1 files changed, 58 insertions, 0 deletions
diff --git a/test/fixedbugs/issue31419.go b/test/fixedbugs/issue31419.go
new file mode 100644
index 0000000..233111a
--- /dev/null
+++ b/test/fixedbugs/issue31419.go
@@ -0,0 +1,58 @@
+// 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
+}