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cmd/compile: don't truncate tiny float constants to 0 in error messages
Fixes #13559. Change-Id: I6fe8b5083192e8eb6c1b3ca1919fde81a00ccb7e Reviewed-on: https://go-review.googlesource.com/17695 Run-TryBot: Robert Griesemer <gri@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Alan Donovan <adonovan@google.com>
This commit is contained in:
Robert Griesemer
parent
e05b48e22c
commit
732e2cd746
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@ -212,31 +212,40 @@ func Fconv(fvp *Mpflt, flag int) string {
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return sign + "Inf"
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}
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// Use fmt formatting if in float64 range (common case).
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if x, _ := f.Float64(); !math.IsInf(x, 0) {
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// Use exact fmt formatting if in float64 range (common case):
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// proceed if f doesn't underflow to 0 or overflow to inf.
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if x, _ := f.Float64(); f.Sign() == 0 == (x == 0) && !math.IsInf(x, 0) {
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return fmt.Sprintf("%s%.6g", sign, x)
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}
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// Out of float64 range. Do approximate manual to decimal
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// conversion to avoid precise but possibly slow Float
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// formatting. The exponent is > 0 since a negative out-
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// of-range exponent would have underflowed and led to 0.
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// formatting.
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// f = mant * 2**exp
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var mant big.Float
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exp := float64(f.MantExp(&mant)) // 0.5 <= mant < 1.0, exp > 0
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exp := f.MantExp(&mant) // 0.5 <= mant < 1.0
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// approximate float64 mantissa m and decimal exponent d
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// f ~ m * 10**d
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m, _ := mant.Float64() // 0.5 <= m < 1.0
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d := exp * (math.Ln2 / math.Ln10) // log_10(2)
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m, _ := mant.Float64() // 0.5 <= m < 1.0
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d := float64(exp) * (math.Ln2 / math.Ln10) // log_10(2)
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// adjust m for truncated (integer) decimal exponent e
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e := int64(d)
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m *= math.Pow(10, d-float64(e))
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for m >= 10 {
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// ensure 1 <= m < 10
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switch {
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case m < 1-0.5e-6:
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// The %.6g format below rounds m to 5 digits after the
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// decimal point. Make sure that m*10 < 10 even after
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// rounding up: m*10 + 0.5e-5 < 10 => m < 1 - 0.5e6.
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m *= 10
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e--
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case m >= 10:
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m /= 10
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e++
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}
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return fmt.Sprintf("%s%.5fe+%d", sign, m, e)
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return fmt.Sprintf("%s%.6ge%+d", sign, m, e)
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}
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@ -18,14 +18,14 @@ func main() {
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// Any implementation must be able to handle these constants at
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// compile time (even though they cannot be assigned to a float64).
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var _ = 1e646456992 // ERROR "1.00000e\+646456992 overflows float64"
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var _ = 1e64645699 // ERROR "1.00000e\+64645699 overflows float64"
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var _ = 1e6464569 // ERROR "1.00000e\+6464569 overflows float64"
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var _ = 1e646456 // ERROR "1.00000e\+646456 overflows float64"
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var _ = 1e64645 // ERROR "1.00000e\+64645 overflows float64"
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var _ = 1e6464 // ERROR "1.00000e\+6464 overflows float64"
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var _ = 1e646 // ERROR "1.00000e\+646 overflows float64"
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var _ = 1e309 // ERROR "1.00000e\+309 overflows float64"
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var _ = 1e646456992 // ERROR "1e\+646456992 overflows float64"
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var _ = 1e64645699 // ERROR "1e\+64645699 overflows float64"
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var _ = 1e6464569 // ERROR "1e\+6464569 overflows float64"
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var _ = 1e646456 // ERROR "1e\+646456 overflows float64"
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var _ = 1e64645 // ERROR "1e\+64645 overflows float64"
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var _ = 1e6464 // ERROR "1e\+6464 overflows float64"
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var _ = 1e646 // ERROR "1e\+646 overflows float64"
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var _ = 1e309 // ERROR "1e\+309 overflows float64"
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var _ = 1e308
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}
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@ -8,4 +8,4 @@ package p
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var _ = int8(4) * 300 // ERROR "constant 300 overflows int8" "constant 1200 overflows int8"
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var _ = complex64(1) * 1e200 // ERROR "constant 1e\+200 overflows complex64"
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var _ = complex128(1) * 1e500 // ERROR "constant 1\.00000e\+500 overflows complex128"
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var _ = complex128(1) * 1e500 // ERROR "constant 1e\+500 overflows complex128"
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@ -9,17 +9,17 @@
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package main
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func main() {
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const _ int64 = 1e646456992 // ERROR "1.00000e\+646456992 overflows integer"
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const _ int32 = 1e64645699 // ERROR "1.00000e\+64645699 overflows integer"
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const _ int16 = 1e6464569 // ERROR "1.00000e\+6464569 overflows integer"
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const _ int8 = 1e646456 // ERROR "1.00000e\+646456 overflows integer"
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const _ int = 1e64645 // ERROR "1.00000e\+64645 overflows integer"
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const _ int64 = 1e646456992 // ERROR "1e\+646456992 overflows integer"
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const _ int32 = 1e64645699 // ERROR "1e\+64645699 overflows integer"
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const _ int16 = 1e6464569 // ERROR "1e\+6464569 overflows integer"
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const _ int8 = 1e646456 // ERROR "1e\+646456 overflows integer"
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const _ int = 1e64645 // ERROR "1e\+64645 overflows integer"
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const _ uint64 = 1e646456992 // ERROR "1.00000e\+646456992 overflows integer"
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const _ uint32 = 1e64645699 // ERROR "1.00000e\+64645699 overflows integer"
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const _ uint16 = 1e6464569 // ERROR "1.00000e\+6464569 overflows integer"
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const _ uint8 = 1e646456 // ERROR "1.00000e\+646456 overflows integer"
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const _ uint = 1e64645 // ERROR "1.00000e\+64645 overflows integer"
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const _ uint64 = 1e646456992 // ERROR "1e\+646456992 overflows integer"
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const _ uint32 = 1e64645699 // ERROR "1e\+64645699 overflows integer"
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const _ uint16 = 1e6464569 // ERROR "1e\+6464569 overflows integer"
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const _ uint8 = 1e646456 // ERROR "1e\+646456 overflows integer"
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const _ uint = 1e64645 // ERROR "1e\+64645 overflows integer"
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const _ rune = 1e64645 // ERROR "1.00000e\+64645 overflows integer"
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const _ rune = 1e64645 // ERROR "1e\+64645 overflows integer"
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}
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89
test/fixedbugs/issue13559.go
Normal file
89
test/fixedbugs/issue13559.go
Normal file
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@ -0,0 +1,89 @@
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// errorcheck
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Verify that error messages print meaningful values
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// for various extreme floating-point constants.
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package p
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// failure case in issue
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const _ int64 = 1e-10000 // ERROR "1e\-10000 truncated"
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const (
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_ int64 = 1e10000000 // ERROR "1e\+10000000 overflows"
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_ int64 = 1e1000000 // ERROR "1e\+1000000 overflows"
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_ int64 = 1e100000 // ERROR "1e\+100000 overflows"
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_ int64 = 1e10000 // ERROR "1e\+10000 overflows"
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_ int64 = 1e1000 // ERROR "1e\+1000 overflows"
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_ int64 = 1e100 // ERROR "10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
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_ int64 = 1e10
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_ int64 = 1e1
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_ int64 = 1e0
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_ int64 = 1e-1 // ERROR "0\.1 truncated"
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_ int64 = 1e-10 // ERROR "1e\-10 truncated"
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_ int64 = 1e-100 // ERROR "1e\-100 truncated"
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_ int64 = 1e-1000 // ERROR "1e\-1000 truncated"
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_ int64 = 1e-10000 // ERROR "1e\-10000 truncated"
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_ int64 = 1e-100000 // ERROR "1e\-100000 truncated"
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_ int64 = 1e-1000000 // ERROR "1e\-1000000 truncated"
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)
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const (
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_ int64 = -1e10000000 // ERROR "\-1e\+10000000 overflows"
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_ int64 = -1e1000000 // ERROR "\-1e\+1000000 overflows"
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_ int64 = -1e100000 // ERROR "\-1e\+100000 overflows"
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_ int64 = -1e10000 // ERROR "\-1e\+10000 overflows"
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_ int64 = -1e1000 // ERROR "\-1e\+1000 overflows"
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_ int64 = -1e100 // ERROR "\-10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
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_ int64 = -1e10
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_ int64 = -1e1
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_ int64 = -1e0
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_ int64 = -1e-1 // ERROR "\-0\.1 truncated"
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_ int64 = -1e-10 // ERROR "\-1e\-10 truncated"
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_ int64 = -1e-100 // ERROR "\-1e\-100 truncated"
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_ int64 = -1e-1000 // ERROR "\-1e\-1000 truncated"
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_ int64 = -1e-10000 // ERROR "\-1e\-10000 truncated"
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_ int64 = -1e-100000 // ERROR "\-1e\-100000 truncated"
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_ int64 = -1e-1000000 // ERROR "\-1e\-1000000 truncated"
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)
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const (
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_ int64 = 1.23456789e10000000 // ERROR "1\.23457e\+10000000 overflows"
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_ int64 = 1.23456789e1000000 // ERROR "1\.23457e\+1000000 overflows"
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_ int64 = 1.23456789e100000 // ERROR "1\.23457e\+100000 overflows"
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_ int64 = 1.23456789e10000 // ERROR "1\.23457e\+10000 overflows"
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_ int64 = 1.23456789e1000 // ERROR "1\.23457e\+1000 overflows"
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_ int64 = 1.23456789e100 // ERROR "12345678900000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
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_ int64 = 1.23456789e10
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_ int64 = 1.23456789e1 // ERROR "12\.3457 truncated"
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_ int64 = 1.23456789e0 // ERROR "1\.23457 truncated"
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_ int64 = 1.23456789e-1 // ERROR "0\.123457 truncated"
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_ int64 = 1.23456789e-10 // ERROR "1\.23457e\-10 truncated"
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_ int64 = 1.23456789e-100 // ERROR "1\.23457e\-100 truncated"
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_ int64 = 1.23456789e-1000 // ERROR "1\.23457e\-1000 truncated"
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_ int64 = 1.23456789e-10000 // ERROR "1\.23457e\-10000 truncated"
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_ int64 = 1.23456789e-100000 // ERROR "1\.23457e\-100000 truncated"
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_ int64 = 1.23456789e-1000000 // ERROR "1\.23457e\-1000000 truncated"
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)
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const (
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_ int64 = -1.23456789e10000000 // ERROR "\-1\.23457e\+10000000 overflows"
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_ int64 = -1.23456789e1000000 // ERROR "\-1\.23457e\+1000000 overflows"
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_ int64 = -1.23456789e100000 // ERROR "\-1\.23457e\+100000 overflows"
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_ int64 = -1.23456789e10000 // ERROR "\-1\.23457e\+10000 overflows"
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_ int64 = -1.23456789e1000 // ERROR "\-1\.23457e\+1000 overflows"
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_ int64 = -1.23456789e100 // ERROR "\-12345678900000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 overflows"
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_ int64 = -1.23456789e10
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_ int64 = -1.23456789e1 // ERROR "\-12\.3457 truncated"
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_ int64 = -1.23456789e0 // ERROR "\-1\.23457 truncated"
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_ int64 = -1.23456789e-1 // ERROR "\-0\.123457 truncated"
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_ int64 = -1.23456789e-10 // ERROR "\-1\.23457e\-10 truncated"
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_ int64 = -1.23456789e-100 // ERROR "\-1\.23457e\-100 truncated"
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_ int64 = -1.23456789e-1000 // ERROR "\-1\.23457e\-1000 truncated"
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_ int64 = -1.23456789e-10000 // ERROR "\-1\.23457e\-10000 truncated"
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_ int64 = -1.23456789e-100000 // ERROR "\-1\.23457e\-100000 truncated"
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_ int64 = -1.23456789e-1000000 // ERROR "\-1\.23457e\-1000000 truncated"
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)
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