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Asked: 2026-06-10T06:19:54+00:00

I’m trying to build Boost 1.49.0 using GCC 4.7.0 (MinGW). I keep getting the

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I’m trying to build Boost 1.49.0 using GCC 4.7.0 (MinGW). I keep getting the following error message several dozen times:

c:\tools\mingw\bin../lib/gcc/i686-pc-mingw32/4.7.0/../../../../include/c++/4.7.0/cmath:1096:11: error: ‘::hypot’ has not been declared

Line 1096 of cmath contains

using ::hypot;

cmath includes math.h which declares the hypot function as 

extern double __cdecl hypot (double, double); /* in libmoldname.a */

In both files, a couple of lines after the ones quoted above, are identical statements for the hypotl function (except the type is long double instead of double) and that one seems happy.

Any ideas why I am getting this error?

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1 Answer

  1. Editorial Team

    Found the answer in this forum post. It seems that pyconfig.h has the following lines:

    #if defined(__GNUC__) && defined(_WIN32)
// ...
#define hypot _hypot
// ...
#endif /* GNUC */

    but cmath included with MinGW expects the function to be named hypot and not _hypot, which causes the compilation errors.

    The fix was to include the following to my bjam command line’s cxxflags option

    bjam ... cxxflags="-include cmath "

    This indicates that g++ should include the cmath header at the beginning of every source file.

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