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-rw-r--r--test/float_lit3.go47
1 files changed, 47 insertions, 0 deletions
diff --git a/test/float_lit3.go b/test/float_lit3.go
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+// 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|cannot convert.*to type 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|cannot convert.*to type 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.
+ float64(max64 + ulp64/2 - two1024/two256), // ok
+ float64(max64 + ulp64/2 - 1), // ok
+ float64(max64 + ulp64/2), // ERROR "constant 1\.79769e\+308 overflows float64|cannot convert.*to type float64"
+
+ float64(-max64 - ulp64/2 + two1024/two256), // ok
+ float64(-max64 - ulp64/2 + 1), // ok
+ float64(-max64 - ulp64/2), // ERROR "constant -1\.79769e\+308 overflows float64|cannot convert.*to type float64"
+}