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dd7cbf3a84
Make sure that when we're assigning to a map, we evaluate the right-hand side before we attempt to insert into the map. We used to evaluate the left-hand side to a pointer-to-slot-in-bucket (which as a side effect does len(m)++), then evaluate the right-hand side, then do the assignment. That clearly isn't correct when the right-hand side might panic. Fixes #22881 Change-Id: I42a62870ff4bf480568c9bdbf0bb18958962bdf0 Reviewed-on: https://go-review.googlesource.com/81817 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
73 lines
1.1 KiB
Go
73 lines
1.1 KiB
Go
// run
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// Copyright 2017 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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// Test to make sure RHS is evaluated before map insert is started.
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// The RHS panics in all of these cases.
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package main
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import "fmt"
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func main() {
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for i, f := range []func(map[int]int){
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f0, f1, f2, f3, f4, f5, f6, f7,
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} {
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m := map[int]int{}
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func() { // wrapper to scope the defer.
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defer func() {
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recover()
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}()
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f(m) // Will panic. Shouldn't modify m.
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fmt.Printf("RHS didn't panic, case f%d\n", i)
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}()
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if len(m) != 0 {
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fmt.Printf("map insert happened, case f%d\n", i)
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}
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}
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}
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func f0(m map[int]int) {
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var p *int
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m[0] = *p
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}
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func f1(m map[int]int) {
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var p *int
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m[0] += *p
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}
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func f2(m map[int]int) {
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var p *int
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sink, m[0] = sink, *p
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}
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func f3(m map[int]int) {
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var p *chan int
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m[0], sink = <-(*p)
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}
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func f4(m map[int]int) {
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var p *interface{}
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m[0], sink = (*p).(int)
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}
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func f5(m map[int]int) {
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var p *map[int]int
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m[0], sink = (*p)[0]
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}
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func f6(m map[int]int) {
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var z int
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m[0] /= z
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}
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func f7(m map[int]int) {
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var a []int
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m[0] = a[0]
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}
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var sink bool
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