1 files changed, 46 insertions, 0 deletions
diff --git a/test/typeparam/index.go b/test/typeparam/index.go
new file mode 100644
index 0000000000..83e65acdd0
--- /dev/null
+++ b/test/typeparam/index.go
@@ -0,0 +1,46 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 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.
+
+package main
+
+import (
+	"fmt"
+)
+
+// Index returns the index of x in s, or -1 if not found.
+func index[T comparable](s []T, x T) int {
+	for i, v := range s {
+		// v and x are type T, which has the comparable
+		// constraint, so we can use == here.
+		if v == x {
+			return i
+		}
+	}
+	return -1
+}
+
+type obj struct {
+	x int
+}
+
+func main() {
+	want := 2
+
+	vec1 := []string{"ab", "cd", "ef"}
+	if got := index(vec1, "ef"); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec2 := []byte{'c', '6', '@'}
+	if got := index(vec2, '@'); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec3 := []*obj{&obj{2}, &obj{42}, &obj{1}}
+	if got := index(vec3, vec3[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}