Header dependency changes
Some C++ Standard Library headers have been changed to no longer include other headers that they do need to depend on. As such, C++ programs that used standard library components without including the right headers will no longer compile.
The following headers are used less widely in libstdc++ and may need to be included explicitly when compiled with GCC 11:
(for std::numeric_limits)
(for std::unique_ptr, std::shared_ptr etc.)
(for std::pair, std::tuple_size, std::index_sequence etc.)
(for members of namespace std::this_thread.)
maybe this is related: http://gcc.gnu.org/gcc-11/porting_to.html