[clang] [C99] Claim conformance for _Complex support (PR #88161)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> > > Note that
> > > ```c++
> > > auto div(_Complex float lhs, _Complex float rhs) {
> > >   return lhs / rhs;
> > > }
> > > 
> > > int main() {
> > >   return __real div(1.f, 2.f);
> > > }
> > > ```
> > > 
> > > 
> > >     
> > >       
> > >     
> > > 
> > >       
> > >     
> > > 
> > >     
> > >   
> > > will fail to link on windows due to `__divsc3` not being available. Similar programs probably also fail due to other compiler-rt functions not being available.
> > 
> > 
> > I _think_ Clang still gets to claim conformance here because we handle the language side of things correctly and the user is responsible for linking to a runtime library with appropriate support for the platform. However, this sure does straddle the line in some ways, so I could see this being a reason to claim "partial" conformance.
> 
> IIRC the problem is that you can't get compiler-rt on windows. If it was just a matter of compiling compiler-rt with clang I'd be 100% with you. Partial conformance with a note that some operations require compiler-rt functions that aren't available on windows seems like a good compromise to me.

Yeah, that seems like a reasonable compromise. I'll make updates for that, thanks!

https://github.com/llvm/llvm-project/pull/88161