(fix) no more broken CI

Author: kevin-valerio

README.md

@@ -119,6 +119,7 @@ GOROOT=/path/to/go-panikint /path/to/go-panikint/bin/go test -v .
 ```
 
 Note: the upstream Go distribution tests in `$GOROOT/test` intentionally rely on integer wrap-around.
+The go-panikint unit tests live in `$GOROOT/tests` (plural) and should run with overflow checks enabled.
 When running `cmd/internal/testdir` (for example via `src/all.bash`), we disable overflow instrumentation using `GOPANIKINT_DISABLE_OVERFLOW=1`.
 
 ### Examples

src/cmd/compile/internal/ssagen/ssa.go

@@ -5698,13 +5698,18 @@ func isStandardLibraryFile(filename string) bool {
 		return false
 	}
 
+	filename = filepath.Clean(filename)
+
 	// Check if file is from GOROOT (standard library)
 	if buildcfg.GOROOT != "" {
-		gorootSrc := filepath.Join(buildcfg.GOROOT, "src")
+		sep := string(filepath.Separator)
+
+		gorootSrc := filepath.Join(buildcfg.GOROOT, "src") + sep
 		if strings.HasPrefix(filename, gorootSrc) {
 			return true
 		}
-		gorootTest := filepath.Join(buildcfg.GOROOT, "test")
+
+		gorootTest := filepath.Join(buildcfg.GOROOT, "test") + sep
 		if strings.HasPrefix(filename, gorootTest) {
 			return true
 		}