Update CONTRIBUTING.md
Fixes#77215
As mentioned in #77215, the current CONTRIBUTING.md links to the rustc-dev-guide.
Even though the rustc-dev-guide has lots of useful information for contributors,
one is already confused by reading the first line of the current CONTRIBUTING.md.
> To get started, read the [Getting Started] guide in the [rustc-dev-guide].
This line tells the contributor to go and read the rustc-dev-guide. What is
the rustc-dev-guide? What does rustc even mean? These are some of the
questions that went into my head when reading this line as a first-time
contributor. By explaining what the rustc-dev-guide is and some platforms
to get help, a new contributor understands what the first step is and the process
is much clearer. The `About the [rustc-dev-guide]` section explains what
the rustc-dev-guide is, what rustc is, and the purpose out of reading the
guide. The `Getting help` section points the user to some places where
they can get help, find a mentor, and introduce themselves.
Update Cargo
Output of `git log --oneline c68432f1e..970bc67c3`:
970bc67c3 (HEAD, origin/master, origin/auto-cargo, origin/HEAD) Auto merge of #9243 - wickerwaka:configurable-env-doc, r=ehuss
4d7a29b75 Document the configurable-env usntable option
f7a7a3f91 Auto merge of #9229 - alexcrichton:fix-borrow-mut, r=ehuss
3f2ece7a9 Fix a `BorrowMut` error when stdout is closed
7441e8c23 Auto merge of #8825 - Aaron1011:feature/report-future-incompat, r=ehuss
139ed73f5 Add future-incompat tracking issue number.
9ea350368 Fix some minor formatting issues.
f03d47ce4 Address review comments
6177c6584 Implement future incompatibility report support
c69409658 Auto merge of #9022 - nagisa:nagisa/manifest_path, r=alexcrichton
548300b20 Add the path to the manifest in json output
99e714c05 Auto merge of #9230 - kornelski:nobinaries, r=alexcrichton
61a31bc5f Auto merge of #9236 - kornelski:track-assert, r=Eh2406
3f7f0942c track_caller on custom assert functions
6977dee10 Explain `cargo install` is not for libraries
e4aebf0a0 Auto merge of #9231 - joshtriplett:clear-to-eol-if-color, r=alexcrichton
b219f0eb7 Auto merge of #9181 - jyn514:computer-says-no, r=ehuss
0b1816578 Remove unhelpful link to Cargo book
ea46f5ce3 Use ANSI clear-to-EOL if color is force-enabled
a6394bcc1 Remove unnecessary `config` argument to `Features::add`
3a86ecf2d Fix TODO about nightly features
09677c83c Be less unix-centric in error messages
ecfdced0d Fix test that assumed tests always were run on the stable channel
eba541994 Update comment in build_script_env
a5720117f Make `nightly_features_allowed` a field instead of a function
169b09ce7 Compute `enable_nightly_features` once instead of on each call
8fc86e155 Remove unused thread_locals
4b096beae Fix `masquerade_as_nightly_cargo` in work threads
e56417c8c Suggest RUSTC_BOOTSTRAP=crate instead of RUSTC_BOOTSTRAP=1
418129dae Downgrade error to a warning when `RUSTC_BOOTSTRAP` is set or this is the nightly channel
6c422a2c0 Restrict RUSTC_BOOTSTRAP in build.rs
Change x64 size checks to not apply to x32.
Rust contains various size checks conditional on target_arch = "x86_64", but these checks were never intended to apply to x86_64-unknown-linux-gnux32. Add target_pointer_width = "64" to the conditions.
Bump libc dependency of std to 0.2.88.
This PR bumps the `libc` dependency of `std` to 0.2.88. This will fix `TcpListener::accept` for Android on x86 platforms (31a2777d8f).
This will really finally fix https://github.com/rust-lang/rust/issues/82400 for the main branch :)
r? ``@JohnTitor``
or-patterns: disallow in `let` bindings
~~Blocked on https://github.com/rust-lang/rust/pull/81869~~
Disallows top-level or-patterns before type ascription. We want to reserve this syntactic space for possible future generalized type ascription.
r? ``@petrochenkov``
Added #[repr(transparent)] to core::cmp::Reverse
I found casting from an `&T` to an `&Reverse<T>` potentially useful, but found that `Reverse` was not `#[repr(transparent)]`, so after asking about it [on Reddit](https://www.reddit.com/r/rust/comments/le60uv/make_stdcmpreverse_reprtransparent_and_add_a/), I decided to go ahead and make a pull request which simply adds the attribute to the struct.
Improve sift_down performance in BinaryHeap
Replacing `child < end - 1` with `child <= end.saturating_sub(2)` in `BinaryHeap::sift_down_range` (surprisingly) results in a significant speedup of `BinaryHeap::into_sorted_vec`. The same substitution can be done for `BinaryHeap::sift_down_to_bottom`, which causes a slight but probably statistically insignificant speedup for `BinaryHeap::pop`. It's interesting that benchmarks aside from `bench_into_sorted_vec` are barely affected, even those that do use `sift_down_*` methods internally.
| Benchmark | Before (ns/iter) | After (ns/iter) | Speedup |
|--------------------------|------------------|-----------------|---------|
| bench_find_smallest_1000<sup>1</sup> | 392,617 | 385,200 | 1.02 |
| bench_from_vec<sup>1</sup> | 506,016 | 504,444 | 1.00 |
| bench_into_sorted_vec<sup>1</sup> | 476,869 | 384,458 | 1.24 |
| bench_peek_mut_deref_mut<sup>3</sup> | 518,753 | 519,792 | 1.00 |
| bench_pop<sup>2</sup> | 446,718 | 444,409 | 1.01 |
| bench_push<sup>3</sup> | 772,481 | 770,208 | 1.00 |
<sup>1</sup>: internally calls `sift_down_range`
<sup>2</sup>: internally calls `sift_down_to_bottom`
<sup>3</sup>: should not be affected
rustdoc: Cleanup `html::render::Context`
- Move most shared fields to `SharedContext` (except for `cache`, which
isn't mutated anyway)
- Replace a use of `Arc` with `Rc`
- Make a bunch of fields private
- Add static size assertion for `Context`
- Don't share `id_map` and `deref_id_map`
Fixes#77215
As mentioned in #77215, the current CONTRIBUTING.md links to the rustc-dev-guide.
Even though the rustc-dev-guide has lots of useful information for contributors,
one is already confused by reading the first line of the current CONTRIBUTING.md.
> To get started, read the [Getting Started] guide in the [rustc-dev-guide].
This line tells the contributor to go and read the rustc-dev-guide. What is
the rustc-dev-guide? What does rustc even mean? These are some of the
questions that went into my head when reading this line as a first time
contributor. By explaining what the rustc-dev-guide is and some platforms
to get help, a new contributor understands what the first step is and the process
is much clearer. The `About the [rustc-dev-guide]` section explains what
the rustc-dev-guide is, what rustc is, and the purpose out of reading the
guide. The `Getting help` section points the user to some places where
they can get help, find a mentor, and introduce themsevles.
Revert switch of env locking to rwlock, to fix deadlock in process spawning
This reverts commit 354f19cf24, reversing changes made to 0cfba2fd09.
PR https://github.com/rust-lang/rust/pull/81850 switched the environment lock from a mutex to an rwlock. However, process spawning (when not able to use `posix_spawn`) locks the environment before forking, and unlocks it after forking (in both the parent and the child). With a mutex, this works (although probably not correct even with a mutex). With an rwlock, on at least some targets, unlocking in the child does not work correctly, resulting in a deadlock.
This has manifested as CI hangs on i686 Linux; that target doesn't use `posix_spawn` in the CI environment due to the age of the installed C library (currently glibc 2.23). (Switching to `posix_spawn` would just mask this issue, though, which would still arise in any case that can't use `posix_spawn`.)
Some additional cleanup of environment handling around process spawning may help, but for now, revert the PR and go back to a standard mutex.
Fixes#82221
diagnostics: Be clear about "crate root" and `::foo` paths in resolve diagnostics
Various changes to make sure the diagnostics are clear about the differences in `::foo` paths across editions:
- `::foo` will say "crate root" in 2015 and "list of imported crates" in 2018
- `crate::` will never reference imported crates in 2018
Fixes https://github.com/rust-lang/rust/issues/82876
Add note about the `#[doc(no-inline)]` usage
This is required to correctly build the documentation (including all submodules, that are only available in certain targets).
See the linked issue and #82861 for reference.
Update minifier dependency version
Very small PR simply upgrading the minifier-rs version we use in rustdoc.
Some details might be useful: there were a few bug fixes and a lot of cleanup/code improvements.
r? `@camelid`
Generalize Write impl for Vec<u8> to Vec<u8, A>
As discussed in the [issue tracker for the wg-allocators working group][1], updating this impl for allocator support was most likely just forgotten previously. This PR fixes this.
r? `````@TimDiekmann`````
[1]: https://github.com/rust-lang/wg-allocators/issues/86
Refactor confirm_builtin_call, remove partial if
Pass callee expr to `confirm_builtin_call`. This removes a partial
pattern match in `confirm_builtin_call` and the `panic` in the `else`
branch. The diff is large because of indentation changes caused by
removing the if-let.
Disable destination propagation on all mir-opt-levels
The new `// compile-flags: -Zunsound-mir-opts` are inserted without an extra newline to avoid introducing a large mir-opt diff.
Implement built-in attribute macro `#[cfg_eval]` + some refactoring
This PR implements a built-in attribute macro `#[cfg_eval]` as it was suggested in https://github.com/rust-lang/rust/pull/79078 to avoid `#[derive()]` without arguments being abused as a way to configure input for other attributes.
The macro is used for eagerly expanding all `#[cfg]` and `#[cfg_attr]` attributes in its input ("fully configuring" the input).
The effect is identical to effect of `#[derive(Foo, Bar)]` which also fully configures its input before passing it to macros `Foo` and `Bar`, but unlike `#[derive]` `#[cfg_eval]` can be applied to any syntax nodes supporting macro attributes, not only certain items.
`cfg_eval` was the first name suggested in https://github.com/rust-lang/rust/pull/79078, but other alternatives are also possible, e.g. `cfg_expand`.
```rust
#[cfg_eval]
#[my_attr] // Receives `struct S {}` as input, the field is configured away by `#[cfg_eval]`
struct S {
#[cfg(FALSE)]
field: u8,
}
```
Tracking issue: https://github.com/rust-lang/rust/issues/82679
Remove Item::kind, use tagged enum. Rename variants to match
Fixes#82299, by making the ItemEnum tagged. Doesn't remove ItemKind as it's still used in other places.
r? `````@jyn514`````
`````@rustbot````` label: +A-rustdoc-json +T-rustdoc
Add natvis for Result, NonNull, CString, CStr, and Cow
This adds natvis support (used for Windows debugging) to the following types: `Result`, `NonNull`, `CString`, `CStr`, and `Cow`.
expand: Refactor module loading
This is an accompanying PR to https://github.com/rust-lang/rust/pull/82399, but they can be landed independently.
See individual commits for more details.
Anyone should be able to review this equally well because all people actually familiar with this code left the project.
bypass auto_da_alloc for metadata files
This saves about 0.7% when rerunning the UI test suite. I.e. when the metadata files exist and will be overwritten. No improvements expected for a clean build. So it might show up in incr-patched perf results.
```
regular rename:
Benchmark #1: touch src/tools/compiletest/src/main.rs ; RUSTC_WRAPPER="" schedtool -B -e ./x.py test src/test/ui
Time (mean ± σ): 47.305 s ± 0.170 s [User: 1631.540 s, System: 412.648 s]
Range (min … max): 47.125 s … 47.856 s 20 runs
non-durable rename:
Benchmark #1: touch src/tools/compiletest/src/main.rs ; RUSTC_WRAPPER="" schedtool -B -e ./x.py test src/test/ui
Time (mean ± σ): 46.930 s ± 0.064 s [User: 1634.344 s, System: 396.038 s]
Range (min … max): 46.759 s … 47.043 s 20 runs
```
There are more places that trigger auto_da_alloc behavior by overwriting existing files with O_TRUNC, but those are much harder to locate because `O_TRUNC` is set on `open()` but the writeback is triggered on `close()`. The latter is the part which shows up in profiles.
Backport some LLVM compile-time improvements
Pick up two LLVM patches that reduce number of alias analysis queries, to see whether that gives any visible improvement.
r? `@ghost`
Let a portion of DefPathHash uniquely identify the DefPath's crate.
This allows to directly map from a `DefPathHash` to the crate it originates from, without constructing side tables to do that mapping -- something that is useful for incremental compilation where we deal with `DefPathHash` instead of `DefId` a lot.
It also allows to reliably and cheaply check for `DefPathHash` collisions which allows the compiler to gracefully abort compilation instead of running into a subsequent ICE at some random place in the code.
The following new piece of documentation describes the most interesting aspects of the changes:
```rust
/// A `DefPathHash` is a fixed-size representation of a `DefPath` that is
/// stable across crate and compilation session boundaries. It consists of two
/// separate 64-bit hashes. The first uniquely identifies the crate this
/// `DefPathHash` originates from (see [StableCrateId]), and the second
/// uniquely identifies the corresponding `DefPath` within that crate. Together
/// they form a unique identifier within an entire crate graph.
///
/// There is a very small chance of hash collisions, which would mean that two
/// different `DefPath`s map to the same `DefPathHash`. Proceeding compilation
/// with such a hash collision would very probably lead to an ICE and, in the
/// worst case, to a silent mis-compilation. The compiler therefore actively
/// and exhaustively checks for such hash collisions and aborts compilation if
/// it finds one.
///
/// `DefPathHash` uses 64-bit hashes for both the crate-id part and the
/// crate-internal part, even though it is likely that there are many more
/// `LocalDefId`s in a single crate than there are individual crates in a crate
/// graph. Since we use the same number of bits in both cases, the collision
/// probability for the crate-local part will be quite a bit higher (though
/// still very small).
///
/// This imbalance is not by accident: A hash collision in the
/// crate-local part of a `DefPathHash` will be detected and reported while
/// compiling the crate in question. Such a collision does not depend on
/// outside factors and can be easily fixed by the crate maintainer (e.g. by
/// renaming the item in question or by bumping the crate version in a harmless
/// way).
///
/// A collision between crate-id hashes on the other hand is harder to fix
/// because it depends on the set of crates in the entire crate graph of a
/// compilation session. Again, using the same crate with a different version
/// number would fix the issue with a high probability -- but that might be
/// easier said then done if the crates in questions are dependencies of
/// third-party crates.
///
/// That being said, given a high quality hash function, the collision
/// probabilities in question are very small. For example, for a big crate like
/// `rustc_middle` (with ~50000 `LocalDefId`s as of the time of writing) there
/// is a probability of roughly 1 in 14,750,000,000 of a crate-internal
/// collision occurring. For a big crate graph with 1000 crates in it, there is
/// a probability of 1 in 36,890,000,000,000 of a `StableCrateId` collision.
```
Given the probabilities involved I hope that no one will ever actually see the error messages. Nonetheless, I'd be glad about some feedback on how to improve them. Should we create a GH issue describing the problem and possible solutions to point to? Or a page in the rustc book?
r? `@pnkfelix` (feel free to re-assign)
Output of `git log --oneline c68432f1e..970bc67c3`:
970bc67c3 (HEAD, origin/master, origin/auto-cargo, origin/HEAD) Auto merge of #9243 - wickerwaka:configurable-env-doc, r=ehuss
4d7a29b75 Document the configurable-env usntable option
f7a7a3f91 Auto merge of #9229 - alexcrichton:fix-borrow-mut, r=ehuss
3f2ece7a9 Fix a `BorrowMut` error when stdout is closed
7441e8c23 Auto merge of #8825 - Aaron1011:feature/report-future-incompat, r=ehuss
139ed73f5 Add future-incompat tracking issue number.
9ea350368 Fix some minor formatting issues.
f03d47ce4 Address review comments
6177c6584 Implement future incompatibility report support
c69409658 Auto merge of #9022 - nagisa:nagisa/manifest_path, r=alexcrichton
548300b20 Add the path to the manifest in json output
99e714c05 Auto merge of #9230 - kornelski:nobinaries, r=alexcrichton
61a31bc5f Auto merge of #9236 - kornelski:track-assert, r=Eh2406
3f7f0942c track_caller on custom assert functions
6977dee10 Explain `cargo install` is not for libraries
e4aebf0a0 Auto merge of #9231 - joshtriplett:clear-to-eol-if-color, r=alexcrichton
b219f0eb7 Auto merge of #9181 - jyn514:computer-says-no, r=ehuss
0b1816578 Remove unhelpful link to Cargo book
ea46f5ce3 Use ANSI clear-to-EOL if color is force-enabled
a6394bcc1 Remove unnecessary `config` argument to `Features::add`
3a86ecf2d Fix TODO about nightly features
09677c83c Be less unix-centric in error messages
ecfdced0d Fix test that assumed tests always were run on the stable channel
eba541994 Update comment in build_script_env
a5720117f Make `nightly_features_allowed` a field instead of a function
169b09ce7 Compute `enable_nightly_features` once instead of on each call
8fc86e155 Remove unused thread_locals
4b096beae Fix `masquerade_as_nightly_cargo` in work threads
e56417c8c Suggest RUSTC_BOOTSTRAP=crate instead of RUSTC_BOOTSTRAP=1
418129dae Downgrade error to a warning when `RUSTC_BOOTSTRAP` is set or this is the nightly channel
6c422a2c0 Restrict RUSTC_BOOTSTRAP in build.rs
