Remove bigint_helper_methods for *signed* types
This PR inspired by `@cuviper's` comment @ https://github.com/rust-lang/rust/issues/90541#issuecomment-967309808
These are working well for *unsigned* types, so keep those, but for the the *signed* ones there are a bunch of questions about what the semantics and API should be. For the main "helpers for big integer implementations" use, there's no need for the signed versions anyway. There are plenty of other methods which exist for unsigned types but not signed ones, like `next_power_of_two`, so this isn't unusual.
Fixes#90541
Tracking issue #85532
Rename WASI's `is_character_device` to `is_char_device`.
Rename WASI's `FileTypeExt::is_character_device` to
`FileTypeExt::is_char_device`, for consistency with the Unix
`FileTypeExt::is_char_device`.
Also, add a `FileTypeExt::is_socket` function, for consistency with the
Unix `FileTypeExt::is_socket` function.
r? `@alexcrichton`
MIRI says `reverse` is UB, so replace it with something LLVM can vectorize
For small types with padding, the current implementation is UB because it does integer operations on uninit values.
```
error: Undefined Behavior: using uninitialized data, but this operation requires initialized memory
--> /playground/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/mod.rs:836:5
|
836 | / uint_impl! { u32, u32, i32, 32, 4294967295, 8, "0x10000b3", "0xb301", "0x12345678",
837 | | "0x78563412", "0x1e6a2c48", "[0x78, 0x56, 0x34, 0x12]", "[0x12, 0x34, 0x56, 0x78]", "", "" }
| |________________________________________________________________________________________________^ using uninitialized data, but this operation requires initialized memory
|
= help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
= help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
= note: inside `core::num::<impl u32>::rotate_left` at /playground/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/uint_macros.rs:211:13
= note: inside `core::slice::<impl [Foo]>::reverse` at /playground/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/slice/mod.rs:701:58
```
<https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=340739f22ca5b457e1da6f361768edc6>
But LLVM has gotten smarter since I wrote the previous implementation in 2017, so this PR removes all the manual magic and just writes it in such a way that LLVM will vectorize. This code is much simpler and has very little `unsafe`, and is actually faster to boot!
If you're curious to see the codegen: <https://rust.godbolt.org/z/Pcn13Y9E3>
Before:
```
running 7 tests
test slice::reverse_simd_f64x4 ... bench: 17,940 ns/iter (+/- 481) = 58448 MB/s
test slice::reverse_u128 ... bench: 17,758 ns/iter (+/- 205) = 59048 MB/s
test slice::reverse_u16 ... bench: 158,234 ns/iter (+/- 6,876) = 6626 MB/s
test slice::reverse_u32 ... bench: 62,047 ns/iter (+/- 1,117) = 16899 MB/s
test slice::reverse_u64 ... bench: 31,582 ns/iter (+/- 552) = 33201 MB/s
test slice::reverse_u8 ... bench: 81,253 ns/iter (+/- 1,510) = 12905 MB/s
test slice::reverse_u8x3 ... bench: 270,615 ns/iter (+/- 11,463) = 3874 MB/s
```
After:
```
running 7 tests
test slice::reverse_simd_f64x4 ... bench: 17,731 ns/iter (+/- 306) = 59137 MB/s
test slice::reverse_u128 ... bench: 17,919 ns/iter (+/- 239) = 58517 MB/s
test slice::reverse_u16 ... bench: 43,160 ns/iter (+/- 607) = 24295 MB/s
test slice::reverse_u32 ... bench: 21,065 ns/iter (+/- 371) = 49778 MB/s
test slice::reverse_u64 ... bench: 21,118 ns/iter (+/- 482) = 49653 MB/s
test slice::reverse_u8 ... bench: 76,878 ns/iter (+/- 1,688) = 13639 MB/s
test slice::reverse_u8x3 ... bench: 264,723 ns/iter (+/- 5,544) = 3961 MB/s
```
Those are the existing benches, <14a2fd640e/library/alloc/benches/slice.rs (L322-L346)>
Optimize BinaryHeap::extend from Vec
This improves the performance of extending `BinaryHeap`s from vectors directly. Future work may involve extending this optimization to other, similar, cases where the length of the added elements is well-known, but this is not yet done in this PR.
Stabilize `const_raw_ptr_deref` for `*const T`
This stabilizes dereferencing immutable raw pointers in const contexts.
It does not stabilize `*mut T` dereferencing. This is behind the
same feature gate as mutable references.
closes https://github.com/rust-lang/rust/issues/51911
Make RawVec private to alloc
RawVec was previously exposed for compiler-internal use (libarena specifically) in 1acbb0a935
Since it is unstable, doc-hidden and has no associated tracking issue it was never meant for public use. And since
it is no longer used outside alloc itself it can be made private again.
Also remove some functions that are dead due to lack of internal users.
proc_macro: Add an expand_expr method to TokenStream
This feature is aimed at giving proc macros access to powers similar to those used by builtin macros such as `format_args!` or `concat!`. These macros are able to accept macros in place of string literal parameters, such as the format string, as they perform recursive macro expansion while being expanded.
This can be especially useful in many cases thanks to helper macros like `concat!`, `stringify!` and `include_str!` which are often used to construct string literals at compile-time in user code.
For now, this method only allows expanding macros which produce literals, although more expressions will be supported before the method is stabilized.
In earlier versions of this PR, this method exclusively returned `Literal`, and spans on returned literals were stripped of expansion context before being returned to be as conservative as possible about permission leakage. The method's naming has been generalized to eventually support arbitrary expressions, and the context stripping has been removed (https://github.com/rust-lang/rust/pull/87264#discussion_r674863279), which should allow for more general APIs like "format_args_implicits" (https://github.com/rust-lang/rust/issues/67984) to be supported as well.
## API Surface
```rust
impl TokenStream {
pub fn expand_expr(&self) -> Result<TokenStream, ExpandError>;
}
#[non_exhaustive]
pub struct ExpandError;
impl Debug for ExpandError { ... }
impl Display for ExpandError { ... }
impl Error for ExpandError {}
impl !Send for ExpandError {}
impl !Sync for ExpandError {}
```
Re-enable `copy[_nonoverlapping]()` debug-checks
This commit re-enables the debug checks for valid usages of the two functions `copy()` and `copy_nonoverlapping()`. Those checks were commented out in #79684 in order to make the functions const. All that's been left was a FIXME, that could not be resolved until there is was way to only do the checks at runtime.
Since #89247 there is such a way: `const_eval_select()`. This commit uses that new intrinsic in order to either do nothing (at compile time) or to do the old checks (at runtime).
The change itself is rather small: in order to make the checks usable with `const_eval_select`, they are moved into a local function (one for `copy` and one for `copy_nonoverlapping` to keep symmetry).
The change does not break referential transparency, as there is nothing you can do at compile time, which you cannot do on runtime without getting undefined behavior. The CTFE-engine won't allow missuses. The other way round is also fine.
I've refactored the code to use `#[cfg(debug_assertions)]` on the new items. If that is not desired, the second commit can be dropped.
I haven't added any checks, as I currently don't know, how to test this properly.
Closes#90012.
cc `@rust-lang/lang,` `@rust-lang/libs` and `@rust-lang/wg-const-eval` (as those teams are linked in the issue above).
pub use core::simd;
A portable abstraction over SIMD has been a major pursuit in recent years for several programming languages. In Rust, `std::arch` offers explicit SIMD acceleration via compiler intrinsics, but it does so at the cost of having to individually maintain each and every single such API, and is almost completely `unsafe` to use. `core::simd` offers safe abstractions that are resolved to the appropriate SIMD instructions by LLVM during compilation, including scalar instructions if that is all that is available.
`core::simd` is enabled by the `#![portable_simd]` nightly feature tracked in https://github.com/rust-lang/rust/issues/86656 and is introduced here by pulling in the https://github.com/rust-lang/portable-simd repository as a subtree. We built the repository out-of-tree to allow faster compilation and a stochastic test suite backed by the proptest crate to verify that different targets, features, and optimizations produce the same result, so that using this library does not introduce any surprises. As these tests are technically non-deterministic, and thus can introduce overly interesting Heisenbugs if included in the rustc CI, they are visible in the commit history of the subtree but do nothing here. Some tests **are** introduced via the documentation, but these use deterministic asserts.
There are multiple unsolved problems with the library at the current moment, including a want for better documentation, technical issues with LLVM scalarizing and lowering to libm, room for improvement for the APIs, and so far I have not added the necessary plumbing for allowing the more experimental or libm-dependent APIs to be used. However, I thought it would be prudent to open this for review in its current condition, as it is both usable and it is likely I am going to learn something else needs to be fixed when bors tries this out.
The major types are
- `core::simd::Simd<T, N>`
- `core::simd::Mask<T, N>`
There is also the `LaneCount` struct, which, together with the SimdElement and SupportedLaneCount traits, limit the implementation's maximum support to vectors we know will actually compile and provide supporting logic for bitmasks. I'm hoping to simplify at least some of these out of the way as the compiler and library evolve.
These are working well for *unsigned* types, for the the signed ones there are a bunch of questions about what the semantics and API should be. And for the main "helpers for big integer implementations" use, there's no need for the signed versions anyway.
And there are plenty of other methods which exist for unsigned types but not signed ones, like `next_power_of_two`, so this isn't unusual.
Fixes 90541
These tests just verify some basic APIs of core::simd function, and
guarantees that attempting to access the wrong things doesn't work.
The majority of tests are stochastic, and so remain upstream, but
a few deterministic tests arrive in the subtree as doc tests.
This enables programmers to use a safe alternative to the current
`extern "platform-intrinsics"` API for writing portable SIMD code.
This is `#![feature(portable_simd)]` as tracked in #86656
This makes a few changes to the weak symbol macros in `sys::unix`:
- `dlsym!` is added to keep the functionality for runtime `dlsym`
lookups, like for `__pthread_get_minstack@GLIBC_PRIVATE` that we don't
want to show up in ELF symbol tables.
- `weak!` now uses `#[linkage = "extern_weak"]` symbols, so its runtime
behavior is just a simple null check. This is also used by `syscall!`.
- On non-ELF targets (macos/ios) where that linkage is not known to
behave, `weak!` is just an alias to `dlsym!` for the old behavior.
- `raw_syscall!` is added to always call `libc::syscall` on linux and
android, for cases like `clone3` that have no known libc wrapper.
The new `weak!` linkage does mean that you'll get versioned symbols if
you build with a newer glibc, like `WEAK DEFAULT UND statx@GLIBC_2.28`.
This might seem problematic, but old non-weak symbols can tie the build
to new versions too, like `dlsym@GLIBC_2.34` from their recent library
unification. If you build with an old glibc like `dist-x86_64-linux`
does, you'll still get unversioned `WEAK DEFAULT UND statx`, which may
be resolved based on the runtime glibc.
I also found a few functions that don't need to be weak anymore:
- Android can directly use `ftruncate64`, `pread64`, and `pwrite64`, as
these were added in API 12, and our baseline is API 14.
- Linux can directly use `splice`, added way back in glibc 2.5 and
similarly old musl. Android only added it in API 21 though.
This feature is aimed at giving proc macros access to powers similar to
those used by builtin macros such as `format_args!` or `concat!`. These
macros are able to accept macros in place of string literal parameters,
such as the format string, as they perform recursive macro expansion
while being expanded.
This can be especially useful in many cases thanks to helper macros like
`concat!`, `stringify!` and `include_str!` which are often used to
construct string literals at compile-time in user code.
For now, this method only allows expanding macros which produce
literals, although more expresisons will be supported before the method
is stabilized.
Document `unreachable!` custom panic message
The `unreachable!` docs previously did not mention that there was a second form, `unreachable!("message")` that could be used to specify a custom panic message,
The docs now mention this feature in the same wording as currently used for `unimplemented!`:
https://doc.rust-lang.org/core/macro.unimplemented.html#panics
Rename WASI's `FileTypeExt::is_character_device` to
`FileTypeExt::is_char_device`, for consistency with the Unix
`FileTypeExt::is_char_device`.
Also, add a `FileTypeExt::is_socket` function, for consistency with the
Unix `FileTypeExt::is_socket` function.
For small types with padding, the current implementation is UB because it does integer operations on uninit values. But LLVM has gotten smarter since I wrote the previous implementation in 2017, so remove all the manual magic and just write it in such a way that LLVM will vectorize. This code is much simpler (albeit nuanced) and has very little `unsafe`, and is actually faster to boot!
As discussed here
https://github.com/rust-lang/rust/pull/88300#issuecomment-936097710
I felt this was the best place to put this (rather than next to
ExitStatusExt). After all, it's a property of the ExitStatus type on
Unix.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
As discussed here
https://github.com/rust-lang/rust/pull/88300#issuecomment-936085371
exit is (conventionally) a library function, with _exit being the
actual system call.
I have checked the other references and they say "if the process
terminated by calling `exti`". I think despite the slight
imprecision (strictly, it should read iff ... `_exit`), this is
clearer. Anyone who knows about the distinction between `exit` and
`_exit` will not be confused.
`_exit` is the correct traditional name for the system call, despite
Linux calling it `exit_group` or `exit`:
https://www.freebsd.org/cgi/man.cgi?query=_exit&sektion=2&n=1
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
The `unreachable!` docs previously did not mention that there was a second
form, `unreachable!("message")` that could be used to specify a custom panic
message,
The docs now mention this in the same style as currently used for `unimplemented!`:
https://doc.rust-lang.org/core/macro.unimplemented.html#panics
Fix assertion failures in `OwnedHandle` with `windows_subsystem`.
As discussed in #88576, raw handle values in Windows can be null, such
as in `windows_subsystem` mode, or when consoles are detached from a
process. So, don't use `NonNull` to hold them, don't assert that they're
not null, and remove `OwnedHandle`'s `repr(transparent)`. Introduce a
new `HandleOrNull` type, similar to `HandleOrInvalid`, to cover the FFI
use case.
r? `@joshtriplett`
Only use `clone3` when needed for pidfd
In #89522 we learned that `clone3` is interacting poorly with Gentoo's
`sandbox` tool. We only need that for the unstable pidfd extensions, so
otherwise avoid that and use a normal `fork`.
This is a re-application of beta #89924, now that we're aware that we need
more than just a temporary release fix. I also reverted 12fbabd27f, as
that was just fallout from using `clone3` instead of `fork`.
r? `@Mark-Simulacrum`
cc `@joshtriplett`
This commit tweaks the expansion of `thread_local!` when combined with a
`const { ... }` value to help ensure that the rules which apply to
`const { ... }` blocks will be the same as when they're stabilized.
Previously with this invocation:
thread_local!(static NAME: Type = const { init_expr });
this would generate (on supporting platforms):
#[thread_local]
static NAME: Type = init_expr;
instead the macro now expands to:
const INIT_EXPR: Type = init_expr;
#[thread_local]
static NAME: Type = INIT_EXPR;
with the hope that because `init_expr` is defined as a `const` item then
it's not accidentally allowing more behavior than if it were put into a
`static`. For example on the stabilization issue [this example][ex] now
gives the same error both ways.
[ex]: https://github.com/rust-lang/rust/issues/84223#issuecomment-953384298
* Add wasm64 variants for inline assembly along the same lines as wasm32
* Update a few directives in libtest to check for `target_family`
instead of `target_arch`
* Update some rustc codegen and typechecks specialized for wasm32 to
also work for wasm64.
This commit goes through and updates various `#[cfg]` as appropriate to
get the wasm64-unknown-unknown target behaving similarly to the
wasm32-unknown-unknown target. Most of this is just updating various
conditions for `target_arch = "wasm32"` to also account for `target_arch
= "wasm64"` where appropriate. This commit also lists `wasm64` as an
allow-listed architecture to not have the `restricted_std` feature
enabled, enabling experimentation with `-Z build-std` externally.
The main goal of this commit is to enable playing around with
`wasm64-unknown-unknown` externally via `-Z build-std` in a way that's
similar to the `wasm32-unknown-unknown` target. These targets are
effectively the same and only differ in their pointer size, but wasm64
is much newer and has much less ecosystem/library support so it'll still
take time to get wasm64 fully-fledged.
Because after PR 86041, the optimizer no longer load-merges at the LLVM IR level, which might be part of the perf loss. (I'll run perf and see if this makes a difference.)
Also I added a codegen test so this hopefully won't regress in future -- it passes on stable and with my change here, but not on the 2021-11-09 nightly.
Update books
## nomicon
1 commits in 358e6a61d5f4f0496d0a81e70cdcd25d05307342..c6b4bf831e9a40aec34f53067d20634839a6778b
2021-10-20 11:23:12 -0700 to 2021-11-09 02:30:56 +0900
- Replace some use of variant with covariant (rust-lang/nomicon#322)
## book
11 commits in fd9299792852c9a368cb236748781852f75cdac6..5c5dbc5b196c9564422b3193264f3288d2a051ce
2021-10-22 21:59:46 -0400 to 2021-11-09 19:30:43 -0500
- Fix constants link.
- Fix updated anchor
- Propagate edits to chapter 2 back
- Edits to nostarch's chapter 3 edits
- ch 3 from nostarch
- Fix Cargo.toml snippet about custom derive macros
- Snapshot of chapter 9 for nostarch
- Create tmp/src for converting quotes, not sure why this broke but ok
- Update question mark to better explain where it can be used
- Clarify sentence about Results in functions that don't return Result. Fixesrust-lang/book#2912.
- Merge pull request rust-lang/book#2913 from covariant/patch-1
## rust-by-example
2 commits in 27f1ff5e440ef78828b68ab882b98e1b10d9af32..e9d45342d7a6c1def4731f1782d87ea317ba30c3
2021-10-13 08:04:40 -0300 to 2021-11-02 13:33:03 -0500
- Enums: Linked-List Needs Re-Wording (rust-lang/rust-by-example#1469)
- fix: Use the point as top left corner for `square` (rust-lang/rust-by-example#1471)
## rustc-dev-guide
13 commits in b06008731af0f7d07cd0614e820c8276dfed1c18..196ef69aa68f2cef44f37566ee7db37daf00301b
2021-10-21 15:13:09 -0500 to 2021-11-07 07:48:47 -0600
- Fix typo: [upv.rs_mentioned] -> [upvars_mentioned]
- Add note to emphasize replacing TARGET_TRIPLE (rust-lang/rustc-dev-guide#1250)
- Remove some legacy test suites.
- tiny capitalization fix
- Fix date
- Update some date-check comments
- Ensure date-check cron job is using latest stable Rust
- enhance subtree docs, link to clippy docs
- Edit introduction to bootstrapping
- Some minor adjustments to the diagnostic documentation
- Edit "About this guide" for semantic line feeds
- Fix `rustc_mir` related links (rust-lang/rustc-dev-guide#1228)
- Add documentation for LLVM CFI support
## edition-guide
3 commits in 7c0088ca744d293a5f4b1e2ac378e7c23d30fe55..27f4a84d3852e9416cae5861254fa53a825c56bd
2021-10-05 13:28:05 +0200 to 2021-11-08 10:13:20 -0500
- Add a missing period (rust-lang/edition-guide#271)
- Fix syntax error in code example (rust-lang/edition-guide#270)
- Fixed an example error of prelude.md (rust-lang/edition-guide#269)
Rollup of 7 pull requests
Successful merges:
- #89561 (Type inference for inline consts)
- #90035 (implement rfc-2528 type_changing-struct-update)
- #90613 (Allow to run a specific rustdoc-js* test)
- #90683 (Make `compiler-docs` only control the default instead of being a hard off-switch)
- #90685 (x.py: remove fixme by deleting code)
- #90701 (Record more artifact sizes during self-profiling.)
- #90723 (Better document `Box` and `alloc::alloc::box_free` connection)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Hashing does not have to use the whole Components parsing machinery because we only need it to match the
normalizations that Components does.
* stripping redundant separators -> skipping separators
* stripping redundant '.' directories -> skipping '.' following after a separator
That's all it takes.
And instead of hashing individual slices for each component we feed the bytes directly into the hasher which avoids
hashing the length of each component in addition to its contents.
Better document `Box` and `alloc::alloc::box_free` connection
The internal `alloc::alloc::box_free` function requires that its signature matches the `owned_box` struct's declaration, but previously that connection was only documented on the `box_free` function.
This PR makes the documentation two-way to help anyone making theoretical changes to `Box` to see the connection, since changes are more likely to originate from `Box`.
This commit re-enables the debug checks for valid usages of the two
functions `copy()` and `copy_nonoverlapping()`. Those checks were com-
mented out in #79684 in order to make the functions const. All that's
been left was a FIXME, that could not be resolved until there is was way
to only do the checks at runtime.
Since #89247 there is such a way: `const_eval_select()`. This commit
uses that new intrinsic in order to either do nothing (at compile time)
or to do the old checks (at runtime).
The change itself is rather small: in order to make the checks usable
with `const_eval_select`, they are moved into a local function (one for
`copy` and one for `copy_nonoverlapping` to keep symmetry).
The change does not break referential transparency, as there is nothing
you can do at compile time, which you cannot do on runtime without get-
ting undefined behavior. The CTFE-engine won't allow missuses. The other
way round is also fine.
Make `std:🧵:available_concurrency` support process-limited number of CPUs
Use `libc::sched_getaffinity` and count the number of CPUs in the returned mask. This handles cases where the process doesn't have access to all CPUs, such as when limited via `taskset` or similar.
This also covers cgroup cpusets.
Add features gates for experimental asm features
This PR splits off parts of `asm!` into separate features because they are not ready for stabilization.
Specifically this adds:
- `asm_const` for `const` operands.
- `asm_sym` for `sym` operands.
- `asm_experimental_arch` for architectures other than x86, x86_64, arm, aarch64 and riscv.
r? `@nagisa`
This stabilizes dereferencing immutable raw pointers in const contexts.
It does not stabilize `*mut T` dereferencing. This is placed behind the
`const_raw_mut_ptr_deref` feature gate.
Append .0 to unsuffixed float if it would otherwise become int token
Previously the unsuffixed f32/f64 constructors of `proc_macro::Literal` would create literal tokens that are definitely not a float:
```rust
Literal::f32_unsuffixed(10.0) // 10
Literal::f32_suffixed(10.0) // 10f32
Literal::f64_unsuffixed(10.0) // 10
Literal::f64_suffixed(10.0) // 10f64
```
Notice that the `10` are actually integer tokens if you were to reparse them, not float tokens.
This diff updates `Literal::f32_unsuffixed` and `Literal::f64_unsuffixed` to produce tokens that unambiguously parse as a float. This matches longstanding behavior of the proc-macro2 crate's implementation of these APIs dating back at least 3.5 years, so it's likely an unobjectionable behavior.
```rust
Literal::f32_unsuffixed(10.0) // 10.0
Literal::f32_suffixed(10.0) // 10f32
Literal::f64_unsuffixed(10.0) // 10.0
Literal::f64_suffixed(10.0) // 10f64
```
Fixes https://github.com/dtolnay/syn/issues/1085.
In #89522 we learned that `clone3` is interacting poorly with Gentoo's
`sandbox` tool. We only need that for the unstable pidfd extensions, so
otherwise avoid that and use a normal `fork`.
Re-export some iterators from `core` in `std`
These iterators seem to have been forgotten to be re-exported from `std` (through `alloc`)
These are stable:
`core::slice::{SplitInclusive, SplitInclusiveMut}`
This one is still unstable:
`core::slice::EscapeAscii` (cc #77174)
Implement `RefUnwindSafe` for `Rc<T>`
This PR implements `RefUnwindSafe` for `Rc<T>`, where `T: RefUnwindSafe`.
This impl was omitted by an apparent oversight. `Rc<T>` already implements `UnwindSafe`. `Arc<T>` implements both `UnwindSafe` and `RefUnwindSafe`. There is no reason why an `&Rc<T>` is any less unwind safe than a `Rc<T>` or an `&Arc<T>`, so this should be safe to add.
Resolves#45924.
RawVec was previously exposed for compiler-internal use (libarena specifically) in 1acbb0a935
Since it is unstable, doc-hidden and has no associated tracking issue it was never meant for public use. And since
it is no longer used outside alloc itself it can be made private again.
Also remove some functions that are dead due to lack of internal users.
Replace `std::os::raw::c_ssize_t` with `std::os::raw::c_ptrdiff_t`
The discussions in #88345 brought up that `ssize_t` is not actually the signed index type defined in stddef.h, but instead it's `ptrdiff_t`. It seems pretty clear that the use of `ssize_t` here was a mistake on my part, and that if we're going to bother having a isize-alike for FFI in `std::os::raw`, it should be `ptrdiff_t` and not `ssize_t`.
Anyway, both this and `c_size_t` are dubious in the face of the discussion in https://internals.rust-lang.org/t/pre-rfc-usize-is-not-size-t/15369, and any RFC/project-group/etc that handles those issues there should contend with these types in some manner, but that doesn't mean we shouldn't fix something wrong like this, even if it is unstable.
All that said, `size_t` is *vastly* more common in function signatures than either `ssize_t` or `ptrdiff_t`, so I'm going to update the tracking issue's list of unresolved questions to note that perhaps we only want `c_size_t` — I mostly added the signed version for symmetry, rather than to meet a need. (Given this, I'm also fine with modifying this patch to instead remove `c_ssize_t` without a replacement)
CC `@magicant` (who brought the issue up)
CC `@chorman0773` (who has a significantly firmer grasp on the minutae of the C standard than I do)
r? `@joshtriplett` (original reviewer, active in the discussions around this)
Windows thread-local keyless drop
`#[thread_local]` allows us to maintain a per-thread list of destructors. This also avoids the need to synchronize global data (which is particularly tricky within the TLS callback function).
r? `@alexcrichton`
Add JoinHandle::is_running.
This adds:
```rust
impl<T> JoinHandle<T> {
/// Checks if the the associated thread is still running its main function.
///
/// This might return `false` for a brief moment after the thread's main
/// function has returned, but before the thread itself has stopped running.
pub fn is_running(&self) -> bool;
}
```
The usual way to check if a background thread is still running is to set some atomic flag at the end of its main function. We already do that, in the form of dropping an Arc which will reduce the reference counter. So we might as well expose that information.
This is useful in applications with a main loop (e.g. a game, gui, control system, ..) where you spawn some background task, and check every frame/iteration whether the background task is finished to .join() it in that frame/iteration while keeping the program responsive.
`#[thread_local]` allows us to maintain a per-thread list of destructors. This also avoids the need to synchronize global data (which is particularly tricky within the TLS callback function).
Add #[must_use] to remaining std functions (O-Z)
I've run out of compelling reasons to group functions together across crates so I'm just going to go module-by-module. This is half of the remaining items from the `std` crate, from O-Z.
`panicking::take_hook` has a side effect: it unregisters the current panic hook, returning it. I almost ignored it, but the documentation example shows `let _ = panic::take_hook();`, so following suit I went ahead and added a `#[must_use]`.
```rust
std::panicking fn take_hook() -> Box<dyn Fn(&PanicInfo<'_>) + 'static + Sync + Send>;
```
I added these functions that clippy did not flag:
```rust
std::path::Path fn starts_with<P: AsRef<Path>>(&self, base: P) -> bool;
std::path::Path fn ends_with<P: AsRef<Path>>(&self, child: P) -> bool;
std::path::Path fn with_file_name<S: AsRef<OsStr>>(&self, file_name: S) -> PathBuf;
std::path::Path fn with_extension<S: AsRef<OsStr>>(&self, extension: S) -> PathBuf;
```
Parent issue: #89692
r? `@joshtriplett`
Add #[must_use] to alloc functions that would leak memory
As [requested](https://github.com/rust-lang/rust/pull/89899#issuecomment-955600779) by `@joshtriplett.`
> Please do go ahead and add the ones whose only legitimate use for ignoring the return value is leaking memory. (In a separate PR please.) I think it's sufficiently error-prone to call something like alloc and ignore the result that it's legitimate to require `let _ =` for that.
I added `realloc` myself. Clippy ignored it because of its `mut` argument.
```rust
alloc/src/alloc.rs:123:1 alloc unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8;
```
Parent issue: #89692
r? `@joshtriplett`
Add #[must_use] to remaining core functions
I've run out of compelling reasons to group functions together across crates so I'm just going to go module-by-module. This is everything remaining from the `core` crate.
Ignored by clippy for reasons unknown:
```rust
core::alloc::Layout unsafe fn for_value_raw<T: ?Sized>(t: *const T) -> Self;
core::any const fn type_name_of_val<T: ?Sized>(_val: &T) -> &'static str;
```
Ignored by clippy because of `mut`:
```rust
str fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str);
```
<del>
Ignored by clippy presumably because a caller might want `f` called for side effects. That seems like a bad usage of `map` to me.
```rust
core::cell::Ref<'b, T> fn map<U: ?Sized, F>(orig: Ref<'b, T>, f: F) -> Ref<'b, T>;
core::cell::Ref<'b, T> fn map_split<U: ?Sized, V: ?Sized, F>(orig: Ref<'b, T>, f: F) -> (Ref<'b, U>, Ref<'b, V>);
```
</del>
Parent issue: #89692
r? ```@joshtriplett```
Add #[must_use] to mem/ptr functions
There's a lot of low-level / unsafe stuff here. Are there legit use cases for ignoring any of these return values?
* No regressions in `./x.py test --stage 1 library/std src/tools/clippy`.
* One regression in `./x.py test --stage 1 src/test/ui`. Fixed.
* I am unable to run `./x.py doc` on my machine so I'll need to wait for the CI to verify doctests pass. I eyeballed all the adjacent tests and they all look okay.
Parent issue: #89692
r? ```@joshtriplett```
Add #[must_use] to expensive computations
The unifying theme for this commit is weak, admittedly. I put together a list of "expensive" functions when I originally proposed this whole effort, but nobody's cared about that criterion. Still, it's a decent way to bite off a not-too-big chunk of work.
Given the grab bag nature of this commit, the messages I used vary quite a bit. I'm open to wording changes.
For some reason clippy flagged four `BTreeSet` methods but didn't say boo about equivalent ones on `HashSet`. I stared at them for a while but I can't figure out the difference so I added the `HashSet` ones in.
```rust
// Flagged by clippy.
alloc::collections::btree_set::BTreeSet<T> fn difference<'a>(&'a self, other: &'a BTreeSet<T>) -> Difference<'a, T>;
alloc::collections::btree_set::BTreeSet<T> fn symmetric_difference<'a>(&'a self, other: &'a BTreeSet<T>) -> SymmetricDifference<'a, T>
alloc::collections::btree_set::BTreeSet<T> fn intersection<'a>(&'a self, other: &'a BTreeSet<T>) -> Intersection<'a, T>;
alloc::collections::btree_set::BTreeSet<T> fn union<'a>(&'a self, other: &'a BTreeSet<T>) -> Union<'a, T>;
// Ignored by clippy, but not by me.
std::collections::HashSet<T, S> fn difference<'a>(&'a self, other: &'a HashSet<T, S>) -> Difference<'a, T, S>;
std::collections::HashSet<T, S> fn symmetric_difference<'a>(&'a self, other: &'a HashSet<T, S>) -> SymmetricDifference<'a, T, S>
std::collections::HashSet<T, S> fn intersection<'a>(&'a self, other: &'a HashSet<T, S>) -> Intersection<'a, T, S>;
std::collections::HashSet<T, S> fn union<'a>(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S>;
```
Parent issue: #89692
r? ```@joshtriplett```
Stabilize `is_symlink()` for `Metadata` and `Path`
I'm not fully sure about `since` version, correct me if I'm wrong
Needs update after stabilization: [cargo-test-support](8063672238/crates/cargo-test-support/src/paths.rs (L202))
Linked issue: #85748
track_caller for slice length assertions
`clone_from_slice` was missing `#[track_caller]`, and its assert did not report a useful location.
These are small generic methods, so hopefully track_caller gets inlined into nothingness, but it may be worth running a benchmark on this.
Use libc::sched_getaffinity and count the number of CPUs in the returned
mask. This handles cases where the process doesn't have access to all
CPUs, such as when limited via taskset or similar.
Repace use of `static_nobundle` with `native_link_modifiers` within Rust codebase
This fixes warnings when building Rust and running tests:
```
warning: library kind `static-nobundle` has been superseded by specifying `-bundle` on library kind `static`. Try `static:-bundle`
warning: `rustc_llvm` (lib) generated 2 warnings (1 duplicate)
```
Make `core::slice::from_raw_parts[_mut]` const
Responses to #90012 seem to allow ``@rust-lang/wg-const-eval`` to decide on use of `const_eval_select`, so we can make `core::slice::from_raw_parts[_mut]` const :)
---
This PR marks the following APIs as const:
```rust
// core::slice
pub const unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T];
pub const unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T];
```
---
Resolves#90011
r? ``@oli-obk``
Make most std::ops traits const on numeric types
This PR makes existing implementations of `std::ops` traits (`Add`, `Sub`, etc) [`impl const`](https://github.com/rust-lang/rust/issues/67792) where possible.
This affects:
- All numeric primitives (`u*`, `i*`, `f*`)
- `NonZero*`
- `Wrapping`
This is under the `rustc_const_unstable` feature `const_ops`.
I will write tests once I know what can and can't be kept for the final version of this PR.
Since this is my first PR to rustc (and hopefully one of many), please give me feedback on how to better handle the PR process wherever possible. Thanks
[Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Const.20std.3A.3Aops.20traits.20PR)
Automatically convert paths to verbatim for filesystem operations that support it
This allows using longer paths without the user needing to `canonicalize` or manually prefix paths. If the path is already verbatim then this has no effect.
Fixes: #32689
Replace some operators in libcore with their short-circuiting equivalents
In libcore there are a few occurrences of bitwise operators used in boolean expressions instead of their short-circuiting equivalents. This makes it harder to perform some kinds of source code analysis over libcore, for example [MC/DC] code coverage (a requirement in safety-critical environments).
This PR aims to remove as many bitwise operators in boolean expressions from libcore as possible, without any performance regression and without other changes. This means not all bitwise operators are removed, only the ones that don't have any difference with their short-circuiting counterparts. This already simplifies achieving MC/DC coverage, and the other functions can be changed in future PRs.
The PR is best reviewed commit-by-commit, and each commit has the resulting assembly in the message.
## Checked integer methods
These methods recently switched to bitwise operators in PRs https://github.com/rust-lang/rust/pull/89459 and https://github.com/rust-lang/rust/pull/89351. I confirmed bitwise operators are needed in most of the functions, except these two:
* `{integer}::checked_div` ([Godbolt link (nightly)](https://rust.godbolt.org/z/17efh5jPc))
* `{integer}::checked_rem` ([Godbolt link (nightly)](https://rust.godbolt.org/z/85qGWc94K))
`@tspiteri` already mentioned this was the case in https://github.com/rust-lang/rust/pull/89459#issuecomment-932728384, but opted to also switch those two to bitwise operators for consistency. As that makes MC/DC analysis harder this PR proposes switching those two back to short-circuiting operators.
## `{unsigned_ints}::carrying_add`
[Godbolt link (1.56.0)](https://rust.godbolt.org/z/vG9vx8x48)
In this instance replacing the `|` with `||` produces the exact same assembly when optimizations are enabled, so switching to the short-circuiting operator shouldn't have any impact.
## `{unsigned_ints}::borrowing_sub`
[Godbolt link (1.56.0)](https://rust.godbolt.org/z/asEfKaGE4)
In this instance replacing the `|` with `||` produces the exact same assembly when optimizations are enabled, so switching to the short-circuiting operator shouldn't have any impact.
## String UTF-8 validation
[Godbolt link (1.56.0)](https://rust.godbolt.org/z/a4rEbTvvx)
In this instance replacing the `|` with `||` produces practically the same assembly, with the two operands for the "or" swapped:
```asm
; Old
mov rax, qword ptr [rdi + rdx + 8]
or rax, qword ptr [rdi + rdx]
test rax, r9
je .LBB0_7
; New
mov rax, qword ptr [rdi + rdx]
or rax, qword ptr [rdi + rdx + 8]
test rax, r8
je .LBB0_7
```
[MC/DC]: https://en.wikipedia.org/wiki/Modified_condition/decision_coverage
Revert "Add rustc lint, warning when iterating over hashmaps"
Fixes perf regressions introduced in https://github.com/rust-lang/rust/pull/90235 by temporarily reverting the relevant PR.
Remove extra lines in examples for `Duration::try_from_secs_*`
None of the other examples have extra lines below the `#![feature(...)]` statements, so I thought it appropriate that these examples shouldn't either.
Rollup of 5 pull requests
Successful merges:
- #90239 (Consistent big O notation in map.rs)
- #90267 (fix: inner attribute followed by outer attribute causing ICE)
- #90288 (Add hint for people missing `TryFrom`, `TryInto`, `FromIterator` import pre-2021)
- #90304 (Add regression test for #75961)
- #90344 (Add tracking issue number to const_cstr_unchecked)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Add tracking issue number to const_cstr_unchecked
Also created a tracking issue, see #90343.
I think it makes sense to stabilize this somewhat soon considering abuse of `transmute` to have this feature in constants, see https://crates.io/crates/cstr for an example. Code can be rewritten to use `mem::transmute` to work on stable.
Clean up special function const checks
Mark them as const and `#[rustc_do_not_const_check]` instead of hard-coding them in const-eval checks.
r? `@oli-obk`
`@rustbot` label A-const-eval T-compiler
Using short-circuit operators makes it easier to perform some kinds of
source code analysis, like MC/DC code coverage (a requirement in
safety-critical environments). The optimized x86 assembly is the same
between the old and new versions:
```
xor eax, eax
test esi, esi
je .LBB0_1
cmp edi, -2147483648
jne .LBB0_4
cmp esi, -1
jne .LBB0_4
ret
.LBB0_1:
ret
.LBB0_4:
mov eax, edi
cdq
idiv esi
mov eax, 1
ret
```
Using short-circuit operators makes it easier to perform some kinds of
source code analysis, like MC/DC code coverage (a requirement in
safety-critical environments). The optimized x86 assembly is the same
between the old and new versions:
```
xor eax, eax
test esi, esi
je .LBB0_1
cmp edi, -2147483648
jne .LBB0_4
cmp esi, -1
jne .LBB0_4
ret
.LBB0_1:
ret
.LBB0_4:
mov eax, edi
cdq
idiv esi
mov edx, eax
mov eax, 1
ret
```
Using short-circuiting operators makes it easier to perform some kinds
of source code analysis, like MC/DC code coverage (a requirement in
safety-critical environments). The optimized x86_64 assembly is
equivalent between the old and new versions.
Old assembly of that condition:
```
mov rax, qword ptr [rdi + rdx + 8]
or rax, qword ptr [rdi + rdx]
test rax, r9
je .LBB0_7
```
New assembly of that condition:
```
mov rax, qword ptr [rdi + rdx]
or rax, qword ptr [rdi + rdx + 8]
test rax, r8
je .LBB0_7
```
Using short-circuiting operators makes it easier to perform some kinds
of source code analysis, like MC/DC code coverage (a requirement in
safety-critical environments). The optimized x86_64 assembly is the same
between the old and new versions:
```
mov eax, edi
add dl, -1
sbb eax, esi
setb dl
ret
```
Using short-circuiting operators makes it easier to perform some kinds
of source code analysis, like MC/DC code coverage (a requirement in
safety-critical environments). The optimized x86_64 assembly is the same
between the old and new versions:
```
mov eax, edi
add dl, -1
adc eax, esi
setb dl
ret
```
Remove fNN::lerp
Lerp is [surprisingly complex with multiple tradeoffs depending on what guarantees you want to provide](https://github.com/rust-lang/rust/issues/86269#issuecomment-869108301) (and what you're willing to drop for raw speed), so we don't have consensus on what implementation to use, let alone what signature - `t.lerp(a, b)` nicely puts `a, b` together, but makes dispatch to lerp custom types with the same signature basically impossible, and major ecosystem crates (e.g. nalgebra, glium) use `a.lerp(b, t)`, which is easily confusable. It was suggested to maybe provide a `Lerp<T>` trait and `t.lerp([a, b])`, which _could_ be implemented by downstream math libraries for their types, but also significantly raises the bar from a simple fNN method to a full trait, and does nothing to solve the implementation question. (It also raises the question of whether we'd support higher-order bezier interpolation.)
The only consensus we have is the lack of consensus, and the [general temperature](https://github.com/rust-lang/rust/issues/86269#issuecomment-951347135) is that we should just remove this method (giving the method space back to 3rd party libs) and revisit this if (and likely only if) IEEE adds lerp to their specification.
If people want a lerp, they're _probably_ already using (or writing) a math support library, which provides a lerp function for its custom math types and can provide the same lerp implementation for the primitive types via an extension trait.
See also [previous Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/lerp.20API.20design)
cc ``@clarfonthey`` (original PR author), ``@m-ou-se`` (original r+), ``@scottmcm`` (last voice in tracking issue, prompted me to post this)
Closes#86269 (removed)
Fix copy-paste error in String::as_mut_vec() docs
Did not expect the comments to be perfectly justified... can't wait to be told to change it to `Vec<u8>`, which destroys the justification 😼
Fix and extent ControlFlow `traverse_inorder` example
Fix and extent ControlFlow `traverse_inorder` example
1. The existing example compiles on its own, but any usage fails to be monomorphised and so doesn't compile. Fix that by using Fn trait instead of FnMut.
2. Added an example usage of `traverse_inorder` showing how we can terminate the traversal early.
Fixes#90063
1. The existing example compiles on its own, but any usage fails
to be monomorphised and so doesn't compile. Fix that by using
a mutable reference as an input argument.
2. Added an example usage of `traverse_inorder` showing how we
can terminate the traversal early.
Fixes#90063
This fixes warning when building Rust and running tests:
```
warning: library kind `static-nobundle` has been superseded by specifying `-bundle` on library kind `static`. Try `static:-bundle`
warning: `rustc_llvm` (lib) generated 2 warnings (1 duplicate)
```
Fix and extent ControlFlow `traverse_inorder` example
1. The existing example compiles on its own, but any usage fails to be monomorphised and so doesn't compile. Fix that by using Fn trait instead of FnMut.
2. Added an example usage of `traverse_inorder` showing how we can terminate the traversal early.
Fixes#90063
Make RSplit<T, P>: Clone not require T: Clone
This addresses a TODO comment. The behavior of `#[derive(Clone)]` *does* result in a `T: Clone` requirement. Playground example:
https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=a8b1a9581ff8893baf401d624a53d35b
Add a manual `Clone` implementation, mirroring `Split` and `SplitInclusive`.
`(R)?SplitN(Mut)?` don't have any `Clone` implementations, but I'll leave that for its own pull request.
Stabilise unix_process_wait_more, extra ExitStatusExt methods
This stabilises the feature `unix_process_wait_more`. Tracking issue #80695, FCP needed.
This was implemented in #79982 and merged in January.
Implement split_array and split_array_mut
This implements `[T]::split_array::<const N>() -> (&[T; N], &[T])` and `[T; N]::split_array::<const M>() -> (&[T; M], &[T])` and their mutable equivalents. These are another few “missing” array implementations now that const generics are a thing, similar to #74373, #75026, etc. Fixes#74674.
This implements `[T; N]::split_array` returning an array and a slice. Ultimately, this is probably not what we want, we would want the second return value to be an array of length N-M, which will likely be possible with future const generics enhancements. We need to implement the array method now though, to immediately shadow the slice method. This way, when the slice methods get stabilized, calling them on an array will not be automatic through coercion, so we won't have trouble stabilizing the array methods later (cf. into_iter debacle).
An unchecked version of `[T]::split_array` could also be added as in #76014. This would not be needed for `[T; N]::split_array` as that can be compile-time checked. Edit: actually, since split_at_unchecked is internal-only it could be changed to be split_array-only.
My change to use `Type::def_id()` (formerly `Type::def_id_full()`) in
more places caused some docs to show up that used to be missed by
rustdoc. Those docs contained unescaped square brackets, which triggered
linkcheck errors. This commit escapes the square brackets and adds this
particular instance to the linkcheck exception list.
