recognize a defined constant

as a new name in a later declaration
(bug 144)

R=r
OCL=27850
CL=27850

src/cmd/gc/go.y

@@ -845,6 +845,7 @@ pexpr:
 |	laconst
 	{
 		$$ = nod(OLITERAL, N, N);
+		$$->sym = $1;
 		$$->val = $1->oconst->val;
 		$$->type = $1->oconst->type;
 	}

src/cmd/gc/walk.c

@@ -3050,12 +3050,29 @@ out:
 	return n;
 }
 
+int
+colasname(Node *n)
+{
+	switch(n->op) {
+	case ONAME:
+	case ONONAME:
+		break;
+	case OLITERAL:
+		if(n->sym != S)
+			break;
+		// fallthrough
+	default:
+		return 0;
+	}
+	return 1;
+}
+
 Node*
 old2new(Node *n, Type *t)
 {
 	Node *l;
 
-	if(n->op != ONAME && n->op != ONONAME) {
+	if(!colasname(n)) {
 		yyerror("left side of := must be a name");
 		return n;
 	}
@@ -3092,7 +3109,7 @@ checkmixed(Node *nl)
 		t = l->type;
 		l = l->left;
 
-		if(l->op != ONAME && l->op != ONONAME)
+		if(!colasname(l))
 			goto allnew;
 		if(l->sym->block == block) {
 			if(!eqtype(l->type, t, 0))

test/golden.out

@@ -121,14 +121,6 @@ bugs/bug140.go:6: syntax error near L1
 bugs/bug140.go:7: syntax error near L2
 BUG should compile
 
-=========== bugs/bug144.go
-bugs/bug144.go:8: left side of := must be a name
-bugs/bug144.go:8: operation LITERAL not allowed in assignment context
-bugs/bug144.go:8: illegal types for operand: AS
-	ideal
-	int
-BUG should compile
-
 =========== fixedbugs/bug016.go
 fixedbugs/bug016.go:7: constant -3 overflows uint