1 files changed, 63 insertions, 0 deletions
diff --git a/test/fixedbugs/issue21576.go b/test/fixedbugs/issue21576.go
new file mode 100644
index 0000000..8e1e3ad
--- /dev/null
+++ b/test/fixedbugs/issue21576.go
@@ -0,0 +1,63 @@
+// run
+
+// +build !nacl,!js,!wasip1,!gccgo
+
+// 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.
+//
+// Ensure that deadlock detection can still
+// run even with an import of "_ os/signal".
+
+package main
+
+import (
+	"bytes"
+	"context"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"time"
+)
+
+const prog = `
+package main
+
+import _ "os/signal"
+
+func main() {
+  c := make(chan int)
+  c <- 1
+}
+`
+
+func main() {
+	dir, err := ioutil.TempDir("", "21576")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	file := filepath.Join(dir, "main.go")
+	if err := ioutil.WriteFile(file, []byte(prog), 0655); err != nil {
+		log.Fatalf("Write error %v", err)
+	}
+
+	// Using a timeout of 1 minute in case other factors might slow
+	// down the start of "go run". See https://golang.org/issue/34836.
+	ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "go", "run", file)
+	output, err := cmd.CombinedOutput()
+	if err == nil {
+		log.Fatalf("Passed, expected an error")
+	}
+
+	want := []byte("fatal error: all goroutines are asleep - deadlock!")
+	if !bytes.Contains(output, want) {
+		log.Fatalf("Unmatched error message %q:\nin\n%s\nError: %v", want, output, err)
+	}
+}