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go/test/fixedbugs/issue4313.go
Russ Cox 1b3244e0db cmd/gc: fix eval order in select
Ordinary variable load was assumed to be not worth saving,
but not if one of the function calls later might change
its value.

Fixes #4313.

R=ken2
CC=golang-dev
https://golang.org/cl/6997047
2012-12-22 16:46:01 -05:00

29 lines
547 B
Go

// run
// 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.
// Order of operations in select.
package main
func main() {
c := make(chan int, 1)
x := 0
select {
case c <- x: // should see x = 0, not x = 42 (after makec)
case <-makec(&x): // should be evaluated only after c and x on previous line
}
y := <-c
if y != 0 {
panic(y)
}
}
func makec(px *int) chan bool {
if false { for {} }
*px = 42
return make(chan bool, 0)
}