cmd/gc: more robust checking of OIND nodes.

Fixes #4610.

R=golang-dev, remyoudompheng, rsc
CC=golang-dev, nigeltao
https://golang.org/cl/7058057

src/cmd/gc/typecheck.c

@@ -482,9 +482,12 @@ reswitch:
 			n->left = N;
 			goto ret;
 		}
-		if((top & (Erv | Etop)) && !isptr[t->etype]) {
-			yyerror("invalid indirect of %lN", n->left);
-			goto error;
+		if(!isptr[t->etype]) {
+			if(top & (Erv | Etop)) {
+				yyerror("invalid indirect of %lN", n->left);
+				goto error;
+			}
+			goto ret;
 		}
 		ok |= Erv;
 		n->type = t->type;

test/fixedbugs/issue4610.go

+// errorcheck
+
+// Copyright 2012 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.
+
+package main
+
+type bar struct {
+	x int
+}
+
+func main() {
+	var foo bar
+	_ = &foo{} // ERROR "is not a type"
+}
+