code review 4528116: gc: typecheck the whole tree before walking. preparati...

src/cmd/gc/walk.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        "go.h"
 
 static  Node*   walkprint(Node*, NodeList**, int);
 static  Node*   conv(Node*, Type*);
 static  Node*   mapfn(char*, Type*);
 static  Node*   makenewvar(Type*, NodeList**, Node**);
@@ skipping 48 matching lines @@
 
 void
 walk(Node *fn)
 {
         char s[50];
         NodeList *l;
         Node *n;
         int lno;
 
         curfn = fn;
+
         if(debug['W']) {
                 snprint(s, sizeof(s), "\nbefore %S", curfn->nname->sym);
                 dumplist(s, curfn->nbody);
         }
         if(curfn->type->outtuple)
                 if(walkret(curfn->nbody))
                         yyerror("function ends without a return statement");
-        typechecklist(curfn->nbody, Etop);
+
         lno = lineno;
         for(l=fn->dcl; l; l=l->next) {
                 n = l->n;
                 if(n->op != ONAME || n->class != PAUTO)
                         continue;
                 lineno = n->lineno;
                 typecheck(&n, Erv | Easgn);     // only needed for unused variables
                 if(!n->used && n->sym->name[0] != '&' && !nsyntaxerrors)
                         yyerror("%S declared and not used", n->sym);
         }
@@ skipping 374 matching lines @@
         case OCALLINTER:
         case OCALL:
         case OCALLFUNC:
         case OSEND:
         case ORECV:
         case OPRINT:
         case OPRINTN:
         case OPANIC:
         case OEMPTY:
         case ORECOVER:
-                if(n->typecheck == 0)
+                if(n->typecheck == 0) {
+                        dump("missing typecheck:", n);
                         fatal("missing typecheck");
+                }
                 init = n->ninit;
                 n->ninit = nil;
                 walkexpr(&n, &init);
                 n->ninit = concat(init, n->ninit);
                 break;
 
         case OBREAK:
         case ODCL:
         case OCONTINUE:
         case OFALL:
@@ skipping 1965 matching lines @@
                 l = list(l, nod(OAS, nx, a->n));        // s[n] = arg
                 if (a->next != nil)
                         l = list(l, nod(OAS, nn, nod(OADD, nn, nodintconst(1))));  // n = n + 1
         }
 
         typechecklist(l, Etop);
         walkstmtlist(l);
         *init = concat(*init, l);
         return ns;
 }