Add u16::is_utf16_surrogate
Right now, there are methods in the standard library for encoding and decoding UTF-16, but at least for the moment, there aren't any methods specifically for `u16` to help work with UTF-16 data. Since the full logic already exists, this wouldn't really add any code, just expose what's already there.
This method in particular is useful for working with the data returned by Windows `OsStrExt::encode_wide`. Initially, I was planning to also offer a `TryFrom<u16> for char`, but decided against it for now. There is plenty of code in rustc that could be rewritten to use this method, but I only checked within the standard library to replace them.
I think that offering more UTF-16-related methods to u16 would be useful, but I think this one is a good start. For example, one useful method might be `u16::is_pattern_whitespace`, which would check if something is the Unicode `Pattern_Whitespace` category. We can get away with this because all of the `Pattern_Whitespace` characters are in the basic multilingual plane, and hence we don't need to check for surrogates.
add perf side effect docs to `Iterator::cloned()`
Now that #90209 has been closed, as the current state of affairs is neither here nor there, this at least adds a paragraph + example on what to expect performance-wise and how to deal with it to the .cloned() docs.
cc `@the8472`
Fold aarch64 feature +fp into +neon
Arm's FEAT_FP and Feat_AdvSIMD describe the same thing on AArch64:
The Neon unit, which handles both floating point and SIMD instructions.
Moreover, a configuration for AArch64 must include both or neither.
Arm says "entirely proprietary" toolchains may omit floating point:
https://developer.arm.com/documentation/102374/0101/Data-processing---floating-point
In the Programmer's Guide for Armv8-A, Arm says AArch64 can have
both FP and Neon or neither in custom implementations:
https://developer.arm.com/documentation/den0024/a/AArch64-Floating-point-and-NEON
In "Bare metal boot code for Armv8-A", enabling Neon and FP
is just disabling the same trap flag:
https://developer.arm.com/documentation/dai0527/a
In an unlikely future where "Neon and FP" become unrelated,
we can add "[+-]fp" as its own feature flag.
Until then, we can simplify programming with Rust on AArch64 by
folding both into "[+-]neon", which is valid as it supersets both.
"[+-]neon" is retained for niche uses such as firmware, kernels,
"I just hate floats", and so on.
I am... pretty sure no one is relying on this.
An argument could be made that, as we are not an "entirely proprietary" toolchain, we should not support AArch64 without floats at all. I think that's a bit excessive. However, I want to recognize the intent: programming for AArch64 should be simplified where possible. For x86-64, programmers regularly set up illegal feature configurations because it's hard to understand them, see https://github.com/rust-lang/rust/issues/89586. And per the above notes, plus the discussion in https://github.com/rust-lang/rust/issues/86941, there should be no real use cases for leaving these features split: the two should in fact always go together.
- Fixesrust-lang/rust#95002.
- Fixesrust-lang/rust#95064.
- Fixesrust-lang/rust#95122.
Instead of suggesting that the body always replace the last character on the
line, presuming it must be a semicolon, the parser should instead check what
the last character is, and append the body if it is anything else.
Fixes#83104
Arm's FEAT_FP and Feat_AdvSIMD describe the same thing on AArch64:
The Neon unit, which handles both floating point and SIMD instructions.
Moreover, a configuration for AArch64 must include both or neither.
Arm says "entirely proprietary" toolchains may omit floating point:
https://developer.arm.com/documentation/102374/0101/Data-processing---floating-point
In the Programmer's Guide for Armv8-A, Arm says AArch64 can have
both FP and Neon or neither in custom implementations:
https://developer.arm.com/documentation/den0024/a/AArch64-Floating-point-and-NEON
In "Bare metal boot code for Armv8-A", enabling Neon and FP
is just disabling the same trap flag:
https://developer.arm.com/documentation/dai0527/a
In an unlikely future where "Neon and FP" become unrelated,
we can add "[+-]fp" as its own feature flag.
Until then, we can simplify programming with Rust on AArch64 by
folding both into "[+-]neon", which is valid as it supersets both.
"[+-]neon" is retained for niche uses such as firmware, kernels,
"I just hate floats", and so on.
Introduce `TtParser`
These commits make a number of changes to declarative macro expansion, resulting in code that is shorter, simpler, and faster.
Best reviewed one commit at a time.
r? `@petrochenkov`
- The edition should be 2021 to avoid warnings.
- The `external_crate` feature was removed in commit 45bf1ed1a1
("rustc: Allow changing the default allocator").
Note that commit d620ae1070 ("Auto merge of #84266") removed
the old test, but the new one introduced passed the `--cfg` like
in the old one.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
As its name suggests, `TokenTreeOrTokenTreeSlice` is either a single
`TokenTree` or a slice of them. It has methods `len` and `get_tt` that
let it be treated much like an ordinary slice. The reason it isn't an
ordinary slice is that for `TokenTree::Delimited` the open and close
delimiters are represented implicitly, and when they are needed they are
constructed on the fly with `Delimited::{open,close}_tt`, rather than
being present in memory.
This commit changes `Delimited` so the open and close delimiters are
represented explicitly. As a result, `TokenTreeOrTokenTreeSlice` is no
longer needed and `MatcherPos` and `MatcherTtFrame` can just use an
ordinary slice. `TokenTree::{len,get_tt}` are also removed, because they
were only needed to support `TokenTreeOrTokenTreeSlice`.
The change makes the code shorter and a little bit faster on benchmarks
that use macro expansion heavily, partly because `MatcherPos` is a lot
smaller (less data to `memcpy`) and partly because ordinary slice
operations are faster than `TokenTreeOrTokenTreeSlice::{len,get_tt}`.
update Termination trait docs
this pr add some statement about intending to provide `Termination` trait only on standard library's runtime.
from #93448
r? `@Lokathor`
Suggest constraining param for unary ops when missing trait impl
This PR adds a suggestion of constraining param for unary ops `-` and `!` when the corresponding trait implementation
is missing.
Fixs #94543.
BTW, this is my first time to touch rustc, please correct me if I did anything wrong.
rename LocalState::Uninitialized to Unallocated
This is to avoid confusion with `Uninit` as in `ScalarMaybeUninit`, which is very different.
r? `@oli-obk`
Inline some parser functions
Some crates that do a lot of complex declarative macro expansion spend a lot of time parsing (and reparsing) tokens. These commits inline some functions for some minor speed wins.
r? `@ghost`
Preserve the Windows `GetLastError` error in `HandleOrInvalid`.
In the `TryFrom<HandleOrInvalid> for OwnedHandle` and
`TryFrom<HandleOrNull> for OwnedHandle` implemenations, `forget` the
owned handle on the error path, to avoid calling `CloseHandle` on an
invalid handle. It's harmless, except that it may overwrite the
thread's `GetLastError` error.
r? `@joshtriplett`
Disable almost certainly unsound early otherwise branch MIR opt
Originally thought this was just an MIR semantics issue, but it's not.
r? rust-lang/mir-opt
The call site within `Parser::bump` is hot.
Also add an inline annotation to `Parser::next_tok`. It was already
being inlined by the compiler; this just makes sure that continues.
