cmd/go: replace some more stats with fsys.Stat

To support overlays

For #39958

Change-Id: I5ffd72aeb7f5f30f6c60f6334a01a0a1383c7945
Reviewed-on: https://go-review.googlesource.com/c/go/+/264478
Trust: Michael Matloob <matloob@golang.org>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/internal/imports/scan.go

@@ -7,7 +7,6 @@ package imports
 import (
 	"fmt"
 	"io/fs"
-	"os"
 	"path/filepath"
 	"sort"
 	"strconv"
@@ -28,7 +27,7 @@ func ScanDir(dir string, tags map[string]bool) ([]string, []string, error) {
 		// If the directory entry is a symlink, stat it to obtain the info for the
 		// link target instead of the link itself.
 		if info.Mode()&fs.ModeSymlink != 0 {
-			info, err = os.Stat(filepath.Join(dir, name))
+			info, err = fsys.Stat(filepath.Join(dir, name))
 			if err != nil {
 				continue // Ignore broken symlinks.
 			}

src/cmd/go/internal/modload/load.go

@@ -112,6 +112,7 @@ import (
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
+	"cmd/go/internal/fsys"
 	"cmd/go/internal/imports"
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/mvs"
@@ -361,7 +362,7 @@ func resolveLocalPackage(dir string) (string, error) {
 		// If the named directory does not exist or contains no Go files,
 		// the package does not exist.
 		// Other errors may affect package loading, but not resolution.
-		if _, err := os.Stat(absDir); err != nil {
+		if _, err := fsys.Stat(absDir); err != nil {
 			if os.IsNotExist(err) {
 				// Canonicalize OS-specific errors to errDirectoryNotFound so that error
 				// messages will be easier for users to search for.

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

@@ -87,7 +87,7 @@ func matchPackages(ctx context.Context, m *search.Match, tags map[string]bool, f
 
 			if !fi.IsDir() {
 				if fi.Mode()&fs.ModeSymlink != 0 && want {
-					if target, err := os.Stat(path); err == nil && target.IsDir() {
+					if target, err := fsys.Stat(path); err == nil && target.IsDir() {
 						fmt.Fprintf(os.Stderr, "warning: ignoring symlink %s\n", path)
 					}
 				}

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

@@ -156,7 +156,7 @@ func (m *Match) MatchPackages() {
 
 			if !fi.IsDir() {
 				if fi.Mode()&fs.ModeSymlink != 0 && want {
-					if target, err := os.Stat(path); err == nil && target.IsDir() {
+					if target, err := fsys.Stat(path); err == nil && target.IsDir() {
 						fmt.Fprintf(os.Stderr, "warning: ignoring symlink %s\n", path)
 					}
 				}