issue46725.go

     1  // run
     2  
     3  // Copyright 2021 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"
    10  
    11  type T [4]int // N.B., [4]int avoids runtime's tiny object allocator
    12  
    13  //go:noinline
    14  func g(x []*T) ([]*T, []*T) { return x, x }
    15  
    16  func main() {
    17  	const Jenny = 8675309
    18  	s := [10]*T{{Jenny}}
    19  
    20  	done := make(chan struct{})
    21  	runtime.SetFinalizer(s[0], func(p *T) { close(done) })
    22  
    23  	var h, _ interface{} = g(s[:])
    24  
    25  	if wait(done) {
    26  		panic("GC'd early")
    27  	}
    28  
    29  	if h.([]*T)[0][0] != Jenny {
    30  		panic("lost Jenny's number")
    31  	}
    32  
    33  	if !wait(done) {
    34  		panic("never GC'd")
    35  	}
    36  }
    37  
    38  func wait(done <-chan struct{}) bool {
    39  	for i := 0; i < 10; i++ {
    40  		runtime.GC()
    41  		select {
    42  		case <-done:
    43  			return true
    44  		default:
    45  		}
    46  	}
    47  	return false
    48  }
    49
View as plain text