Upgrade to Go 1.24

Fixes #13381

tpl/internal/go_templates/testenv/exec.go

@@ -31,20 +31,17 @@ import (
 // If exec is not supported, testenv.SyscallIsNotSupported will return true
 // for the resulting error.
 func MustHaveExec(t testing.TB) {
-	tryExecOnce.Do(func() {
-		tryExecErr = tryExec()
-	})
-	if tryExecErr != nil {
-		t.Skipf("skipping test: cannot exec subprocess on %s/%s: %v", runtime.GOOS, runtime.GOARCH, tryExecErr)
+	if err := tryExec(); err != nil {
+		msg := fmt.Sprintf("cannot exec subprocess on %s/%s: %v", runtime.GOOS, runtime.GOARCH, err)
+		if t == nil {
+			panic(msg)
+		}
+		t.Helper()
+		t.Skip("skipping test:", msg)
 	}
 }
 
-var (
-	tryExecOnce sync.Once
-	tryExecErr  error
-)
-
-func tryExec() error {
+var tryExec = sync.OnceValue(func() error {
 	switch runtime.GOOS {
 	case "wasip1", "js", "ios":
 	default:
@@ -70,15 +67,37 @@ func tryExec() error {
 
 	// We know that this is a test executable. We should be able to run it with a
 	// no-op flag to check for overall exec support.
-	exe, err := os.Executable()
+	exe, err := exePath()
 	if err != nil {
 		return fmt.Errorf("can't probe for exec support: %w", err)
 	}
 	cmd := exec.Command(exe, "-test.list=^$")
 	cmd.Env = origEnv
 	return cmd.Run()
+})
+
+// Executable is a wrapper around [MustHaveExec] and [os.Executable].
+// It returns the path name for the executable that started the current process,
+// or skips the test if the current system can't start new processes,
+// or fails the test if the path can not be obtained.
+func Executable(t testing.TB) string {
+	MustHaveExec(t)
+
+	exe, err := exePath()
+	if err != nil {
+		msg := fmt.Sprintf("os.Executable error: %v", err)
+		if t == nil {
+			panic(msg)
+		}
+		t.Fatal(msg)
+	}
+	return exe
 }
 
+var exePath = sync.OnceValues(func() (string, error) {
+	return os.Executable()
+})
+
 var execPaths sync.Map // path -> error
 
 // MustHaveExecPath checks that the current system can start the named executable
@@ -93,6 +112,7 @@ func MustHaveExecPath(t testing.TB, path string) {
 		err, _ = execPaths.LoadOrStore(path, err)
 	}
 	if err != nil {
+		t.Helper()
 		t.Skipf("skipping test: %s: %s", path, err)
 	}
 }