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.

The divide-by-zero exception is new in MPFR 3.1. However it should not introduce incompatible changes for programs that strictly follow the MPFR API since the exception can only be seen via new functions.

As of MPFR 3.1, the mpfr.h header can be included several times, while still supporting optional functions (see Headers and Libraries).