std docs: edit `PathBuf::set_file_name` example
To make explicit that `set_file_name` might replace or remove the
extension, not just the file stem.
Also edit docs for `Path::with_file_name`, which calls `set_file_name`.
Some of these relations were already mentioned in the text, but that
Send is implemented for &mut impl Send was not mentioned,
neither did the docs list when &T is Sync.
Make `mem::replace` simpler in codegen
Since they'd mentioned more intrinsics for simplifying stuff recently,
r? `@WaffleLapkin`
This is a continuation of me looking at foundational stuff that ends up with more instructions than it really needs. Specifically I noticed this one because `Range::next` isn't MIR-inlining, and one of the largest parts of it is a `replace::<usize>` that's a good dozen instructions instead of the two it could be.
So this means that `ptr::write` with a `Copy` type no longer generates worse IR than manually dereferencing (well, at least in LLVM -- MIR still has bonus pointer casts), and in doing so means that we're finally down to just the two essential `memcpy`s when emitting `mem::replace` for a large type, rather than the bonus-`alloca` and three `memcpy`s we emitted before this ([or the 6 we currently emit in 1.69 stable](https://rust.godbolt.org/z/67W8on6nP)). That said, LLVM does _usually_ manage to optimize the extra code away. But it's still nice for it not to have to do as much, thanks to (for example) not going through an `alloca` when `replace`ing a primitive like a `usize`.
(This is a new intrinsic, but one that's immediately lowered to existing MIR constructs, so not anything that MIRI or the codegen backends or MIR semantics needs to do work to handle.)
Tweak await span to not contain dot
Fixes a discrepancy between method calls and await expressions where the latter are desugared to have a span that *contains* the dot (i.e. `.await`) but method call identifiers don't contain the dot. This leads to weird suggestions suggestions in borrowck -- see linked issue.
Fixes#110761
This mostly touches a bunch of tests to tighten their `await` span.
`inline(always)` for `lt`/`le`/`ge`/`gt` on integers and floats
I happened to notice one of these not getting inlined as part of `Range::next` in <https://rust.godbolt.org/z/4WKWWxj1G>
```rust
bb1: {
StorageLive(_5);
_6 = &mut _4;
StorageLive(_21);
StorageLive(_14);
StorageLive(_15);
_15 = &((*_6).0: usize);
StorageLive(_16);
_16 = &((*_6).1: usize);
_14 = <usize as PartialOrd>::lt(move _15, move _16) -> bb7;
}
```
So since a call for something that's just one instruction is never the right choice, `#[inline(always)]` seems appropriate, like we have it on things like the rotate methods on integers.
Improve internal field comments on `slice::Iter(Mut)`
I wrote these in a previous PR that I ended up withdrawing, so might as well submit them separately.
`@bors` rollup=always
Make sure that some stdlib method signatures aren't accidental refinements
In the process of implementing https://rust-lang.github.io/rfcs/3245-refined-impls.html, I found a bunch of stdlib implementations that accidentally "refined" their method signatures by dropping (unnecessary) bounds.
This isn't currently a problem, but may become one if/when method signature refining is stabilized in the future. Shouldn't hurt to make these signatures a bit more accurate anyways.
NOTE (just to be clear lol): This does not affect behavior at all, since we don't actually take advantage of refined implementations yet!
Use MIR's `Offset` for pointer `add` too
~~Status: draft while waiting for #110822 to land, since this is built atop that.~~
~~r? `@ghost~~`
Canonical Rust code has mostly moved to `add`/`sub` on pointers, which take `usize`, instead of `offset` which takes `isize`. (And, relatedly, when `sub_ptr` was added it turned out it replaced every single in-tree use of `offset_from`, because `usize` is just so much more useful than `isize` in Rust.)
Unfortunately, `intrinsics::offset` could only accept `*const` and `isize`, so there's a *huge* amount of type conversions back and forth being done. They're identity conversions in the backend, but still end up producing quite a lot of unhelpful MIR.
This PR changes `intrinsics::offset` to accept `*const` *and* `*mut` along with `isize` *and* `usize`. Conveniently, the backends and CTFE already handle this, since MIR's `BinOp::Offset` [already supports all four combinations](adaac6b166/compiler/rustc_const_eval/src/transform/validate.rs (L523-L528)).
To demonstrate the difference, I added some `mir-opt/pre-codegen/` tests around slice indexing. Here's the difference to `[T]::get_mut`, since it uses `<*mut _>::add` internally:
```diff
`@@` -79,30 +70,21 `@@` fn slice_get_mut_usize(_1: &mut [u32], _2: usize) -> Option<&mut u32> {
StorageLive(_12); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageLive(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
_9 = _8 as *mut u32 (PtrToPtr); // scope 11 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageLive(_13); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _13 = _2 as isize (IntToInt); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageLive(_14); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageLive(_15); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _15 = _9 as *const u32 (Pointer(MutToConstPointer)); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _14 = Offset(move _15, _13); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageDead(_15); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- _7 = move _14 as *mut u32 (PtrToPtr); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageDead(_14); // scope 15 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
- StorageDead(_13); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
+ _7 = Offset(_9, _2); // scope 13 at $SRC_DIR/core/src/ptr/mut_ptr.rs:LL:COL
StorageDead(_9); // scope 6 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_12); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
StorageDead(_11); // scope 3 at $SRC_DIR/core/src/slice/index.rs:LL:COL
```
1c1c8e442a (diff-a841b6a4538657add3f39bc895744331453d0625e7aace128b1f604f0b63c8fdR80)
I happened to notice one of these not getting inlined as part of `Range::next` in <https://rust.godbolt.org/z/4WKWWxj1G>
```rust
bb1: {
StorageLive(_5);
_6 = &mut _4;
StorageLive(_21);
StorageLive(_14);
StorageLive(_15);
_15 = &((*_6).0: usize);
StorageLive(_16);
_16 = &((*_6).1: usize);
_14 = <usize as PartialOrd>::lt(move _15, move _16) -> bb7;
}
```
So since a call for something this trivial is never the right choice, `#[inline(always)]` seems appropriate.
`remove_dir_all`: try deleting the directory even if `FILE_LIST_DIRECTORY` access is denied
If opening a directory with `FILE_LIST_DIRECTORY` access fails then we should try opening without requesting that access. We may still be able to delete it if it's empty or a link.
Fixes https://github.com/rust-lang/cargo/issues/12042
More core::fmt::rt cleanup.
- Removes the `V1` suffix from the `Argument` and `Flag` types.
- Moves more of the format_args lang items into the `core::fmt::rt` module. (The only remaining lang item in `core::fmt` is `Arguments` itself, which is a public type.)
Part of https://github.com/rust-lang/rust/issues/99012
Follow-up to https://github.com/rust-lang/rust/pull/110616
Document `const {}` syntax for `std::thread_local`.
It exists and is pretty cool. More people should use it.
It was added in #83416 and stabilized in #91355 with the tracking issue #84223.
If opening a directory with `FILE_LIST_DIRECTORY` access fails then we should try opening without requesting that access. We may still be able to delete it if it's empty or a link.
Change memory ordering in System wrapper example
Currently, the `SeqCst` ordering is used, which seems unnecessary:
+ Even `Relaxed` ordering guarantees that all updates are atomic and are executed in total order
+ User code only reads atomic for monitoring purposes, no "happens-before" relationships with actual allocations and deallocations are needed for this
If argumentation above is correct, I propose changing ordering to `Relaxed` to clarify that no synchronization is required here, and improve performance (if somebody copy-pastes this example into their code).
Correct `std::prelude` comment
(Read the changed file first for context.)
First, `alloc` has no prelude.
Second, the docs for `v1` don't matter since the [prelude module] already has all the doc links. The `rust_2021` module for instance also doesnt have a convenient doc page. However as I understand glob imports still cant be used because the items dont have the same stabilisation versions.
[prelude module]: https://doc.rust-lang.org/std/prelude/index.html
docs(std): clarify remove_dir_all errors
When using `remove_dir_all`, I assumed that the function was idempotent and that I could always call it to remove a directory if it existed. That's not the case and it bit me in production, so I figured I'd submit this to clarify the docs.
