c2hs confused by clang headers on the Windows platform

[Kleidukos]

Symptoms described at vmchale/libarchive#34

This is presumably because starting from 9.4 GHC uses clang instead of gcc on Windows, thus different headers, which c2hs is incapable to deal with.

[wz1000]

Here is the bit of the header it chokes on:

static __inline__ unsigned long long __DEFAULT_FN_ATTRS_CAST
_castf64_u64(double __A) {
  return __builtin_bit_cast(unsigned long long, __A);
}

Error: p/ghc/9.4.7/mingw/lib/clang/14.0.6/include/ia32intrin.h:222: (column 29) [ERROR]  >>> Syntax error !
  The symbol `unsigned' does not fit here.

[wz1000]

It seems like __builtin_bit_cast is a C++ construct, so it is not surprising that c2hs chokes on it.

[Bodigrim]

Maybe, but basically it seems c2hs is dysfunctional on Windows since GHC 9.4, whatever you do. It would be nice to fix it, even if in ad-hoc way.

[deech]

I don't have access to Windows machine at the moment but can you try invoking c2hs like this:

c2hs -C -D"__builtin_bit_cast(A,B)=((A)B)" <file.chs>

The double quotes escape their contents on zsh, for sh you probably need single quotes:

c2hs -C -D'__builtin_bit_cast(A,B)=((A)B)' <file.chs>

This will just parse __builtin_bit_cast(unsigned long long, __A) as ((unsigned long long) __A).

[bgamari]

I have addressed this in visq/language-c#96