cmd/compile: ambiguous selector with generic interface & embedded types #53419
Description
What version of Go are you using (go version)?
$ go version go version go1.18.3 linux/amd64
Does this issue reproduce with the latest release?
yes
What operating system and processor architecture are you using (go env)?
go env Output
$ go env GOARCH="amd64" GOOS="linux"
What did you do?
package main
import "fmt"
type MyString string
type MyByteSlice []byte
type Both struct {
MyString
MyByteSlice
}
func (s1 MyString) Concat(s2 MyString) MyString { return s1 + s2 }
func (bs1 MyByteSlice) Concat(bs2 MyByteSlice) MyByteSlice { return append(bs1, bs2...) }
func (b1 Both) Concat(b2 Both) Both {
return Both{
b1.MyString.Concat(b2.MyString),
b1.MyByteSlice.Concat(b2.MyByteSlice),
}
}
type Concatable[T any] interface {
Concat(T) T
}
func Repeat[T Concatable[T]](c T) T {
return c.Concat(c)
}
func main() {
s := MyString("foo")
bs := MyByteSlice("foo")
b := Both{MyString("foo"), MyByteSlice("foo")}
fmt.Println(Repeat(s))
fmt.Println(Repeat(bs))
fmt.Println(Repeat(b))
}https://go.dev/play/p/Jyws-pz9k5X
What did you expect to see?
successful compilation
What did you see instead?
./prog.go:26:10: ambiguous selector c.Concat
Go build failed.
The error is with the Both type (as if I remove it, the issue goes away). However on Both, Concat is not ambiguous. Both has it's own Concat method, and should not be trying to fall through to either of the embedded types.