go/type: parenthesized receiver types are ignored (esoteric)

[griesemer]

For

// +build ignore

package p

type T struct{}

func ((*T)) m()
func (*(T)) n()

var _ = (*T).m
var _ = (*T).n

go/types complains with

x.go:10:9: invalid operation: (*T) (type) has no field or method m
x.go:11:9: invalid operation: (*T) (type) has no field or method n

but per the spec, parentheses are ok around receiver types. Also, cmd/compile accepts this.

Trivial to fix, but esoteric, and probably has been like this from the beginning.

[gopherbot]

Change https://golang.org/cl/83918 mentions this issue: go/types: collect methods with parenthesized receiver types

[griesemer]

Fix is trivial; unproblematic for 1.10.