string, target arch.Arch, cache *asmhdrCache) (strin
 		return "", nil, errors.New("a file that includes go_asm.h needs a target architecture: name the file _<arch>.s or pass -GOARCH")
 	}
 	if cache != nil {
-		dir, err := cache.dirFor(filepath.Dir(path), goarchName(target))
+		dir, err := cache.dirFor(filepath.Dir(path), goos, goarchName(target))
 		return dir, func() {}, err
 	}
 	root, err := os.MkdirTemp("", "gasm-asmhdr")
 	if err != nil {
 		return "", nil, err
 	}
-	dir, err := generateGoAsmHeader(filepath.Dir(path), goarchName(target), root)
+	dir, err := generateGoAsmHeader(filepath.Dir(path), goos, goarchName(target), root)
 	if err != nil {
 		os.RemoveAll(root)
 		return "", nil, err