Summary:
tbv2: remove unnecessary copy in Element
`IntrospectionResult::const_iterator` iterates through the `Element`s in an
`IntrospectionResult`. `Element` currently copies the `type_path` which is a
`std::vector<string_view>` every time the iterator is incremented. This is
unnecessary as the data in the vector only changes slightly between iterations.
This change changes the `type_path` field in `Element` to a
`std::span<const std::string_view>`. Doing this previously caused SEGVs because
of the iterator's potential to be copied. To make it possible we do two things:
1. Make all copies explicit using a clone interface as in `ContainerInfo`. This
prevents accidental copies of an expensive structure.
2. After calling the copy constructor in `clone()` update the `span` in `next_`
to point at the newly copied structure.
Moves are fine because the `span` points at the allocation of the `vector`, not
the vector itself.
Test Plan:
- CI
- `FILTER='OilIntegration.*' make test`
- Ran `OilgenIntegration.std_vector_vector_int_some` which SEGVd with the
`span` change before and now doesn't. This now passes cleanly with ASAN
enabled on the target, though isn't available in `main` (only works on my
machine).
Differential Revision: D53472595
Pulled By: JakeHillion
