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// run
// Copyright 2019 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.
// Issue 31419: race in getitab when two goroutines try
// to do the same failed interface conversion.
package main
type T int
func (t T) M() {}
type I interface {
M()
M2()
}
var t T
var e interface{} = &t
var ok = false
var ch = make(chan int)
func main() {
_, ok = e.(I) // populate itab cache with a false result
go f() // get itab in a loop
var i I
for k := 0; k < 10000; k++ {
i, ok = e.(I) // read the cached itab
if ok {
println("iteration", k, "i =", i, "&t =", &t)
panic("conversion succeeded")
}
}
<-ch
}
func f() {
for i := 0; i < 10000; i++ {
f1()
}
ch <- 1
}
func f1() {
defer func() {
err := recover()
if err == nil {
panic("did not panic")
}
}()
i := e.(I) // triggers itab.init, for getting the panic string
_ = i
}
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