issue59404.go

     1  // build -gcflags=-l=4
     2  
     3  // Copyright 2023 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 p
     8  
     9  type Interface interface {
    10  	MonitoredResource() (resType string, labels map[string]string)
    11  	Done()
    12  }
    13  
    14  func Autodetect() Interface {
    15  	return func() Interface {
    16  		Do(func() {
    17  			var ad, gd Interface
    18  
    19  			go func() {
    20  				defer gd.Done()
    21  				ad = aad()
    22  			}()
    23  			go func() {
    24  				defer ad.Done()
    25  				gd = aad()
    26  				defer func() { recover() }()
    27  			}()
    28  
    29  			autoDetected = ad
    30  			if gd != nil {
    31  				autoDetected = gd
    32  			}
    33  		})
    34  		return autoDetected
    35  	}()
    36  }
    37  
    38  var autoDetected Interface
    39  var G int
    40  
    41  type If int
    42  
    43  func (x If) MonitoredResource() (resType string, labels map[string]string) {
    44  	return "", nil
    45  }
    46  
    47  //go:noinline
    48  func (x If) Done() {
    49  	G++
    50  }
    51  
    52  //go:noinline
    53  func Do(fn func()) {
    54  	fn()
    55  }
    56  
    57  //go:noinline
    58  func aad() Interface {
    59  	var x If
    60  	return x
    61  }
    62
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