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RE: _GLIBCXX_USE_C99 not working?


On 17 May 2007 21:32, Christian Franke wrote:

> Defining _GLIBCXX_USE_C99 does not work with current Cygwin C++ includes.
> 
> Testcase:
> 
> #define _GLIBCXX_USE_C99 1 // need std::llabs()


  Can you point me at any documentation that says this is a valid thing to do?
AFAICT that's an internal symbol in the '_' namespace that user code has no
business messing around with.  Cygwin is not a glibc program so telling
libstdc that it is seems inherently bogus to me.


/artimi/software/firmware $ grep -wB1 _GLIBCXX_USE_C99
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/i686-pc-cygwin/bits/c++config.h
// Define if C99 features such as lldiv_t, llabs, lldiv should be exposed.
/* #undef _GLIBCXX_USE_C99 */


  As you see, it is part of the internal configuration, generated by autoconf
or some similar process at the time the library is compiled and installed.

http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/c++config_8h.html
"This is an internal header file, included by other library headers. You
should not attempt to use it directly."

  If you want this to work, I guess we shoult implement strtold in newlib, or
patch libstdc for finer granularity in what it assumes _GLIBCXX_USE_C99
implies is available.

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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