go blank 源码
golang blank 代码
文件路径：/test/blank.go
// run
// Copyright 2009 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.
// Test behavior of the blank identifier (_).
package main
import (
"os"
"unsafe"
)
import _ "fmt"
var call string
type T struct {
_, _, _ int
}
func (T) _() {
}
func (T) _() {
}
type U struct {
_ struct{ a, b, c int }
}
const (
c0 = iota
_
_
_
c4
)
var ints = []string{
"1",
"2",
"3",
}
func f() (int, int) {
call += "f"
return 1, 2
}
func g() (float64, float64) {
call += "g"
return 3, 4
}
func h(_ int, _ float64) {
}
func i() int {
call += "i"
return 23
}
var _ = i()
func main() {
if call != "i" {
panic("init did not run")
}
call = ""
_, _ = f()
a, _ := f()
if a != 1 {
panic(a)
}
b, _ := g()
if b != 3 {
panic(b)
}
_, a = f()
if a != 2 {
panic(a)
}
_, b = g()
if b != 4 {
panic(b)
}
_ = i()
if call != "ffgfgi" {
panic(call)
}
if c4 != 4 {
panic(c4)
}
out := ""
for _, s := range ints {
out += s
}
if out != "123" {
panic(out)
}
sum := 0
for s := range ints {
sum += s
}
if sum != 3 {
panic(sum)
}
// go.tools/ssa/interp cannot support unsafe.Pointer.
if os.Getenv("GOSSAINTERP") == "" {
type T1 struct{ x, y, z int }
t1 := *(*T)(unsafe.Pointer(&T1{1, 2, 3}))
t2 := *(*T)(unsafe.Pointer(&T1{4, 5, 6}))
if t1 != t2 {
panic("T{} != T{}")
}
var u1, u2 interface{}
u1 = *(*U)(unsafe.Pointer(&T1{1, 2, 3}))
u2 = *(*U)(unsafe.Pointer(&T1{4, 5, 6}))
if u1 != u2 {
panic("U{} != U{}")
}
}
h(a, b)
m()
}
type I interface {
M(_ int, y int)
}
type TI struct{}
func (_ TI) M(x int, y int) {
if x != y {
println("invalid M call:", x, y)
panic("bad M")
}
}
var fp = func(_ int, y int) {}
func init() {
fp = fp1
}
func fp1(x, y int) {
if x != y {
println("invalid fp1 call:", x, y)
panic("bad fp1")
}
}
func m() {
var i I
i = TI{}
i.M(1, 1)
i.M(2, 2)
fp(1, 1)
fp(2, 2)
}
// useless but legal
var _ int = 1
var _ = 2
var _, _ = 3, 4
const _ = 3
const _, _ = 4, 5
type _ int
func _() {
panic("oops")
}
func ff() {
var _ int = 1
}
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