fix(allocator): prevent putting drop types into arena

[overlookmotel]

Should not be merged.

Is a quick and dirty check that we do not put any drop types into either oxc_allocator::Box or oxc_allocator::Vec.

Unfortunately, this is probably not reliable enough to use. From needs_drop's docs:

May be implemented conservatively: it may return true for types that don’t actually need to be dropped. As such always returning true would be a valid implementation of this function. However if this function actually returns false, then you can be certain dropping T has no side effect.

So the fact that tests and conformance pass on this PR does prove that no code path that they exercise attempts to put Drop types into Box or Vec. So this demonstrates that #6623 does not introduce any memory leaks. Good!

However, as the docs say, we cannot rely on needs_drop not producing false positives, so this could start producing erroneous compilation errors in a future version of Rust.

[overlookmotel]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• fix(allocator): prevent putting drop types into arena #6626 👈
• fix(allocator)!: make Vec non-drop #6623
• fix(isolated_declarations): fix potential memory leak #6622
• main

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[codspeed-hq]

CodSpeed Performance Report

Merging #6626 will not alter performance

_{Comparing 10-16-fix_allocator_prevent_putting_drop_types_into_arena (240ea95) with 10-16-refactor_allocator_make_vec_non-drop (45bdb68)}

Summary

✅ 30 untouched benchmarks