issue22781.go

     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  
     7  package main
     8  
     9  import "runtime/debug"
    10  
    11  type T struct {
    12  	// >= 16 bytes to avoid tiny alloc.
    13  	a, b int
    14  }
    15  
    16  func 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
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