Add new unstable feature `const_eq_ignore_ascii_case`
Tracking issue - #131719
Mark `[u8]`, `str` `eq_ignore_ascii_case` functions const
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The codegen for this implementation matches the existing `iter::zip` implementation better than incrementing with a counter
while loop with counter - https://rust.godbolt.org/z/h9cs5zajc
while let - https://rust.godbolt.org/z/ecMeMjjEb
make char::is_whitespace unstably const
I am adding this to the existing https://github.com/rust-lang/rust/issues/132241 feature gate, since `is_digit` and `is_whitespace` seem similar enough that one can group them together.
Rollup of 8 pull requests
Successful merges:
- #132259 (rustc_codegen_llvm: Add a new 'pc' option to branch-protection)
- #132409 (CI: switch 7 linux jobs to free runners)
- #132498 (Suggest fixing typos and let bindings at the same time)
- #132524 (chore(style): sync submodule exclusion list between tidy and rustfmt)
- #132567 (Properly suggest `E::assoc` when we encounter `E::Variant::assoc`)
- #132571 (add const_eval_select macro to reduce redundancy)
- #132637 (Do not filter empty lint passes & re-do CTFE pass)
- #132642 (Add documentation on `ast::Attribute`)
r? `@ghost`
`@rustbot` modify labels: rollup
add const_eval_select macro to reduce redundancy
I played around a bit with a macro to make const_eval_select invocations look a bit nicer and avoid repeating the argument lists. Here's what I got. What do you think?
I didn't apply this everywhere yet because I wanted to gather feedback first.
The second commit moves the macros from https://github.com/rust-lang/rust/pull/132542 into a more sensible place. It didn't seem worth its own PR and would conflict with this PR if done separately.
Cc ``@oli-obk`` ``@saethlin`` ``@tgross35``
try-job: dist-aarch64-msvc
[core/fmt] Replace checked slice indexing by unchecked to support panic-free code
Fixes#126425
Replace the potentially panicking `[]` indexing with `get_unchecked()` to prevent linking with panic-related code.
Stabilise `const_char_encode_utf16`.
Closes: #130660
This PR stabilises the `const_char_encode_utf16` feature gate (i.e. support for `char::encode_utf16` in constant expressions).
~~Note that the linked tracking issue is as of this writing currently awaiting FCP until 2024-11-02.~~
Improve example of `impl Pattern for &[char]`
The previous version used `['l', 'l']` as pattern, which would suggest that it matches the `ll` of `Hello world` as a whole.
remove const-support for align_offset and is_aligned
As part of the recent discussion to stabilize `ptr.is_null()` in const context, the general vibe was that it's okay for a const function to panic when the same operation would work at runtime (that's just a case of "dynamically detecting that something is not supported as a const operation"), but it is *not* okay for a const function to just return a different result.
Following that, `is_aligned` and `is_aligned_to` have their const status revoked in this PR, since they do return actively wrong results at const time. In the future we can consider having a new intrinsic or so that can check whether a pointer is "guaranteed to be aligned", but the current implementation based on `align_offset` does not have the behavior we want.
In fact `align_offset` itself behaves quite strangely in const, and that support needs a bunch of special hacks. That doesn't seem worth it. Instead, the users that can fall back to a different implementation should just use const_eval_select directly, and everything else should not be made const-callable. So this PR does exactly that, and entirely removes const support for align_offset.
Closes some tracking issues by removing the associated features:
Closes https://github.com/rust-lang/rust/issues/90962
Closes https://github.com/rust-lang/rust/issues/104203
Cc `@rust-lang/wg-const-eval` `@rust-lang/libs-api`
Yeet the `effects` feature, move it onto `const_trait_impl`
This PR merges the `effects` feature into the `const_trait_impl` feature. There's really no need to have two feature gates for one feature.
After this PR, if `const_trait_impl` **is** enabled:
* Users can use and define const traits
* `HostEffect` const conditions will be enforced on the HIR
* We re-check the predicates in MIR just to make sure that we don't "leak" anything during MIR lowering
And if `const_trait_impl` **is not** enabled:
* Users cannot use nor define const traits
* `HostEffect` const conditions are not enforced on the HIR
* We will raise a const validation error if we call a function that has any const conditions (i.e. const traits and functions with any `~const` in their where clasues)
This should be the last step for us to be able to enable const traits in the standard library. We still need to re-constify `Drop` and `Destruct` and stuff for const traits to be particularly *useful* for some cases, but this is a good step :D
r? fee1-dead
cc `@rust-lang/project-const-traits`
Operations like is_aligned would return actively wrong results at compile-time,
i.e. calling it on the same pointer at compiletime and runtime could yield
different results. That's no good.
Instead of having hacks to make align_offset kind-of work in const-eval, just
use const_eval_select in the few places where it makes sense, which also ensures
those places are all aware they need to make sure the fallback behavior is
consistent.
This change updates the documentation for `NonZero` integer types to
explicitly reference the underlying integer type each `NonZero` variant
wraps, instead of using a general "integer" term.
better test for const HashMap; remove const_hash leftovers
The existing `const_with_hasher` test is kind of silly since the HashMap it constructs can never contain any elements. So this adjusts the test to construct a usable HashMap, which is a bit non-trivial since the default hash builder cannot be built in `const`. `BuildHasherDefault::new()` helps but is unstable (https://github.com/rust-lang/rust/issues/123197), so we also have a test that does not involve that type.
The second commit removes the last remnants of https://github.com/rust-lang/rust/issues/104061, since they aren't actually useful -- without const traits, you can't do any hashing in `const`.
Cc ``@rust-lang/libs-api`` ``@rust-lang/wg-const-eval``
Closes#104061
Related to https://github.com/rust-lang/rust/issues/102575
Add LowerExp and UpperExp implementations to NonZero
Adds `LowerExp` and `UpperExp` trait implementations to `NonZero`, as discussed in rust-lang/libs-team#458.
I had to modify the macro to mark the new impls with a different rust version. Let me know if this is the right way to do it (first timer here!)
get rid of a whole bunch of unnecessary rustc_const_unstable attributes
In general, when a `const fn` is still unstable, it doesn't need a `#[rustc_const_unstable]` attribute. The only exception is functions that internally use things that can't be used in stable const fn yet.
So this gets rid of a whole bunch of `#[rustc_const_unstable]` in libcore.
library: fix some stability annotations
This PR updates some stability attributes to correctly reflect when some items actually got stabilized. Found while testing https://github.com/rust-lang/rust/pull/132481.
### `core::char` / `std::char`
In https://github.com/rust-lang/rust/pull/26192, the `core::char` module got "stabilized" for 1.2.0, but the `core` crate itself was still unstable until 1.6.0.
In https://github.com/rust-lang/rust/pull/49698, the `std::char` module was changed to a re-export of `core::char`, making `std::char` appear as "stable since 1.2.0", even though it was already stable in 1.0.0.
By marking `core::char` as stable since 1.0.0, the docs will show correct versions for both `core::char` (since 1.6.0) and `std::char` (since 1.0.0). This is also consistent with the stabilities of similar re-exported modules like `core::mem`/`std::mem` for example.
### `{core,std}::array` and `{core,std}::array::TryFromSliceError`
In https://github.com/rust-lang/rust/pull/58302, the `core::array::TryFromSliceError` type got stabilized for 1.34.0, together with `TryFrom`. At that point the `core::array` module was still unstable and a `std::array` re-export didn't exist, but `core::array::TryFromSliceError` could still be named due to https://github.com/rust-lang/rust/pull/95956 to existing yet.
Then, `core::array` got stabilized and `std::array` got added, first targeting 1.36.0 in https://github.com/rust-lang/rust/pull/60657, but then getting backported for 1.35.0 in https://github.com/rust-lang/rust/pull/60838.
This means that `core::array` and `std::array` actually got stabilized in 1.35.0 and `core::array::TryFromSliceError` was accessible through the unstable module in 1.34.0 -- mark them as such so that the docs display the correct versions.
feat(byte_sub_ptr): unstably add ptr::byte_sub_ptr
This is an API that naturally should exist as a combination of byte_offset_from and sub_ptr
both existing (they showed up at similar times so this union was never made). Adding these
is a logical (and perhaps final) precondition of stabilizing ptr_sub_ptr (https://github.com/rust-lang/rust/issues/95892).
Original PR by ``@Gankra`` (https://github.com/rust-lang/rust/pull/121919), I am just reviving it. The 2nd commit (with a small docs tweak) is by me.
make const_alloc_layout feature gate only about functions that are already stable
The const_alloc_layout feature gate has two kinds of functions: those that are stable, but not yet const-stable, and those that are fully unstable.
I think we should split that up. So this PR makes const_alloc_layout just about functions that are already stable but waiting for const-stability; all the other functions now have their constness guarded by the gate that also guards their regular stability.
Cc https://github.com/rust-lang/rust/issues/67521
remove some unnecessary rustc_allow_const_fn_unstable
These are either unstable functions that don't need the attribute, or the attribute refers to a feature that is already stable.
Cleanup attributes around unchecked shifts and unchecked negation in const
The underlying intrinsic is marked as "safe to expose on stable", so we shouldn't need any `rustc_allow_const_fn_unstable(unchecked_shifts)` anywhere. However, bootstrap rustc doesn't yet have the new const stability checks, so these changes only apply under `cfg(not(bootstrap))`.
This is an API that naturally should exist as a combination of byte_offset_from and sub_ptr
both existing (they showed up at similar times so this union was never made). Adding these
is a logical (and perhaps final) precondition of stabilizing ptr_sub_ptr (#95892).
