The problem was that Catch2 did not reliably include `<exception>`
before it checked for the feature test macro for
`std::uncaught_exceptions`. To avoid overhead of including
`<exception>` everywhere, the configuration check was split out
into a separate header.
Closes#2021
Some compilers, e.g. the Green Hills C++ compiler, react badly to the
appearance of std::exception_ptr, std::current_exception,
std::rethrow_exception and std::uncaught_exception(s). To allow usage of
Catch2 with these compilers when exceptions are disabled, hide the usage
of std::exception_ptr etc. when compiling with
CATCH_CONFIG_DISABLE_EXCEPTIONS.
This should improve the compilation times by decreasing the number
of TUs compiled, without making overly big TUs that would cause
problems with heavy-tailed compilation times.
There is one "combined TU" for the top level part, and each subpart,
except for Reporters, which currently do not have any trivial TUs.
Martin Hořeňovský
Matthias Blankertz