golang a 代码
文件路径：/test/typeparam/mutualimp.dir/a.go
// 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 a
type X int
func (x X) M() X { return x }
func F[T interface{ M() U }, U interface{ M() T }]() {}
func G() { F[X, X]() }