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Rollup of 5 pull requests #97729
Rollup of 5 pull requests #97729
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Avoid zero-sized allocs in ThinBox if T and H are both ZSTs. This was surprisingly tricky, and took longer to get right than expected. `ThinBox` is a surprisingly subtle piece of code. That said, in the end, a lot of this was due to overthinking[^overthink] -- ultimately the fix ended up fairly clean and simple. [^overthink]: Honestly, for a while I was convinced this couldn't be done without allocations or runtime branches in these cases, but that's obviously untrue. Anyway, as a result of spending all that time debugging, I've extended the tests quite a bit, and also added more debug assertions. Many of these helped for subtle bugs I made in the middle (for example, the alloc/drop tracking is because I ended up double-dropping the value in the case where both were ZSTs), they're arguably a bit of overkill at this point, although I imagine they could help in the future too. Anyway, these tests cover a wide range of size/align cases, nd fully pass under miri[^1]. They also do some smoke-check asserting that the value has the correct alignment, although in practice it's totally within the compiler's rights to delete these assertions since we'd have already done UB if they get hit. They have more boilerplate than they really need, but it's not *too* bad on a per-test basis. A notable absence from testing is atypical header types, but at the moment it's impossible to manually implement `Pointee`. It would be really nice to have testing here, since it's not 100% obvious to me that the aligned read/write we use for `H` are correct in the face of arbitrary combinations of `size_of::<H>()`, `align_of::<H>()`, and `align_of::<T>()`. (That said, I spent a while thinking through it and am *pretty* sure it's fine -- I'd just feel... better if we could test some cases for non-ZST headers which have unequal and align). [^1]: Or at least, they pass under miri if I copy the code and tests into a new crate and run miri on it (after making it less stdlibified). Fixes rust-lang#96485. I'd request review ``@yaahc,`` but I believe you're taking some time away from reviews, so I'll request from the previous PR's reviewer (I think that the context helps, even if the actual change didn't end up being bad here). r? ``@joshtriplett``
Lazily allocate and initialize pthread locks. Lazily allocate and initialize pthread locks. This allows {Mutex, Condvar, RwLock}::new() to be const, while still using the platform's native locks for features like priority inheritance and debug tooling. E.g. on macOS, we cannot directly use the (private) APIs that pthread's locks are implemented with, making it impossible for us to use anything other than pthread while still preserving priority inheritance, etc. This PR doesn't yet make the public APIs const. That's for a separate PR with an FCP. Tracking issue: rust-lang#93740
…g, r=wesleywiser Support the `#[expect]` attribute on fn parameters (RFC-2383) A small PR to allow the `#[expect]` attribute on function parameters. Nothing more to say, I hope everyone reading this has a lovely day. --- r? ``@wesleywiser`` closes: rust-lang#97650 cc: rust-lang#85549
…eywiser Fix reachability analysis for const methods Use `method_might_be_inlined` directly for `ImplItemKind::Fn` instead of duplicating the logic in `def_id_represents_local_inlined_item`. This is parallel to how we use `item_might_be_inlined` for `ItemKind::Fn` in that same body. Fixes rust-lang#97708
…rror-spans, r=Dylan-DPC Tighten spans for bad fields in struct deriving `Copy` r? `@estebank` Closes rust-lang#89137 for good, I think Not sure if this is what you were looking for in rust-lang#89137 (comment)
@bors r+ rollup=never p=5 |
📌 Commit 8c4c698 has been approved by |
☀️ Test successful - checks-actions |
Finished benchmarking commit (c7b0452): comparison url. Instruction countThis benchmark run did not return any relevant results for this metric. Max RSS (memory usage)Results
CyclesResults
If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. @rustbot label: -perf-regression Footnotes |
Successful merges:
#[expect]
attribute on fn parameters (RFC-2383) #97715 (Support the#[expect]
attribute on fn parameters (RFC-2383))Copy
#97722 (Tighten spans for bad fields in struct derivingCopy
)Failed merges:
r? @ghost
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