Rollup of 6 pull requests #86417
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Rollup of 6 pull requests #86417
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Linear interpolation rust-lang#71016 is a previous attempt at implementation that was closed by the author. I decided to reuse the feature request issue (rust-lang#71015) as a tracking issue. A member of the rust-lang org will have to edit the original post to be formatted correctly as I am not the issue's original author. The common name `lerp` is used because it is the term used by most code in a wide variety of contexts; it also happens to be the recently chosen name of the function that was added to C++20. To ensure symmetry as a method, this breaks the usual ordering of the method from `lerp(a, b, t)` to `t.lerp(a, b)`. This makes the most sense to me personally, and there will definitely be discussion before stabilisation anyway. Implementing lerp "correctly" is very dififcult even though it's a very common building-block used in all sorts of applications. A good prior reading is [this proposal](http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0811r2.html#linear-interpolation) for the C++20 lerp which talks about the various guarantees, which I've simplified down to: 1. Exactness: `(0.0).lerp(start, end) == start` and `(1.0).lerp(start, end) == end` 2. Consistency: `anything.lerp(x, x) == x` 3. Monotonicity: once you go up don't go down Fun story: the version provided in that proposal, from what I understand, isn't actually monotonic. I messed around with a *lot* of different lerp implementations because I kind of got a bit obsessed and I ultimately landed on one that uses the fused `mul_add` instruction. Floating-point lerp lore is hard to come by, so, just trust me when I say that this ticks all the boxes. I'm only 90% certain that it's monotonic, but I'm sure that people who care deeply about this will be there to discuss before stabilisation. The main reason for using `mul_add` is that, in general, it ticks more boxes with fewer branches to be "correct." Although it will be slower on architectures without the fused `mul_add`, that's becoming more and more rare and I have a feeling that most people who will find themselves needing `lerp` will also have an efficient `mul_add` instruction available.
…-ou-se Specialize `io::Bytes::size_hint` for more types Improve the result of `<io::Bytes as Iterator>::size_hint` for some readers. I did not manage to specialize `SizeHint` for `io::Cursor` Side question: would it be interesting for `io::Read` to have an optional `size_hint` method ?
…, r=m-ou-se Rely on libc for correct integer types in os/unix/net/ancillary.rs. This PR is a small maintainability improvement. It simplifies `unix/net/ancillary.rs` in `std` by removing the `cfg_ifs` for casting to the correct integer type, and just rely on libc to define the struct correctly.
…Artichaut Make `s` pre-interned Now we should be able to pre-intern `s` as the test `ui/lint/rfc-2457-non-ascii-idents/lint-confusable-idents.rs` no longer fails.
…tichaut Fix ICE when using `#[doc(keyword = "...")]` on non-items This pull request fixes rust-lang#83512. The code for checking attributes calls `expect_item()` when it shouldn't, thus causing an ICE. I have implemented a proper check for the node kind, so that an error is reported instead of the ICE.
…te, r=Mark-Simulacrum Add incr-comp note for 1.53.0 relnotes
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@bors r+ rollup=never p=6 |
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📌 Commit 4ec05e0 has been approved by |
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☀️ Test successful - checks-actions |
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Successful merges:
io::Bytes::size_hintfor more types #86202 (Specializeio::Bytes::size_hintfor more types)spre-interned #86388 (Makespre-interned)#[doc(keyword = "...")]on non-items #86401 (Fix ICE when using#[doc(keyword = "...")]on non-items)Failed merges:
r? @ghost
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