Make useless_ptr_null_checks smarter about some std functions
This teaches the `useless_ptr_null_checks` lint that some std functions can't ever return null pointers, because they need to point to valid data, get references as input, etc.
This is achieved by introducing an `#[rustc_never_returns_null_ptr]` attribute and adding it to these std functions (gated behind bootstrap `cfg_attr`).
Later on, the attribute could maybe be used to tell LLVM that the returned pointer is never null. I don't expect much impact of that though, as the functions are pretty shallow and usually the input data is already never null.
Follow-up of PR #113657Fixes#114442
Improve invalid let expression handling
- Move all of the checks for valid let expression positions to parsing.
- Add a field to ExprKind::Let in AST/HIR to mark whether it's in a valid location.
- Suppress some later errors and MIR construction for invalid let expressions.
- Fix a (drop) scope issue that was also responsible for #104172.
Fixes#104172Fixes#104868
Don't ICE when computing ctype's `repr_nullable_ptr` for possibly-unsized ty
We may not always be able to compute the layout of a type like `&T` when `T: ?Sized`, even if we're able to estimate its size skeleton.
r? davidtwco
Fixes#115628
There was an incomplete version of the check in parsing and a second
version in AST validation. This meant that some, but not all, invalid
uses were allowed inside macros/disabled cfgs. It also means that later
passes have a hard time knowing when the let expression is in a valid
location, sometimes causing ICEs.
- Add a field to ExprKind::Let in AST/HIR to mark whether it's in a
valid location.
- Suppress later errors and MIR construction for invalid let
expressions.
Call `LateLintPass::check_attribute` from `with_lint_attrs`
Fixes#115571
For regular `register_late_pass` lints also means that `last_node_with_lint_attrs` is correct when in `check_attribute`, I've added a test that previously failed for `clippy::allow_attributes`
As far as I can see the only late lint in rustc that uses `check_attribute` is `unstable_features` which is allow by default and deprecated so this is mostly for clippy (or future rustc lints)
The lint panicked for an input like 'extern "C" fn(Option<&<T as FooTrait>::FooType>)' because the type T therein cannot be normalized. The normalization failure caused SizeSkeleton::compute() to return an error and trigger a panic in the unwrap().
Lint on invalid usage of `UnsafeCell::raw_get` in reference casting
This PR proposes to take into account `UnsafeCell::raw_get` method call for non-Freeze types for the `invalid_reference_casting` lint.
The goal of this is to catch those kind of invalid reference casting:
```rust
fn as_mut<T>(x: &T) -> &mut T {
unsafe { &mut *std::cell::UnsafeCell::raw_get(x as *const _ as *const _) }
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
}
```
r? `@est31`
refactor(lint): translate `RenamedOrRemovedLint`
I was trying to address <https://github.com/rust-lang/cargo/issues/12495> and found that maybe I should refactor relevant lints a bit.
This PR translates `RenamedOrRemovedLint` into fluent file. To make diagnostic types clearer and easier to organize, this PR splits it into two structs.
The second commit adds lifetime annotations for removing unnecessary clones. If people feel too noisy, we can revert such change.
### Possibly relevant UI tests:
* `tests/ui/lint-removed*`
* `tests/ui/lint-renamed*`
* `tests/ui/rustdoc-renamed.rs`
* `tests/rustdoc-ui/lints/unknown-renamed-lints.rs`
Add support for `ptr::write`s for the `invalid_reference_casting` lint
This PR adds support for `ptr::write` and others for the `invalid_reference_casting` lint.
Detecting instances where instead of using the deref (`*`) operator to assign someone uses `ptr::write`, `ptr::write_unaligned` or `ptr::write_volatile`.
```rust
let data_len = 5u64;
std::ptr::write(
std::mem::transmute::<*const u64, *mut u64>(&data_len),
new_data_len,
);
```
r? ``@est31``
Warn on elided lifetimes in associated constants (`ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT`)
Elided lifetimes in associated constants (in impls) erroneously resolve to fresh lifetime parameters on the impl since #97313. This is not correct behavior (see #38831).
I originally opened #114716 to fix this, but given the time that has passed, the crater results seem pretty bad: https://github.com/rust-lang/rust/pull/114716#issuecomment-1682091952
This PR alternatively implements a lint against this behavior, and I'm hoping to bump this to deny in a few versions.
Also consider `mem::transmute` with the `invalid_reference_casting` lint
This PR extend the `invalid_reference_casting` lint with regard to the `std::mem::transmute` function.
```
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:27:16
|
LL | let _num = &mut *std::mem::transmute::<_, *mut i32>(&num);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
*I encourage anyone reviewing this PR to do so [without whitespaces](https://github.blog/2011-10-21-github-secrets/#whitespace).*
rustc: Move `features` from `Session` to `GlobalCtxt`
Removes one more piece of mutable state.
Follow up to #114622.
The rule I used for passing feature in function signatures:
- if a crate already depends on `rustc_middle`, then `Session` is replaced with `TyCtxt`
- otherwise session and features are passed as a pair `sess: &Session, features: &Features`
The code in `rustc_lint` is ultimately used for implementing a trait from `rustc_expand`, so it also doesn't use tcx despite the dependency on `rustc_middle`.
Avoid invalid NaN lint machine-applicable suggestion in const context
This PR removes the machine-applicable suggestion in const context for the `invalid_nan_comparision` lint ~~and replace it with a simple help~~.
Fixes https://github.com/rust-lang/rust/issues/114471
Convert builtin "global" late lints to run per module
The compiler currently has 4 non-incremental lints:
1. `clashing_extern_declarations`;
2. `missing_debug_implementations`;
3. ~`unnameable_test_items`;~ changed by https://github.com/rust-lang/rust/pull/114414
4. `missing_docs`.
Non-incremental lints get reexecuted for each compilation, which is slow. Moreover, those lints are allow-by-default, so run for nothing most of the time. This PR attempts to make them more incremental-friendly.
`clashing_extern_declarations` is moved to a standalone query.
`missing_debug_implementation` can use `non_blanket_impls_for_ty` instead of recomputing it.
`missing_docs` is harder as it needs to track if there is a `doc(hidden)` module surrounding. I hack around this using the lint level engine. That's easy to implement and allows to re-enable the lint for a re-exported module, while a more proper solution would reuse the same device as `unnameable_test_items`.
