6.5 Other Changes

For users of a C++ compiler, the way how the availability of intmax_t is detected has changed in MPFR 3.0. In MPFR 2.x, if a macro INTMAX_C or UINTMAX_C was defined (e.g. when the __STDC_CONSTANT_MACROS macro had been defined before <stdint.h> or <inttypes.h> has been included), intmax_t was assumed to be defined. However this was not always the case (more precisely, intmax_t can be defined only in the namespace std, as with Boost), so that compilations could fail. Thus the check for INTMAX_C or UINTMAX_C is now disabled for C++ compilers, with the following consequences:

• Programs written for MPFR 2.x that need intmax_t may no longer be compiled against MPFR 3.0: a #define MPFR_USE_INTMAX_T may be necessary before ‘mpfr.h’ is included.
• The compilation of programs that work with MPFR 3.0 may fail with MPFR 2.x due to the problem described above. Workarounds are possible, such as defining intmax_t and uintmax_t in the global namespace, though this is not clean.