1 files changed, 83 insertions, 0 deletions
diff --git a/test/typeparam/ifaceconv.go b/test/typeparam/ifaceconv.go
new file mode 100644
index 0000000000..ee3a9e0dc3
--- /dev/null
+++ b/test/typeparam/ifaceconv.go
@@ -0,0 +1,83 @@
+// 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.
+
+// Test that we can convert type parameters to both empty
+// and nonempty interfaces, and named and nonnamed versions
+// thereof.
+
+package main
+
+import "fmt"
+
+type E interface{}
+
+func f[T any](x T) interface{} {
+	var i interface{} = x
+	return i
+}
+
+func fs[T any](x T) interface{} {
+	y := []T{x}
+	var i interface{} = y
+	return i
+}
+
+func g[T any](x T) E {
+	var i E = x
+	return i
+}
+
+type C interface {
+	foo() int
+}
+
+type myInt int
+
+func (x myInt) foo() int {
+	return int(x + 1)
+}
+
+func h[T C](x T) interface{ foo() int } {
+	var i interface{ foo() int } = x
+	return i
+}
+func i[T C](x T) C {
+	var i C = x // conversion in assignment
+	return i
+}
+
+func j[T C](t T) C {
+	return C(t) // explicit conversion
+}
+
+func js[T any](x T) interface{} {
+	y := []T{x}
+	return interface{}(y)
+}
+
+func main() {
+	if got, want := f[int](7), 7; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := fs[int](7), []int{7}; got.([]int)[0] != want[0] {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := g[int](7), 7; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := h[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := i[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := j[myInt](7).foo(), 8; got != want {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+	if got, want := js[int](7), []int{7}; got.([]int)[0] != want[0] {
+		panic(fmt.Sprintf("got %d want %d", got, want))
+	}
+}