Re: Using libcxx with musl's math.h

[Rich Felker <dalias@libc.org>]

On Thu, Mar 10, 2016 at 06:46:12PM +0000, Jeroen Ketema wrote:
> Hello,
> 
> I'm trying to use libcxx's cmath header together with musl's math.h.
> However this currently fails, because libcxx expects certain symbols
> to be functions, while musl defines them as macros. For example
> (compiling with clang):
> 
> cmath:309:9: error: no member named 'signbit' in the global
>       namespace; did you mean '__signbit'?
> using ::signbit;
>       ~~^
> 
> where signbit is a macro in musl, but where libcxx expects it to be
> a function.
> 
> My question is: what would be the proper way to fix this? The main
> issue being of course that I cannot simply define signbit to be a
> function, because it requires a form of overloading.

I think this is a libcxx bug. C requires signbit to be a macro. If C++
has different requirements then the C++ implementation should be
providing an overlay header that satisfies them.

Rich