Fix ice for feature-gated `cfg` attributes applied to the crate
This PR fixes two fixes:
1. When a feature gated option of the `cfg` attribute is applied to the crate, an ICE would occur because features are not yet available at that stage. This is fixed by ignoring the feature gate at that point, the attribute will later be re-checked (this was already done) when the feature gate is available. Fixes https://github.com/rust-lang/rust/issues/143977
2. Errors and lints on the `cfg` attribute applied to the crate would be produced twice, because of the re-checking. This is fixed by not producing any errors and lints during the first run.
The added regression test checks both problems.
r? ``@jdonszelmann``
Implement unstable trait impl
This PR allows marking impls of stable trait with stable type as unstable.
## Approach
In std/core, an impl can be marked as unstable by annotating it with ``#[unstable_feature_bound(feat_name)]``. This will add a ``ClauseKind::Unstable_Feature(feat_name)`` to the list of predicates in ``predicates_of`` .
When an unstable impl's function is called, we will first iterate through all the goals in ``param_env`` to check if there is any ``ClauseKind::UnstableFeature(feat_name)`` in ``param_env``.
The existence of ``ClauseKind::Unstable_Feature(feat_name)`` in ``param_env`` means an``#[unstable_feature_bound(feat_name)]`` is present at the call site of the function, so we allow the check to succeed in this case.
If ``ClauseKind::UnstableFeature(feat_name)`` does not exist in ``param_env``, we will still allow the check to succeed for either of the cases below:
1. The feature is enabled through ``#[feature(feat_name)]`` outside of std / core.
2. We are in codegen because we may be monomorphizing a body from an upstream crate which had an unstable feature enabled that the downstream crate do not.
For the rest of the case, it will fail with ambiguity.
## Limitation
In this PR, we do not support:
1. using items that need ``#[unstable_feature_bound]`` within stable APIs
2. annotate main function with ``#[unstable_feature_bound]``
3. annotate ``#[unstable_feature_bound]`` on items other than free function and impl
## Acknowledgement
The design and mentoring are done by `@BoxyUwU`
setup typos check in CI
This allows to check typos in CI, currently for compiler only (to reduce commit size with fixes). With current setup, exclude list is quite short, so it worth trying?
Also includes commits with actual typo fixes.
MCP: https://github.com/rust-lang/compiler-team/issues/817
typos check currently turned for:
* ./compiler
* ./library
* ./src/bootstrap
* ./src/librustdoc
After merging, PRs which enables checks for other crates (tools) can be implemented too.
Found typos will **not break** other jobs immediately: (tests, building compiler for perf run). Job will be marked as red on completion in ~ 20 secs, so you will not forget to fix it whenever you want, before merging pr.
Check typos: `python x.py test tidy --extra-checks=spellcheck`
Apply typo fixes: `python x.py test tidy --extra-checks=spellcheck:fix` (in case if there only 1 suggestion of each typo)
Current fail in this pr is expected and shows how typo errors emitted. Commit with error will be removed after r+.
Attribute rework: a parser for single attributes without arguments
Part of rust-lang/rust#131229
r? `@jdonszelmann`
I think code (with comments) speaks for itself.
The only subtlety: now `#[cold]`, `#[no_mangle]`, & `#[track_caller]` do not get thrown away when malformed (i.e. have arguments). This doesn't matter too much (I think), because an error gets emitted either way, so the compilation will not finish.
Port `#[rustc_layout_scalar_valid_range_start/end]` to the new attrib…
Ports `rustc_layout_scalar_valid_range_start` and `rustc_layout_scalar_valid_range_end` to the new attribute parsing infrastructure for https://github.com/rust-lang/rust/issues/131229#issuecomment-2971353197
r? `@jdonszelmann`
