cmd/fmt: Always write to stdout

There was an explicit check that would prevent writing to stdout if
the formatting didn't change anything.

This makes sense for the "write to file" or "diff" options as we can
save work by bailing out early, but if configured to write the file
contents to stdout we should do so in all cases.

Fixes: #2235
Signed-off-by: Patrick East <east.patrick@gmail.com>

cmd/fmt.go

@@ -106,10 +106,6 @@ func formatFile(filename string, info os.FileInfo, err error) error {
 		return newError("failed to parse Rego source file: %v", err)
 	}
 
-	if bytes.Equal(formatted, contents) {
-		return nil
-	}
-
 	var out io.Writer = os.Stdout
 	if fmtParams.list {
 		fmt.Fprintln(out, filename)
@@ -158,15 +154,15 @@ func formatStdin(r io.Reader, w io.Writer) error {
 		return err
 	}
 
-	if !bytes.Equal(formatted, contents) {
-		_, err := w.Write(formatted)
-		return err
-	}
-
-	return nil
+	_, err = w.Write(formatted)
+	return err
 }
 
 func doDiff(old, new []byte) (stdout, stderr bytes.Buffer, err error) {
+	if bytes.Equal(old, new) {
+		return stdout, stderr, nil
+	}
+
 	o, err := ioutil.TempFile("", ".opafmt")
 	if err != nil {
 		return stdout, stderr, err