experimental type selection is not checked when argument of a match type.

[bishabosha]

Compiler version

Scala 3.3.0-RC3

Minimized code

import annotation.experimental

class Foo { @experimental type Bar = (Int, String) }

val f: Foo = Foo()

def g: Tuple.Elem[f.Bar, 0] = ???

Output

// defined class Foo
val f: Foo = Foo@6921cfa
def g: Int

Expectation

There should be an error that we accessed f.Bar. This is mostly going to effect macros that compile against newly added experimental types, such as the proposed Mirror.Product.MirroredElementHasDefaults