cmd/go: resolve TODO by replacing InDir() function

Change-Id: Idf886bbc4e66c9ee2a41c90034075301e0a21a58
Reviewed-on: https://go-review.googlesource.com/c/go/+/271909
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Jay Conrod <jayconrod@google.com>

src/cmd/go/internal/search/search.go

@@ -571,7 +571,6 @@ func IsRelativePath(pattern string) bool {
 // If so, InDir returns an equivalent path relative to dir.
 // If not, InDir returns an empty string.
 // InDir makes some effort to succeed even in the presence of symbolic links.
-// TODO(rsc): Replace internal/test.inDir with a call to this function for Go 1.12.
 func InDir(path, dir string) string {
 	if rel := inDirLex(path, dir); rel != "" {
 		return rel

src/cmd/go/internal/test/test.go

@@ -29,6 +29,7 @@ import (
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
 	"cmd/go/internal/lockedfile"
+	"cmd/go/internal/search"
 	"cmd/go/internal/str"
 	"cmd/go/internal/trace"
 	"cmd/go/internal/work"
@@ -1499,7 +1500,7 @@ func computeTestInputsID(a *work.Action, testlog []byte) (cache.ActionID, error)
 			if !filepath.IsAbs(name) {
 				name = filepath.Join(pwd, name)
 			}
-			if a.Package.Root == "" || !inDir(name, a.Package.Root) {
+			if a.Package.Root == "" || search.InDir(name, a.Package.Root) == "" {
 				// Do not recheck files outside the module, GOPATH, or GOROOT root.
 				break
 			}
@@ -1508,7 +1509,7 @@ func computeTestInputsID(a *work.Action, testlog []byte) (cache.ActionID, error)
 			if !filepath.IsAbs(name) {
 				name = filepath.Join(pwd, name)
 			}
-			if a.Package.Root == "" || !inDir(name, a.Package.Root) {
+			if a.Package.Root == "" || search.InDir(name, a.Package.Root) == "" {
 				// Do not recheck files outside the module, GOPATH, or GOROOT root.
 				break
 			}
@@ -1526,18 +1527,6 @@ func computeTestInputsID(a *work.Action, testlog []byte) (cache.ActionID, error)
 	return sum, nil
 }
 
-func inDir(path, dir string) bool {
-	if str.HasFilePathPrefix(path, dir) {
-		return true
-	}
-	xpath, err1 := filepath.EvalSymlinks(path)
-	xdir, err2 := filepath.EvalSymlinks(dir)
-	if err1 == nil && err2 == nil && str.HasFilePathPrefix(xpath, xdir) {
-		return true
-	}
-	return false
-}
-
 func hashGetenv(name string) cache.ActionID {
 	h := cache.NewHash("getenv")
 	v, ok := os.LookupEnv(name)