See the BUGS file. The Reporting Bugs section of the MPFR manual gives details on how to report new bugs.
Changes from version 4.2.1 to version 4.2.2
In order to resolve a portability issue with the _Float128 fallback to __float128 for binary128 support (e.g. with Clang and glibc�2.41), the prototypes of the corresponding conversion functions had to be changed, with _Float128 replaced by mpfr_float128, where mpfr_float128 is a macro defined as _Float128 by default. This changes neither the ABI nor the API (except that the end user of MPFR would need to define mpfr_float128 as the actual type for the binary128 format if this is not the standard _Float128 type).
Other bug fixes (see the fixed bugs on the MPFR�4.2.1 page and/or the ChangeLog file). In particular, the formatted output functions behaved incorrectly with %c on the value�0; such a use is uncommon, but this bug may have security implications.
Improved MPFR manual.
Detect the use of GMP's buggy vsnprintf replacement at configure time. With it, the tests of "%a" will be disabled to avoid an assertion failure in the MPFR testsuite. A warning will be displayed in the configure output in such a case.
Platforms Known to Support MPFR
MPFR 4.2.2 has been successfully compiled and checked on the following platforms:
aarch64-apple-darwin21.6.0 (clang 14.0.0);
aarch64-unknown-linux-gnu (gcc 8.5.0 and 14.2.0, clang 19.1.7 on Termux/Android, tcc mob branch);
aarch64-unknown-linux-musl (gcc 14.2.0);
i586-unknown-freebsd13.3 (clang 17.0.6);
i686-w64-mingw32 (Wine, gcc 14-win32);
mips-unknown-linux-gnu (o32 and n32 ABI, gcc 8.3.0);