test: test of goto restrictions

R=gri, iant, bradfitz, fvbommel, r
CC=golang-dev
https://golang.org/cl/4652041

test/errchk

@@ -81,6 +81,19 @@ sub chk {
 			next;
 		}
 		$regexp = $1;
+		
+		# Turn relative line number in message into absolute line number.
+		if($regexp =~ /LINE(([+-])([0-9]+))?/) {
+			my $n = $line;
+			if(defined($1)) {
+				if($2 eq "+") {
+					$n += int($3);
+				} else {
+					$n -= int($3);
+				}
+			}
+			$regexp = "$`$file:$n$'";
+		}
 
 		@errmsg = grep { /$file:$line[:[]/ } @out;
 		@out = grep { !/$file:$line[:[]/ } @out;
@@ -93,6 +106,9 @@ sub chk {
 		if(@match == 0) {
 			bug();
 			print STDERR "errchk: $file:$line: error message does not match '$regexp'\n";
+			foreach my $l (@errmsg) {
+				print STDERR "> $l";
+			}
 			next;
 		}
 	}

test/goto.go

+// errchk $G -e $D/$F.go
+
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Each test is in a separate function just so that if the
+// compiler stops processing after one error, we don't
+// lose other ones.
+
+package main
+
+var (
+	i, n int
+	x    []int
+	c    chan int
+	m    map[int]int
+	s    string
+)
+
+// goto after declaration okay
+func _() {
+	x := 1
+	goto L
+L:
+	_ = x
+}
+
+// goto before declaration okay
+func _() {
+	goto L
+L:
+	x := 1
+	_ = x
+}
+
+// goto across declaration not okay
+func _() {
+	goto L // ERROR "goto L jumps over declaration of x at LINE+1"
+	x := 1
+	_ = x
+L:
+}
+
+// goto across declaration in inner scope okay
+func _() {
+	goto L
+	{
+		x := 1
+		_ = x
+	}
+L:
+}
+
+// goto across declaration after inner scope not okay
+func _() {
+	goto L // ERROR "goto L jumps over declaration of x at LINE+5"
+	{
+		x := 1
+		_ = x
+	}
+	x := 1
+	_ = x
+L:
+}
+
+// goto across declaration in reverse okay
+func _() {
+L:
+	x := 1
+	_ = x
+	goto L
+}
+
+// error shows first offending variable
+func _() {
+	goto L // ERROR "goto L jumps over declaration of x at LINE+1"
+	x := 1
+	_ = x
+	y := 1
+	_ = y
+L:
+}
+
+// goto not okay even if code path is dead
+func _() {
+	goto L // ERROR "goto L jumps over declaration of x at LINE+1"
+	x := 1
+	_ = x
+	y := 1
+	_ = y
+	return
+L:
+}
+
+// goto into outer block okay
+func _() {
+	{
+		goto L
+	}
+L:
+}
+
+// goto backward into outer block okay
+func _() {
+L:
+	{
+		goto L
+	}
+}
+
+// goto into inner block not okay
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	{
+	L:
+	}
+}
+
+// goto backward into inner block still not okay
+func _() {
+	{
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+// error shows first (outermost) offending block
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	{
+		{
+			{
+			L:
+			}
+		}
+	}
+}
+
+// error prefers block diagnostic over declaration diagnostic
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+3"
+	x := 1
+	_ = x
+	{
+	L:
+	}
+}
+
+// many kinds of blocks, all invalid to jump into or among,
+// but valid to jump out of
+
+// if
+
+func _() {
+L:
+	if true {
+		goto L
+	}
+}
+
+func _() {
+L:
+	if true {
+		goto L
+	} else {
+	}
+}
+
+func _() {
+L:
+	if false {
+	} else {
+		goto L
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	if true {
+	L:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	if true {
+	L:
+	} else {
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	if true {
+	} else {
+	L:
+	}
+}
+
+func _() {
+	if false {
+	L:
+	} else {
+		goto L // ERROR "goto L jumps into block starting at LINE-3"
+	}
+}
+
+func _() {
+	if true {
+		goto L // ERROR "goto L jumps into block starting at LINE+1"
+	} else {
+	L:
+	}
+}
+
+func _() {
+	if true {
+		goto L // ERROR "goto L jumps into block starting at LINE+1"
+	} else if false {
+	L:
+	}
+}
+
+func _() {
+	if true {
+		goto L // ERROR "goto L jumps into block starting at LINE+1"
+	} else if false {
+	L:
+	} else {
+	}
+}
+
+func _() {
+	// This one is tricky.  There is an implicit scope
+	// starting at the second if statement, and it contains
+	// the final else, so the outermost offending scope
+	// really is LINE+1 (like in the previous test),
+	// even though it looks like it might be LINE+3 instead.
+	if true {
+		goto L // ERROR "goto L jumps into block starting at LINE+1"
+	} else if false {
+	} else {
+	L:
+	}
+}
+
+/* Want to enable these tests but gofmt mangles them.  Issue 1972.
+
+func _() {
+	// This one is okay, because the else is in the
+	// implicit whole-if block and has no inner block
+	// (no { }) around it.
+	if true {
+		goto L
+	} else
+		L:
+}
+
+func _() {
+	// Still not okay.
+	if true {
+	L:
+	} else
+		goto L //// ERROR "goto L jumps into block starting at LINE-3"
+}
+
+*/
+
+// for
+
+func _() {
+	for {
+		goto L
+	}
+L:
+}
+
+func _() {
+	for {
+		goto L
+	L:
+	}
+}
+
+func _() {
+	for {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+func _() {
+	for {
+		goto L
+	L1:
+	}
+L:
+	goto L1 // ERROR "goto L1 jumps into block starting at LINE-5"
+}
+
+func _() {
+	for i < n {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+func _() {
+	for i = 0; i < n; i++ {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+func _() {
+	for i = range x {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+func _() {
+	for i = range c {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+func _() {
+	for i = range m {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+func _() {
+	for i = range s {
+	L:
+	}
+	goto L // ERROR "goto L jumps into block starting at LINE-3"
+}
+
+// switch
+
+func _() {
+L:
+	switch i {
+	case 0:
+		goto L
+	}
+}
+
+func _() {
+L:
+	switch i {
+	case 0:
+
+	default:
+		goto L
+	}
+}
+
+func _() {
+	switch i {
+	case 0:
+
+	default:
+	L:
+		goto L
+	}
+}
+
+func _() {
+	switch i {
+	case 0:
+
+	default:
+		goto L
+	L:
+	}
+}
+
+func _() {
+	switch i {
+	case 0:
+		goto L
+	L:
+		;
+	default:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	switch i {
+	case 0:
+	L:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	switch i {
+	case 0:
+	L:
+		;
+	default:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+1"
+	switch i {
+	case 0:
+	default:
+	L:
+	}
+}
+
+func _() {
+	switch i {
+	default:
+		goto L // ERROR "goto L jumps into block starting at LINE+1"
+	case 0:
+	L:
+	}
+}
+
+func _() {
+	switch i {
+	case 0:
+	L:
+		;
+	default:
+		goto L // ERROR "goto L jumps into block starting at LINE-4"
+	}
+}
+
+// select
+// different from switch.  the statement has no implicit block around it.
+
+func _() {
+L:
+	select {
+	case <-c:
+		goto L
+	}
+}
+
+func _() {
+L:
+	select {
+	case c <- 1:
+
+	default:
+		goto L
+	}
+}
+
+func _() {
+	select {
+	case <-c:
+
+	default:
+	L:
+		goto L
+	}
+}
+
+func _() {
+	select {
+	case c <- 1:
+
+	default:
+		goto L
+	L:
+	}
+}
+
+func _() {
+	select {
+	case <-c:
+		goto L
+	L:
+		;
+	default:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+2"
+	select {
+	case c <- 1:
+	L:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+2"
+	select {
+	case c <- 1:
+	L:
+		;
+	default:
+	}
+}
+
+func _() {
+	goto L // ERROR "goto L jumps into block starting at LINE+3"
+	select {
+	case <-c:
+	default:
+	L:
+	}
+}
+
+func _() {
+	select {
+	default:
+		goto L // ERROR "goto L jumps into block starting at LINE+1"
+	case <-c:
+	L:
+	}
+}
+
+func _() {
+	select {
+	case <-c:
+	L:
+		;
+	default:
+		goto L // ERROR "goto L jumps into block starting at LINE-4"
+	}
+}