[Bug libstdc++/1773] __cplusplus defined to 1, should be 199711L

[ro at CeBiTec dot Uni-Bielefeld.DE]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=1773

--- Comment #73 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot 
Uni-Bielefeld.DE> 2011-03-07 19:05:14 UTC ---
> --- Comment #72 from Paolo Carlini <paolo.carlini at oracle dot com> 
> 2011-03-07 16:38:06 UTC ---
> If I remember correctly, mostly Solaris issues prevented us from defining
> __cplusplus to a meaningful value. Since now we have a pretty active
> maintainer, Rainer, I'm adding him in CC and asking him to play a bit with the
> straightforward cpp_init_builtins patch defining __cplusplus to 199711 for
> c++98 (and 201103 in c++0x mode?)

I've used the following patch and gave it a try on Solaris 8 to 11, both
SPARC and x86:

diff -r 599e2b06493d libcpp/init.c
--- a/libcpp/init.c    Fri Mar 04 18:31:41 2011 +0100
+++ b/libcpp/init.c    Mon Mar 07 20:02:13 2011 +0100
@@ -452,8 +452,12 @@
       || CPP_OPTION (pfile, std)))
     _cpp_define_builtin (pfile, "__STDC__ 1");

-  if (CPP_OPTION (pfile, cplusplus))
-    _cpp_define_builtin (pfile, "__cplusplus 1");
+  if (CPP_OPTION (pfile, lang) == CLK_CXX98
+      || CPP_OPTION (pfile, lang) == CLK_GNUCXX)
+    _cpp_define_builtin (pfile, "__cplusplus 19971L");
+  else if (CPP_OPTION (pfile, lang) == CLK_CXX0X
+      || CPP_OPTION (pfile, lang) == CLK_GNUCXX0X)
+    _cpp_define_builtin (pfile, "__cplusplus 201103L");
   else if (CPP_OPTION (pfile, lang) == CLK_ASM)
     _cpp_define_builtin (pfile, "__ASSEMBLER__ 1");
   else if (CPP_OPTION (pfile, lang) == CLK_STDC94)

Unfortunately, even on Solaris 11/x86 bootstrap breaks quickly building
i386-pc-solaris2.11/bits/stdc++.h.gch/O2ggnu++0x.gch:

In file included from
/vol/gcc/src/hg/trunk/local/libstdc++-v3/include/precompiled/stdc++.h:42:0:
/var/gcc/regression/trunk/11-gcc-gas/build/i386-pc-solaris2.11/libstdc++-v3/include/cmath:
In function 'double std::abs(double)':
/var/gcc/regression/trunk/11-gcc-gas/build/i386-pc-solaris2.11/libstdc++-v3/include/cmath:82:3:
error: redefinition of 'double std::abs(double)'
/usr/include/iso/math_iso.h:159:16: error: 'double std::abs(double)' previously
defined here

and many many more errors.

cmath has

  inline double
  abs(double __x)
  { return __builtin_fabs(__x); }

while <iso/math_iso.h> has

    inline double abs(double __X) { return fabs(__X); }

I haven't looked at the failures on older Solaris versions yet, which
will likely be different.

    Rainer