[cfe-dev] Objective-C++11: concerns about adding static_assert support to @interface / @implementation?

[Aaron Ballman via cfe-dev]

On Fri, Mar 8, 2019 at 11:52 AM Nico Weber <thakis at chromium.org> wrote:
>
> On Fri, Mar 8, 2019 at 11:23 AM Aaron Ballman <aaron at aaronballman.com> wrote:
>>
>> On Fri, Mar 8, 2019 at 11:20 AM Nico Weber via cfe-dev
>> <cfe-dev at lists.llvm.org> wrote:
>> >
>> > Hi,
>> >
>> > I'm trying to enable -Wextra-semi in Chromium. I'm almost there; the last remaining issue is that we have a macro THREAD_CHECKER(name) that expands to nothing in release builds but to `ThreadChecker name` in debug builds. It's supposed to be used like
>> >
>> > class C {
>> >   THREAD_CHECKER(checker_);
>> > };
>> >
>> > And then in the implementation, you do CHECK_CALLED_ON_VALID_THREAD(checker_); which again does nothing in release builds but calls a method on checker_ in debug builds.
>> >
>> > Since this is a declaration, this triggers -Wextra-semi. I figured the way to spell the usual `do {} while (0)` you tag on the end of a statement macro to silence this warning could be `static_assert(1, "")`, so I changed THREAD_CHECKER() to expand to that in release builds instead of nothing.
>> >
>> > This works beautifully, but Objective-C interfaces don't support static_assert()s as I have learned. So I'd like to add support for that.
>>
>> Do they support _Static_assert() instead (the C11 spelling)
>
>
> No.

Good to know!

I'd also like to see _Static_assert() supported in Objective-C and
static_assert() supported in Objective-C++; I think they'd be useful.
However, I'm not certain of the relationship between ObjC/C++ versions
and the language standard version of C/C++ and whether there might be
concerns there.

~Aaron