type parameter can not infer the shared underlying type (unsure if bug or feature request)

[dans-stuff]

What version of Go are you using (go version)?

$ go version
go version go1.18 darwin/arm64

Does this issue reproduce with the latest release?

Yes

What did you do?

https://go.dev/play/p/TR_hVFrldXH

What did you expect to see?

I expect the compiler to infer that A and B have the same underlying type.

This expectation comes from being able to pass an A{}, and a map[string]int{} and having the underlying type correctly inferred, and from being able to specify the underlying type manually to overcome the failed inference.

What did you see instead?

I get a compile error type B of B{} does not match inferred type A for M

[seankhliao]

m1, m2 M means you want the same type for both.

func Equal2[K, V comparable](m1, m2 map[K]V) bool {
	return true
}

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