[cxx-abi-dev] Passing non-trivial types through ...

[Dennis Handly]

>From: John McCall <rjmccall at apple.com>
>Oh, yes, that’s definitely a language requirement: you can’t outright reject
>this construct if it’s not potentially-evaluated.  A lot of template
>metaprogramming tricks rely on overloads like this.  But it doesn’t affect
>whether you consider it undefined behavior when it *isn’t* potentially
>evaluated.

It turns out we fixed the compiler long ago to not warn for sizeof.
So that leaves me with no bug test cases of a customer using it.
But that's only negative evidence.