cmd/go/internal/toolchain: use sync.OnceValue

Rename initPathExts to pathExts, make it return the slice of extensions, and wrap into sync.OnceValue. While at it, return early if PATHEXT is empty. Change-Id: I33508762e87edd226e0a52df4063473c496c0210 Reviewed-on: https://go-review.googlesource.com/c/go/+/611017 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Auto-Submit: Ian Lance Taylor <iant@google.com>
aytanet · Sep 6, 2024 · 4777fd3 · 4777fd3
1 parent ba2a16c
commit 4777fd3
Showing 1 changed file with 15 additions and 22 deletions.
diff --git a/src/cmd/go/internal/toolchain/path_windows.go b/src/cmd/go/internal/toolchain/path_windows.go
@@ -14,30 +14,24 @@ import (
 	"cmd/go/internal/gover"
 )
 
-// pathExts is a cached PATHEXT list.
-var pathExts struct {
-	once sync.Once
-	list []string
-}
+var pathExts = sync.OnceValue(func() []string {
+	x := os.Getenv(`PATHEXT`)
+	if x == "" {
+		return []string{".com", ".exe", ".bat", ".cmd"}
+	}
 
-func initPathExts() {
 	var exts []string
-	x := os.Getenv(`PATHEXT`)
-	if x != "" {
-		for _, e := range strings.Split(strings.ToLower(x), `;`) {
-			if e == "" {
-				continue
-			}
-			if e[0] != '.' {
-				e = "." + e
-			}
-			exts = append(exts, e)
+	for _, e := range strings.Split(strings.ToLower(x), `;`) {
+		if e == "" {
+			continue
+		}
+		if e[0] != '.' {
+			e = "." + e
 		}
-	} else {
-		exts = []string{".com", ".exe", ".bat", ".cmd"}
+		exts = append(exts, e)
 	}
-	pathExts.list = exts
-}
+	return exts
+})
 
 // pathDirs returns the directories in the system search path.
 func pathDirs() []string {
@@ -48,8 +42,7 @@ func pathDirs() []string {
 // described by de and info in directory dir.
 // The analysis only uses the name itself; it does not run the program.
 func pathVersion(dir string, de fs.DirEntry, info fs.FileInfo) (string, bool) {
-	pathExts.once.Do(initPathExts)
-	name, _, ok := cutExt(de.Name(), pathExts.list)
+	name, _, ok := cutExt(de.Name(), pathExts())
 	if !ok {
 		return "", false
 	}