`ExpressibleByXxxLiteral` gotcha

[bbrk24]

@tera

I don't see this behaviour documented in ExpressibleByIntegerLiteral so I am unaware of it.

This is SE-0213.

@tera

You'd think changing from Foo(123) to .init(123) or vice versa is benign... yet here it's an observable behavioural change.

Yes, this part is surprising to me as well.