1// errorcheck
2
3// Check flagging of invalid conversion of constant to float32/float64 near min/max boundaries.
4
5// Copyright 2014 The Go Authors. All rights reserved.
6// Use of this source code is governed by a BSD-style
7// license that can be found in the LICENSE file.
8
9package main
10
11// See float_lit2.go for motivation for these values.
12const (
13	two24   = 1.0 * (1 << 24)
14	two53   = 1.0 * (1 << 53)
15	two64   = 1.0 * (1 << 64)
16	two128  = two64 * two64
17	two256  = two128 * two128
18	two512  = two256 * two256
19	two768  = two512 * two256
20	two1024 = two512 * two512
21
22	ulp32 = two128 / two24
23	max32 = two128 - ulp32
24
25	ulp64 = two1024 / two53
26	max64 = two1024 - ulp64
27)
28
29var x = []interface{}{
30	float32(max32 + ulp32/2 - 1),             // ok
31	float32(max32 + ulp32/2 - two128/two256), // ok
32	float32(max32 + ulp32/2),                 // ERROR "constant 3\.40282e\+38 overflows float32|cannot convert.*to type float32"
33
34	float32(-max32 - ulp32/2 + 1),             // ok
35	float32(-max32 - ulp32/2 + two128/two256), // ok
36	float32(-max32 - ulp32/2),                 // ERROR "constant -3\.40282e\+38 overflows float32|cannot convert.*to type float32"
37
38	// If the compiler's internal floating point representation
39	// is shorter than 1024 bits, it cannot distinguish max64+ulp64/2-1 and max64+ulp64/2.
40	float64(max64 + ulp64/2 - two1024/two256), // ok
41	float64(max64 + ulp64/2 - 1),              // ok
42	float64(max64 + ulp64/2),                  // ERROR "constant 1\.79769e\+308 overflows float64|cannot convert.*to type float64"
43
44	float64(-max64 - ulp64/2 + two1024/two256), // ok
45	float64(-max64 - ulp64/2 + 1),              // ok
46	float64(-max64 - ulp64/2),                  // ERROR "constant -1\.79769e\+308 overflows float64|cannot convert.*to type float64"
47}
48