[libcxx] r291329 - Add _LIBCPP_ABI_[ITANIUM|MICROSOFT] macros.

[Eric Fiselier via cfe-commits]

On Sat, Jan 7, 2017 at 1:29 AM, Shoaib Meenai <smeenai at fb.com> wrote:

> Do you think it's worth also checking for the presence of cxxabi.h and
> assuming the Itanium ABI if it's found, since the MS ABI shouldn't be using
> any ABI library?
>

No I don't think we should check for `cxxabi.h`.It's entirely possible to
want to compile
for the Microsoft ABI when `cxxabi.h` is in your path.

That being said I don't think the current configuration is correct either.
I'm just using it
until we change Clang to provide the needed macros.


>
> (_LIBCPP_BUILDING_HAS_NO_ABI_LIBRARY would have been ideal were it
> available
> persistently rather than only during the build of libc++ itself. It could
> still work if this macro isn't used in any headers though.)
>
> Also, is there ever a case where _MSC_VER would be defined and _WIN32
> wouldn't? The current check seems slightly redundant.
>
> On 1/6/17, 6:43 PM, "cfe-commits on behalf of Eric Fiselier via
> cfe-commits" <cfe-commits-bounces at lists.llvm.org on behalf of
> cfe-commits at lists.llvm.org> wrote:
>
>     Author: ericwf
>     Date: Fri Jan  6 20:43:58 2017
>     New Revision: 291329
>
>     URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.
> org_viewvc_llvm-2Dproject-3Frev-3D291329-26view-3Drev&d=DgIGaQ&c=
> 5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=vt8N_ZR6syyL2-CBgE_
> SBSS0YTQdKIMfcLf4r8leu2c&s=fVFRdDSSgXSZHuGlbfQI1SHyPLDGvuVdhQdxOsU30hI&e=
>     Log:
>     Add _LIBCPP_ABI_[ITANIUM|MICROSOFT] macros.
>
>     This patch adds a libc++ configuration macro for the ABI we
>     are targeting, either Itanium or Microsoft. For now we configure
>     for the Microsoft ABI when on Windows with a compiler that defines
>     _MSC_VER. However this is only temporary until Clang implements
>     builtin macros we can use.
>
>     Modified:
>         libcxx/trunk/include/__config
>
>     Modified: libcxx/trunk/include/__config
>     URL: https://urldefense.proofpoint.com/v2/url?u=http-3A__llvm.
> org_viewvc_llvm-2Dproject_libcxx_trunk_include_-5F-
> 5Fconfig-3Frev-3D291329-26r1-3D291328-26r2-3D291329-26view-
> 3Ddiff&d=DgIGaQ&c=5VD0RTtNlTh3ycd41b3MUw&r=o3kDXzdBUE3ljQXKeTWOMw&m=vt8N_
> ZR6syyL2-CBgE_SBSS0YTQdKIMfcLf4r8leu2c&s=46ge62wLL0LHhhQmWVsvb0uPoh8oV4
> 4DG0fsq0nEPs8&e=
>     ============================================================
> ==================
>     --- libcxx/trunk/include/__config (original)
>     +++ libcxx/trunk/include/__config Fri Jan  6 20:43:58 2017
>     @@ -111,6 +111,15 @@
>      #define _LIBCPP_COMPILER_IBM
>      #endif
>
>     +// FIXME: ABI detection should be done via compiler builtin macros.
> This
>     +// is just a placeholder until Clang implements such macros. For now
> assume
>     +// that Windows compilers pretending to be MSVC++ target the
> microsoft ABI.
>     +#if defined(_WIN32) && defined(_MSC_VER)
>     +# define _LIBCPP_ABI_MICROSOFT
>     +#else
>     +# define _LIBCPP_ABI_ITANIUM
>     +#endif
>     +
>      // Need to detect which libc we're using if we're on Linux.
>      #if defined(__linux__)
>      #include <features.h>
>
>
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>
>
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