// Copyright 2012 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. // constant conversions package const1 import "math" const( mi = ^int(0) mu = ^uint(0) mp = ^uintptr(0) logSizeofInt = uint(mi>>8&1 + mi>>16&1 + mi>>32&1) logSizeofUint = uint(mu>>8&1 + mu>>16&1 + mu>>32&1) logSizeofUintptr = uint(mp>>8&1 + mp>>16&1 + mp>>32&1) ) const ( minInt8 = -1<<(8< 0) _ = assert(smallestFloat64 > 0) ) const ( maxFloat32 = 1<<127 * (1<<24 - 1) / (1.0<<23) // TODO(gri) The compiler limits integers to 512 bit and thus // we cannot compute the value 1<<1023 // without overflow. For now we match the compiler. // See also issue #44057. // maxFloat64 = 1<<1023 * (1<<53 - 1) / (1.0<<52) maxFloat64 = math.MaxFloat64 ) const ( _ int8 = minInt8 /* ERROR "overflows" */ - 1 _ int8 = minInt8 _ int8 = maxInt8 _ int8 = maxInt8 /* ERROR "overflows" */ + 1 _ int8 = smallestFloat64 /* ERROR "truncated" */ _ = int8(minInt8 /* ERROR "overflows" */ - 1) _ = int8(minInt8) _ = int8(maxInt8) _ = int8(maxInt8 /* ERROR "overflows" */ + 1) _ = int8(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ int16 = minInt16 /* ERROR "overflows" */ - 1 _ int16 = minInt16 _ int16 = maxInt16 _ int16 = maxInt16 /* ERROR "overflows" */ + 1 _ int16 = smallestFloat64 /* ERROR "truncated" */ _ = int16(minInt16 /* ERROR "overflows" */ - 1) _ = int16(minInt16) _ = int16(maxInt16) _ = int16(maxInt16 /* ERROR "overflows" */ + 1) _ = int16(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ int32 = minInt32 /* ERROR "overflows" */ - 1 _ int32 = minInt32 _ int32 = maxInt32 _ int32 = maxInt32 /* ERROR "overflows" */ + 1 _ int32 = smallestFloat64 /* ERROR "truncated" */ _ = int32(minInt32 /* ERROR "overflows" */ - 1) _ = int32(minInt32) _ = int32(maxInt32) _ = int32(maxInt32 /* ERROR "overflows" */ + 1) _ = int32(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ int64 = minInt64 /* ERROR "overflows" */ - 1 _ int64 = minInt64 _ int64 = maxInt64 _ int64 = maxInt64 /* ERROR "overflows" */ + 1 _ int64 = smallestFloat64 /* ERROR "truncated" */ _ = int64(minInt64 /* ERROR "overflows" */ - 1) _ = int64(minInt64) _ = int64(maxInt64) _ = int64(maxInt64 /* ERROR "overflows" */ + 1) _ = int64(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ int = minInt /* ERROR "overflows" */ - 1 _ int = minInt _ int = maxInt _ int = maxInt /* ERROR "overflows" */ + 1 _ int = smallestFloat64 /* ERROR "truncated" */ _ = int(minInt /* ERROR "overflows" */ - 1) _ = int(minInt) _ = int(maxInt) _ = int(maxInt /* ERROR "overflows" */ + 1) _ = int(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ uint8 = 0 /* ERROR "overflows" */ - 1 _ uint8 = 0 _ uint8 = maxUint8 _ uint8 = maxUint8 /* ERROR "overflows" */ + 1 _ uint8 = smallestFloat64 /* ERROR "truncated" */ _ = uint8(0 /* ERROR "overflows" */ - 1) _ = uint8(0) _ = uint8(maxUint8) _ = uint8(maxUint8 /* ERROR "overflows" */ + 1) _ = uint8(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ uint16 = 0 /* ERROR "overflows" */ - 1 _ uint16 = 0 _ uint16 = maxUint16 _ uint16 = maxUint16 /* ERROR "overflows" */ + 1 _ uint16 = smallestFloat64 /* ERROR "truncated" */ _ = uint16(0 /* ERROR "overflows" */ - 1) _ = uint16(0) _ = uint16(maxUint16) _ = uint16(maxUint16 /* ERROR "overflows" */ + 1) _ = uint16(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ uint32 = 0 /* ERROR "overflows" */ - 1 _ uint32 = 0 _ uint32 = maxUint32 _ uint32 = maxUint32 /* ERROR "overflows" */ + 1 _ uint32 = smallestFloat64 /* ERROR "truncated" */ _ = uint32(0 /* ERROR "overflows" */ - 1) _ = uint32(0) _ = uint32(maxUint32) _ = uint32(maxUint32 /* ERROR "overflows" */ + 1) _ = uint32(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ uint64 = 0 /* ERROR "overflows" */ - 1 _ uint64 = 0 _ uint64 = maxUint64 _ uint64 = maxUint64 /* ERROR "overflows" */ + 1 _ uint64 = smallestFloat64 /* ERROR "truncated" */ _ = uint64(0 /* ERROR "overflows" */ - 1) _ = uint64(0) _ = uint64(maxUint64) _ = uint64(maxUint64 /* ERROR "overflows" */ + 1) _ = uint64(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ uint = 0 /* ERROR "overflows" */ - 1 _ uint = 0 _ uint = maxUint _ uint = maxUint /* ERROR "overflows" */ + 1 _ uint = smallestFloat64 /* ERROR "truncated" */ _ = uint(0 /* ERROR "overflows" */ - 1) _ = uint(0) _ = uint(maxUint) _ = uint(maxUint /* ERROR "overflows" */ + 1) _ = uint(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ uintptr = 0 /* ERROR "overflows" */ - 1 _ uintptr = 0 _ uintptr = maxUintptr _ uintptr = maxUintptr /* ERROR "overflows" */ + 1 _ uintptr = smallestFloat64 /* ERROR "truncated" */ _ = uintptr(0 /* ERROR "overflows" */ - 1) _ = uintptr(0) _ = uintptr(maxUintptr) _ = uintptr(maxUintptr /* ERROR "overflows" */ + 1) _ = uintptr(smallestFloat64 /* ERROR "cannot convert" */) ) const ( _ float32 = minInt64 _ float64 = minInt64 _ complex64 = minInt64 _ complex128 = minInt64 _ = float32(minInt64) _ = float64(minInt64) _ = complex64(minInt64) _ = complex128(minInt64) ) const ( _ float32 = maxUint64 _ float64 = maxUint64 _ complex64 = maxUint64 _ complex128 = maxUint64 _ = float32(maxUint64) _ = float64(maxUint64) _ = complex64(maxUint64) _ = complex128(maxUint64) ) // TODO(gri) find smaller deltas below const delta32 = maxFloat32/(1 << 23) const ( _ float32 = - /* ERROR "overflow" */ (maxFloat32 + delta32) _ float32 = -maxFloat32 _ float32 = maxFloat32 _ float32 = maxFloat32 /* ERROR "overflow" */ + delta32 _ = float32(- /* ERROR "cannot convert" */ (maxFloat32 + delta32)) _ = float32(-maxFloat32) _ = float32(maxFloat32) _ = float32(maxFloat32 /* ERROR "cannot convert" */ + delta32) _ = assert(float32(smallestFloat32) == smallestFloat32) _ = assert(float32(smallestFloat32/2) == 0) _ = assert(float32(smallestFloat64) == 0) _ = assert(float32(smallestFloat64/2) == 0) ) const delta64 = maxFloat64/(1 << 52) const ( _ float64 = - /* ERROR "overflow" */ (maxFloat64 + delta64) _ float64 = -maxFloat64 _ float64 = maxFloat64 _ float64 = maxFloat64 /* ERROR "overflow" */ + delta64 _ = float64(- /* ERROR "cannot convert" */ (maxFloat64 + delta64)) _ = float64(-maxFloat64) _ = float64(maxFloat64) _ = float64(maxFloat64 /* ERROR "cannot convert" */ + delta64) _ = assert(float64(smallestFloat32) == smallestFloat32) _ = assert(float64(smallestFloat32/2) == smallestFloat32/2) _ = assert(float64(smallestFloat64) == smallestFloat64) _ = assert(float64(smallestFloat64/2) == 0) ) const ( _ complex64 = - /* ERROR "overflow" */ (maxFloat32 + delta32) _ complex64 = -maxFloat32 _ complex64 = maxFloat32 _ complex64 = maxFloat32 /* ERROR "overflow" */ + delta32 _ = complex64(- /* ERROR "cannot convert" */ (maxFloat32 + delta32)) _ = complex64(-maxFloat32) _ = complex64(maxFloat32) _ = complex64(maxFloat32 /* ERROR "cannot convert" */ + delta32) ) const ( _ complex128 = - /* ERROR "overflow" */ (maxFloat64 + delta64) _ complex128 = -maxFloat64 _ complex128 = maxFloat64 _ complex128 = maxFloat64 /* ERROR "overflow" */ + delta64 _ = complex128(- /* ERROR "cannot convert" */ (maxFloat64 + delta64)) _ = complex128(-maxFloat64) _ = complex128(maxFloat64) _ = complex128(maxFloat64 /* ERROR "cannot convert" */ + delta64) ) // Initialization of typed constant and conversion are the same: const ( f32 = 1 + smallestFloat32 x32 float32 = f32 y32 = float32(f32) _ = assert(x32 - y32 == 0) ) const ( f64 = 1 + smallestFloat64 x64 float64 = f64 y64 = float64(f64) _ = assert(x64 - y64 == 0) ) const ( _ = int8(-1) << 7 _ = int8 /* ERROR "overflows" */ (-1) << 8 _ = uint32(1) << 31 _ = uint32 /* ERROR "overflows" */ (1) << 32 )