cmd/gofmt: remove -tabwidth and -tabs flags

Having these flags misleads people into thinking they're acceptable
for code that "must be gofmt'd".

If an organization wishes to use gofmt internally with
different settings, they can fork gofmt trivially. But "gofmt"
as used by the community with open source Go code should not
support these old knobs.

Also removes the -comments flag.

Fixes #7101

R=r, gri
CC=golang-codereviews
https://golang.org/cl/52170043

src/cmd/gofmt/doc.go

@@ -4,6 +4,7 @@
 
 /*
 Gofmt formats Go programs.
+It uses tabs (width = 8) for indentation and blanks for alignment.
 
 Without an explicit path, it processes the standard input.  Given a file,
 it operates on that file; given a directory, it operates on all .go files in
@@ -33,13 +34,9 @@ The flags are:
 		If a file's formatting is different from gofmt's, overwrite it
 		with gofmt's version.
 
-Formatting control flags:
-	-comments=true
-		Print comments; if false, all comments are elided from the output.
-	-tabs=true
-		Indent with tabs; if false, spaces are used instead.
-	-tabwidth=8
-		Tab width in spaces.
+Debugging support:
+	-cpuprofile filename
+		Write cpu profile to the specified file.
 
 
 The rewrite rule specified with the -r flag must be a string of the form:

src/cmd/gofmt/gofmt.go

@@ -31,21 +31,20 @@ var (
 	doDiff      = flag.Bool("d", false, "display diffs instead of rewriting files")
 	allErrors   = flag.Bool("e", false, "report all errors (not just the first 10 on different lines)")
 
-	// layout control
-	comments  = flag.Bool("comments", true, "print comments")
-	tabWidth  = flag.Int("tabwidth", 8, "tab width")
-	tabIndent = flag.Bool("tabs", true, "indent with tabs")
-
 	// debugging
 	cpuprofile = flag.String("cpuprofile", "", "write cpu profile to this file")
 )
 
+const (
+	tabWidth    = 8
+	printerMode = printer.UseSpaces | printer.TabIndent
+)
+
 var (
-	fileSet     = token.NewFileSet() // per process FileSet
-	exitCode    = 0
-	rewrite     func(*ast.File) *ast.File
-	parserMode  parser.Mode
-	printerMode printer.Mode
+	fileSet    = token.NewFileSet() // per process FileSet
+	exitCode   = 0
+	rewrite    func(*ast.File) *ast.File
+	parserMode parser.Mode
 )
 
 func report(err error) {
@@ -60,22 +59,12 @@ func usage() {
 }
 
 func initParserMode() {
-	parserMode = parser.Mode(0)
-	if *comments {
-		parserMode |= parser.ParseComments
-	}
+	parserMode = parser.ParseComments
 	if *allErrors {
 		parserMode |= parser.AllErrors
 	}
 }
 
-func initPrinterMode() {
-	printerMode = printer.UseSpaces
-	if *tabIndent {
-		printerMode |= printer.TabIndent
-	}
-}
-
 func isGoFile(f os.FileInfo) bool {
 	// ignore non-Go files
 	name := f.Name()
@@ -118,7 +107,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 	}
 
 	var buf bytes.Buffer
-	err = (&printer.Config{Mode: printerMode, Tabwidth: *tabWidth}).Fprint(&buf, fileSet, file)
+	err = (&printer.Config{Mode: printerMode, Tabwidth: tabWidth}).Fprint(&buf, fileSet, file)
 	if err != nil {
 		return err
 	}
@@ -180,11 +169,6 @@ func main() {
 func gofmtMain() {
 	flag.Usage = usage
 	flag.Parse()
-	if *tabWidth < 0 {
-		fmt.Fprintf(os.Stderr, "negative tabwidth %d\n", *tabWidth)
-		exitCode = 2
-		return
-	}
 
 	if *cpuprofile != "" {
 		f, err := os.Create(*cpuprofile)
@@ -199,7 +183,6 @@ func gofmtMain() {
 	}
 
 	initParserMode()
-	initPrinterMode()
 	initRewrite()
 
 	if flag.NArg() == 0 {

src/cmd/gofmt/gofmt_test.go

@@ -40,7 +40,6 @@ func runTest(t *testing.T, in, out, flags string) {
 	}
 
 	initParserMode()
-	initPrinterMode()
 	initRewrite()
 
 	var buf bytes.Buffer

src/cmd/gofmt/long_test.go

@@ -38,7 +38,7 @@ func gofmt(fset *token.FileSet, filename string, src *bytes.Buffer) error {
 	}
 	ast.SortImports(fset, f)
 	src.Reset()
-	return (&printer.Config{Mode: printerMode, Tabwidth: *tabWidth}).Fprint(src, fset, f)
+	return (&printer.Config{Mode: printerMode, Tabwidth: tabWidth}).Fprint(src, fset, f)
 }
 
 func testFile(t *testing.T, b1, b2 *bytes.Buffer, filename string) {