cmd/gc: diagnose "make([]T, non-integer)" correctly.

Fixes #7223.

LGTM=rsc
R=golang-codereviews, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/63040043

src/cmd/gc/typecheck.c

@@ -3231,6 +3231,11 @@ static int
 checkmake(Type *t, char *arg, Node *n)
 {
 	if(n->op == OLITERAL) {
+		switch(n->val.ctype) {
+		case CTINT:
+		case CTRUNE:
+		case CTFLT:
+		case CTCPLX:
 			n->val = toint(n->val);
 			if(mpcmpfixc(n->val.u.xval, 0) < 0) {
 				yyerror("negative %s argument in make(%T)", arg, t);
@@ -3245,15 +3250,19 @@ checkmake(Type *t, char *arg, Node *n)
 			// a redundant "constant NNN overflows int" error.
 			defaultlit(&n, types[TINT]);
 			return 0;
+		default:
+		       	break;
+		}
 	}
 
-	// Defaultlit still necessary for non-constant: n might be 1<<k.
-	defaultlit(&n, types[TINT]);
-
-	if(!isint[n->type->etype]) {
+	if(!isint[n->type->etype] && n->type->etype != TIDEAL) {
 		yyerror("non-integer %s argument in make(%T) - %T", arg, t, n->type);
 		return -1;
 	}
+
+	// Defaultlit still necessary for non-constant: n might be 1<<k.
+	defaultlit(&n, types[TINT]);
+
 	return 0;
 }
 

test/fixedbugs/issue7223.go

+// errorcheck
+
+// Copyright 2014 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
+
+var bits1 uint = 10
+const bits2 uint = 10
+
+func main() {
+	_ = make([]byte, 1<<bits1)
+	_ = make([]byte, 1<<bits2)
+	_ = make([]byte, nil) // ERROR "non-integer.*len"
+	_ = make([]byte, nil, 2) // ERROR "non-integer.*len"
+	_ = make([]byte, 1, nil) // ERROR "non-integer.*cap"
+	_ = make([]byte, true) // ERROR "non-integer.*len"
+	_ = make([]byte, "abc") // ERROR "non-integer.*len"
+}