code review 7838050: cmd/gc: fix nil pointer dereferences.

src/cmd/gc/dcl.c

 // Copyright 2009 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.
 
 #include        <u.h>
 #include        <libc.h>
 #include        "go.h"
 #include        "y.tab.h"
 
 static  void    funcargs(Node*);
@@ skipping 1321 matching lines @@
         pa = getthisx(t)->type; // ptr to this structure
         if(pa == T) {
                 yyerror("missing receiver");
                 return;
         }
 
         pa = pa->type;
         f = methtype(pa, 1);
         if(f == T) {
                 t = pa;
+                if(t == T) // rely on typecheck having complained before
+                        return;
                 if(t != T) {

[dave_cheney.net, 2013/03/25 02:49:42]

Do you need this check? The line above ensures if t == T 1344 won't be reached.

                         if(isptr[t->etype]) {
                                 if(t->sym != S) {
                                         yyerror("invalid receiver type %T (%T is a pointer type)", pa, t);
                                         return;
                                 }
                                 t = t->type;
                         }
-                }
-                if(t->broke) // rely on typecheck having complained before
-                        return;
-                if(t != T) {
+                        if(t->broke) // rely on typecheck having complained before
+                                return;
                         if(t->sym == S) {
                                 yyerror("invalid receiver type %T (%T is an unnamed type)", pa, t);
                                 return;
                         }
                         if(isptr[t->etype]) {
                                 yyerror("invalid receiver type %T (%T is a pointer type)", pa, t);
                                 return;
                         }
                         if(t->etype == TINTER) {
                                 yyerror("invalid receiver type %T (%T is an interface type)", pa, t);
@@ skipping 99 matching lines @@
         p = smprint("%s·f", s->name);
         s1 = pkglookup(p, s->pkg);
         free(p);
         if(s1->def == N) {
                 s1->def = newname(s1);
                 s1->def->shortname = newname(s);
                 funcsyms = list(funcsyms, s1->def);
         }
         return s1;
 }