Remove P: Unpin bound on impl Future for Pin #81363

jonhoo · 2021-01-25T01:00:45Z

We can safely produce a Pin<&mut P::Target> without moving out of the Pin by using Pin::as_mut directly.

The Unpin bound was originally added in #56939 following the recommendation of @withoutboats in #55766 (comment)

That comment does not give explicit justification for why the bound should be added. The relevant context was:

[ ] Remove impl Unpin for Pin

This impl is not justified by our standard justification for unpin impls: there is no pointer direction between Pin and P. Its usefulness is covered by the impls for pointers themselves.

This futures impl (link to the impl changed in this PR) will need to change to add a P: Unpin bound.

The decision to remove the unconditional impl of Unpin for Pin is sound (these days there is just an auto-impl for when P: Unpin). But, I think the decision to also add the Unpin bound for impl Future may have been unnecessary. Or if that's not the case, I'd be very interested to have the argument for why written down somewhere. The bound appears to not be needed, as demonstrated by the change requiring no unsafe code and by the existence of Pin::as_mut.

rust-highfive · 2021-01-25T01:00:49Z

r? @cramertj

(rust-highfive has picked a reviewer for you, use r? to override)

jonhoo · 2021-01-25T01:25:32Z

Hmm, I'm not quite sure how this change can make https://github.com/rust-lang/rust/blob/1d0d76f8dd4f5f6ecbeab575b87edaf1c9f56bb8/src/test/ui/async-await/issues/issue-65419/issue-65419-async-fn-resume-after-completion.rs and https://github.com/rust-lang/rust/blob/master/src/test/ui/async-await/issues/issue-65419/issue-65419-async-fn-resume-after-panic.rs suddenly run successfully?

taiki-e · 2021-01-25T02:48:12Z

I agree that this bound doesn't actually seem necessary.

Hmm, I'm not quite sure how this change can make https://github.com/rust-lang/rust/blob/1d0d76f8dd4f5f6ecbeab575b87edaf1c9f56bb8/src/test/ui/async-await/issues/issue-65419/issue-65419-async-fn-resume-after-completion.rs and https://github.com/rust-lang/rust/blob/master/src/test/ui/async-await/issues/issue-65419/issue-65419-async-fn-resume-after-panic.rs suddenly run successfully?

I think both test need to fail -- autoderef might be doing something funky #79023 (comment)

jonhoo · 2021-01-25T05:06:42Z

Ah, I see what's going on. The method takes Pin<&mut Self>, and since Self is Pin, what we take in is a Pin<&mut Pin>. The compiler points this out (and the infinite recursion that causes the test to fail) if the call to poll is changed to

<P::Target as Future>::poll(

When I call Pin::as_mut, that just turns Pin<&mut Pin> into itself (we're already in "Pin<&mut _> mode").What we need is to deref through Self, which I don't think we can safely unfortunately. And also makes the original argument for why this should be okay moot (that is, that it could be done with safe code). Now, I still think that Pin<&mut Pin> to Pin<&mut P::Target> should be a safe transformation, but need to think more carefully about it. Could use some other eyes on it too.

Nemo157 · 2021-01-25T08:55:47Z

Trying to come up with a counter-example (https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=1bed9fe6c3266e8d4437a1513df9fb6b) I do think this is justified by the requirements on constructing a Pin where P: DerefMut. But also because of those same requirements I don't see any way a type that guarantees them wouldn't be unconditionally Unpin (technically the bound should be Pin: Unpin, but since Unpin for Pin is structural that is the same thing).

jonhoo · 2021-01-26T01:19:52Z

@Nemo157 I do think this is justified

Just to check, do you mean that the bound is justified, or that the removal of the bound is justified?

Nemo157 · 2021-01-26T08:23:50Z

The removal of the bound is justified, since I couldn't see any way to make my counter-example actually compile 😁

Nemo157 · 2021-01-29T12:37:37Z

Should this be a new method on Pin, so if other traits like Stream want a similar delegating impl they don't need to use unsafe too?

jonhoo · 2021-01-29T20:04:27Z

That's not a bad idea. Basically a way to "strip back" one layer of Pin?

jonhoo · 2021-02-04T06:32:45Z

@Nemo157 Just pushed a commit that makes the method public behind an unstable feature flag. Is something like that what you had in mind?

bors · 2021-02-05T14:56:51Z

☔ The latest upstream changes (presumably #81784) made this pull request unmergeable. Please resolve the merge conflicts.

library/core/src/pin.rs

@withoutboats

The `Unpin` bound was originally added in rust-lang#56939 following the recommendation of @withoutboats in rust-lang#55766 (comment) That comment does not give explicit justification for why the bound should be added. The relevant context was: > [ ] Remove `impl Unpin for Pin` > > This impl is not justified by our standard justification for unpin > impls: there is no pointer direction between `Pin` and `P`. Its > usefulness is covered by the impls for pointers themselves. > > This futures impl (link to the impl changed in this PR) will need to > change to add a `P: Unpin` bound. The decision to remove the unconditional impl of `Unpin for Pin` is sound (these days there is just an auto-impl for when `P: Unpin`). But, I think the decision to also add the `Unpin` bound for `impl Future` may have been unnecessary. Or if that's not the case, I'd be very interested to have the argument for why written down somewhere. The bound _appears_ to not be needed, since the presence of a `Pin` should indicate that it's safe to project to `Pin<&mut P::Target>` just like for `Pin::as_mut`.

rfcbot · 2021-07-15T13:46:03Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

The RFC will be merged soon.

m-ou-se · 2021-07-28T14:43:44Z

@bors r+

bors · 2021-07-28T14:43:46Z

📌 Commit cf40292 has been approved by m-ou-se

… r=m-ou-se Remove P: Unpin bound on impl Future for Pin We can safely produce a `Pin<&mut P::Target>` without moving out of the `Pin` by using `Pin::as_mut` directly. The `Unpin` bound was originally added in rust-lang#56939 following the recommendation of `@withoutboats` in rust-lang#55766 (comment) That comment does not give explicit justification for why the bound should be added. The relevant context was: > [ ] Remove `impl Unpin for Pin` > > This impl is not justified by our standard justification for unpin impls: there is no pointer direction between `Pin` and `P`. Its usefulness is covered by the impls for pointers themselves. > > This futures impl (link to the impl changed in this PR) will need to change to add a `P: Unpin` bound. The decision to remove the unconditional impl of `Unpin for Pin` is sound (these days there is just an auto-impl for when `P: Unpin`). But, I think the decision to also add the `Unpin` bound for `impl Future` may have been unnecessary. Or if that's not the case, I'd be very interested to have the argument for why written down somewhere. The bound _appears_ to not be needed, as demonstrated by the change requiring no unsafe code and by the existence of `Pin::as_mut`.

Rollup of 10 pull requests Successful merges: - rust-lang#81050 (Stabilize core::task::ready!) - rust-lang#81363 (Remove P: Unpin bound on impl Future for Pin) - rust-lang#86839 (Add doc aliases to fs.rs) - rust-lang#87435 (fix example code for E0617) - rust-lang#87451 (Add support for tuple struct field documentation) - rust-lang#87491 (Integrate context into the memorial to Anna) - rust-lang#87521 (Add long explanation for E0498) - rust-lang#87527 (Don't run MIR unsafeck at all when using `-Zthir-unsafeck`) - rust-lang#87550 (Add `CI_ONLY_WHEN_CHANNEL` and run `x86_64-gnu-stable` only on nightly) - rust-lang#87565 (Use backticks when referring to `core::future::Ready` in panic message) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

bors · 2021-07-29T00:31:13Z

☔ The latest upstream changes (presumably #87569) made this pull request unmergeable. Please resolve the merge conflicts.

Pkgsrc changes: * Remove one now-longer-applicable patch, adjust a few others * Bump bootstrap requirements to 1.55.0. Upstream changes: Version 1.56.0 (2021-10-21) ======================== Language -------- - [The 2021 Edition is now stable.][rust#88100] See [the edition guide][rust-2021-edition-guide] for more details. - [The pattern in `binding @ pattern` can now also introduce new bindings.] [rust#85305] - [Union field access is permitted in `const fn`.][rust#85769] [rust-2021-edition-guide]: https://doc.rust-lang.org/nightly/edition-guide/rust-2021/index.html Compiler -------- - [Upgrade to LLVM 13.][rust#87570] - [Support memory, address, and thread sanitizers on aarch64-unknown-freebsd.][rust#88023] - [Allow specifying a deployment target version for all iOS targets][rust#87699] - [Warnings can be forced on with `--force-warn`.][rust#87472] This feature is primarily intended for usage by `cargo fix`, rather than end users. - [Promote `aarch64-apple-ios-sim` to Tier 2\*.][rust#87760] - [Add `powerpc-unknown-freebsd` at Tier 3\*.][rust#87370] - [Add `riscv32imc-esp-espidf` at Tier 3\*.][rust#87666] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Allow writing of incomplete UTF-8 sequences via stdout/stderr on Windows.] [rust#83342] The Windows console still requires valid Unicode, but this change allows splitting a UTF-8 character across multiple write calls. This allows, for instance, programs that just read and write data buffers (e.g. copying a file to stdout) without regard for Unicode or character boundaries. - [Prefer `AtomicU{64,128}` over Mutex for Instant backsliding protection.] [rust#83093] For this use case, atomics scale much better under contention. - [Implement `Extend<(A, B)>` for `(Extend<A>, Extend)`][rust#85835] - [impl Default, Copy, Clone for std::io::Sink and std::io::Empty][rust#86744] - [`impl From<[(K, V); N]>` for all collections.][rust#84111] - [Remove `P: Unpin` bound on impl Future for Pin.][rust#81363] - [Treat invalid environment variable names as non-existent.][rust#86183] Previously, the environment functions would panic if given a variable name with an internal null character or equal sign (`=`). Now, these functions will just treat such names as non-existent variables, since the OS cannot represent the existence of a variable with such a name. Stabilised APIs --------------- - [`std::os::unix::fs::chroot`] - [`UnsafeCell::raw_get`] - [`BufWriter::into_parts`] - [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`] These APIs were previously stable in `std`, but are now also available in `core`. - [`Vec::shrink_to`] - [`String::shrink_to`] - [`OsString::shrink_to`] - [`PathBuf::shrink_to`] - [`BinaryHeap::shrink_to`] - [`VecDeque::shrink_to`] - [`HashMap::shrink_to`] - [`HashSet::shrink_to`] These APIs are now usable in const contexts: - [`std::mem::transmute`] - [`[T]::first`][`slice::first`] - [`[T]::split_first`][`slice::split_first`] - [`[T]::last`][`slice::last`] - [`[T]::split_last`][`slice::split_last`] Cargo ----- - [Cargo supports specifying a minimum supported Rust version in Cargo.toml.] [`rust-version`] This has no effect at present on dependency version selection. We encourage crates to specify their minimum supported Rust version, and we encourage CI systems that support Rust code to include a crate's specified minimum version in the text matrix for that crate by default. Compatibility notes ------------------- - [Update to new argument parsing rules on Windows.][rust#87580] This adjusts Rust's standard library to match the behavior of the standard libraries for C/C++. The rules have changed slightly over time, and this PR brings us to the latest set of rules (changed in 2008). - [Disallow the aapcs calling convention on aarch64][rust#88399] This was already not supported by LLVM; this change surfaces this lack of support with a better error message. - [Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default][rust#87385] - [Warn when an escaped newline skips multiple lines.][rust#87671] - [Calls to `libc::getpid` / `std::process::id` from `Command::pre_exec` may return different values on glibc <= 2.24.][rust#81825] Rust now invokes the `clone3` system call directly, when available, to use new functionality available via that system call. Older versions of glibc cache the result of `getpid`, and only update that cache when calling glibc's clone/fork functions, so a direct system call bypasses that cache update. glibc 2.25 and newer no longer cache `getpid` for exactly this reason. Internal changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [LLVM is compiled with PGO in published x86_64-unknown-linux-gnu artifacts.][rust#88069] This improves the performance of most Rust builds. - [Unify representation of macros in internal data structures.][rust#88019] This change fixes a host of bugs with the handling of macros by the compiler, as well as rustdoc. [`std::os::unix::fs::chroot`]: https://doc.rust-lang.org/stable/std/os/unix/fs/fn.chroot.html [`Iterator::intersperse`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse [`Iterator::intersperse_with`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse [`UnsafeCell::raw_get`]: https://doc.rust-lang.org/stable/std/cell/struct.UnsafeCell.html#method.raw_get [`BufWriter::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.BufWriter.html#method.into_parts [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]: rust-lang/rust#84662 [`Vec::shrink_to`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.shrink_to [`String::shrink_to`]: https://doc.rust-lang.org/stable/std/string/struct.String.html#method.shrink_to [`OsString::shrink_to`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.shrink_to [`PathBuf::shrink_to`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.shrink_to [`BinaryHeap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.shrink_to [`VecDeque::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.shrink_to [`HashMap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_map/struct.HashMap.html#method.shrink_to [`HashSet::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_set/struct.HashSet.html#method.shrink_to [`std::mem::transmute`]: https://doc.rust-lang.org/stable/std/mem/fn.transmute.html [`slice::first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first [`slice::split_first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first [`slice::last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last [`slice::split_last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last [`rust-version`]: https://doc.rust-lang.org/nightly/cargo/reference/manifest.html#the-rust-version-field [rust#87671]: rust-lang/rust#87671 [rust#86183]: rust-lang/rust#86183 [rust#87385]: rust-lang/rust#87385 [rust#88100]: rust-lang/rust#88100 [rust#86860]: rust-lang/rust#86860 [rust#84039]: rust-lang/rust#84039 [rust#86492]: rust-lang/rust#86492 [rust#88363]: rust-lang/rust#88363 [rust#85305]: rust-lang/rust#85305 [rust#87832]: rust-lang/rust#87832 [rust#88069]: rust-lang/rust#88069 [rust#87472]: rust-lang/rust#87472 [rust#87699]: rust-lang/rust#87699 [rust#87570]: rust-lang/rust#87570 [rust#88023]: rust-lang/rust#88023 [rust#87760]: rust-lang/rust#87760 [rust#87370]: rust-lang/rust#87370 [rust#87580]: rust-lang/rust#87580 [rust#83342]: rust-lang/rust#83342 [rust#83093]: rust-lang/rust#83093 [rust#88177]: rust-lang/rust#88177 [rust#88548]: rust-lang/rust#88548 [rust#88551]: rust-lang/rust#88551 [rust#88299]: rust-lang/rust#88299 [rust#88220]: rust-lang/rust#88220 [rust#85835]: rust-lang/rust#85835 [rust#86879]: rust-lang/rust#86879 [rust#86744]: rust-lang/rust#86744 [rust#84662]: rust-lang/rust#84662 [rust#86593]: rust-lang/rust#86593 [rust#81050]: rust-lang/rust#81050 [rust#81363]: rust-lang/rust#81363 [rust#84111]: rust-lang/rust#84111 [rust#85769]: rust-lang/rust#85769 (comment) [rust#88490]: rust-lang/rust#88490 [rust#88269]: rust-lang/rust#88269 [rust#84176]: rust-lang/rust#84176 [rust#88399]: rust-lang/rust#88399 [rust#88227]: rust-lang/rust#88227 [rust#88200]: rust-lang/rust#88200 [rust#82776]: rust-lang/rust#82776 [rust#88077]: rust-lang/rust#88077 [rust#87728]: rust-lang/rust#87728 [rust#87050]: rust-lang/rust#87050 [rust#87619]: rust-lang/rust#87619 [rust#81825]: rust-lang/rust#81825 (comment) [rust#88019]: rust-lang/rust#88019 [rust#87666]: rust-lang/rust#87666

Pkgsrc changes: * Bump bootstrap kit version to 1.55.0. * Adjust patches as needed, some no longer apply (so removed) * Update checksum adjustments. * Avoid rust-llvm on SunOS * Optionally build docs * Remove reference to closed/old PR#54621 Upstream changes: Version 1.56.1 (2021-11-01) =========================== - New lints to detect the presence of bidirectional-override Unicode codepoints in the compiled source code ([CVE-2021-42574]) [CVE-2021-42574]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-42574 Version 1.56.0 (2021-10-21) ======================== Language -------- - [The 2021 Edition is now stable.][rust#88100] See [the edition guide][rust-2021-edition-guide] for more details. - [The pattern in `binding @ pattern` can now also introduce new bindings.] [rust#85305] - [Union field access is permitted in `const fn`.][rust#85769] [rust-2021-edition-guide]: https://doc.rust-lang.org/nightly/edition-guide/rust-2021/index.html Compiler -------- - [Upgrade to LLVM 13.][rust#87570] - [Support memory, address, and thread sanitizers on aarch64-unknown-freebsd.] [rust#88023] - [Allow specifying a deployment target version for all iOS targets][rust#87699] - [Warnings can be forced on with `--force-warn`.][rust#87472] This feature is primarily intended for usage by `cargo fix`, rather than end users. - [Promote `aarch64-apple-ios-sim` to Tier 2\*.][rust#87760] - [Add `powerpc-unknown-freebsd` at Tier 3\*.][rust#87370] - [Add `riscv32imc-esp-espidf` at Tier 3\*.][rust#87666] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Allow writing of incomplete UTF-8 sequences via stdout/stderr on Windows.] [rust#83342] The Windows console still requires valid Unicode, but this change allows splitting a UTF-8 character across multiple write calls. This allows, for instance, programs that just read and write data buffers (e.g. copying a file to stdout) without regard for Unicode or character boundaries. - [Prefer `AtomicU{64,128}` over Mutex for Instant backsliding protection.] [rust#83093] For this use case, atomics scale much better under contention. - [Implement `Extend<(A, B)>` for `(Extend<A>, Extend)`][rust#85835] - [impl Default, Copy, Clone for std::io::Sink and std::io::Empty][rust#86744] - [`impl From<[(K, V); N]>` for all collections.][rust#84111] - [Remove `P: Unpin` bound on impl Future for Pin.][rust#81363] - [Treat invalid environment variable names as non-existent.][rust#86183] Previously, the environment functions would panic if given a variable name with an internal null character or equal sign (`=`). Now, these functions will just treat such names as non-existent variables, since the OS cannot represent the existence of a variable with such a name. Stabilised APIs --------------- - [`std::os::unix::fs::chroot`] - [`UnsafeCell::raw_get`] - [`BufWriter::into_parts`] - [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`] These APIs were previously stable in `std`, but are now also available in `core`. - [`Vec::shrink_to`] - [`String::shrink_to`] - [`OsString::shrink_to`] - [`PathBuf::shrink_to`] - [`BinaryHeap::shrink_to`] - [`VecDeque::shrink_to`] - [`HashMap::shrink_to`] - [`HashSet::shrink_to`] These APIs are now usable in const contexts: - [`std::mem::transmute`] - [`[T]::first`][`slice::first`] - [`[T]::split_first`][`slice::split_first`] - [`[T]::last`][`slice::last`] - [`[T]::split_last`][`slice::split_last`] Cargo ----- - [Cargo supports specifying a minimum supported Rust version in Cargo.toml.] [`rust-version`] This has no effect at present on dependency version selection. We encourage crates to specify their minimum supported Rust version, and we encourage CI systems that support Rust code to include a crate's specified minimum version in the text matrix for that crate by default. Compatibility notes ------------------- - [Update to new argument parsing rules on Windows.][rust#87580] This adjusts Rust's standard library to match the behavior of the standard libraries for C/C++. The rules have changed slightly over time, and this PR brings us to the latest set of rules (changed in 2008). - [Disallow the aapcs calling convention on aarch64][rust#88399] This was already not supported by LLVM; this change surfaces this lack of support with a better error message. - [Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default][rust#87385] - [Warn when an escaped newline skips multiple lines.][rust#87671] - [Calls to `libc::getpid` / `std::process::id` from `Command::pre_exec` may return different values on glibc <= 2.24.][rust#81825] Rust now invokes the `clone3` system call directly, when available, to use new functionality available via that system call. Older versions of glibc cache the result of `getpid`, and only update that cache when calling glibc's clone/fork functions, so a direct system call bypasses that cache update. glibc 2.25 and newer no longer cache `getpid` for exactly this reason. Internal changes ---------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [LLVM is compiled with PGO in published x86_64-unknown-linux-gnu artifacts.] [rust#88069] This improves the performance of most Rust builds. - [Unify representation of macros in internal data structures.][rust#88019] This change fixes a host of bugs with the handling of macros by the compiler, as well as rustdoc. [`std::os::unix::fs::chroot`]: https://doc.rust-lang.org/stable/std/os/unix/fs/fn.chroot.html [`Iterator::intersperse`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse [`Iterator::intersperse_with`]: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.intersperse [`UnsafeCell::raw_get`]: https://doc.rust-lang.org/stable/std/cell/struct.UnsafeCell.html#method.raw_get [`BufWriter::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.BufWriter.html#method.into_parts [`core::panic::{UnwindSafe, RefUnwindSafe, AssertUnwindSafe}`]: rust-lang/rust#84662 [`Vec::shrink_to`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.shrink_to [`String::shrink_to`]: https://doc.rust-lang.org/stable/std/string/struct.String.html#method.shrink_to [`OsString::shrink_to`]: https://doc.rust-lang.org/stable/std/ffi/struct.OsString.html#method.shrink_to [`PathBuf::shrink_to`]: https://doc.rust-lang.org/stable/std/path/struct.PathBuf.html#method.shrink_to [`BinaryHeap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.BinaryHeap.html#method.shrink_to [`VecDeque::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/struct.VecDeque.html#method.shrink_to [`HashMap::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_map/struct.HashMap.html#method.shrink_to [`HashSet::shrink_to`]: https://doc.rust-lang.org/stable/std/collections/hash_set/struct.HashSet.html#method.shrink_to [`std::mem::transmute`]: https://doc.rust-lang.org/stable/std/mem/fn.transmute.html [`slice::first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.first [`slice::split_first`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_first [`slice::last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.last [`slice::split_last`]: https://doc.rust-lang.org/stable/std/primitive.slice.html#method.split_last [`rust-version`]: https://doc.rust-lang.org/nightly/cargo/reference/manifest.html#the-rust-version-field [rust#87671]: rust-lang/rust#87671 [rust#86183]: rust-lang/rust#86183 [rust#87385]: rust-lang/rust#87385 [rust#88100]: rust-lang/rust#88100 [rust#86860]: rust-lang/rust#86860 [rust#84039]: rust-lang/rust#84039 [rust#86492]: rust-lang/rust#86492 [rust#88363]: rust-lang/rust#88363 [rust#85305]: rust-lang/rust#85305 [rust#87832]: rust-lang/rust#87832 [rust#88069]: rust-lang/rust#88069 [rust#87472]: rust-lang/rust#87472 [rust#87699]: rust-lang/rust#87699 [rust#87570]: rust-lang/rust#87570 [rust#88023]: rust-lang/rust#88023 [rust#87760]: rust-lang/rust#87760 [rust#87370]: rust-lang/rust#87370 [rust#87580]: rust-lang/rust#87580 [rust#83342]: rust-lang/rust#83342 [rust#83093]: rust-lang/rust#83093 [rust#88177]: rust-lang/rust#88177 [rust#88548]: rust-lang/rust#88548 [rust#88551]: rust-lang/rust#88551 [rust#88299]: rust-lang/rust#88299 [rust#88220]: rust-lang/rust#88220 [rust#85835]: rust-lang/rust#85835 [rust#86879]: rust-lang/rust#86879 [rust#86744]: rust-lang/rust#86744 [rust#84662]: rust-lang/rust#84662 [rust#86593]: rust-lang/rust#86593 [rust#81050]: rust-lang/rust#81050 [rust#81363]: rust-lang/rust#81363 [rust#84111]: rust-lang/rust#84111 [rust#85769]: rust-lang/rust#85769 (comment) [rust#88490]: rust-lang/rust#88490 [rust#88269]: rust-lang/rust#88269 [rust#84176]: rust-lang/rust#84176 [rust#88399]: rust-lang/rust#88399 [rust#88227]: rust-lang/rust#88227 [rust#88200]: rust-lang/rust#88200 [rust#82776]: rust-lang/rust#82776 [rust#88077]: rust-lang/rust#88077 [rust#87728]: rust-lang/rust#87728 [rust#87050]: rust-lang/rust#87050 [rust#87619]: rust-lang/rust#87619 [rust#81825]: rust-lang/rust#81825 (comment) [rust#88019]: rust-lang/rust#88019 [rust#87666]: rust-lang/rust#87666 Version 1.55.0 (2021-09-09) ============================ Language -------- - [You can now write open "from" range patterns (`X..`), which will start at `X` and will end at the maximum value of the integer.][83918] - [You can now explicitly import the prelude of different editions through `std::prelude` (e.g. `use std::prelude::rust_2021::*;`).][86294] Compiler -------- - [Added tier 3\* support for `powerpc64le-unknown-freebsd`.][83572] \* Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Updated std's float parsing to use the Eisel-Lemire algorithm.][86761] These improvements should in general provide faster string parsing of floats, no longer reject certain valid floating point values, and reduce the produced code size for non-stripped artifacts. - [`string::Drain` now implements `AsRef<str>` and `AsRef<[u8]>`.][86858] Stabilised APIs --------------- - [`Bound::cloned`] - [`Drain::as_str`] - [`IntoInnerError::into_error`] - [`IntoInnerError::into_parts`] - [`MaybeUninit::assume_init_mut`] - [`MaybeUninit::assume_init_ref`] - [`MaybeUninit::write`] - [`array::map`] - [`ops::ControlFlow`] - [`x86::_bittest`] - [`x86::_bittestandcomplement`] - [`x86::_bittestandreset`] - [`x86::_bittestandset`] - [`x86_64::_bittest64`] - [`x86_64::_bittestandcomplement64`] - [`x86_64::_bittestandreset64`] - [`x86_64::_bittestandset64`] The following previously stable functions are now `const`. - [`str::from_utf8_unchecked`] Cargo ----- - [Cargo will now deduplicate compiler diagnostics to the terminal when invoking rustc in parallel such as when using `cargo test`.][cargo/9675] - [The package definition in `cargo metadata` now includes the `"default_run"` field from the manifest.][cargo/9550] - [Added `cargo d` as an alias for `cargo doc`.][cargo/9680] - [Added `{lib}` as formatting option for `cargo tree` to print the `"lib_name"` of packages.][cargo/9663] Rustdoc ------- - [Added "Go to item on exact match" search option.][85876] - [The "Implementors" section on traits no longer shows redundant method definitions.][85970] - [Trait implementations are toggled open by default.][86260] This should make the implementations more searchable by tools like `CTRL+F` in your browser. - [Intra-doc links should now correctly resolve associated items (e.g. methods) through type aliases.][86334] - [Traits which are marked with `#[doc(hidden)]` will no longer appear in the "Trait Implementations" section.][86513] Compatibility Notes ------------------- - [std functions that return an `io::Error` will no longer use the `ErrorKind::Other` variant.][85746] This is to better reflect that these kinds of errors could be categorised [into newer more specific `ErrorKind` variants][79965], and that they do not represent a user error. - [Using environment variable names with `process::Command` on Windows now behaves as expected.][85270] Previously using envionment variables with `Command` would cause them to be ASCII-uppercased. - [Rustdoc will now warn on using rustdoc lints that aren't prefixed with `rustdoc::`][86849] [86849]: rust-lang/rust#86849 [86513]: rust-lang/rust#86513 [86334]: rust-lang/rust#86334 [86260]: rust-lang/rust#86260 [85970]: rust-lang/rust#85970 [85876]: rust-lang/rust#85876 [83572]: rust-lang/rust#83572 [86294]: rust-lang/rust#86294 [86858]: rust-lang/rust#86858 [86761]: rust-lang/rust#86761 [85769]: rust-lang/rust#85769 [85746]: rust-lang/rust#85746 [85305]: rust-lang/rust#85305 [85270]: rust-lang/rust#85270 [84111]: rust-lang/rust#84111 [83918]: rust-lang/rust#83918 [79965]: rust-lang/rust#79965 [87370]: rust-lang/rust#87370 [87298]: rust-lang/rust#87298 [cargo/9663]: rust-lang/cargo#9663 [cargo/9675]: rust-lang/cargo#9675 [cargo/9550]: rust-lang/cargo#9550 [cargo/9680]: rust-lang/cargo#9680 [cargo/9663]: rust-lang/cargo#9663 [`array::map`]: https://doc.rust-lang.org/stable/std/primitive.array.html#method.map [`Bound::cloned`]: https://doc.rust-lang.org/stable/std/ops/enum.Bound.html#method.cloned [`Drain::as_str`]: https://doc.rust-lang.org/stable/std/string/struct.Drain.html#method.as_str [`IntoInnerError::into_error`]: https://doc.rust-lang.org/stable/std/io/struct.IntoInnerError.html#method.into_error [`IntoInnerError::into_parts`]: https://doc.rust-lang.org/stable/std/io/struct.IntoInnerError.html#method.into_parts [`MaybeUninit::assume_init_mut`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_mut [`MaybeUninit::assume_init_ref`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.assume_init_ref [`MaybeUninit::write`]: https://doc.rust-lang.org/stable/std/mem/union.MaybeUninit.html#method.write [`Seek::rewind`]: https://doc.rust-lang.org/stable/std/io/trait.Seek.html#method.rewind [`ops::ControlFlow`]: https://doc.rust-lang.org/stable/std/ops/enum.ControlFlow.html [`str::from_utf8_unchecked`]: https://doc.rust-lang.org/stable/std/str/fn.from_utf8_unchecked.html [`x86::_bittest`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittest.html [`x86::_bittestandcomplement`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandcomplement.html [`x86::_bittestandreset`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandreset.html [`x86::_bittestandset`]: https://doc.rust-lang.org/stable/core/arch/x86/fn._bittestandset.html [`x86_64::_bittest64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittest64.html [`x86_64::_bittestandcomplement64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandcomplement64.html [`x86_64::_bittestandreset64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandreset64.html [`x86_64::_bittestandset64`]: https://doc.rust-lang.org/stable/core/arch/x86_64/fn._bittestandset64.html

Remove P: Unpin bound on impl Stream for Pin Similar to rust-lang#81363.

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jonhoo force-pushed the no-unpin-in-pin-future-impl branch from 50a6b11 to acb8348 Compare February 6, 2021 03:43

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camelid added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Mar 25, 2021

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Tracking Issue for pin_deref_mut #86918

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Rollup of 11 pull requests #87567

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Rollup of 10 pull requests #87569

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Amend RFC 2996 to replace Stream with AsyncIterator rust-lang/rfcs#3208

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Remove P: Unpin bound on impl Stream for Pin #92020

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Rollup merge of rust-lang#92020 - Folyd:stream-unpin, r=m-ou-se

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Remove P: Unpin bound on impl Stream for Pin Similar to rust-lang#81363.

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Rollup merge of rust-lang#92020 - Folyd:stream-unpin, r=m-ou-se

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Remove P: Unpin bound on impl Stream for Pin Similar to rust-lang#81363.

coolreader18 mentioned this pull request Nov 16, 2023

Implement Read/Write for Pin hyperium/hyper#3413

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Remove P: Unpin bound on impl Future for Pin #81363

Remove P: Unpin bound on impl Future for Pin #81363

jonhoo commented Jan 25, 2021 •

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Remove P: Unpin bound on impl Future for Pin #81363

Remove P: Unpin bound on impl Future for Pin #81363

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