Turns out people are bad at not combining code compiled with GCC
and Clang, and the improvement from `trivial_abi` on `unique_ptr`
is not worth the maintenance cost of having this be an opt-in
change.
Closes#2344
This decreases code size and improves performance of passing around
`unique_ptr` instances by value somewhat. It virtually guarantees
problems when combining code compiled with Clang and GCC, but that
was never supported anyway.
This simplified variant supports only a subset of the functionality
in `std::unique_ptr<T>`. `Catch::Detail::unique_ptr<T>` only supports
single element pointer (no array support) with default deleter.
By removing the support for custom deleters, we also avoid requiring
significant machinery to support EBO, speeding up instantiations of
`unique_ptr<T>` significantly. Catch2 also currently does not need
to support `unique_ptr<T[]>`, so that is not supported either.
Tim Lyon
Lars Toenning
Martin Hořeňovský