1// run
2
3// Copyright 2017 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7package main
8
9import "runtime/debug"
10
11type T struct {
12	// >= 16 bytes to avoid tiny alloc.
13	a, b int
14}
15
16func main() {
17	debug.SetGCPercent(1)
18	for i := 0; i < 100000; i++ {
19		m := make(map[*T]struct{}, 0)
20		for j := 0; j < 20; j++ {
21			// During the call to mapassign_fast64, the key argument
22			// was incorrectly treated as a uint64. If the stack was
23			// scanned during that call, the only pointer to k was
24			// missed, leading to *k being collected prematurely.
25			k := new(T)
26			m[k] = struct{}{}
27		}
28	}
29}
30