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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
commit 149665afbd
3 changed files with 15 additions and 9 deletions
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2
clippy_lints/src/deprecated_lints.rs
View File

@ -166,7 +166,7 @@ macro_rules! declare_with_version {
#[clippy::version = ""]
("clippy::positional_named_format_parameters", "named_arguments_used_positionally"),
#[clippy::version = ""]
("clippy::temporary_cstring_as_ptr", "temporary_cstring_as_ptr"),
("clippy::temporary_cstring_as_ptr", "dangling_pointers_from_temporaries"),
#[clippy::version = ""]
("clippy::undropped_manually_drops", "undropped_manually_drops"),
#[clippy::version = ""]

4
tests/ui/rename.fixed
View File

@ -54,7 +54,7 @@
#![allow(enum_intrinsics_non_enums)]
#![allow(non_fmt_panics)]
#![allow(named_arguments_used_positionally)]
#![allow(temporary_cstring_as_ptr)]
#![allow(dangling_pointers_from_temporaries)]
#![allow(undropped_manually_drops)]
#![allow(unknown_lints)]
#![allow(unused_labels)]
@ -120,7 +120,7 @@
#![warn(unexpected_cfgs)] //~ ERROR: lint `clippy::mismatched_target_os`
#![warn(non_fmt_panics)] //~ ERROR: lint `clippy::panic_params`
#![warn(named_arguments_used_positionally)] //~ ERROR: lint `clippy::positional_named_format_parameters`
#![warn(temporary_cstring_as_ptr)] //~ ERROR: lint `clippy::temporary_cstring_as_ptr`
#![warn(dangling_pointers_from_temporaries)] //~ ERROR: lint `clippy::temporary_cstring_as_ptr`
#![warn(undropped_manually_drops)] //~ ERROR: lint `clippy::undropped_manually_drops`
#![warn(unknown_lints)] //~ ERROR: lint `clippy::unknown_clippy_lints`
#![warn(unused_labels)] //~ ERROR: lint `clippy::unused_label`

18
tests/ui/rename.stderr
View File

@ -1,11 +1,17 @@
error: lint `temporary_cstring_as_ptr` has been renamed to `dangling_pointers_from_temporaries`
--> tests/ui/rename.rs:57:10
|
LL | #![allow(temporary_cstring_as_ptr)]
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `dangling_pointers_from_temporaries`
|
= note: `-D renamed-and-removed-lints` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(renamed_and_removed_lints)]`
error: lint `clippy::almost_complete_letter_range` has been renamed to `clippy::almost_complete_range`
--> tests/ui/rename.rs:63:9
|
LL | #![warn(clippy::almost_complete_letter_range)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::almost_complete_range`
|
= note: `-D renamed-and-removed-lints` implied by `-D warnings`
= help: to override `-D warnings` add `#[allow(renamed_and_removed_lints)]`
error: lint `clippy::blacklisted_name` has been renamed to `clippy::disallowed_names`
--> tests/ui/rename.rs:64:9
@ -361,11 +367,11 @@ error: lint `clippy::positional_named_format_parameters` has been renamed to `na
LL | #![warn(clippy::positional_named_format_parameters)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `named_arguments_used_positionally`
error: lint `clippy::temporary_cstring_as_ptr` has been renamed to `temporary_cstring_as_ptr`
error: lint `clippy::temporary_cstring_as_ptr` has been renamed to `dangling_pointers_from_temporaries`
--> tests/ui/rename.rs:123:9
|
LL | #![warn(clippy::temporary_cstring_as_ptr)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `temporary_cstring_as_ptr`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `dangling_pointers_from_temporaries`
error: lint `clippy::undropped_manually_drops` has been renamed to `undropped_manually_drops`
--> tests/ui/rename.rs:124:9
@ -397,5 +403,5 @@ error: lint `clippy::reverse_range_loop` has been renamed to `clippy::reversed_e
LL | #![warn(clippy::reverse_range_loop)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `clippy::reversed_empty_ranges`
error: aborting due to 66 previous errors
error: aborting due to 67 previous errors