cmd/compile: error message refers to aliased type instead of the alias type name

[griesemer]

package p

func f[P any](x P) P { return x }

func _() {
	type A = int
	var a A
	b := f(a) // type of B is A
	_ = b + "foo"
}

produces

...: invalid operation: b + "foo" (mismatched types int and untyped string)

It should say:

mismatched types A and untyped string

cc: @findleyr

[griesemer]

Related to #67547.

[findleyr]

Presumably this is because the inference algorithm strips alias information. I would expect that the type of b is int, not A.
This may be difficult to fix.

[griesemer]

I would expect that the type of b is int, not A.

That's what the error message says. But I think it should say A. Not sure why you say it should be int.

[gopherbot]

Change https://go.dev/cl/588797 mentions this issue: go/types, types2: don't lose alias information during unification

[findleyr]

I would expect that the type of b is int, not A.

That's what the error message says. But I think it should say A. Not sure why you say it should be int.

I merely meant that the type is int, not that it should be int. In other words, the problem is inference, not the error message.