mirror of
https://github.com/golang/go
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142 lines
2.5 KiB
Go
142 lines
2.5 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2010 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 of recover during recursive panics.
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// Here be dragons.
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package main
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import "runtime"
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func main() {
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test1()
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test2()
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test3()
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test4()
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test5()
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test6()
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test7()
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}
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func die() {
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runtime.Breakpoint() // can't depend on panic
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}
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func mustRecover(x interface{}) {
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mustNotRecover() // because it's not a defer call
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v := recover()
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if v == nil {
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println("missing recover")
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die() // panic is useless here
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}
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if v != x {
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println("wrong value", v, x)
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die()
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}
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// the value should be gone now regardless
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v = recover()
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if v != nil {
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println("recover didn't recover")
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die()
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}
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}
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func mustNotRecover() {
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v := recover()
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if v != nil {
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println("spurious recover")
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die()
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}
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}
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func withoutRecover() {
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mustNotRecover() // because it's a sub-call
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}
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func test1() {
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// Easy nested recursive panic.
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defer mustRecover(1)
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defer func() {
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defer mustRecover(2)
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panic(2)
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}()
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panic(1)
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}
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func test2() {
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// Sequential panic.
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defer mustNotRecover()
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defer func() {
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v := recover()
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if v == nil || v.(int) != 2 {
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println("wrong value", v, 2)
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die()
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}
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defer mustRecover(3)
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panic(3)
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}()
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panic(2)
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}
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func test3() {
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// Sequential panic - like test2 but less picky.
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defer mustNotRecover()
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defer func() {
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recover()
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defer mustRecover(3)
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panic(3)
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}()
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panic(2)
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}
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func test4() {
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// Single panic.
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defer mustNotRecover()
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defer func() {
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recover()
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}()
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panic(4)
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}
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func test5() {
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// Single panic but recover called via defer
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defer mustNotRecover()
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defer func() {
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defer recover()
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}()
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panic(5)
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}
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func test6() {
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// Sequential panic.
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// Like test3, but changed recover to defer (same change as test4 → test5).
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defer mustNotRecover()
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defer func() {
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defer recover() // like a normal call from this func; runs because mustRecover stops the panic
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defer mustRecover(3)
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panic(3)
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}()
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panic(2)
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}
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func test7() {
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// Like test6, but swapped defer order.
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// The recover in "defer recover()" is now a no-op,
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// because it runs called from panic, not from the func,
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// and therefore cannot see the panic of 2.
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// (Alternately, it cannot see the panic of 2 because
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// there is an active panic of 3. And it cannot see the
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// panic of 3 because it is at the wrong level (too high on the stack).)
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defer mustRecover(2)
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defer func() {
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defer mustRecover(3)
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defer recover() // now a no-op, unlike in test6.
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panic(3)
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}()
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panic(2)
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}
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