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X-Authentication-Warning: hp2.xraylith.wisc.edu: khan owned process doing -bs
Date: Fri, 7 Jan 2000 13:08:27 -0600 (CST)
From: Mumit Khan <khan AT NanoTech DOT Wisc DOT EDU>
To: cygwin-developers AT sourceware DOT cygnus DOT com
Subject: use of __builtin_memset
Message-ID: <Pine.HPP.3.96.1000107125535.1532V-100000@hp2.xraylith.wisc.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

I see that the use of __builtin_memset has been turned on in the
last winsup snapshot, which breaks building under gcc-2.95.x, which 
doesn't really support it. Interestingly enough, gcc-2.95.2 seems to 
have __builtin_memset in its code, but c++ front-end rejects the code 
unless properly prototyped.

A good way to handle this is to use autoconf.

Here's how you can do this in configure.in:

  # Test for builtin mem* functions.
  AC_LANG_SAVE
  AC_LANG_CPLUSPLUS
  AC_TRY_COMPILE([
  #include <string.h>
  void foo (char *s, int c, size_t n)
  {  
      __builtin_memset(s, c, n);
  }
  ], [ ],
  use_builtin_memset=yes, use_builtin_memset=no)
  if test "$use_builtin_memset" = "yes"; then
    AC_DEFINE(WINSUP_HAS_BUILTIN_MEMSET)
  fi
  AC_LANG_RESTORE

and so on for all the other builtin's that are "new". If there are going
to be more, then we should consider the use of config.h{.in} and using
that instead of passing cpp macros flags on the command line.

I can work up a patch if interested. 

Regards,
Mumit