Fedora 29 ships with
glibc version 2.28, which brings many bug fixes, performance improvements, better POSIX compliance, and many other enhancements.
For detailed information about this release, see the NEWS upstream. (Note that you will need to scroll down to version 2.28.)
Some packaging changes are required. See 2.28 Packaging Changes for detailed information.
Since the first release of Fedora,
gcc-C++ were installed by default in every buildroot.
At that time this was useful for most packages as they were typically written in C or C++.
However, many packages today are written in other languages and they do not need a C/C++ compiler, and at the same time, installing
gcc-C++ takes time which is wasted if they are not required.
Starting with this release,
gcc-C++ are no longer installed by default in every buildroot, which results in quicker builds for packages which do not require them, better package compliance with the Packaging Guidelines, and a cleaner buildroot environment.
You can test that your Fedora package still builds after the change by running
fedpkg mockbuild with a modified configuration file that excludes
gcc-C++ from the buildroot.
Detailed instructions have been provided on the devel mailing list.