cmd/gc: fix line number for 'missing return' in closure

R=ken2
CC=golang-dev
https://codereview.appspot.com/7838048

1 files changed, 1436 insertions, 0 deletions

diff --git a/test/return.go b/test/return.go
index aebbf78b7..dcf32f86f 100644
--- a/test/return.go
+++ b/test/return.go
@@ -1450,4 +1450,1440 @@ L:
 	}
 } // ERROR "missing return"
 
+// again, with func literals
+
+var _ = func() int {
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+} // ERROR "missing return"
+
+// return is okay
+var _ = func() int {
+	print(1)
+	return 2
+}
+
+// goto is okay
+var _ = func() int {
+L:
+	print(1)
+	goto L
+}
+
+// panic is okay
+var _ = func() int {
+	print(1)
+	panic(2)
+}
+
+// but only builtin panic
+var _ = func() int {
+	var panic = func(int) {}
+	print(1)
+	panic(2)
+} // ERROR "missing return"
+
+// block ending in terminating statement is okay
+var _ = func() int {
+	{
+		print(1)
+		return 2
+	}
+}
+
+// block ending in terminating statement is okay
+var _ = func() int {
+L:
+	{
+		print(1)
+		goto L
+	}
+}
+
+// block ending in terminating statement is okay
+var _ = func() int {
+	print(1)
+	{
+		panic(2)
+	}
+}
+
+// adding more code - even though it is dead - now requires a return
+
+var _ = func() int {
+	print(1)
+	return 2
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	print(1)
+	goto L
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	panic(2)
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		print(1)
+		return 2
+		print(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		print(1)
+		goto L
+		print(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	{
+		panic(2)
+		print(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		print(1)
+		return 2
+	}
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		print(1)
+		goto L
+	}
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	{
+		panic(2)
+	}
+	print(3)
+} // ERROR "missing return"
+
+// even an empty dead block triggers the message, because it
+// becomes the final statement.
+
+var _ = func() int {
+	print(1)
+	return 2
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	print(1)
+	goto L
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	panic(2)
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		print(1)
+		return 2
+		{}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		print(1)
+		goto L
+		{}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	{
+		panic(2)
+		{}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		print(1)
+		return 2
+	}
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		print(1)
+		goto L
+	}
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	{
+		panic(2)
+	}
+	{}
+} // ERROR "missing return"
+
+// if-else chain with final else and all terminating is okay
+
+var _ = func() int {
+	print(1)
+	if x == nil {
+		panic(2)
+	} else {
+		panic(3)
+	}
+}
+
+var _ = func() int {
+L:
+	print(1)
+	if x == nil {
+		panic(2)
+	} else {
+		goto L
+	}
+}
+
+var _ = func() int {
+L:
+	print(1)
+	if x == nil {
+		panic(2)
+	} else if x == 1 {
+		return 0
+	} else if x != 2 {
+		panic(3)
+	} else {
+		goto L
+	}
+}
+
+// if-else chain missing final else is not okay, even if the
+// conditions cover every possible case.
+
+var _ = func() int {
+	print(1)
+	if x == nil {
+		panic(2)
+	} else if x != nil {
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	if x == nil {
+		panic(2)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	print(1)
+	if x == nil {
+		panic(2)
+	} else if x == 1 {
+		return 0
+	} else if x != 1 {
+		panic(3)
+	}
+} // ERROR "missing return"
+
+
+// for { loops that never break are okay.
+
+var _ = func() int {
+	print(1)
+	for {}
+}
+
+var _ = func() int {
+	for {
+		for {
+			break
+		}
+	}
+}
+
+var _ = func() int {
+	for {
+		L:
+		for {
+			break L
+		}
+	}
+}
+
+// for { loops that break are not okay.
+
+var _ = func() int {
+	print(1)
+	for { break }
+} // ERROR "missing return"
+
+var _ = func() int {
+	for {
+		for {
+		}
+		break
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	for {
+		for {
+			break L
+		}
+	}
+} // ERROR "missing return"
+
+// if there's a condition - even "true" - the loops are no longer syntactically terminating
+
+var _ = func() int {
+	print(1)
+	for x == nil {}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for x == nil {
+		for {
+			break
+		}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for x == nil {
+		L:
+		for {
+			break L
+		}
+	}	
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	for true {}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for true {
+		for {
+			break
+		}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for true {
+		L:
+		for {
+			break L
+		}
+	}
+} // ERROR "missing return"
+
+// select in which all cases terminate and none break are okay.
+
+var _ = func() int {
+	print(1)
+	select{}
+}
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	}
+}
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		for{}
+	}
+}
+
+var _ = func() int {
+L:
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	case c <- 1:
+		print(2)
+		goto L
+	}
+}
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	default:
+		select{}
+	}
+}
+
+// if any cases don't terminate, the select isn't okay anymore
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(2)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+		goto L
+	case c <- 1:
+		print(2)
+	}
+} // ERROR "missing return"
+
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	default:
+		print(2)
+	}
+} // ERROR "missing return"
+
+
+// if any breaks refer to the select, the select isn't okay anymore, even if they're dead
+
+var _ = func() int {
+	print(1)
+	select{ default: break }
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+		break
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+L:
+	select {
+	case <-c:
+		print(2)
+		for{ break L }
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+L:
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	case c <- 1:
+		print(2)
+		break L
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	select {
+	case <-c:
+		print(1)
+		panic("abc")
+	default:
+		select{}
+		break
+	}
+} // ERROR "missing return"
+
+// switch with default in which all cases terminate is okay
+
+var _ = func() int {
+	print(1)
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+	default:
+		return 4
+	}
+}
+
+var _ = func() int {
+	print(1)
+	switch x {
+	default:
+		return 4
+	case 1:
+		print(2)
+		panic(3)
+	}
+}
+
+var _ = func() int {
+	print(1)
+	switch x {
+	case 1:
+		print(2)
+		fallthrough
+	default:
+		return 4
+	}
+}
+
+// if no default or some case doesn't terminate, switch is no longer okay
+
+var _ = func() int {
+	print(1)
+	switch {
+	}
+} // ERROR "missing return"
+
+
+var _ = func() int {
+	print(1)
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+	case 2:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x {
+	case 2:
+		return 4
+	case 1:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x {
+	case 1:
+		print(2)
+		fallthrough
+	case 2:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+// if any breaks refer to the switch, switch is no longer okay
+
+var _ = func() int {
+	print(1)
+L:
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+		break L
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x {
+	default:
+		return 4
+		break
+	case 1:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+L:
+	switch x {
+	case 1:
+		print(2)
+		for {
+			break L
+		}
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+// type switch with default in which all cases terminate is okay
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+	default:
+		return 4
+	}
+}
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	default:
+		return 4
+	case int:
+		print(2)
+		panic(3)
+	}
+}
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	case int:
+		print(2)
+		fallthrough
+	default:
+		return 4
+	}
+}
+
+// if no default or some case doesn't terminate, switch is no longer okay
+
+var _ = func() int {
+	print(1)
+	switch {
+	}
+} // ERROR "missing return"
+
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+	case float64:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	case float64:
+		return 4
+	case int:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	case int:
+		print(2)
+		fallthrough
+	case float64:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+// if any breaks refer to the switch, switch is no longer okay
+
+var _ = func() int {
+	print(1)
+L:
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+		break L
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+	switch x.(type) {
+	default:
+		return 4
+		break
+	case int:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	print(1)
+L:
+	switch x.(type) {
+	case int:
+		print(2)
+		for {
+			break L
+		}
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+// again, but without the leading print(1).
+// testing that everything works when the terminating statement is first.
+
+var _ = func() int {
+} // ERROR "missing return"
+
+// return is okay
+var _ = func() int {
+	return 2
+}
+
+// goto is okay
+var _ = func() int {
+L:
+	goto L
+}
+
+// panic is okay
+var _ = func() int {
+	panic(2)
+}
+
+// but only builtin panic
+var _ = func() int {
+	var panic = func(int) {}
+	panic(2)
+} // ERROR "missing return"
+
+// block ending in terminating statement is okay
+var _ = func() int {
+	{
+		return 2
+	}
+}
+
+// block ending in terminating statement is okay
+var _ = func() int {
+L:
+	{
+		goto L
+	}
+}
+
+// block ending in terminating statement is okay
+var _ = func() int {
+	{
+		panic(2)
+	}
+}
+
+// adding more code - even though it is dead - now requires a return
+
+var _ = func() int {
+	return 2
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	goto L
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+	panic(2)
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		return 2
+		print(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		goto L
+		print(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		panic(2)
+		print(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		return 2
+	}
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		goto L
+	}
+	print(3)
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		panic(2)
+	}
+	print(3)
+} // ERROR "missing return"
+
+// even an empty dead block triggers the message, because it
+// becomes the final statement.
+
+var _ = func() int {
+	return 2
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	goto L
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+	panic(2)
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		return 2
+		{}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		goto L
+		{}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		panic(2)
+		{}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		return 2
+	}
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	{
+		goto L
+	}
+	{}
+} // ERROR "missing return"
+
+var _ = func() int {
+	{
+		panic(2)
+	}
+	{}
+} // ERROR "missing return"
+
+// if-else chain with final else and all terminating is okay
+
+var _ = func() int {
+	if x == nil {
+		panic(2)
+	} else {
+		panic(3)
+	}
+}
+
+var _ = func() int {
+L:
+	if x == nil {
+		panic(2)
+	} else {
+		goto L
+	}
+}
+
+var _ = func() int {
+L:
+	if x == nil {
+		panic(2)
+	} else if x == 1 {
+		return 0
+	} else if x != 2 {
+		panic(3)
+	} else {
+		goto L
+	}
+}
+
+// if-else chain missing final else is not okay, even if the
+// conditions cover every possible case.
+
+var _ = func() int {
+	if x == nil {
+		panic(2)
+	} else if x != nil {
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	if x == nil {
+		panic(2)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	if x == nil {
+		panic(2)
+	} else if x == 1 {
+		return 0
+	} else if x != 1 {
+		panic(3)
+	}
+} // ERROR "missing return"
+
+
+// for { loops that never break are okay.
+
+var _ = func() int {
+	for {}
+}
+
+var _ = func() int {
+	for {
+		for {
+			break
+		}
+	}
+}
+
+var _ = func() int {
+	for {
+		L:
+		for {
+			break L
+		}
+	}
+}
+
+// for { loops that break are not okay.
+
+var _ = func() int {
+	for { break }
+} // ERROR "missing return"
+
+var _ = func() int {
+	for {
+		for {
+		}
+		break
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	for {
+		for {
+			break L
+		}
+	}
+} // ERROR "missing return"
+
+// if there's a condition - even "true" - the loops are no longer syntactically terminating
+
+var _ = func() int {
+	for x == nil {}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for x == nil {
+		for {
+			break
+		}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for x == nil {
+		L:
+		for {
+			break L
+		}
+	}	
+} // ERROR "missing return"
+
+var _ = func() int {
+	for true {}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for true {
+		for {
+			break
+		}
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	for true {
+		L:
+		for {
+			break L
+		}
+	}
+} // ERROR "missing return"
+
+// select in which all cases terminate and none break are okay.
+
+var _ = func() int {
+	select{}
+}
+
+var _ = func() int {
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	}
+}
+
+var _ = func() int {
+	select {
+	case <-c:
+		print(2)
+		for{}
+	}
+}
+
+var _ = func() int {
+L:
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	case c <- 1:
+		print(2)
+		goto L
+	}
+}
+
+var _ = func() int {
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	default:
+		select{}
+	}
+}
+
+// if any cases don't terminate, the select isn't okay anymore
+
+var _ = func() int {
+	select {
+	case <-c:
+		print(2)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+		goto L
+	case c <- 1:
+		print(2)
+	}
+} // ERROR "missing return"
+
+
+var _ = func() int {
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	default:
+		print(2)
+	}
+} // ERROR "missing return"
+
+
+// if any breaks refer to the select, the select isn't okay anymore, even if they're dead
+
+var _ = func() int {
+	select{ default: break }
+} // ERROR "missing return"
+
+var _ = func() int {
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+		break
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	select {
+	case <-c:
+		print(2)
+		for{ break L }
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	select {
+	case <-c:
+		print(2)
+		panic("abc")
+	case c <- 1:
+		print(2)
+		break L
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	select {
+	case <-c:
+		panic("abc")
+	default:
+		select{}
+		break
+	}
+} // ERROR "missing return"
+
+// switch with default in which all cases terminate is okay
+
+var _ = func() int {
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+	default:
+		return 4
+	}
+}
+
+var _ = func() int {
+	switch x {
+	default:
+		return 4
+	case 1:
+		print(2)
+		panic(3)
+	}
+}
+
+var _ = func() int {
+	switch x {
+	case 1:
+		print(2)
+		fallthrough
+	default:
+		return 4
+	}
+}
+
+// if no default or some case doesn't terminate, switch is no longer okay
+
+var _ = func() int {
+	switch {
+	}
+} // ERROR "missing return"
+
+
+var _ = func() int {
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+	case 2:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x {
+	case 2:
+		return 4
+	case 1:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x {
+	case 1:
+		print(2)
+		fallthrough
+	case 2:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+// if any breaks refer to the switch, switch is no longer okay
+
+var _ = func() int {
+L:
+	switch x {
+	case 1:
+		print(2)
+		panic(3)
+		break L
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x {
+	default:
+		return 4
+		break
+	case 1:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	switch x {
+	case 1:
+		print(2)
+		for {
+			break L
+		}
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+// type switch with default in which all cases terminate is okay
+
+var _ = func() int {
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+	default:
+		return 4
+	}
+}
+
+var _ = func() int {
+	switch x.(type) {
+	default:
+		return 4
+	case int:
+		print(2)
+		panic(3)
+	}
+}
+
+var _ = func() int {
+	switch x.(type) {
+	case int:
+		print(2)
+		fallthrough
+	default:
+		return 4
+	}
+}
+
+// if no default or some case doesn't terminate, switch is no longer okay
+
+var _ = func() int {
+	switch {
+	}
+} // ERROR "missing return"
+
+
+var _ = func() int {
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+	case float64:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x.(type) {
+	case float64:
+		return 4
+	case int:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x.(type) {
+	case int:
+		print(2)
+		fallthrough
+	case float64:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+// if any breaks refer to the switch, switch is no longer okay
+
+var _ = func() int {
+L:
+	switch x.(type) {
+	case int:
+		print(2)
+		panic(3)
+		break L
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+	switch x.(type) {
+	default:
+		return 4
+		break
+	case int:
+		print(2)
+		panic(3)
+	}
+} // ERROR "missing return"
+
+var _ = func() int {
+L:
+	switch x.(type) {
+	case int:
+		print(2)
+		for {
+			break L
+		}
+	default:
+		return 4
+	}
+} // ERROR "missing return"
+
 /**/