issue23522.go

     1  // run
     2  
     3  // Copyright 2018 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 (
    10  	"math"
    11  )
    12  
    13  type S struct {
    14  	u int64
    15  	n int32
    16  }
    17  
    18  func F1(f float64) *S {
    19  	s := f
    20  	pf := math.Copysign(f, 1)
    21  	u := math.Floor(pf)
    22  	return &S{
    23  		u: int64(math.Copysign(u, s)),
    24  		n: int32(math.Copysign((pf-u)*1e9, s)),
    25  	}
    26  }
    27  
    28  func F2(f float64) *S {
    29  	s := f
    30  	f = math.Copysign(f, 1)
    31  	u := math.Floor(f)
    32  	return &S{
    33  		u: int64(math.Copysign(u, s)),
    34  		n: int32(math.Copysign((f-u)*1e9, s)),
    35  	}
    36  }
    37  
    38  func main() {
    39  	s1 := F1(-1)
    40  	s2 := F2(-1)
    41  	if *s1 != *s2 {
    42  		println("F1:", s1.u, s1.n)
    43  		println("F2:", s2.u, s2.n)
    44  		panic("different")
    45  	}
    46  }
    47
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