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gcc4: OpenMP vs. <math.h>
- From: "Yaakov (Cygwin/X)" <yselkowitz at users dot sourceforge dot net>
- To: cygwin at cygwin dot com
- Date: Fri, 08 Jan 2010 01:40:33 -0600
- Subject: gcc4: OpenMP vs. <math.h>
POSIX allows for <math.h> functions to also be defined as macros.
Currently, only log2 and log2f are so defined.
These macros pose problems with a few projects which define their own
static/inline/template log2() (off the top of my head, I can think of 2:
the CRAN rgl module, and OpenCV; both are C++). Of course, those can be
fixed with an #undef log2 after the #include's.
However, I just encountered tonight a much larger conflict: OpenMP/C++
and <math.h> are incompatible. STC attached:
$ g++ -D_GLIBCXX_PARALLEL -fopenmp openmp.cxx -lgomp
In file included from
/usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/parallel/algobase.h:46,
from
/usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/stl_algobase.h:1137,
from
/usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/char_traits.h:46,
from /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/ios:46,
from
/usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/ostream:45,
from
/usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/iostream:45,
from openmp.cxx:7:
/usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/parallel/base.h:112:
error: expected `)' before ‘/’ token
It gets even worse if you #include <algorithm> as well, and no, it
doesn't help to #include <cmath>, although moving the math include after
all other includes does work.
I see two possible solutions:
1) Make the log2 macros dependent on #ifndef __cplusplus;
2) Make the parallel/* headers #undef log2 and log2f.
Thoughts?
Yaakov
Attachment:
openmp.cxx
Description: Text document
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