1 files changed, 81 insertions, 0 deletions
diff --git a/test/typeparam/index.go b/test/typeparam/index.go
new file mode 100644
index 0000000..064d33c
--- /dev/null
+++ b/test/typeparam/index.go
@@ -0,0 +1,81 @@
+// run
+
+// 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
+}
+
+type obj2 struct {
+	x int8
+	y float64
+}
+
+type obj3 struct {
+	x int64
+	y int8
+}
+
+type inner struct {
+	y int64
+	z int32
+}
+
+type obj4 struct {
+	x int32
+	s inner
+}
+
+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))
+	}
+
+	vec4 := []obj2{obj2{2, 3.0}, obj2{3, 4.0}, obj2{4, 5.0}}
+	if got := Index(vec4, vec4[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec5 := []obj3{obj3{2, 3}, obj3{3, 4}, obj3{4, 5}}
+	if got := Index(vec5, vec5[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+
+	vec6 := []obj4{obj4{2, inner{3, 4}}, obj4{3, inner{4, 5}}, obj4{4, inner{5, 6}}}
+	if got := Index(vec6, vec6[2]); got != want {
+		panic(fmt.Sprintf("got %d, want %d", got, want))
+	}
+}