filepath: make EvalSymlinks work on Windows

Fixes #1830.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4526060

src/pkg/path/filepath/path.go

@@ -9,6 +9,7 @@ package filepath
 import (
 	"bytes"
 	"os"
+	"runtime"
 	"sort"
 	"strings"
 )
@@ -178,6 +179,14 @@ func Ext(path string) string {
 // links.
 // If path is relative it will be evaluated relative to the current directory.
 func EvalSymlinks(path string) (string, os.Error) {
+	if runtime.GOOS == "windows" {
+		// Symlinks are not supported under windows.
+		_, err := os.Lstat(path)
+		if err != nil {
+			return "", err
+		}
+		return Clean(path), nil
+	}
 	const maxIter = 255
 	originalPath := path
 	// consume path by taking each frontmost path element,

src/pkg/path/filepath/path_test.go

@@ -440,48 +440,64 @@ var EvalSymlinksTests = []EvalSymlinksTest{
 	{"test/link2/link3/test", "test"},
 }
 
-func TestEvalSymlinks(t *testing.T) {
-	// Symlinks are not supported under windows.
-	if runtime.GOOS == "windows" {
-		return
+var EvalSymlinksAbsWindowsTests = []EvalSymlinksTest{
+	{`c:\`, `c:\`},
 }
+
+func testEvalSymlinks(t *testing.T, tests []EvalSymlinksTest) {
+	for _, d := range tests {
+		if p, err := filepath.EvalSymlinks(d.path); err != nil {
+			t.Errorf("EvalSymlinks(%q) error: %v", d.path, err)
+		} else if filepath.Clean(p) != filepath.Clean(d.dest) {
+			t.Errorf("EvalSymlinks(%q)=%q, want %q", d.path, p, d.dest)
+		}
+	}
+}
+
+func TestEvalSymlinks(t *testing.T) {
 	defer os.RemoveAll("test")
 	for _, d := range EvalSymlinksTestDirs {
 		var err os.Error
 		if d.dest == "" {
 			err = os.Mkdir(d.path, 0755)
 		} else {
+			if runtime.GOOS != "windows" {
 				err = os.Symlink(d.dest, d.path)
 			}
+		}
 		if err != nil {
 			t.Fatal(err)
 		}
 	}
-	// relative
+	var tests []EvalSymlinksTest
+	if runtime.GOOS == "windows" {
 		for _, d := range EvalSymlinksTests {
-		if p, err := filepath.EvalSymlinks(d.path); err != nil {
-			t.Errorf("EvalSymlinks(%q) error: %v", d.path, err)
-		} else if p != d.dest {
-			t.Errorf("EvalSymlinks(%q)=%q, want %q", d.path, p, d.dest)
+			if d.path == d.dest {
+				// will test only real files and directories
+				tests = append(tests, d)
 			}
 		}
+	} else {
+		tests = EvalSymlinksTests
+	}
+	// relative
+	testEvalSymlinks(t, tests)
 	// absolute
 	goroot, err := filepath.EvalSymlinks(os.Getenv("GOROOT"))
 	if err != nil {
 		t.Fatalf("EvalSymlinks(%q) error: %v", os.Getenv("GOROOT"), err)
 	}
 	testroot := filepath.Join(goroot, "src", "pkg", "path", "filepath")
-	for _, d := range EvalSymlinksTests {
-		a := EvalSymlinksTest{
-			filepath.Join(testroot, d.path),
-			filepath.Join(testroot, d.dest),
+	for i, d := range tests {
+		tests[i].path = filepath.Join(testroot, d.path)
+		tests[i].dest = filepath.Join(testroot, d.dest)
 	}
-		if p, err := filepath.EvalSymlinks(a.path); err != nil {
-			t.Errorf("EvalSymlinks(%q) error: %v", a.path, err)
-		} else if p != a.dest {
-			t.Errorf("EvalSymlinks(%q)=%q, want %q", a.path, p, a.dest)
+	if runtime.GOOS == "windows" {
+		for _, d := range EvalSymlinksAbsWindowsTests {
+			tests = append(tests, d)
 		}
 	}
+	testEvalSymlinks(t, tests)
 }
 
 // Test paths relative to $GOROOT/src