Auto merge of #128985 - GrigorenkoPV:instantly-dangling-pointer, r=Urgau

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Lint against getting pointers from immediately dropped temporaries

Fixes #123613

## Changes:
1. New lint: `dangling_pointers_from_temporaries`. Is a generalization of `temporary_cstring_as_ptr` for more types and more ways to get a temporary.
2. `temporary_cstring_as_ptr` is removed and marked as renamed to `dangling_pointers_from_temporaries`.
3. `clippy::temporary_cstring_as_ptr` is marked as renamed to `dangling_pointers_from_temporaries`.
4. Fixed a false positive[^fp] for when the pointer is not actually dangling because of lifetime extension for function/method call arguments.
5. `core::cell::Cell` is now `rustc_diagnostic_item = "Cell"`

## Questions:
- [ ]  Instead of manually checking for a list of known methods and diagnostic items, maybe add some sort of annotation to those methods in library and check for the presence of that annotation? https://github.com/rust-lang/rust/pull/128985#issuecomment-2318714312

## Known limitations:

### False negatives[^fn]:

See the comments in `compiler/rustc_lint/src/dangling.rs`

1. Method calls that are not checked for:
   - `temporary_unsafe_cell.get()`
   - `temporary_sync_unsafe_cell.get()`
2. Ways to get a temporary that are not recognized:
   - `owning_temporary.field`
   - `owning_temporary[index]`
3. No checks for ref-to-ptr conversions:
   - `&raw [mut] temporary`
   - `&temporary as *(const|mut) _`
    - `ptr::from_ref(&temporary)` and friends

[^fn]: lint **should** be emitted, but **is not**

[^fp]: lint **should not** be emitted, but **is**

...

This commit is contained in:

bors 2024-10-29 00:24:07 +00:00

parent aecc3e7984 bfeadff2b2

commit 0dc8c6c224

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