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**
Rollup of 4 pull requests
Successful merges:
- #131391 (Stabilize `isqrt` feature)
- #132248 (rustc_transmute: Directly use types from rustc_abi)
- #132252 (compiler: rename LayoutS to LayoutData)
- #132253 (Known-bug test for `keyword_idents` lint not propagating to other files)
r? `@ghost`
`@rustbot` modify labels: rollup
Known-bug test for `keyword_idents` lint not propagating to other files
Known-bug test for `keyword_idents` lint not propagating to other files when configured via attribute (#132218).
compiler: rename LayoutS to LayoutData
Bid `LayoutS` goodbye because it looks like a typo.
`LayoutS` is the last of the types that use the "`{TypeName}` is the interned type, `{TypeName}S` is the backing data that is interned" convention. This is pretty confusing to those not intimately familiar with the history of rustc's names for its types over time, and doubly so now that there are no other examples in the tree. Abolish this convention.
I.e. the following situation:
```
fn foo() {
mod bar {
fn qux() {
// Prelude path here (e.g. macro use prelude or extern prelude).
}
}
}
```
Those were previously unresolved, because, in order to support `self` and `super` properly, since #15148 we do not ascend block paths when there is a module in between, but only crate def maps register preludes, not block def maps, and we can't change this because block def map prelude can always be overridden by another block. E.g.
```
fn foo() {
struct WithTheSameNameAsPreludeItem;
{
WithTheSameNameAsPreludeItem
}
}
```
Here `WithTheSameNameAsPreludeItem` refer to the item from the top block, but if we would register prelude items in each block the child block would overwrite it incorrectly.
