People keep making fun of this signature for being so gnarly.
Associated type bounds lend it a much simpler scribbling.
ChangeOutputType can also come along for the ride.
fix: build on haiku
## What does this PR do
The std is broken on haiku, this PR fixes it.
## To reproduce the issue
```sh
$ cargo +nightly --version
cargo 1.81.0-nightly (b1feb75d0 2024-06-07)
$ cargo new hello
$ cd hello
$ cargo +nightly check -Zbuild-std --target x86_64-unknown-haiku -q
error[E0433]: failed to resolve: use of undeclared crate or module `std`
--> ~/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/pal/unix/os.rs:468:13
|
468 | std::ptr::null_mut(),
| ^^^ use of undeclared crate or module `std`
|
help: consider importing one of these items
|
8 + use core::ptr;
|
8 + use crate::ptr;
|
help: if you import `ptr`, refer to it directly
|
468 - std::ptr::null_mut(),
468 + ptr::null_mut(),
|
error[E0433]: failed to resolve: use of undeclared crate or module `std`
--> ~/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/pal/unix/os.rs:470:13
|
470 | std::ptr::null_mut(),
| ^^^ use of undeclared crate or module `std`
|
help: consider importing one of these items
|
8 + use core::ptr;
```
Fix `NonZero` doctest inconsistencies
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`NonZero`'s doctests contain both `?` and `.unwrap()` with no obvious reason for the difference, so this changes all of them to `?`. Also removes an explicit `std::num::NonZero`.
Clarify that they always have the same alignment as u8/i8, (unlike other atomic types).
Clarify in from_ptr that alignment is never an issue because of this.
Rollup of 4 pull requests
Successful merges:
- #126172 (Weekly `cargo update`)
- #126176 (rustdoc-search: use lowercase, non-normalized name for type search)
- #126190 (Autolabel run-make tests, remind to update tracking issue)
- #126194 (Migrate more things to `WinError`)
r? `@ghost`
`@rustbot` modify labels: rollup
Add `FRAC_1_SQRT_2PI` constant to f16/f32/f64/f128
This adds the `FRAC_1_SQRT_2PI` to the `f16`, `f32`, `f64` and `f128` as [`1/√(2π)`](https://www.wolframalpha.com/input?i=1%2Fsqrt%282*pi%29). The rationale is that while `FRAC_1_SQRT_PI` already exists, [Gaussian calculations](https://en.wikipedia.org/wiki/Gaussian_function) for random normal distributions require a `1/(σ√(2π))` term, which could then be directly expressed e.g. as `f32::FRAC_1_SQRT_2PI / sigma`.
The actual value is approximately `1/√(2π) = 0.3989422804014326779399460599343818684758586311649346576659258296…`. Truncated/rounded forms were used for the individual types.
---
~~I did not any of the `#[unstable]` attributes since I am not aware of their implications.~~
**Edit:** I applied the stability attributes from the surrounding types according to what seemed most likely correct. I believe the `more_float_constants` feature marker is incorrectly applied, but I wasn't sure how to proceed.
std::unix::os current_exe implementation simplification for haiku.
_get_net_image_info is a bit overkill as it allows to get broader informations about the process.
std::unix::fs::get_mode implementation for illumos/solaris.
they both support the F_GETFL fctnl flag/O_ACCMODE mask to get the file descriptor access modes.
In general, the I/O interface of hermit-abi is more POSIX-like
interface. Consequently, platform abstraction layer for HermitOS
has slightly adjusted and some inaccuracies remove.
Size optimize int formatting
Let's use the new feature flag!
This uses a simpler algorithm to format integers.
It is slower, but also smaller.
It also saves having to import the 200 byte rodata lookup table.
In a test of mine this saves ~300 bytes total of a cortex-m binary that does integer formatting.
For a 16KB device, that's almost 2%.
Note though that for opt-level 3 the text size actually grows by 116 bytes.
Still a win in total. I'm not sure why the generated code is bigger than the more fancy algo. Maybe the smaller algo lends itself more to inlining and duplicating?
Prevent copy-paste errors from producing new starved-for-resources
threaded platforms by raising `DEFAULT_MIN_STACK_SIZE` from 4096 bytes
to at least 64KiB.
Two platforms "affected" by this have no actual threads:
- UEFI
- "unsupported"
Platforms that this actually affects:
- wasm32-wasi with "atomics" enabled
- wasm32-wasi-p1-threads
Two exceptions:
- SGX: a "secure code execution" platform, stays at 4096B
- TEEOS: also a "secure code execution" platform, stays at 8192B
I believe either of these may have sufficiently "interesting" semantics
around threads, or significant external library support. Either would
mean making any choices here for them is suspect.
Rollup of 9 pull requests
Successful merges:
- #124840 (resolve: mark it undetermined if single import is not has any bindings)
- #125622 (Winnow private method candidates instead of assuming any candidate of the right name will apply)
- #125648 (Remove unused(?) `~/rustsrc` folder from docker script)
- #125672 (Add more ABI test cases to miri (RFC 3391))
- #125800 (Fix `mut` static task queue in SGX target)
- #125871 (Orphanck[old solver]: Consider opaque types to never cover type parameters)
- #125893 (Handle all GVN binops in a single place.)
- #126008 (Port `tests/run-make-fulldeps/issue-19371` to ui-fulldeps)
- #126032 (Update description of the `IsTerminal` example)
r? `@ghost`
`@rustbot` modify labels: rollup
Fix `mut` static task queue in SGX target
[PR 125046](https://github.com/rust-lang/rust/pull/125046) prevents mutable references to statics with `#[linkage]`. Such a construct was used with the tests for the `x86_64-fortanix-unknown-sgx` target. This PR fixes this and cleans up code a bit in 5 steps. Each step passes CI:
- The `mut` static is removed, and `Task` explicitly implements `Send`
- Renaming of the `task_queue::lock` function
- Pass function for `Thread` as `Send` to `Thread::imp` and update when `Packet<'scope, T>` implements `Sync`
- Storing `Task::p` as a type that implements `Send`
- Letting the compiler auto implement `Send` for `Task`
cc: ``@jethrogb``
std::unix::fs::get_path: using fcntl codepath for netbsd instead.
on netbsd, procfs is not as central as on linux/solaris thus can be perfectly not mounted.
Thus using fcntl with F_GETPATH, the kernel deals with MAXPATHLEN internally too.
Use inline const blocks to create arrays of `MaybeUninit`.
This PR contains 2 changes enabled by the fact that [`inline_const` is now stable](https://github.com/rust-lang/rust/pull/104087), and was split out of #125082.
1. Use inline const instead of `unsafe` to construct arrays in `MaybeUninit` examples.
Rationale: Demonstrate good practice of avoiding `unsafe` code where it is not strictly necessary.
4. Use inline const instead of `unsafe` to implement `MaybeUninit::uninit_array()`.
This is arguably giving the compiler more work to do, in exchange for eliminating just one single internal unsafe block, so it's less certain that this is good on net.
r? `@Nilstrieb`
Add `size_of` and `size_of_val` and `align_of` and `align_of_val` to the prelude
(Note: need to update the PR to add `align_of` and `align_of_val`, and remove the second commit with the myriad changes to appease the lint.)
Many, many projects use `size_of` to get the size of a type. However,
it's also often equally easy to hardcode a size (e.g. `8` instead of
`size_of::<u64>()`). Minimizing friction in the use of `size_of` helps
ensure that people use it and make code more self-documenting.
The name `size_of` is unambiguous: the name alone, without any prefix or
path, is self-explanatory and unmistakeable for any other functionality.
Adding it to the prelude cannot produce any name conflicts, as any local
definition will silently shadow the one from the prelude. Thus, we don't
need to wait for a new edition prelude to add it.
Fix typo in the docs of `HashMap::raw_entry_mut`
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Ignore `vec_deque_alloc_error::test_shrink_to_unwind` test on non-unwind targets
https://github.com/rust-lang/rust/pull/123803 added this test which requires unwinding to succeed. This conditionally ignores the test on non-unwind targets (as is the case with other tests using `catch_unwind`).
Explain differences between `{Once,Lazy}{Cell,Lock}` types
The question of "which once-ish cell-ish type should I use?" has been raised multiple times, and is especially important now that we have stabilized the `LazyCell` and `LazyLock` types. The answer for the `Lazy*` types is that you would be better off using them if you want to use what is by far the most common pattern: initialize it with a single nullary function that you would call at every `get_or_init` site. For everything else there's the `Once*` types.
"For everything else" is a somewhat weak motivation, as it only describes by negation. While contrasting them is inevitable, I feel positive motivations are more understandable. For this, I now offer a distinct example that helps explain why `OnceLock` can be useful, despite `LazyLock` existing: you can do some cool stuff with it that `LazyLock` simply can't support due to its mere definition.
The pair of `std::sync::*Lock`s are usable inside a `static`, and can serve roles in async or multithreaded (or asynchronously multithreaded) programs that `*Cell`s cannot. Because of this, they received most of my attention.
Fixes#124696Fixes#125615
Add function `core::iter::chain`
The addition of `core::iter::zip` (#82917) set a precedent for adding plain functions for iterator adaptors. Adding `chain` makes it a little easier to `chain` two iterators.
```rust
for (x, y) in chain(xs, ys) {}
// vs.
for (x, y) in xs.into_iter().chain(ys) {}
```
There is prior art for the utility of this in [`itertools::chain`](https://docs.rs/itertools/latest/itertools/fn.chain.html).
Approved ACP https://github.com/rust-lang/libs-team/issues/154
The addition of `core::iter::zip` (#82917) set a precedent for adding
plain functions for iterator adaptors. Adding `chain` makes it a little
easier to `chain` two iterators.
```
for (x, y) in chain(xs, ys) {}
// vs.
for (x, y) in xs.into_iter().chain(ys) {}
```
Change pedantically incorrect OnceCell/OnceLock wording
While the semantic intent of a OnceCell/OnceLock is that it can only be written to once (upon init), the fact of the matter is that both these types offer a `take(&mut self) -> Option<T>` mechanism that, when successful, resets the cell to its initial state, thereby [technically allowing it to be written to again](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=415c023a6ae1ef35f371a2d3bb1aa735)
Despite the fact that this can only happen with a mutable reference (generally only used during the construction of the OnceCell/OnceLock), it would be incorrect to say that the type itself as a whole *categorically* prevents being initialized or written to more than once (since it is possible to imagine an identical type only without the `take()` method that actually fulfills that contract).
To clarify, change "that cannot be.." to "that nominally cannot.." and add a note to OnceCell about what can be done with an `&mut Self` reference.
```@rustbot``` label +A-rustdocs
Make TLS accessors closures that return pointers
The current TLS macros generate a function that returns an `Option<&'static T>`. This is both risky as we lie about lifetimes, and necessitates that those functions are `unsafe`. By returning a `*const T` instead, the accessor function do not have safety requirements any longer and can be made closures without hassle. This PR does exactly that!
For native TLS, the closure approach makes it trivial to select the right accessor function at compile-time, which could result in a slight speed-up (I have the hope that the accessors are now simple enough for the MIR-inliner to kick in).
on netbsd, procfs is not as central as on linux/solaris thus
can be perfectly not mounted.
Thus using fcntl with F_GETPATH, the kernel deals with MAXPATHLEN
internally too.
While slightly verbose, it helps explain "why bother with OnceLock?"
This is a point of confusion that has been raised multiple times
shortly before and after the stabilization of LazyLock.
This example is spiritually an example of LazyLock, as it computes a
variable at runtime but accepts no inputs into that process.
It is also slightly simpler and thus easier to understand.
Change it to an even-more concise version and move it to LazyLock.
The example now editorializes slightly more. This may be unnecessary,
but it can be educational for the reader.
The `mir!` macro has multiple parts:
- An optional return type annotation.
- A sequence of zero or more local declarations.
- A mandatory starting anonymous basic block, which is brace-delimited.
- A sequence of zero of more additional named basic blocks.
Some `mir!` invocations use braces with a "block" style, like so:
```
mir! {
let _unit: ();
{
let non_copy = S(42);
let ptr = std::ptr::addr_of_mut!(non_copy);
// Inside `callee`, the first argument and `*ptr` are basically
// aliasing places!
Call(_unit = callee(Move(*ptr), ptr), ReturnTo(after_call), UnwindContinue())
}
after_call = {
Return()
}
}
```
Some invocations use parens with a "block" style, like so:
```
mir!(
let x: [i32; 2];
let one: i32;
{
x = [42, 43];
one = 1;
x = [one, 2];
RET = Move(x);
Return()
}
)
```
And some invocations uses parens with a "tighter" style, like so:
```
mir!({
SetDiscriminant(*b, 0);
Return()
})
```
This last style is generally used for cases where just the mandatory
starting basic block is present. Its braces are placed next to the
parens.
This commit changes all `mir!` invocations to use braces with a "block"
style. Why?
- Consistency is good.
- The contents of the invocation is a block of code, so it's odd to use
parens. They are more normally used for function-like macros.
- Most importantly, the next commit will enable rustfmt for
`tests/mir-opt/`. rustfmt is more aggressive about formatting macros
that use parens than macros that use braces. Without this commit's
changes, rustfmt would break a couple of `mir!` macro invocations that
use braces within `tests/mir-opt` by inserting an extraneous comma.
E.g.:
```
mir!(type RET = (i32, bool);, { // extraneous comma after ';'
RET.0 = 1;
RET.1 = true;
Return()
})
```
Switching those `mir!` invocations to use braces avoids that problem,
resulting in this, which is nicer to read as well as being valid
syntax:
```
mir! {
type RET = (i32, bool);
{
RET.0 = 1;
RET.1 = true;
Return()
}
}
```
Implement feature `integer_sign_cast`
Tracking issue: https://github.com/rust-lang/rust/issues/125882
Since this is my first time making a library addition I wasn't sure where to place the new code relative to existing code. I decided to place it near the top where there are already some other basic bitwise manipulation functions. If there is an official guideline for the ordering of functions, please let me know.
Change f32::midpoint to upcast to f64
This has been verified by kani as a correct optimization
see: https://github.com/rust-lang/rust/issues/110840#issuecomment-1942587398
The new implementation is branchless and only differs in which NaN values are produced (if any are produced at all), which is fine to change. Aside from NaN handling, this implementation produces bitwise identical results to the original implementation.
Question: do we need a codegen test for this? I didn't add one, since the original PR #92048 didn't have any codegen tests.
std::pal::unix::thread fetching min stack size on netbsd.
PTHREAD_STACK_MIN is not defined however sysconf/_SC_THREAD_STACK_MIN returns it as it can vary from arch to another.
This has been verified by kani as a correct optimization
see: https://github.com/rust-lang/rust/issues/110840#issuecomment-1942587398
The new implementation is branchless, and only differs in which NaN
values are produced (if any are produced at all). Which is fine to change.
Aside from NaN handling, this implementation produces bitwise identical
results to the original implementation.
The new implementation is gated on targets that have a fast 64-bit
floating point implementation in hardware, and on WASM.
Unroll first iteration of checked_ilog loop
This follows the optimization of #115913. As shown in https://github.com/rust-lang/rust/pull/115913#issuecomment-2066788006, the performance was improved in all important cases, but some regressions were introduced for the benchmarks `u32_log_random_small`, `u8_log_random` and `u8_log_random_small`.
Basically, #115913 changed the implementation from one division per iteration to one multiplication per iteration plus one division. When there are zero iterations, this is a regression from zero divisions to one division.
This PR avoids this by avoiding the division if we need zero iterations by returning `Some(0)` early. It also reduces the number of multiplications by one in all other cases.
Apply `x clippy --fix` and `x fmt` on Rustc
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Just run `x clippy --fix` and `x fmt`, and remove some changes like `impl Default`.
Implement `needs_async_drop` in rustc and optimize async drop glue
This PR expands on #121801 and implements `Ty::needs_async_drop` which works almost exactly the same as `Ty::needs_drop`, which is needed for #123948.
Also made compiler's async drop code to look more like compiler's regular drop code, which enabled me to write an optimization where types which do not use `AsyncDrop` can simply forward async drop glue to `drop_in_place`. This made size of the async block from the [async_drop test](67980dd6fb/tests/ui/async-await/async-drop.rs) to decrease by 12%.
Make `std::env::{set_var, remove_var}` unsafe in edition 2024
Allow calling these functions without `unsafe` blocks in editions up until 2021, but don't trigger the `unused_unsafe` lint for `unsafe` blocks containing these functions.
Fixes#27970.
Fixes#90308.
CC #124866.
drop_in_place: weaken the claim of equivalence with drop(ptr.read())
The two are *not* semantically equivalent in all cases, so let's not be so definite about this.
Fixes https://github.com/rust-lang/rust/issues/112015
Add lang items for `AsyncFn*`, `Future`, `AsyncFnKindHelper`'s associated types
Adds lang items for `AsyncFnOnce::Output`, `AsyncFnOnce::CallOnceFuture`, `AsyncFnMut::CallRefFuture`, and uses them in the new solver. I'm mostly interested in doing this to help accelerate uplifting the new trait solver into a separate crate.
The old solver is kind of spaghetti, so I haven't moved that to use these lang items (i.e. it still uses `item_name`-based comparisons).
update: Also adds lang items for `Future::Output` and `AsyncFnKindHelper::Upvars`.
cc ``@lcnr``
Allow calling these functions without `unsafe` blocks in editions up
until 2021, but don't trigger the `unused_unsafe` lint for `unsafe`
blocks containing these functions.
Fixes#27970.
Fixes#90308.
CC #124866.
This is create symmetry between the already existing TAU constant (2pi)
and the newly-introduced FRAC_1_SQRT_2PI, keeping the more common
name while increasing visibility.
Make more of the test suite run on Mac Catalyst
Combined with https://github.com/rust-lang/rust/pull/125225, the only failing parts of the test suite are in `tests/rustdoc-js`, `tests/rustdoc-js-std` and `tests/debuginfo`. Tested with:
```console
./x test --target=aarch64-apple-ios-macabi library/std
./x test --target=aarch64-apple-ios-macabi --skip=tests/rustdoc-js --skip=tests/rustdoc-js-std --skip=tests/debuginfo tests
```
Will probably put up a PR later to enable _running_ on (not just compiling for) Mac Catalyst in CI, though not sure where exactly I should do so? `src/ci/github-actions/jobs.yml`?
Note that I've deliberately _not_ enabled stack overflow handlers on iOS/tvOS/watchOS/visionOS (see https://github.com/rust-lang/rust/issues/25872), but rather just skipped those tests, as it uses quite a few APIs that I'd be weary about getting rejected by the App Store (note that Swift doesn't do it on those platforms either).
r? ``@workingjubilee``
CC ``@thomcc``
``@rustbot`` label O-ios O-apple
rustfmt fixes
The `rmake.rs` entries in `rustfmt.toml` are causing major problems for `x fmt`. This PR removes them and does some minor related cleanups.
r? ``@GuillaumeGomez``
This adds the `only-apple`/`ignore-apple` compiletest directive, and
uses that basically everywhere instead of `only-macos`/`ignore-macos`.
Some of the updates in `run-make` are a bit redundant, as they use
`ignore-cross-compile` and won't run on iOS - but using Apple in these
is still more correct, so I've made that change anyhow.
It's reasonable to want to, but in the current implementation this
causes multiple problems.
- All the `rmake.rs` files are formatted every time even when they
haven't changed. This is because they get whitelisted unconditionally
in the `OverrideBuilder`, before the changed files get added.
- The way `OverrideBuilder` works, if any files gets whitelisted then no
unmentioned files will get traversed. This is surprising, and means
that the `rmake.rs` entries broke the use of explicit paths to `x
fmt`, and also broke `GITHUB_ACTIONS=true git check --fmt`.
The commit removes the `rmake.rs` entries, fixes the formatting of a
couple of files that were misformatted (not previously caught due to the
`GITHUB_ACTIONS` breakage), and bans `!`-prefixed entries in
`rustfmt.toml` because they cause all these problems.
update tracking issue for lazy_cell_consume
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Bump backtrace to 0.3.72
This removes a bunch of dead code, contains critical aarch64-windows fixes, some less-critical windows-in-general improvements, adds visionOS support (and probably improves support for a bunch of Apple platforms...), and harmonizes backtrace's dependencies with rustc/std's.
See https://github.com/rust-lang/backtrace-rs/compare/0.3.71...0.3.72
r? `@ghost`
Always use the general case char count with `optimize_for_size`
The faster algo is really expensive, over a kilobyte if the full algo is present in a binary.
With this PR the general case algo is picked always instead of only for small strings.
In a test of mine this change makes the total binary go from 3116 bytes to 2032 bytes in opt-level 3 and from 1652 bytes to 1428 bytes in opt-level z. I've seen it much worse in real application, so the savings (especially on 'z') will be higher in many cases.
This is the second pr of this kind after #125606
Less syscalls for the `copy_file_range` probe
If it's obvious from the actual syscall results themselves that the syscall is supported or unsupported, don't do an extra syscall with an invalid file descriptor.
CC #122052
Panic if `PathBuf::set_extension` would add a path separator
This is likely never intended and potentially a security vulnerability if it happens.
I'd guess that it's mostly literal strings that are passed to this function in practice, so I'm guessing this doesn't break anyone.
CC #125060
Fix `VecDeque::shrink_to` UB when `handle_alloc_error` unwinds.
Fixes#123369
For `VecDeque` it's relatively simple to restore the buffer into a consistent state so this PR does just that.
Note that with its current implementation, `shrink_to` may change the internal arrangement of elements in the buffer, so e.g. `[D, <uninit>, A, B, C]` will become `[<uninit>, A, B, C, D]` and `[<uninit>, <uninit>, A, B, C]` may become `[B, C, <uninit>, <uninit>, A]` if `shrink_to` unwinds. This shouldn't be an issue though as we don't make any guarantees about the stability of the internal buffer arrangement (and this case is impossible to hit on stable anyways).
This PR also includes a test with code adapted from #123369 which fails without the new `shrink_to` code. Does this suffice or do we maybe need more exhaustive tests like in #108475?
cc `@Amanieu`
`@rustbot` label +T-libs
Stabilize `LazyCell` and `LazyLock`
Closes#109736
This stabilizes the [`LazyLock`](https://doc.rust-lang.org/stable/std/sync/struct.LazyLock.html) and [`LazyCell`](https://doc.rust-lang.org/stable/std/cell/struct.LazyCell.html) types:
```rust
static HASHMAP: LazyLock<HashMap<i32, String>> = LazyLock::new(|| {
println!("initializing");
let mut m = HashMap::new();
m.insert(13, "Spica".to_string());
m.insert(74, "Hoyten".to_string());
m
});
let lazy: LazyCell<i32> = LazyCell::new(|| {
println!("initializing");
92
});
```
r? libs-api
Add assert_unsafe_precondition to unchecked_{add,sub,neg,mul,shl,shr} methods
(Old PR is haunted, opening a new one. See #117494 for previous discussion.)
This ensures that these preconditions are actually checked in debug mode, and hopefully should let people know if they messed up. I've also replaced the calls (I could find) in the code that use these intrinsics directly with those that use these methods, so that the asserts actually apply.
More discussions on people misusing these methods in the tracking issue: https://github.com/rust-lang/rust/issues/85122.
Add manual Sync impl for ReentrantLockGuard
Fixes: #125526
Tracking Issue: #121440
this impl is even shown in the summary in the tracking issue, but apparently was forgotten in the actual implementation
Bump bootstrap compiler to the latest beta compiler
This PR updates the bootstrap compiler, aka stage0 to the latest beta version, since it contains rust-lang/cargo#13925.
It removes those unconditional Cargo warnings:
```
warning: [...]/rust/library/core/Cargo.toml: unused manifest key: lints.rust.unexpected_cfgs.check-cfg
warning: [...]/rust/library/std/Cargo.toml: unused manifest key: lints.rust.unexpected_cfgs.check-cfg
warning: [...]/rust/library/alloc/Cargo.toml: unused manifest key: lints.rust.unexpected_cfgs.check-cfg
```
for all contributors/users of this repository (including CI).
I don't know if that's something we do, or if it's even advisable, feel free to close.
r? `@Mark-Simulacrum`
Rollup of 5 pull requests
Successful merges:
- #125455 (Make `clamp` inline)
- #125477 (Run rustfmt on files that need it.)
- #125481 (Fix the dead link in the bootstrap README)
- #125482 (Notify kobzol after changes to `opt-dist`)
- #125489 (Revert problematic opaque type change)
r? `@ghost`
`@rustbot` modify labels: rollup
While the semantic intent of a OnceCell/OnceLock is that it can only be written
to once (upon init), the fact of the matter is that both these types offer a
`take(&mut self) -> Option<T>` mechanism that, when successful, resets the cell
to its initial state, thereby technically allowing it to be written to again.
Despite the fact that this can only happen with a mutable reference (generally
only used during the construction of the OnceCell/OnceLock), it would be
incorrect to say that the type itself as a whole categorically prevents being
initialized or written to more than once (since it is possible to imagine an
identical type only without the `take()` method that actually fulfills that
contract).
To clarify, change "that cannot be.." to "that nominally cannot.." and add a
note to OnceCell about what can be done with an `&mut Self` reference.
Run rustfmt on files that need it.
Somehow these files aren't properly formatted. By default `x fmt` and `x tidy` only check files that have changed against master, so if an ill-formatted file somehow slips in it can stay that way as long as it doesn't get modified(?)
I found these when I ran `x fmt` explicitly on every `.rs` file in the repo, while working on
https://github.com/rust-lang/compiler-team/issues/750.
Make `clamp` inline
Context: rust-lang/rust-clippy#12826
This results in slightly more optimized assembly. (And most important, it's now less than lines than just manually clamping a value)
Simplify key-based thread locals
This PR simplifies key-based thread-locals by:
* unifying the macro expansion of `const` and non-`const` initializers
* reducing the amount of code in the expansion
* simply reallocating on recursive initialization instead of going through `LazyKeyInner`
* replacing `catch_unwind` with the shared `abort_on_dtor_unwind`
It does not change the initialization behaviour described in #110897.
Add a fast-path to `Debug` ASCII `&str`
Instead of going through the `EscapeDebug` machinery, we can just skip over ASCII chars that don’t need any escaping.
---
This is an alternative / a companion to https://github.com/rust-lang/rust/pull/121138.
The other PR is adding the fast path deep within `EscapeDebug`, whereas this skips as early as possible.
Validate the special layout restriction on `DynMetadata`
If you look at <https://stdrs.dev/nightly/x86_64-unknown-linux-gnu/std/ptr/struct.DynMetadata.html>, you'd think that `DynMetadata` is a struct with fields.
But it's actually not, because the lang item is special-cased in rustc_middle layout:
7601adcc76/compiler/rustc_middle/src/ty/layout.rs (L861-L864)
That explains the very confusing codegen ICEs I was getting in https://github.com/rust-lang/rust/pull/124251#issuecomment-2128543265
> Tried to extract_field 0 from primitive OperandRef(Immediate((ptr: %5 = load ptr, ptr %4, align 8, !nonnull !3, !align !5, !noundef !3)) @ TyAndLayout { ty: DynMetadata<dyn Callsite>, layout: Layout { size: Size(8 bytes), align: AbiAndPrefAlign { abi: Align(8 bytes), pref: Align(8 bytes) }, abi: Scalar(Initialized { value: Pointer(AddressSpace(0)), valid_range: 1..=18446744073709551615 }), fields: Primitive, largest_niche: Some(Niche { offset: Size(0 bytes), value: Pointer(AddressSpace(0)), valid_range: 1..=18446744073709551615 }), variants: Single { index: 0 }, max_repr_align: None, unadjusted_abi_align: Align(8 bytes) } })
because there was a `Field` projection despite the layout clearly saying it's [`Primitive`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_target/abi/enum.FieldsShape.html#variant.Primitive).
Thus this PR updates the MIR validator to check for such a projection, and changes `libcore` to not ever emit any projections into `DynMetadata`, just to transmute the whole thing when it wants a pointer.
Somehow these files aren't properly formatted. By default `x fmt` and `x
tidy` only check files that have changed against master, so if an
ill-formatted file somehow slips in it can stay that way as long as it
doesn't get modified(?)
I found these when I ran `x fmt` explicitly on every `.rs` file in the
repo, while working on
https://github.com/rust-lang/compiler-team/issues/750.
Rollup of 6 pull requests
Successful merges:
- #125263 (rust-lld: fallback to rustc's sysroot if there's no path to the linker in the target sysroot)
- #125345 (rustc_codegen_llvm: add support for writing summary bitcode)
- #125362 (Actually use TAIT instead of emulating it)
- #125412 (Don't suggest adding the unexpected cfgs to the build-script it-self)
- #125445 (Migrate `run-make/rustdoc-with-short-out-dir-option` to `rmake.rs`)
- #125452 (Cleanup check-cfg handling in core and std)
r? `@ghost`
`@rustbot` modify labels: rollup
Cleanup check-cfg handling in core and std
Follow-up to https://github.com/rust-lang/rust/pull/125296 where we:
- expect any feature cfg in std, due to `#[path]` imports
- move some check-cfg args inside the `build.rs` as per Cargo recommendation
- and replace the fake Cargo feature `"restricted-std"` by the custom cfg `restricted_std`
Fixes https://github.com/rust-lang/rust/pull/125296#issuecomment-2127009301
r? `@bjorn3` (maybe, feel free to re-roll)
Actually use TAIT instead of emulating it
`core`'s `impl_fn_for_zst` macro is just a hacky way of emulating TAIT. TAIT has become stable enough to be used [in other places](e8fbd99128/library/std/src/backtrace.rs (L431)) inside the standard library, so let's use it in `core` as well.
Rollup of 7 pull requests
Successful merges:
- #122382 (Detect unused structs which implement private traits)
- #124389 (Add a warning to proc_macro::Delimiter::None that rustc currently does not respect it.)
- #125224 (Migrate `run-make/issue-53964` to `rmake`)
- #125227 (Migrate `run-make/issue-30063` to `rmake`)
- #125336 (Add dedicated definition for intrinsics)
- #125401 (Migrate `run-make/rustdoc-scrape-examples-macros` to `rmake.rs`)
- #125454 (Improve the doc of query associated_item)
r? `@ghost`
`@rustbot` modify labels: rollup
Add a warning to proc_macro::Delimiter::None that rustc currently does not respect it.
It does not provide the behaviour it is indicated to provide when used in a proc_macro context.
This seems to be a bug, (https://github.com/rust-lang/rust/issues/67062), but it is a long standing one, and hard to discover.
This pull request adds a warning to inform users of this issue, with a link to the relevant issue, and a version number of the last known affected rustc version.
