go shifts 源码
golang shifts 代码
文件路径：/src/cmd/compile/internal/types2/testdata/check/shifts.go
// Copyright 2013 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 shifts
func shifts0() {
// basic constant shifts
const (
s = 10
_ = 0<<0
_ = 1<<s
_ = 1<<- /* ERROR "negative shift count" */ 1
// For the test below we may decide to convert to int
// rather than uint and then report a negative shift
// count instead, which might be a better error. The
// (minor) difference is that this would restrict the
// shift count range by half (from all uint values to
// the positive int values).
// This depends on the exact spec wording which is not
// done yet.
// TODO(gri) revisit and adjust when spec change is done
_ = 1<<- /* ERROR "negative shift count" */ 1.0
_ = 1<<1075 /* ERROR "invalid shift" */
_ = 2.0<<1
_ = 1<<1.0
_ = 1<<(1+0i)
_ int = 2<<s
_ float32 = 2<<s
_ complex64 = 2<<s
_ int = 2.0<<s
_ float32 = 2.0<<s
_ complex64 = 2.0<<s
_ int = 'a'<<s
_ float32 = 'a'<<s
_ complex64 = 'a'<<s
)
}
func shifts1() {
// basic non-constant shifts
var (
i int
u uint
_ = 1<<0
_ = 1<<i
_ = 1<<u
_ = 1<<"foo" /* ERROR "cannot convert" */
_ = i<<0
_ = i<<- /* ERROR "negative shift count" */ 1
_ = i<<1.0
_ = 1<<(1+0i)
_ = 1 /* ERROR "overflows" */ <<100
_ uint = 1 << 0
_ uint = 1 << u
_ float32 = 1 /* ERROR "must be integer" */ << u
// issue #14822
_ = 1<<( /* ERROR "overflows uint" */ 1<<64)
_ = 1<<( /* ERROR "invalid shift count" */ 1<<64-1)
// issue #43697
_ = u<<( /* ERROR "overflows uint" */ 1<<64)
_ = u<<(1<<64-1)
)
}
func shifts2() {
// from the spec
var (
s uint = 33
i = 1<<s // 1 has type int
j int32 = 1<<s // 1 has type int32; j == 0
k = uint64(1<<s) // 1 has type uint64; k == 1<<33
m int = 1.0<<s // 1.0 has type int
n = 1.0<<s != i // 1.0 has type int; n == false if ints are 32bits in size
o = 1<<s == 2<<s // 1 and 2 have type int; o == true if ints are 32bits in size
p = 1<<s == 1<<33 // illegal if ints are 32bits in size: 1 has type int, but 1<<33 overflows int
u = 1.0 /* ERROR "must be integer" */ <<s // illegal: 1.0 has type float64, cannot shift
u1 = 1.0 /* ERROR "must be integer" */ <<s != 0 // illegal: 1.0 has type float64, cannot shift
u2 = 1 /* ERROR "must be integer" */ <<s != 1.0 // illegal: 1 has type float64, cannot shift
v float32 = 1 /* ERROR "must be integer" */ <<s // illegal: 1 has type float32, cannot shift
w int64 = 1.0<<33 // 1.0<<33 is a constant shift expression
)
_, _, _, _, _, _, _, _, _, _, _, _ = i, j, k, m, n, o, p, u, u1, u2, v, w
}
func shifts3(a int16, b float32) {
// random tests
var (
s uint = 11
u = 1 /* ERROR "must be integer" */ <<s + 1.0
v complex128 = 1 /* ERROR "must be integer" */ << s + 1.0 /* ERROR "must be integer" */ << s + 1
)
x := 1.0 /* ERROR "must be integer" */ <<s + 1
shifts3(1.0 << s, 1 /* ERROR "must be integer" */ >> s)
_, _, _ = u, v, x
}
func shifts4() {
// shifts in comparisons w/ untyped operands
var s uint
_ = 1<<s == 1
_ = 1 /* ERROR "integer" */ <<s == 1.
_ = 1. /* ERROR "integer" */ <<s == 1
_ = 1. /* ERROR "integer" */ <<s == 1.
_ = 1<<s + 1 == 1
_ = 1 /* ERROR "integer" */ <<s + 1 == 1.
_ = 1 /* ERROR "integer" */ <<s + 1. == 1
_ = 1 /* ERROR "integer" */ <<s + 1. == 1.
_ = 1. /* ERROR "integer" */ <<s + 1 == 1
_ = 1. /* ERROR "integer" */ <<s + 1 == 1.
_ = 1. /* ERROR "integer" */ <<s + 1. == 1
_ = 1. /* ERROR "integer" */ <<s + 1. == 1.
_ = 1<<s == 1<<s
_ = 1 /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s
_ = 1<<s + 1<<s == 1
_ = 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1.
_ = 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1
_ = 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1.
_ = 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1
_ = 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1.
_ = 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1
_ = 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1.
_ = 1<<s + 1<<s == 1<<s + 1<<s
_ = 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1 /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1 /* ERROR "integer" */ <<s
_ = 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s == 1. /* ERROR "integer" */ <<s + 1. /* ERROR "integer" */ <<s
}
func shifts5() {
// shifts in comparisons w/ typed operands
var s uint
var x int
_ = 1<<s == x
_ = 1.<<s == x
_ = 1.1 /* ERROR "int" */ <<s == x
_ = 1<<s + x == 1
_ = 1<<s + x == 1.
_ = 1<<s + x == 1.1 /* ERROR "int" */
_ = 1.<<s + x == 1
_ = 1.<<s + x == 1.
_ = 1.<<s + x == 1.1 /* ERROR "int" */
_ = 1.1 /* ERROR "int" */ <<s + x == 1
_ = 1.1 /* ERROR "int" */ <<s + x == 1.
_ = 1.1 /* ERROR "int" */ <<s + x == 1.1
_ = 1<<s == x<<s
_ = 1.<<s == x<<s
_ = 1.1 /* ERROR "int" */ <<s == x<<s
}
func shifts6() {
// shifts as operands in non-arithmetic operations and as arguments
var a [10]int
var s uint
_ = a[1<<s]
_ = a[1.0]
_ = a[1.0<<s]
_ = make([]int, 1.0)
_ = make([]int, 1.0<<s)
_ = make([]int, 1.1 /* ERROR "must be integer" */ <<s)
_ = float32(1)
_ = float32(1 /* ERROR "must be integer" */ <<s)
_ = float32(1.0)
_ = float32(1.0 /* ERROR "must be integer" */ <<s)
_ = float32(1.1 /* ERROR "must be integer" */ <<s)
// TODO(gri) port fixes from go/types
// _ = int32(0x80000000 /* ERROR "overflows int32" */ << s)
// TODO(rfindley) Eliminate the redundant error here.
// _ = int32(( /* ERROR "truncated to int32" */ 0x80000000 /* ERROR "truncated to int32" */ + 0i) << s)
_ = int(1+0i<<0)
// _ = int((1+0i)<<s)
// _ = int(1.0<<s)
// _ = int(complex(1, 0)<<s)
_ = int(float32/* ERROR "must be integer" */(1.0) <<s)
_ = int(1.1 /* ERROR must be integer */ <<s)
_ = int(( /* ERROR "must be integer" */ 1+1i) <<s)
_ = complex(1 /* ERROR "must be integer" */ <<s, 0)
var b []int
_ = append(b, 1<<s)
_ = append(b, 1.0<<s)
_ = append(b, (1+0i)<<s)
_ = append(b, 1.1 /* ERROR "must be integer" */ <<s)
_ = append(b, (1 + 0i) <<s)
_ = append(b, ( /* ERROR "must be integer" */ 1 + 1i) <<s)
_ = complex(1.0 /* ERROR "must be integer" */ <<s, 0)
_ = complex(1.1 /* ERROR "must be integer" */ <<s, 0)
_ = complex(0, 1.0 /* ERROR "must be integer" */ <<s)
_ = complex(0, 1.1 /* ERROR "must be integer" */ <<s)
// TODO(gri) The delete below is not type-checked correctly yet.
// var m1 map[int]string
// delete(m1, 1<<s)
}
func shifts7() {
// shifts of shifts
var s uint
var x int
_ = x
_ = 1<<(1<<s)
_ = 1<<(1.<<s)
_ = 1. /* ERROR "integer" */ <<(1<<s)
_ = 1. /* ERROR "integer" */ <<(1.<<s)
x = 1<<(1<<s)
x = 1<<(1.<<s)
x = 1.<<(1<<s)
x = 1.<<(1.<<s)
_ = (1<<s)<<(1<<s)
_ = (1<<s)<<(1.<<s)
_ = ( /* ERROR "integer" */ 1.<<s)<<(1<<s)
_ = ( /* ERROR "integer" */ 1.<<s)<<(1.<<s)
x = (1<<s)<<(1<<s)
x = (1<<s)<<(1.<<s)
x = ( /* ERROR "integer" */ 1.<<s)<<(1<<s)
x = ( /* ERROR "integer" */ 1.<<s)<<(1.<<s)
}
func shifts8() {
// shift examples from shift discussion: better error messages
var s uint
_ = 1.0 /* ERROR "shifted operand 1.0 \(type float64\) must be integer" */ <<s == 1
_ = 1.0 /* ERROR "shifted operand 1.0 \(type float64\) must be integer" */ <<s == 1.0
_ = 1 /* ERROR "shifted operand 1 \(type float64\) must be integer" */ <<s == 1.0
_ = 1 /* ERROR "shifted operand 1 \(type float64\) must be integer" */ <<s + 1.0 == 1
_ = 1 /* ERROR "shifted operand 1 \(type float64\) must be integer" */ <<s + 1.1 == 1
_ = 1 /* ERROR "shifted operand 1 \(type float64\) must be integer" */ <<s + 1 == 1.0
// additional cases
_ = complex(1.0 /* ERROR "shifted operand 1.0 \(type float64\) must be integer" */ <<s, 1)
_ = complex(1.0, 1 /* ERROR "shifted operand 1 \(type float64\) must be integer" */ <<s)
_ = int(1.<<s)
_ = int(1.1 /* ERROR "shifted operand .* must be integer" */ <<s)
_ = float32(1 /* ERROR "shifted operand .* must be integer" */ <<s)
_ = float32(1. /* ERROR "shifted operand .* must be integer" */ <<s)
_ = float32(1.1 /* ERROR "shifted operand .* must be integer" */ <<s)
// TODO(gri) the error messages for these two are incorrect - disabled for now
// _ = complex64(1<<s)
// _ = complex64(1.<<s)
_ = complex64(1.1 /* ERROR "shifted operand .* must be integer" */ <<s)
}
func shifts9() {
// various originally failing snippets of code from the std library
// from src/compress/lzw/reader.go:90
{
var d struct {
bits uint32
width uint
}
_ = uint16(d.bits & (1<<d.width - 1))
}
// from src/debug/dwarf/buf.go:116
{
var ux uint64
var bits uint
x := int64(ux)
if x&(1<<(bits-1)) != 0 {}
}
// from src/encoding/asn1/asn1.go:160
{
var bytes []byte
if bytes[len(bytes)-1]&((1<<bytes[0])-1) != 0 {}
}
// from src/math/big/rat.go:140
{
var exp int
var mantissa uint64
shift := uint64(-1022 - (exp - 1)) // [1..53)
_ = mantissa & (1<<shift - 1)
}
// from src/net/interface.go:51
{
type Flags uint
var f Flags
var i int
if f&(1<<uint(i)) != 0 {}
}
// from src/runtime/softfloat64.go:234
{
var gm uint64
var shift uint
_ = gm & (1<<shift - 1)
}
// from src/strconv/atof.go:326
{
var mant uint64
var mantbits uint
if mant == 2<<mantbits {}
}
// from src/route_bsd.go:82
{
var Addrs int32
const rtaRtMask = 1
var i uint
if Addrs&rtaRtMask&(1<<i) == 0 {}
}
// from src/text/scanner/scanner.go:540
{
var s struct { Whitespace uint64 }
var ch rune
for s.Whitespace&(1<<uint(ch)) != 0 {}
}
}
func issue5895() {
var x = 'a' << 1 // type of x must be rune
var _ rune = x
}
func issue11325() {
var _ = 0 >> 1.1 /* ERROR "truncated to uint" */ // example from issue 11325
_ = 0 >> 1.1 /* ERROR "truncated to uint" */
_ = 0 << 1.1 /* ERROR "truncated to uint" */
_ = 0 >> 1.
_ = 1 >> 1.1 /* ERROR "truncated to uint" */
_ = 1 >> 1.
_ = 1. >> 1
_ = 1. >> 1.
_ = 1.1 /* ERROR "must be integer" */ >> 1
}
func issue11594() {
var _ = complex64 /* ERROR "must be integer" */ (1) << 2 // example from issue 11594
_ = float32 /* ERROR "must be integer" */ (0) << 1
_ = float64 /* ERROR "must be integer" */ (0) >> 2
_ = complex64 /* ERROR "must be integer" */ (0) << 3
_ = complex64 /* ERROR "must be integer" */ (0) >> 4
}
func issue21727() {
var s uint
var a = make([]int, 1<<s + 1.2 /* ERROR "truncated to int" */ )
var _ = a[1<<s - 2.3 /* ERROR "truncated to int" */ ]
var _ int = 1<<s + 3.4 /* ERROR "truncated to int" */
var _ = string(1 /* ERROR shifted operand 1 .* must be integer */ << s)
var _ = string(1.0 /* ERROR "cannot convert" */ << s)
}
func issue22969() {
var s uint
var a []byte
_ = a[0xffffffffffffffff /* ERROR "overflows int" */ <<s] // example from issue 22969
_ = make([]int, 0xffffffffffffffff /* ERROR "overflows int" */ << s)
_ = make([]int, 0, 0xffffffffffffffff /* ERROR "overflows int" */ << s)
var _ byte = 0x100 /* ERROR "overflows byte" */ << s
var _ int8 = 0xff /* ERROR "overflows int8" */ << s
var _ int16 = 0xffff /* ERROR "overflows int16" */ << s
var _ int32 = 0x80000000 /* ERROR "overflows int32" */ << s
}
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