Rollup of 7 pull requests #74493
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Rollup of 7 pull requests #74493
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They are deprecated so doing extra work for error recovery doesn't make sense
Add core::task::ready! macro This PR adds `ready!` as a top-level macro to `libcore` following the implementation of `futures_core::ready`, tracking issue rust-lang#70922. This macro is commonly used when implementing `Future`, `AsyncRead`, `AsyncWrite` and `Stream`. And being only 5 lines, it seems like a useful and straight forward addition to std. ## Example ```rust use core::task::{Context, Poll}; use core::future::Future; use core::pin::Pin; async fn get_num() -> usize { 42 } pub fn do_poll(cx: &mut Context<'_>) -> Poll<()> { let mut f = get_num(); let f = unsafe { Pin::new_unchecked(&mut f) }; let num = ready!(f.poll(cx)); // ... use num Poll::Ready(()) } ``` ## Naming In `async-std` we chose to nest the macro under the `task` module instead of having the macro at the top-level. This is a pattern that currently does not occur in std, mostly due to this not being possible prior to Rust 2018. This PR proposes to add the `ready` macro as `core::ready`. But another option would be to introduce it as `core::task::ready` since it's really only useful when used in conjunction with `task::{Context, Poll}`. ## Implementation questions I tried rendering the documentation locally but the macro didn't show up under `core`. I'm not sure if I quite got this right. I used the [`todo!` macro PR](https://github.com/rust-lang/rust/pull/56348/files) as a reference, and our approaches look similar. ## References - [`futures::ready`](https://docs.rs/futures/0.3.4/futures/macro.ready.html) - [`async_std::task::ready`](https://docs.rs/async-std/1.5.0/async_std/task/index.html) - [`futures_core::ready`](https://docs.rs/futures-core/0.3.4/futures_core/macro.ready.html)
Document the trait keyword Partial fix of rust-lang#34601. This document the trait keyword. To avoid doing too much and forcing more updates as functionalities evolve, I put two links to the reference, especially for trait objects. This mainly documents the "big" parts, not so much the small details that might trip someone experimenting. @rustbot modify labels: T-doc,C-enhancement
impl Index<RangeFrom> for CStr This change implements (partial) slicing for `CStr`. Since a `CStr` must end in a null byte, it's not possible to trim from the right and still have a valid `CStr`. But, it *is* possible to trim from the left. This lets us be a bit more flexible and treat them more like strings. ```rust let string = CStr::from_bytes_with_nul(b"Hello World!\0"); let result = CStr::from_bytes_with_nul(b"World!\0"); assert_eq!(&string[6..], result); ```
rustc_metadata: Make crate loading fully speculative Instead of reporting `span_err`s on the spot crate loading errors are now wrapped into the `CrateError` enum and returned, so they are reported only at the top level `resolve_crate` call, and not reported at all if we are resolving speculatively with `maybe_resolve_crate`. As a result we can attempt loading crates for error recovery (e.g. import suggestions) without any risk of producing extra errors. Also, this means better separation between error reporting and actual logic. Fixes rust-lang#55103 Fixes rust-lang#56590
…-DPC add test for rust-lang#62878 forgot to push this as part of rust-lang#74159 r? @Dylan-DPC
… r=oli-obk Make unreachable_unchecked a const fn This PR makes `std::hint::unreachable_unchecked` a const fn so we can use it inside a const function. r? @RalfJung Fixes rust-lang#53188.
…e-utf8, r=Mark-Simulacrum Revert "Use an UTF-8 locale for the linker." Reverts rust-lang#74416 This is suspected to have caused significant compile time regressions: https://perf.rust-lang.org/compare.html?start=39d5a61f2e4e237123837f5162cc275c2fd7e625&end=d3df8512d2c2afc6d2e7d8b5b951dd7f2ad77b02&stat=instructions:u
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☀️ Test successful - checks-actions, checks-azure |
This was referenced Jul 19, 2020
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This was a big perf win. Presumably it was #74478 that was responsible. However, the improvements here are smaller than those seen on perf CI runs in that PR. (E.g. the best improvement dropped from -42% to -33%.) So it's possible that one of the other PRs in this this rollup caused a significant regression. But it's difficult to say for certain, and I don't know which other PR may be the cause. Argh. |
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The perf results for #74478 landing in this PR (i.e., basically an up to date run) indicates that it essentially accounts for all of the benefits of this PR. Presumably some of the offsets from the original try run were offset by some other changes -- though it is unclear exactly how that could be the case. OTOH, this landed atop 1fa54ad which was a known linker regression (based on perf runs elsewhere). So that may explain some of the offsets in terms of performance we managed to win back. I consider this PR to be fully understood from a perf perspective. |
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r? @ghost