1 files changed, 50 insertions, 0 deletions
diff --git a/test/typeparam/shape1.go b/test/typeparam/shape1.go
new file mode 100644
index 0000000000..de1ea65ed2
--- /dev/null
+++ b/test/typeparam/shape1.go
@@ -0,0 +1,50 @@
+// 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
+
+type I interface {
+	foo() int
+}
+
+// There should be one instantiation of f for both squarer and doubler.
+// Similarly, there should be one instantiation of f for both *incrementer and *decrementer.
+func f[T I](x T) int {
+	return x.foo()
+}
+
+type squarer int
+
+func (x squarer) foo() int {
+	return int(x*x)
+}
+
+type doubler int
+
+func (x doubler) foo() int {
+	return int(2*x)
+}
+
+type incrementer int16
+
+func (x *incrementer) foo() int {
+	return int(*x+1)
+}
+
+type decrementer int32
+
+func (x *decrementer) foo() int{
+	return int(*x-1)
+}
+
+func main() {
+	println(f(squarer(5)))
+	println(f(doubler(5)))
+	var i incrementer = 5
+	println(f(&i))
+	var d decrementer = 5
+	println(f(&d))
+}