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2020-07-27mv std libs to library/mark-565/+0
2020-07-22Revert "std: Switch from libbacktrace to gimli"Mark Rousskov-4/+0
This reverts commit 13db3cc1e8d2fd4b8e7c74d91002274d7b62801b.
2020-07-20Fix duplicate maybe_uninit_extra attributeJethro Beekman-4/+1
2020-07-18Rollup merge of #70817 - yoshuawuyts:task-ready, r=dtolnayManish Goregaokar-0/+1
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 https://github.com/rust-lang/rust/issues/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)
2020-07-18Auto merge of #73441 - alexcrichton:backtrace-gimli, r=Mark-Simulacrumbors-0/+4
std: Switch from libbacktrace to gimli This commit is a proof-of-concept for switching the standard library's backtrace symbolication mechanism on most platforms from libbacktrace to gimli. The standard library's support for `RUST_BACKTRACE=1` requires in-process parsing of object files and DWARF debug information to interpret it and print the filename/line number of stack frames as part of a backtrace. Historically this support in the standard library has come from a library called "libbacktrace". The libbacktrace library seems to have been extracted from gcc at some point and is written in C. We've had a lot of issues with libbacktrace over time, unfortunately, though. The library does not appear to be actively maintained since we've had patches sit for months-to-years without comments. We have discovered a good number of soundness issues with the library itself, both when parsing valid DWARF as well as invalid DWARF. This is enough of an issue that the libs team has previously decided that we cannot feed untrusted inputs to libbacktrace. This also doesn't take into account the portability of libbacktrace which has been difficult to manage and maintain over time. While possible there are lots of exceptions and it's the main C dependency of the standard library right now. For years it's been the desire to switch over to a Rust-based solution for symbolicating backtraces. It's been assumed that we'll be using the Gimli family of crates for this purpose, which are targeted at safely and efficiently parsing DWARF debug information. I've been working recently to shore up the Gimli support in the `backtrace` crate. As of a few weeks ago the `backtrace` crate, by default, uses Gimli when loaded from crates.io. This transition has gone well enough that I figured it was time to start talking seriously about this change to the standard library. This commit is a preview of what's probably the best way to integrate the `backtrace` crate into the standard library with the Gimli feature turned on. While today it's used as a crates.io dependency, this commit switches the `backtrace` crate to a submodule of this repository which will need to be updated manually. This is not done lightly, but is thought to be the best solution. The primary reason for this is that the `backtrace` crate needs to do some pretty nontrivial filesystem interactions to locate debug information. Working without `std::fs` is not an option, and while it might be possible to do some sort of trait-based solution when prototyped it was found to be too unergonomic. Using a submodule allows the `backtrace` crate to build as a submodule of the `std` crate itself, enabling it to use `std::fs` and such. Otherwise this adds new dependencies to the standard library. This step requires extra attention because this means that these crates are now going to be included with all Rust programs by default. It's important to note, however, that we're already shipping libbacktrace with all Rust programs by default and it has a bunch of C code implementing all of this internally anyway, so we're basically already switching already-shipping functionality to Rust from C. * `object` - this crate is used to parse object file headers and contents. Very low-level support is used from this crate and almost all of it is disabled. Largely we're just using struct definitions as well as convenience methods internally to read bytes and such. * `addr2line` - this is the main meat of the implementation for symbolication. This crate depends on `gimli` for DWARF parsing and then provides interfaces needed by the `backtrace` crate to turn an address into a filename / line number. This crate is actually pretty small (fits in a single file almost!) and mirrors most of what `dwarf.c` does for libbacktrace. * `miniz_oxide` - the libbacktrace crate transparently handles compressed debug information which is compressed with zlib. This crate is used to decompress compressed debug sections. * `gimli` - not actually used directly, but a dependency of `addr2line`. * `adler32`- not used directly either, but a dependency of `miniz_oxide`. The goal of this change is to improve the safety of backtrace symbolication in the standard library, especially in the face of possibly malformed DWARF debug information. Even to this day we're still seeing segfaults in libbacktrace which could possibly become security vulnerabilities. This change should almost entirely eliminate this possibility whilc also paving the way forward to adding more features like split debug information. Some references for those interested are: * Original addition of libbacktrace - #12602 * OOM with libbacktrace - #24231 * Backtrace failure due to use of uninitialized value - #28447 * Possibility to feed untrusted data to libbacktrace - #21889 * Soundness fix for libbacktrace - #33729 * Crash in libbacktrace - #39468 * Support for macOS, never merged - ianlancetaylor/libbacktrace#2 * Performance issues with libbacktrace - #29293, #37477 * Update procedure is quite complicated due to how many patches we need to carry - #50955 * Libbacktrace doesn't work on MinGW with dynamic libs - #71060 * Segfault in libbacktrace on macOS - #71397 Switching to Rust will not make us immune to all of these issues. The crashes are expected to go away, but correctness and performance may still have bugs arise. The gimli and `backtrace` crates, however, are actively maintained unlike libbacktrace, so this should enable us to at least efficiently apply fixes as situations come up. --- I want to note that my purpose for creating a PR here is to start a conversation about this. I think that all the various pieces are in place that this is compelling enough that I think this transition should be talked about seriously. There are a number of items which still need to be addressed before actually merging this PR, however: * [ ] `gimli` needs to be published to crates.io * [ ] `addr2line` needs a publish * [ ] `miniz_oxide` needs a publish * [ ] Tests probably shouldn't recommend the `gimli` crate's traits for implementing * [ ] The `backtrace` crate's branch changes need to be merged to the master branch (https://github.com/rust-lang/backtrace-rs/pull/349) * [ ] The support for `libbacktrace` on some platforms needs to be audited to see if we should support more strategies in the gimli implementation - https://github.com/rust-lang/backtrace-rs/issues/325, https://github.com/rust-lang/backtrace-rs/issues/326, https://github.com/rust-lang/backtrace-rs/issues/350, https://github.com/rust-lang/backtrace-rs/issues/351 Most of the merging/publishing I'm not actively pushing on right now. It's a bit wonky for crates to support libstd so I'm holding off on pulling the trigger everywhere until there's a bit more discussion about how to go through with this. Namely https://github.com/rust-lang/backtrace-rs/pull/349 I'm going to hold off merging until we decide to go through with the submodule strategy. In any case this is a pretty major change, so I suspect that the compiler team is likely going to be interested in this. I don't mean to force changes by dumping a bunch of code by any means. Integration of external crates into the standard library is so difficult I wanted to have a proof-of-concept to review while talking about whether to do this at all (hence the PR), but I'm more than happy to follow any processes needed to merge this. I must admit though that I'm not entirely sure myself at this time what the process would be to decide to merge this, so I'm hoping others can help me figure that out!
2020-07-17Rollup merge of #72414 - KodrAus:feat/stdlazy, r=Mark-SimulacrumManish Goregaokar-0/+5
Add lazy initialization primitives to std Follow-up to #68198 Current RFC: https://github.com/rust-lang/rfcs/pull/2788 Rebased and fixed up a few of the dangling comments. Some notes carried over from the previous PR: - [ ] Naming. I'm ok to just roll with the `Sync` prefix like `SyncLazy` for now, but [have a personal preference for `Atomic`](https://github.com/rust-lang/rfcs/pull/2788#issuecomment-574466983) like `AtomicLazy`. - [x] [Poisoning](https://github.com/rust-lang/rfcs/pull/2788#discussion_r366725768). It seems like there's [some regret around poisoning in other `std::sync` types that we might want to just avoid upfront for `std::lazy`, especially if that would align with a future `std::mutex` that doesn't poison](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/parking_lot.3A.3AMutex.20in.20std/near/190331199). Personally, if we're adding these types to `std::lazy` instead of `std::sync`, I'd be on-board with not worrying about poisoning in `std::lazy`, and potentially deprecating `std::sync::Once` and `lazy_static` in favour of `std::lazy` down the track if it's possible, rather than attempting to replicate their behavior. cc @Amanieu @sfackler. - [ ] [Consider making`SyncOnceCell::get` blocking](https://github.com/matklad/once_cell/pull/92). There doesn't seem to be consensus in the linked PR on whether or not that's strictly better than the non-blocking variant. In general, none of these seem to be really blocking an initial unstable merge, so we could possibly kick off a FCP if y'all are happy? cc @matklad @pitdicker have I missed anything, or were there any other considerations that have come up since we last looked at this?
2020-07-18link once_cell feature to #74465Ashley Mannix-1/+1
2020-07-17std: Switch from libbacktrace to gimliAlex Crichton-0/+4
This commit is a proof-of-concept for switching the standard library's backtrace symbolication mechanism on most platforms from libbacktrace to gimli. The standard library's support for `RUST_BACKTRACE=1` requires in-process parsing of object files and DWARF debug information to interpret it and print the filename/line number of stack frames as part of a backtrace. Historically this support in the standard library has come from a library called "libbacktrace". The libbacktrace library seems to have been extracted from gcc at some point and is written in C. We've had a lot of issues with libbacktrace over time, unfortunately, though. The library does not appear to be actively maintained since we've had patches sit for months-to-years without comments. We have discovered a good number of soundness issues with the library itself, both when parsing valid DWARF as well as invalid DWARF. This is enough of an issue that the libs team has previously decided that we cannot feed untrusted inputs to libbacktrace. This also doesn't take into account the portability of libbacktrace which has been difficult to manage and maintain over time. While possible there are lots of exceptions and it's the main C dependency of the standard library right now. For years it's been the desire to switch over to a Rust-based solution for symbolicating backtraces. It's been assumed that we'll be using the Gimli family of crates for this purpose, which are targeted at safely and efficiently parsing DWARF debug information. I've been working recently to shore up the Gimli support in the `backtrace` crate. As of a few weeks ago the `backtrace` crate, by default, uses Gimli when loaded from crates.io. This transition has gone well enough that I figured it was time to start talking seriously about this change to the standard library. This commit is a preview of what's probably the best way to integrate the `backtrace` crate into the standard library with the Gimli feature turned on. While today it's used as a crates.io dependency, this commit switches the `backtrace` crate to a submodule of this repository which will need to be updated manually. This is not done lightly, but is thought to be the best solution. The primary reason for this is that the `backtrace` crate needs to do some pretty nontrivial filesystem interactions to locate debug information. Working without `std::fs` is not an option, and while it might be possible to do some sort of trait-based solution when prototyped it was found to be too unergonomic. Using a submodule allows the `backtrace` crate to build as a submodule of the `std` crate itself, enabling it to use `std::fs` and such. Otherwise this adds new dependencies to the standard library. This step requires extra attention because this means that these crates are now going to be included with all Rust programs by default. It's important to note, however, that we're already shipping libbacktrace with all Rust programs by default and it has a bunch of C code implementing all of this internally anyway, so we're basically already switching already-shipping functionality to Rust from C. * `object` - this crate is used to parse object file headers and contents. Very low-level support is used from this crate and almost all of it is disabled. Largely we're just using struct definitions as well as convenience methods internally to read bytes and such. * `addr2line` - this is the main meat of the implementation for symbolication. This crate depends on `gimli` for DWARF parsing and then provides interfaces needed by the `backtrace` crate to turn an address into a filename / line number. This crate is actually pretty small (fits in a single file almost!) and mirrors most of what `dwarf.c` does for libbacktrace. * `miniz_oxide` - the libbacktrace crate transparently handles compressed debug information which is compressed with zlib. This crate is used to decompress compressed debug sections. * `gimli` - not actually used directly, but a dependency of `addr2line`. * `adler32`- not used directly either, but a dependency of `miniz_oxide`. The goal of this change is to improve the safety of backtrace symbolication in the standard library, especially in the face of possibly malformed DWARF debug information. Even to this day we're still seeing segfaults in libbacktrace which could possibly become security vulnerabilities. This change should almost entirely eliminate this possibility whilc also paving the way forward to adding more features like split debug information. Some references for those interested are: * Original addition of libbacktrace - #12602 * OOM with libbacktrace - #24231 * Backtrace failure due to use of uninitialized value - #28447 * Possibility to feed untrusted data to libbacktrace - #21889 * Soundness fix for libbacktrace - #33729 * Crash in libbacktrace - #39468 * Support for macOS, never merged - ianlancetaylor/libbacktrace#2 * Performance issues with libbacktrace - #29293, #37477 * Update procedure is quite complicated due to how many patches we need to carry - #50955 * Libbacktrace doesn't work on MinGW with dynamic libs - #71060 * Segfault in libbacktrace on macOS - #71397 Switching to Rust will not make us immune to all of these issues. The crashes are expected to go away, but correctness and performance may still have bugs arise. The gimli and `backtrace` crates, however, are actively maintained unlike libbacktrace, so this should enable us to at least efficiently apply fixes as situations come up.
2020-07-17Auto merge of #74395 - Mark-Simulacrum:stage0-next, r=pietroalbinibors-1/+0
Bump version to 1.47 This also bumps to a more recent rustfmt version, just to keep us relatively up to date (though almost nothing has changed in rustfmt we use beyond bumps to the parser infra). No formatting changes as a result of this. r? @pietroalbini
2020-07-16Rollup merge of #74033 - ehuss:std-compile-all-platforms, r=Mark-SimulacrumManish Goregaokar-1/+8
Add build support for Cargo's build-std feature. This makes some changes to the standard library to make it easier to use with Cargo's build-std feature. The primary goal is to make it so that Cargo and its users do not need to know which crates to build and which features to use for every platform. Conditional cfgs are adjusted so that there is usually a fall-through for unsupported platforms. Additionally, there is a "restricted-std" feature to mark `std` as unstable when used with build-std on no_std platforms. There is no intent to stabilize this feature for the foreseeable future. This borrows some of the implementation for wasm which already does what this needs. More code sharing can be done with some other platforms (there is a lot of duplication with cloudabi, hermit, and sgx), but I figure that can be done in a future PR. There are some small changes to stable behavior in this PR: - `std::env::consts::ARCH` on asmjs now reports "wasm32", to match its actual architecture. - Some of the wasm error messages for unsupported features report a slightly different error message so that the code can be reused. There should otherwise not be any changes to how std is built for distribution via bootstrap. This does not yet support all platforms when used with build-std. - It doesn't work with 16-bit targets (hashbrown does not support that). - It does not work with JSON spec targets. - In particular, all target triple snooping will need to be replaced with appropriate target option checking. - Switching to gimli (#73441) will make cross-building *much* easier. - There are still a ton of issues on the Cargo side to resolve. A big one is panic strategy support. Future PRs are intended to address some of these issues.
2020-07-16apply bootstrap cfgsMark Rousskov-1/+0
2020-07-17integrate Lazy into std layoutAshley Mannix-4/+3
This commit refactors the initial implementation to fit into std and makes some other changes: - use MaybeUninit internally in SyncOnceCell - correctly impl Drop for lazy::Once - port Lazy::take from once_cell from: https://github.com/matklad/once_cell/pull/100 Co-Authored-By: Paul Dicker <pitdicker@users.noreply.github.com>
2020-07-17First cut of `std::lazy` moduleAleksey Kladov-0/+6
2020-07-16Revert "Remove spotlight usage"Manish Goregaokar-0/+1
This reverts commit 13c6d5819aae3c0de6a90e7f17ea967bf4487cbb.
2020-07-16Rollup merge of #74037 - JohnTitor:contributing-md, r=Mark-SimulacrumManish Goregaokar-2/+3
Update reference to CONTRIBUTING.md CONTRIBUTING.md has been migrated to the rustc-dev-guide but some still refer there. Update them with the appropriate links. Fixes #74253
2020-07-15Introduce restricted-std feature.Eric Huss-1/+8
2020-07-14Add core::ready! macroYoshua Wuyts-0/+1
2020-07-12Make use of slice::strip_prefix and slice patternLzu Tao-0/+1
2020-07-12Sorting feature attributes in stdLzu Tao-3/+3
2020-07-07Update reference to CONTRIBUTING.mdYuki Okushi-2/+3
2020-07-01Rollup merge of #73909 - eltonlaw:unsafe-libstd-fs-rs, r=sfacklerManish Goregaokar-0/+1
`#[deny(unsafe_op_in_unsafe_fn)]` in libstd/fs.rs The `libstd/fs.rs` part of https://github.com/rust-lang/rust/issues/73904 . Wraps the two calls to an unsafe fn `Initializer::nop()` in an `unsafe` block. Followed instructions in parent issue, ran `./x.py check src/libstd/` after adding the lint and two warnings were given. After adding these changes, those disappear.
2020-06-30Stabilize `#[track_caller]`.Adam Perry-1/+1
Does not yet make its constness stable, though. Use of `Location::caller` in const contexts is still gated by `#![feature(const_caller_location)]`.
2020-06-30enable unsafe_op_in_unsafe_fn lintElton Law-0/+1
2020-06-12add raw_ref macrosRalf Jung-0/+1
2020-05-31Rollup merge of #72683 - RalfJung:char-debug-check, r=Mark-SimulacrumRalf Jung-0/+1
from_u32_unchecked: check validity, and fix UB in Wtf8 Fixes https://github.com/rust-lang/rust/issues/72760
2020-05-30wtf8: use encode_utf8_rawRalf Jung-0/+1
2020-05-29Add Extend::{extend_one,extend_reserve}Josh Stone-0/+1
This adds new optional methods on `Extend`: `extend_one` add a single element to the collection, and `extend_reserve` pre-allocates space for the predicted number of incoming elements. These are used in `Iterator` for `partition` and `unzip` as they shuffle elements one-at-a-time into their respective collections.
2020-05-29Rollup merge of #72568 - golddranks:add_total_cmp_to_floats, r=sfacklerDylan DPC-0/+1
Implement total_cmp for f32, f64 # Overview * Implements method `total_cmp` on `f32` and `f64`. This method implements a float comparison that, unlike the standard `partial_cmp`, is total (defined on all values) in accordance to the IEEE 754 (rev 2008) §5.10 `totalOrder` predicate. * The method has an API similar to `cmp`: `pub fn total_cmp(&self, other: &Self) -> crate::cmp::Ordering { ... }`. * Implements tests. * Has documentation. # Justification for the API * Total ordering for `f32` and `f64` has been discussed many time before: * https://internals.rust-lang.org/t/pre-pre-rfc-range-restricting-wrappers-for-floating-point-types/6701 * https://github.com/rust-lang/rfcs/issues/1249 * https://github.com/rust-lang/rust/pull/53938 * https://github.com/rust-lang/rust/issues/5585 * The lack of total ordering leads to frequent complaints, especially from people new to Rust. * This is an ergonomics issue that needs to be addressed. * However, the default behaviour of implementing only `PartialOrd` is intentional, as relaxing it might lead to correctness issues. * Most earlier implementations and discussions have been focusing on a wrapper type that implements trait `Ord`. Such a wrapper type is, however not easy to add because of the large API surface added. * As a minimal step that hopefully proves uncontroversial, we can implement a stand-alone method `total_cmp` on floating point types. * I expect adding such methods should be uncontroversial because... * Similar methods on `f32` and `f64` would be warranted even in case stdlib would provide a wrapper type that implements `Ord` some day. * It implements functionality that is standardised. (IEEE 754, 2008 rev. §5.10 Note, that the 2019 revision relaxes the ordering. The way we do ordering in this method conforms to the stricter 2008 standard.) * With stdlib APIs such as `slice::sort_by` and `slice::binary_search_by` that allow users to provide a custom ordering criterion, providing additional helper methods is a minimal way of adding ordering functionality. * Not also does it allow easily using aforementioned APIs, it also provides an easy and well-tested primitive for the users and library authors to implement an `Ord`-implementing wrapper, if needed.
2020-05-25Add total_cmp to f32 and f64, plus testsPyry Kontio-0/+1
2020-05-22Add core::future::IntoFutureYoshua Wuyts-0/+3
This patch adds `core::future::IntoFuture`. However unlike earlier PRs this patch does not integrate it into the `async/.await` lowering. That integration should be done in a follow-up PR.
2020-04-26Add Read/Write::can_read/write_vectoredSteven Fackler-0/+1
When working with an arbitrary reader or writer, code that uses vectored operations may end up being slower than code that copies into a single buffer when the underlying reader or writer doesn't actually support vectored operations. These new methods allow you to ask the reader or witer up front if vectored operations are efficiently supported. Currently, you have to use some heuristics to guess by e.g. checking if the read or write only accessed the first buffer. Hyper is one concrete example of a library that has to do this dynamically: https://github.com/hyperium/hyper/blob/0eaf304644a396895a4ce1f0146e596640bb666a/src/proto/h1/io.rs#L582-L594
2020-04-25Bump bootstrap compilerMark Rousskov-4/+3
2020-04-20Auto merge of #71007 - Amanieu:deprecate_asm, r=Mark-Simulacrumbors-0/+1
Deprecate the asm! macro in favor of llvm_asm! Since we will be changing the syntax of `asm!` soon, deprecate it and encourage people to use `llvm_asm!` instead (which preserves the old syntax). This will avoid breakage when `asm!` is changed. RFC: https://github.com/rust-lang/rfcs/pull/2843
2020-04-16Dogfood or_patterns in the standard libraryJosh Stone-0/+1
2020-04-15Deprecate the asm! macroAmanieu d'Antras-0/+1
2020-04-05Remove labels in libstd/lib.rs macro importsYoshua Wuyts-14/+2
These labels were probably moved around when rustfmt was introduced.
2020-03-28Replace last mention of IRC with DiscordBenjamin Kästner-1/+3
Mozilla's IRC service was shut down in March 2020. The official instant messaging variant has been Discord for a while, and most of the links were already replaced by #61524. This was the last line that came up with `irc.mozilla.org` or any combination of "irc.*#[a-z]+" in a `git grep`: git grep -i -E "irc.*#[a-z]+" As there is only one other link directly to Rust's discord, I used the same Markdown link `[rust-discord]` as in `bootstrap/README.md` to stay consistent. This might come in handy if the chat platform changes at a later point again. As an aside: for those interested in the use of IRC, Mozilla's [wiki] still offers a lot of in-depth knowledge. [wiki]: https://wiki.mozilla.org/IRC
2020-03-26Rename asm! to llvm_asm!Amanieu d'Antras-23/+4
asm! is left as a wrapper around llvm_asm! to maintain compatibility.
2020-03-26introduce `negative_impls` feature gate and documentNiko Matsakis-0/+1
They used to be covered by `optin_builtin_traits` but negative impls are now applicable to all traits, not just auto traits. This also adds docs in the unstable book for the current state of auto traits.
2020-03-23Update src/libstd/lib.rsSaoirse Shipwreckt-1/+1
Co-Authored-By: Ashley Mannix <ashleymannix@live.com.au>
2020-03-23Add `wake_trait` feature directive to stdWithout Boats-0/+1
2020-03-23Add Wake trait for safe construction of Wakers.Without Boats-0/+5
Currently, constructing a waker requires calling the unsafe `Waker::from_raw` API. This API requires the user to manually construct a vtable for the waker themself - which is both cumbersome and very error prone. This API would provide an ergonomic, straightforward and guaranteed memory-safe way of constructing a waker. It has been our longstanding intention that the `Waker` type essentially function as an `Arc<dyn Wake>`, with a `Wake` trait as defined here. Two considerations prevented the original API from being shipped as simply an `Arc<dyn Wake>`: - We want to support futures on embedded systems, which may not have an allocator, and in optimized executors for which this API may not be best-suited. Therefore, we have always explicitly supported the maximally-flexible (but also memory-unsafe) `RawWaker` API, and `Waker` has always lived in libcore. - Because `Waker` lives in libcore and `Arc` lives in liballoc, it has not been feasible to provide a constructor for `Waker` from `Arc<dyn Wake>`. Therefore, the Wake trait was left out of the initial version of the task waker API. However, as Rust 1.41, it is possible under the more flexible orphan rules to implement `From<Arc<W>> for Waker where W: Wake` in liballoc. Therefore, we can now define this constructor even though `Waker` lives in libcore. This PR adds these APIs: - A `Wake` trait, which contains two methods - A required method `wake`, which is called by `Waker::wake` - A provided method `wake_by_ref`, which is called by `Waker::wake_by_ref` and which implementors can override if they can optimize this use case. - An implementation of `From<Arc<W>> for Waker where W: Wake + Send + Sync + 'static` - A similar implementation of `From<Arc<W>> for RawWaker`.
2020-03-17Rollup merge of #69870 - petrochenkov:cfgacc, r=matthewjasperMazdak Farrokhzad-0/+1
expand: Implement something similar to `#[cfg(accessible(path))]` cc https://github.com/rust-lang/rust/issues/64797 The feature is implemented as a `#[cfg_accessible(path)]` attribute macro rather than as `#[cfg(accessible(path))]` because it needs to wait until `path` becomes resolvable, and `cfg` cannot wait, but macros can wait. Later we can think about desugaring or not desugaring `#[cfg(accessible(path))]` into `#[cfg_accessible(path)]`. This implementation is also incomplete in the sense that it never returns "false" from `cfg_accessible(path)`, it requires some tweaks to resolve, which is not quite ready to answer queries like this during early resolution. However, the most important part of this PR is not `cfg_accessible` itself, but expansion infrastructure for retrying expansions. Before this PR we could say "we cannot resolve this macro path, let's try it later", with this PR we can say "we cannot expand this macro, let's try it later" as well. This is a pre-requisite for - turning `#[derive(...)]` into a regular attribute macro, - properly supporting eager expansion for macros that cannot yet be resolved like ``` fn main() { println!(not_available_yet!()); } macro_rules! make_available { () => { #[macro_export] macro_rules! not_available_yet { () => { "Hello world!" } }} } make_available!(); ```
2020-03-15Use min_specialization in libstd and libproc_macroMatthew Jasper-1/+2
2020-03-10Rollup merge of #69514 - GuillaumeGomez:remove-spotlight, r=kinnisonMazdak Farrokhzad-1/+0
Remove spotlight I had a few comments saying that this feature was at best misunderstood or not even used so I decided to organize a poll about on [twitter](https://twitter.com/imperioworld_/status/1232769353503956994). After 87 votes, the result is very clear: it's not useful. Considering the amount of code we have just to run it, I think it's definitely worth it to remove it. r? @kinnison cc @ollie27
2020-03-10builtin_macros: Add attribute macro `#[cfg_accessible(path)]`Vadim Petrochenkov-0/+1
2020-03-04Auto merge of #68952 - faern:stabilize-assoc-int-consts, r=dtolnaybors-1/+0
Stabilize assoc_int_consts associated int/float constants The next step in RFC https://github.com/rust-lang/rfcs/pull/2700 (tracking issue #68490). Stabilizing the associated constants that were added in #68325. * Stabilize all constants under the `assoc_int_consts` feature flag. * Update documentation on old constants to say they are soft-deprecated and the new ones should be preferred. * Update documentation examples to use new constants. * Remove `uint_macro` and use `int_macro` for all integer types since the macros were identical anyway. r? @LukasKalbertodt
2020-02-27Remove spotlight usageGuillaume Gomez-1/+0
2020-02-26Rollup merge of #67637 - Mark-Simulacrum:primitive-mod, r=dtolnayDylan DPC-1/+4
Add primitive module to libcore This re-exports the primitive types from libcore at `core::primitive` to allow macro authors to have a reliable location to use them from. Fixes #44865
2020-02-23Bump core::primitive to 1.43David Tolnay-1/+1