Rollup of 8 pull requests
Successful merges:
- #101118 (fs::get_mode enable getting the data via fcntl/F_GETFL on major BSD)
- #102072 (Add `ptr::Alignment` type)
- #102799 (rustdoc: remove hover gap in file picker)
- #102820 (Show let-else suggestion on stable.)
- #102829 (rename `ImplItemKind::TyAlias` to `ImplItemKind::Type`)
- #102831 (Don't use unnormalized type in `Ty::fn_sig` call in rustdoc `clean_middle_ty`)
- #102834 (Remove unnecessary `lift`/`lift_to_tcx` calls from rustdoc)
- #102838 (remove cfg(bootstrap) from Miri)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Reduce CString allocations in std as much as possible
Currently, every operation involving paths in `fs` allocates memory to hold the path before sending it through the syscall. This PR instead uses a stack allocation (chosen size is somewhat arbitrary) when the path is short before falling back to heap allocations for long paths.
Benchmarks show that the stack allocation is ~2x faster for short paths:
```
test sys::unix::fd::tests::bench_heap_path_alloc ... bench: 34 ns/iter (+/- 2)
test sys::unix::fd::tests::bench_stack_path_alloc ... bench: 15 ns/iter (+/- 1)
```
For long paths, I couldn't find any measurable difference.
---
I'd be surprised if I was the first to think of this, so I didn't fully flush out the PR. If this change is desirable, I'll make use of `run_with_cstr` across all platforms in every fs method (currently just unix open for testing). I also added an `impl From<FromBytesWithNulError>` which is presumably a no-no (or at least needs to be done in another PR).
---
Also see https://github.com/nix-rust/nix/pull/1655 with a bunch of discussion where I'm doing something similar.
add a few more assert_unsafe_precondition
Add debug-assertion checking for `ptr.read()`, `ptr.write(_)`, and `unreachable_unchecked.`
This is quite useful for [cargo-careful](https://github.com/RalfJung/cargo-careful).
Miri sync
This is a Miri sync created with my experimental fork of josh. We should probably not merge this yet, but we can use this to check if the sync looks the way it should.
r? `@oli-obk`
Expand VisitMachineValues to cover more pointers in the interpreter
Follow-on to https://github.com/rust-lang/miri/pull/2559
This is making me want to write a proc macro 🤔
r? `@RalfJung`
Add flag to specify the number of cpus
Apparently you can't rename a branch from github's website without it closing all your PRs with that branch. So this is just #2545
Don't back up past the caller when looking for an FnEntry span
Fixes https://github.com/rust-lang/miri/issues/2536
This adds a fix for the logic as well as a regression test. In the new test `tests/fail/stacked_borrows/fnentry_invalidation2.rs`, before this PR, we display this diagnostic:
```
help: <3278> was later invalidated at offsets [0x0..0xc] by a Unique FnEntry retag
--> tests/fail/stacked_borrows/fnentry_invalidation2.rs:13:5
|
13 | inner(&mut t);
| ^^^^^^^^^^^^^
```
Which is very misleading. It is not this call itself, but what happens within the call that invalidates the tag we want. With this PR, we get:
```
help: <2798> was later invalidated at offsets [0x0..0xc] by a Unique FnEntry retag inside this call
--> tests/fail/stacked_borrows/fnentry_invalidation2.rs:20:13
|
20 | let _ = t.sli.as_mut_ptr();
| ^^^^^^^^^^^^^^^^^^
```
Which is much better.
Always print '_, even for erased lifetimes.
Explicit lifetime arguments are now the recommended syntax in rust 2018 and rust 2021. This PR applies this discipline to rustc itself.
