internal/gopathwalk: remove unnecessary call to os.Lstat

internal/gopathwalk.walk remove an unnecessary call to os.Lstat when
checking if a symlink should be traversed. And remove a call to
filepath.EvalSymlinks that should be unnecessary as we are using
os.Stat to compare files.

Change-Id: Ie5ad1cb99cbd6d62f08f2b482a3e84b6fe41114d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/392095
Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
Auto-Submit: Heschi Kreinick <heschi@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Trust: Ian Lance Taylor <iant@golang.org>

internal/gopathwalk/walk.go

@@ -175,8 +175,8 @@ func (w *walker) shouldSkipDir(fi os.FileInfo, dir string) bool {
 
 // walk walks through the given path.
 func (w *walker) walk(path string, typ os.FileMode) error {
-	dir := filepath.Dir(path)
 	if typ.IsRegular() {
+		dir := filepath.Dir(path)
 		if dir == w.root.Path && (w.root.Type == RootGOROOT || w.root.Type == RootGOPATH) {
 			// Doesn't make sense to have regular files
 			// directly in your $GOPATH/src or $GOROOT/src.
@@ -209,12 +209,7 @@ func (w *walker) walk(path string, typ os.FileMode) error {
 			// Emacs noise.
 			return nil
 		}
-		fi, err := os.Lstat(path)
-		if err != nil {
-			// Just ignore it.
-			return nil
-		}
-		if w.shouldTraverse(dir, fi) {
+		if w.shouldTraverse(path) {
 			return fastwalk.ErrTraverseLink
 		}
 	}
@@ -224,13 +219,8 @@ func (w *walker) walk(path string, typ os.FileMode) error {
 // shouldTraverse reports whether the symlink fi, found in dir,
 // should be followed.  It makes sure symlinks were never visited
 // before to avoid symlink loops.
-func (w *walker) shouldTraverse(dir string, fi os.FileInfo) bool {
-	path := filepath.Join(dir, fi.Name())
-	target, err := filepath.EvalSymlinks(path)
-	if err != nil {
-		return false
-	}
-	ts, err := os.Stat(target)
+func (w *walker) shouldTraverse(path string) bool {
+	ts, err := os.Stat(path)
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		return false
@@ -238,7 +228,7 @@ func (w *walker) shouldTraverse(dir string, fi os.FileInfo) bool {
 	if !ts.IsDir() {
 		return false
 	}
-	if w.shouldSkipDir(ts, dir) {
+	if w.shouldSkipDir(ts, filepath.Dir(path)) {
 		return false
 	}
 	// Check for symlink loops by statting each directory component

internal/gopathwalk/walk_test.go

@@ -81,7 +81,7 @@ func TestShouldTraverse(t *testing.T) {
 			continue
 		}
 		var w walker
-		got := w.shouldTraverse(filepath.Join(dir, tt.dir), fi)
+		got := w.shouldTraverse(filepath.Join(dir, tt.dir, fi.Name()))
 		if got != tt.want {
 			t.Errorf("%d. shouldTraverse(%q, %q) = %v; want %v", i, tt.dir, tt.file, got, tt.want)
 		}