gofix: fix diff regression from exec change

Also pass -u to diff to be consistent with gofmt.

Fixes #1619

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/4591041

diff --git a/src/cmd/gofix/main.go b/src/cmd/gofix/main.go
index ba2061a0001c41ecd41dacf2d9ea957e887a2ce6..1b091c18aa5e1ba7141880d3504821c1b15e2d2c 100644 (file)
--- a/src/cmd/gofix/main.go
+++ b/src/cmd/gofix/main.go
@@ -248,5 +248,11 @@ func diff(b1, b2 []byte) (data []byte, err os.Error) {
        f1.Write(b1)
        f2.Write(b2)
 
-       return exec.Command("diff", f1.Name(), f2.Name()).CombinedOutput()
+       data, err = exec.Command("diff", "-u", f1.Name(), f2.Name()).CombinedOutput()
+       if len(data) > 0 {
+               // diff exits with a non-zero status when the files don't match.
+               // Ignore that failure as long as we get output.
+               err = nil
+       }
+       return
 }