1 // run 2 3 // Copyright 2015 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 // Issue 12577: Test that there are no -0 floating-point constants. 8 9 package main 10 11 import "math" 12 13 const ( 14 z0 = 0.0 15 z1 = -0.0 16 z2 = -z0 17 z3 = -z2 18 ) 19 20 var ( 21 x0 float32 = z0 22 x1 float32 = z1 23 x2 float32 = z2 24 x3 float32 = z3 25 26 y0 float64 = z0 27 y1 float64 = z1 28 y2 float64 = z2 29 y3 float64 = z3 30 ) 31 32 func test32(f float32) { 33 if f != 0 || math.Signbit(float64(f)) { 34 println("BUG: got", f, "want 0.0") 35 return 36 } 37 } 38 39 func test64(f float64) { 40 if f != 0 || math.Signbit(f) { 41 println("BUG: got", f, "want 0.0") 42 return 43 } 44 } 45 46 func main() { 47 if f := -x0; f != 0 || !math.Signbit(float64(f)) { 48 println("BUG: got", f, "want -0.0") 49 } 50 51 test32(-0.0) 52 test32(x0) 53 test32(x1) 54 test32(x2) 55 test32(x3) 56 57 if f := -y0; f != 0 || !math.Signbit(f) { 58 println("BUG: got", f, "want -0.0") 59 } 60 61 test64(-0.0) 62 test64(y0) 63 test64(y1) 64 test64(y2) 65 test64(y3) 66 } 67
