mirror of
https://github.com/golang/go
synced 2024-11-02 08:01:26 +00:00
2de449e7a0
Add larger comment explaining testing methodology, and derive tests arithmetically. (These tests are checking rounding again; the derived tests they replace were checking exact values.) LGTM=r, gri R=gri, r CC=golang-codereviews https://golang.org/cl/100660044
48 lines
1.8 KiB
Go
48 lines
1.8 KiB
Go
// errorcheck
|
|
|
|
// Check flagging of invalid conversion of constant to float32/float64 near min/max boundaries.
|
|
|
|
// Copyright 2014 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package main
|
|
|
|
// See float_lit2.go for motivation for these values.
|
|
const (
|
|
two24 = 1.0 * (1 << 24)
|
|
two53 = 1.0 * (1 << 53)
|
|
two64 = 1.0 * (1 << 64)
|
|
two128 = two64 * two64
|
|
two256 = two128 * two128
|
|
two512 = two256 * two256
|
|
two768 = two512 * two256
|
|
two1024 = two512 * two512
|
|
|
|
ulp32 = two128 / two24
|
|
max32 = two128 - ulp32
|
|
|
|
ulp64 = two1024 / two53
|
|
max64 = two1024 - ulp64
|
|
)
|
|
|
|
var x = []interface{}{
|
|
float32(max32 + ulp32/2 - 1), // ok
|
|
float32(max32 + ulp32/2 - two128/two256), // ok
|
|
float32(max32 + ulp32/2), // ERROR "constant 3\.40282e\+38 overflows float32"
|
|
|
|
float32(-max32 - ulp32/2 + 1), // ok
|
|
float32(-max32 - ulp32/2 + two128/two256), // ok
|
|
float32(-max32 - ulp32/2), // ERROR "constant -3\.40282e\+38 overflows float32"
|
|
|
|
// If the compiler's internal floating point representation
|
|
// is shorter than 1024 bits, it cannot distinguish max64+ulp64/2-1 and max64+ulp64/2.
|
|
// gc uses fewer than 1024 bits, so allow it to print the overflow error for the -1 case.
|
|
float64(max64 + ulp64/2 - two1024/two256), // ok
|
|
float64(max64 + ulp64/2 - 1), // GC_ERROR "constant 1\.79769e\+308 overflows float64"
|
|
float64(max64 + ulp64/2), // ERROR "constant 1\.79769e\+308 overflows float64"
|
|
|
|
float64(-max64 - ulp64/2 + two1024/two256), // ok
|
|
float64(-max64 - ulp64/2 + 1), // GC_ERROR "constant -1\.79769e\+308 overflows float64"
|
|
float64(-max64 - ulp64/2), // ERROR "constant -1\.79769e\+308 overflows float64"
|
|
}
|