On Fri, Dec 22, 2023, 18:46 Steve Downey <sdowney@gmail.com> wrote:
A -Wnone on what translation unit? 

When translating the module source that is from "the system".

Example at hand is where `std::optional<int16_t> c{300000};` is warnings clean because the template is in the system header file. Now, this is a case where it probably really ought to warn, but doesn't.

I would expect an instantiation that happens because of the local code to warn, yes.

If compilers don't warn on that today I'd consider it a bug.

But it's also a case where previously clean code is going to fail, but there are probably cases where the warning is triggered by something the client can't control.

Right, a warning created by an instantiation in the module source for a "foreign" module probably shouldn't warn.

Daniel