Don't use posix_spawn_file_actions_addchdir_np on macOS.
There is a bug on macOS where using `posix_spawn_file_actions_addchdir_np` with a relative executable path will cause `posix_spawnp` to return ENOENT, even though it successfully spawned the process in the given directory.
`posix_spawn_file_actions_addchdir_np` was introduced in macOS 10.15 first released in Oct 2019. I have tested macOS 10.15.7 and 11.0.1.
Example offending program:
```rust
use std::fs;
use std::os::unix::fs::PermissionsExt;
use std::process::*;
fn main() {
fs::create_dir_all("bar").unwrap();
fs::create_dir_all("foo").unwrap();
fs::write("foo/foo.sh", "#!/bin/sh\necho hello ${PWD}\n").unwrap();
let perms = fs::Permissions::from_mode(0o755);
fs::set_permissions("foo/foo.sh", perms).unwrap();
let c = Command::new("../foo/foo.sh").current_dir("bar").spawn();
eprintln!("{:?}", c);
}
```
This prints:
```
Err(Os { code: 2, kind: NotFound, message: "No such file or directory" })
hello /Users/eric/Temp/bar
```
I wanted to open this PR to get some feedback on possible solutions. Alternatives:
* Do nothing.
* Document the bug.
* Try to detect if the executable is a relative path on macOS, and avoid using `posix_spawn_file_actions_addchdir_np` only in that case.
I looked at the [XNU source code](https://opensource.apple.com/source/xnu/xnu-6153.141.1/bsd/kern/kern_exec.c.auto.html), but I didn't see anything obvious that would explain the behavior. The actual chdir succeeds, it is something else further down that fails, but I couldn't see where.
EDIT: I forgot to mention, relative exe paths with `current_dir` in general are discouraged (see #37868). I don't know if #37868 is fixable, since normalizing it would change the semantics for some platforms. Another option is to convert the executable to an absolute path with something like joining the cwd with the new cwd and the executable, but I'm uncertain about that.
Don't make tools responsible for checking unknown and renamed lints
Previously, clippy (and any other tool emitting lints) had to have their
own separate UNKNOWN_LINTS pass, because the compiler assumed any tool
lint could be valid. Now, as long as any lint starting with the tool
prefix exists, the compiler will warn when an unknown lint is present.
This may interact with the unstable `tool_lint` feature, which I don't entirely understand, but it will take the burden off those external tools to add their own lint pass, which seems like a step in the right direction to me.
- Don't mark `ineffective_unstable_trait_impl` as an internal lint
- Use clippy's more advanced lint suggestions
- Deprecate the `UNKNOWN_CLIPPY_LINTS` pass (and make it a no-op)
- Say 'unknown lint `clippy::x`' instead of 'unknown lint x'
This is tested by existing clippy tests. When https://github.com/rust-lang/rust/pull/80527 merges, it will also be tested in rustdoc tests. AFAIK there is no way to test this with rustc directly.
Add NonZeroUn::is_power_of_two
This saves instructions on both new and old machines <https://rust.godbolt.org/z/4fjTMz>
- On the default x64 target (with no fancy instructions available) it saves a few instructions by not needing to also check for zero.
- On newer targets (with BMI1) it uses `BLSR` for super-short assembly.
This can be used for things like checks against alignments stored in `NonZeroUsize`.
Force vec![] to expression position only
r? `@oli-obk`
I went with the lazy way of only changing what broke. I moved the test to ui/macros because the diagnostics no longer give suggestions.
Closes#61933
Add benchmark and fast path for BufReader::read_exact
At work, we have a wrapper type that implements this optimization. It would be nice if the standard library were faster.
Before:
```
test io::buffered::tests::bench_buffered_reader_small_reads ... bench: 7,670 ns/iter (+/- 45)
```
After:
```
test io::buffered::tests::bench_buffered_reader_small_reads ... bench: 4,457 ns/iter (+/- 41)
```
BTreeMap: expose new_internal function and sanitize from_new_internal
`new_internal` is the functional core of the imperative `push_internal_level`, and `from_new_internal` can easily do a proper job instead of returning a half-baked node.
r? `@Mark-Simulacrum`
Add `as_rchunks` (and friends) to slices
`@est31` mentioned (https://github.com/rust-lang/rust/issues/76354#issuecomment-717027175) that, for completeness, there needed to be an `as_chunks`-like method that chunks from the end (with the remainder at the beginning) like `rchunks` does.
So here's a PR for `as_rchunks: &[T] -> (&[T], &[[T; N]])` and `as_rchunks_mut: &mut [T] -> (&mut [T], &mut [[T; N]])`.
But as I was doing this and copy-pasting `from_raw_parts` calls, I thought that I should extract that into an unsafe method. It started out a private helper, but it seemed like `as_chunks_unchecked` could be reasonable as a "real" method, so I added docs and made it public. Let me know if you think it doesn't pull its weight.
Rollup of 17 pull requests
Successful merges:
- #78455 (Introduce {Ref, RefMut}::try_map for optional projections in RefCell)
- #80144 (Remove giant badge in README)
- #80614 (Explain why borrows can't be held across yield point in async blocks)
- #80670 (TrustedRandomAaccess specialization composes incorrectly for nested iter::Zips)
- #80681 (Clarify what the effects of a 'logic error' are)
- #80764 (Re-stabilize Weak::as_ptr and friends for unsized T)
- #80901 (Make `x.py --color always` apply to logging too)
- #80902 (Add a regression test for #76281)
- #80941 (Do not suggest invalid code in pattern with loop)
- #80968 (Stabilize the poll_map feature)
- #80971 (Put all feature gate tests under `feature-gates/`)
- #81021 (Remove doctree::Import)
- #81040 (doctest: Reset errors before dropping the parse session)
- #81060 (Add a regression test for #50041)
- #81065 (codegen_cranelift: Fix redundant semicolon warn)
- #81069 (Add sample code for Rc::new_cyclic)
- #81081 (Add test for #34792)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Re-stabilize Weak::as_ptr and friends for unsized T
As per [T-lang consensus](https://hackmd.io/7r3_is6uTz-163fsOV8Vfg), this uses a branch to handle the dangling case. The discussed optimization of only doing the branch in the T: ?Sized case is left for a followup patch, as doing so is not trivial (as it requires specialization) and not _obviously_ better (as it requires using `wrapping_offset` rather than `offset` more).
<details><summary>Basically said optimization</summary>
Specialize on `T: Sized`:
```rust
fn as_ptr(&self) -> *const T {
if [ T is Sized ] || !is_dangling(ptr) {
(ptr as *mut T).set_ptr_value( (ptr as *mut u8).wrapping_offset(data_offset) )
} else {
ptr::null()
}
}
fn from_raw(*const T) -> Self {
if [ T is Sized ] || !ptr.is_null() {
let ptr = (ptr as *mut RcBox).set_ptr_value( (ptr as *mut u8).wrapping_offset(-data_offset) );
Weak { ptr }
} else {
Weak::new()
}
}
```
(but with more `set_ptr_value` to avoid `Sized` restrictions and maintain metadata.)
Written in this fashion, this is not a correctness-critical specialization (i.e. so long as `[ T is Sized ]` is false for unsized `T`, it can be `rand()` for sized `T` without breaking correctness), but it's still touchy, so I'd rather do it in another PR with separate review.
---
</details>
This effectively reverts #80422 and re-establishes #74160. T-libs [previously signed off](https://github.com/rust-lang/rust/pull/74160#issuecomment-660539373) on this stable API change in #74160.
Clarify what the effects of a 'logic error' are
This clarifies what a 'logic error' is (which is a term used to describe what happens if you put things in a hash table or btree and then use something like a refcell to break the internal ordering). This tries to be as vague as possible, as we don't really want to promise what happens, except "bad things, but not UB". This was discussed in #80657
TrustedRandomAaccess specialization composes incorrectly for nested iter::Zips
I found this while working on improvements for TRA.
After partially consuming a Zip adapter and then wrapping it into another Zip where the adapters use their `TrustedRandomAccess` specializations leads to the outer adapter returning elements which should have already been consumed.
If the optimizer gets tripped up by the addition this might affect performance for chained `zip()` iterators even when the inner one is not partially advanced but it would require more extensive fixes to `TrustedRandomAccess` to communicate those offsets earlier.
Included test fails on nightly, [playground link](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=24fa1edf8a104ff31f5a24830593b01f)
Introduce {Ref, RefMut}::try_map for optional projections in RefCell
This fills a usability gap of `RefCell` I've personally encountered to perform optional projections, mostly into collections such as `RefCell<Vec<T>>` or `RefCell<HashMap<U, T>>`:
> This kind of API was briefly featured under Open questions in #10514 back in 2013 (!)
```rust
let values = RefCell::new(vec![1, 2, 3, 4]);
let b = Ref::opt_map(values.borrow(), |vec| vec.get(2));
```
It primarily avoids this alternative approach to accomplish the same kind of projection which is both rather noisy and panicky:
```rust
let values = RefCell::new(vec![1, 2, 3, 4]);
let b = if values.get(2).is_some() {
Some(Ref::map(values.borrow(), |vec| vec.get(2).unwrap()))
} else {
None
};
```
### Open questions
The naming `opt_map` is preliminary. I'm not aware of prior art in std to lean on here, but this name should probably be improved if this functionality is desirable.
Since `opt_map` consumes the guard, and alternative syntax might be more appropriate which instead *tries* to perform the projection, allowing the original borrow to be recovered in case it fails:
```rust
pub fn try_map<U: ?Sized, F>(orig: Ref<'b, T>, f: F) -> Result<Ref<'b, U>, Self>
where
F: FnOnce(&T) -> Option<&U>;
```
This would be more in line with the `try_map` method [provided by parking lot](https://docs.rs/lock_api/0/lock_api/struct.RwLockWriteGuard.html#method.try_map).
implement ptr::write without dedicated intrinsic
This makes `ptr::write` more consistent with `ptr::write_unaligned`, `ptr::read`, `ptr::read_unaligned`, all of which are implemented in terms of `copy_nonoverlapping`.
This means we can also remove `move_val_init` implementations in codegen and Miri, and its special handling in the borrow checker.
Also see [this Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/ptr.3A.3Aread.20vs.20ptr.3A.3Awrite).
It's not an internal lint:
- It's not in the rustc::internal lint group
- It's on unconditionally, because it actually lints `staged_api`, not
the compiler
This fixes a bug where `#[deny(rustc::internal)]` would warn that
`rustc::internal` was an unknown lint.
Remove unreachable panics from VecDeque::{front/back}[_mut]
`VecDeque`'s `front`, `front_mut`, `back` and `back_mut` methods are implemented in terms of the index operator, which causes these functions to contain [unreachable panic calls](https://rust.godbolt.org/z/MTnq1o).
This PR reimplements these methods in terms of `get[_mut]` instead.
Fix formatting specifiers doc links
d36e3e23a80f039ee98117ebba0bb2ea6e34f0c1 seems to have inadvertently changed many of these links to point to `core::fmt` instead of `std::fmt`. The information about formatting specifiers is only documented in [`std::fmt`](https://doc.rust-lang.org/std/fmt/); [`core::fmt`](https://doc.rust-lang.org/core/fmt/) is empty. 3baf6a4a749bd6ac4a8b9f1054d3f2ad2fc91e45 seems to have already fixed a couple of these links to point back to `std::fmt`.
Remove unstable deprecated Vec::remove_item
Closes#40062
The `Vec::remove_item` method was deprecated in `1.46.0` (in August of 2020). This PR now removes that unstable method entirely.
Deprecate atomic::spin_loop_hint in favour of hint::spin_loop
For https://github.com/rust-lang/rust/issues/55002
We wanted to leave `atomic::spin_loop_hint` alone when stabilizing `hint::spin_loop` so folks had some time to migrate. This now deprecates `atomic_spin_loop_hint`.
Fix handling of malicious Readers in read_to_end
A malicious `Read` impl could return overly large values from `read`, which would result in the guard's drop impl setting the buffer's length to greater than its capacity! ~~To fix this, the drop impl now uses the safe `truncate` function instead of `set_len` which ensures that this will not happen. The result of calling the function will be nonsensical, but that's fine given the contract violation of the `Read` impl.~~
~~The `Guard` type is also used by `append_to_string` which does not pass untrusted values into the length field, so I've copied the guard type into each function and only modified the one used by `read_to_end`. We could just keep a single one and modify it, but it seems a bit cleaner to keep the guard code close to the functions and related specifically to them.~~
To fix this, we now assert that the returned length is not larger than the buffer passed to the method.
For reference, this bug has been present for ~2.5 years since 1.20: ecbb896b9e.
Closes#80894.
Add Iterator::intersperse_with
This is a follow-up to #79479, tracking in #79524, as discussed https://github.com/rust-lang/rust/pull/79479#issuecomment-752671731.
~~Note that I had to manually implement `Clone` and `Debug` because `derive` insists on placing a `Clone`-bound on the struct-definition, which is too narrow. There is a long-standing issue # for this somewhere around here :-)~~
Also, note that I refactored the guts of `Intersperse` into private functions and re-used them in `IntersperseWith`, so I also went light on duplicating all the tests.
If this is suitable to be merged, the tracking issue should be updated, since it only mentions `intersperse`.
Happy New Year!
r? ``@m-ou-se``
Add as_ref and as_mut methods for Bound
Add as_ref and as_mut method for std::ops::range::Bound, patterned off
of the methods of the same name on Option.
I'm not quite sure what the process is for introducing new feature gates (this is my first contribution) so I've left these ungated, but happy to do whatever is necessary to gate them.
Add a `std::io::read_to_string` function
I recognize that you're usually supposed to open an issue first, but the
implementation is very small so it's okay if this is closed and it was 'wasted
work' :)
-----
The equivalent of `std::fs::read_to_string`, but generalized to all
`Read` impls.
As the documentation on `std::io::read_to_string` says, the advantage of
this function is that it means you don't have to create a variable first
and it provides more type safety since you can only get the buffer out
if there were no errors. If you use `Read::read_to_string`, you have to
remember to check whether the read succeeded because otherwise your
buffer will be empty.
It's friendlier to newcomers and better in most cases to use an explicit
return value instead of an out parameter.
