Created attachment 2928 [details]
Source Files

The file int64x64-test-suite.cc contains the following code:

#if defined (INT64X64_USE_CAIRO) && !defined (PYTHON_SCAN)
  std::cout << "cairo_impl64:  " << cairo_impl64 << std::endl;
  std::cout << "cairo_impl128: " << cairo_impl128 << std::endl;
#endif

If INT64x64_USE_CAIRO is defined, a build error occurs because cairo_impl64 and cairo_impl128 are undefined.  They are declared in cairo-wideint-private.h as follows:

extern const char * cairo_impl64;
extern const char * cairo_impl128;

but are never defined and end up being undefined externals at link time.