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// $G $D/$F.go && $L $F.$A && ./$A.out
// Copyright 2010 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 of basic recover functionality.
package main
import "runtime"
func main() {
test1()
test1WithClosures()
test2()
test3()
test4()
test5()
test6()
test6WithClosures()
test7()
}
func die() {
runtime.Breakpoint() // can't depend on panic
}
func mustRecover(x interface{}) {
mustNotRecover() // because it's not a defer call
v := recover()
if v == nil {
println("missing recover")
die() // panic is useless here
}
if v != x {
println("wrong value", v, x)
die()
}
// the value should be gone now regardless
v = recover()
if v != nil {
println("recover didn't recover")
die()
}
}
func mustNotRecover() {
v := recover()
if v != nil {
println("spurious recover", v)
die()
}
}
func withoutRecover() {
mustNotRecover() // because it's a sub-call
}
func test1() {
defer mustNotRecover() // because mustRecover will squelch it
defer mustRecover(1) // because of panic below
defer withoutRecover() // should be no-op, leaving for mustRecover to find
panic(1)
}
// Repeat test1 with closures instead of standard function.
// Interesting because recover bases its decision
// on the frame pointer of its caller, and a closure's
// frame pointer is in the middle of its actual arguments
// (after the hidden ones for the closed-over variables).
func test1WithClosures() {
defer func() {
v := recover()
if v != nil {
println("spurious recover in closure")
die()
}
}()
defer func(x interface{}) {
mustNotRecover()
v := recover()
if v == nil {
println("missing recover")
die()
}
if v != x {
println("wrong value", v, x)
die()
}
}(1)
defer func() {
mustNotRecover()
}()
panic(1)
}
func test2() {
// Recover only sees the panic argument
// if it is called from a deferred call.
// It does not see the panic when called from a call within a deferred call (too late)
// nor does it see the panic when it *is* the deferred call (too early).
defer mustRecover(2)
defer recover() // should be no-op
panic(2)
}
func test3() {
defer mustNotRecover()
defer func() {
recover() // should squelch
}()
panic(3)
}
func test4() {
// Equivalent to test3 but using defer to make the call.
defer mustNotRecover()
defer func() {
defer recover() // should squelch
}()
panic(4)
}
// Check that closures can set output arguments.
// Run g(). If it panics, return x; else return deflt.
func try(g func(), deflt interface{}) (x interface{}) {
defer func() {
if v := recover(); v != nil {
x = v
}
}()
defer g()
return deflt
}
// Check that closures can set output arguments.
// Run g(). If it panics, return x; else return deflt.
func try1(g func(), deflt interface{}) (x interface{}) {
defer func() {
if v := recover(); v != nil {
x = v
}
}()
defer g()
x = deflt
return
}
func test5() {
v := try(func() { panic(5) }, 55).(int)
if v != 5 {
println("wrong value", v, 5)
die()
}
s := try(func() {}, "hi").(string)
if s != "hi" {
println("wrong value", s, "hi")
die()
}
v = try1(func() { panic(5) }, 55).(int)
if v != 5 {
println("try1 wrong value", v, 5)
die()
}
s = try1(func() {}, "hi").(string)
if s != "hi" {
println("try1 wrong value", s, "hi")
die()
}
}
// When a deferred big call starts, it must first
// create yet another stack segment to hold the
// giant frame for x. Make sure that doesn't
// confuse recover.
func big(mustRecover bool) {
var x [100000]int
x[0] = 1
x[99999] = 1
_ = x
v := recover()
if mustRecover {
if v == nil {
println("missing big recover")
die()
}
} else {
if v != nil {
println("spurious big recover")
die()
}
}
}
func test6() {
defer big(false)
defer big(true)
panic(6)
}
func test6WithClosures() {
defer func() {
var x [100000]int
x[0] = 1
x[99999] = 1
_ = x
if recover() != nil {
println("spurious big closure recover")
die()
}
}()
defer func() {
var x [100000]int
x[0] = 1
x[99999] = 1
_ = x
if recover() == nil {
println("missing big closure recover")
die()
}
}()
panic("6WithClosures")
}
func test7() {
ok := false
func() {
// should panic, then call mustRecover 7, which stops the panic.
// then should keep processing ordinary defers earlier than that one
// before returning.
// this test checks that the defer func on the next line actually runs.
defer func() { ok = true }()
defer mustRecover(7)
panic(7)
}()
if !ok {
println("did not run ok func")
die()
}
}
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