bug075

R=r
OCL=15192
CL=15192

src/cmd/gc/walk.c

@@ -406,6 +406,7 @@ loop:
 		case OINDEXPTR:
 			if(cl == 2 && cr == 1) {
 				// a,b = map[] - mapaccess2
+				walktype(r->left, Erv);
 				if(!isptrto(r->left->type, TMAP))
 					break;
 				l = mapop(n, top);

src/runtime/map.c

@@ -114,6 +114,7 @@ sys·mapaccess1(Hmap *m, ...)
 	}
 
 	m->valalg->copy(m->valsize, av, 0);
+	throw("sys·mapaccess1: key not in map");
 
 out:
 	if(debug) {