fix memrchr in miri
The previous PR https://github.com/rust-lang/rust/pull/52744 was not enough because it assumed that the split between the `mid` and `end` parts returned by `align_to` was aligned. But really the only guarantee we have is that the `mid` part is aligned, so make use of that.
[NLL] Allow conflicting borrows of promoted length zero arrays
This is currently overkill as there's no way to create two conflicting borrows of any promoted.
It is possible that the following code might not fail due to const eval in the future (@oli-obk?). In which case either the array marked needs to not be promoted, or to be checked for conflicts
```rust
static mut A: () = {
let mut y = None;
let z;
let mut done_y = false;
loop {
let x = &mut [1]; // < this array
if done_y {
z = x;
break;
}
y = Some(x);
done_y = true;
}
some_const_fn(y, z); // some_const_fn expects that y to not alias z.
};
```
r? @pnkfelix @nikomatsakis
closes#52671
cc #51823
After talking about the PR with eddyb, I decided it was best to try to
have some test cases that simplify the problem down to its core, so
that people trying to understand what the issue is here will see those
core examples first.
(Presumably the place that borrow_check ends up reporting for the
error about is no longer the root `Local` itself, and thus the note
diagnostic here stops firing.)
This should address issue 45696.
Since we know dropping a box will not access any `&mut` or `&`
references, it is safe to model its destructor as only touching the
contents *owned* by the box.
Note: At some point we may want to generalize this machinery to other
reference and collection types that are "pure" in the same sense as
box. If we add a `&move` reference type, it would probably also fall
into this branch of code. But for the short term, we will be
conservative and restrict this change to `Box<T>` alone.
The code works by recursively descending a deref of the `Box`. We
prevent `visit_terminator_drop` infinite-loop (which can arise in a
very obscure scenario) via a linked-list of seen types.
Note: A similar style stack-only linked-list definition can be found
in `rustc_mir::borrow_check::places_conflict`. It might be good at
some point in the future to unify the two types and put the resulting
definition into `librustc_data_structures/`.
----
One final note: Review feedback led to significant simplification of
logic here.
During review, eddyb RalfJung and I uncovered the heart of why I
needed a so-called "step 2" aka the Shallow Write to the Deref of the
box. It was because the `visit_terminator_drop`, in its base case,
will not emit any write at all (shallow or deep) to a place unless
that place has a need_drop.
So I was encoding a Shallow Write by hand for a `Box<T>`, as a
separate step from recursively descending through `*a_box` (which was
at the time known as "step 1"; it is now the *only* step, apart from
the change to the base case for `visit_terminator_drop` that this
commit now has encoded).
eddyb aruged that *something* should be emitting some sort of write in
the base case here (even a shallow one), of the dropped place, since
by analogy we also emit a write when you *move* a place. That led
to the revision here in this commit.
* (Its possible that this desired write should be attached in some
manner to StorageDead instead of Drop. But in this PR, I tried to
leave the StorageDead logic alone and focus my attention solely on
how Drop(x) is modelled in MIR-borrowck.)
The PR title says `armv5te-unknown-linux-musl`, but it looks like the final code merge renamed the target to `armv5te-unknown-linux-musleabi`. `rustup` reports this as correct as well.
The [Rust Platform Support](https://forge.rust-lang.org/platform-support.html) page needs this added as well, but I'm not certain what codebase that is generated from.
These migration lints aren't all up to par in terms of a good migration
experience. Some, like `unreachable_pub`, hit bugs like #52665 and unprepared
macros to be handled enough of the time. Others like linting against
`#[macro_use]` are swimming upstream in an ecosystem that's not quite ready (and
slightly buggy pending a few current PRs).
The general idea is that we will continue to recommend the `rust_2018_idioms`
lint group as part of the transition guide (as an optional step) but we'll be
much more selective about which lints make it into this group. Only those with a
strong track record of not causing too much churn will make the cut.
cc #52679
rustc: Handle linker diagnostics from LLVM
Previously linker diagnostic were being hidden when two modules were linked
together but failed to link. This commit fixes the situation by ensuring that we
have a diagnostic handler installed and also adds support for handling linker
diagnostics.
The regression check is to make beta promotion easier, so it makes more
sense to use the Tuesday of the release week (T-2) as the end point of the
regression prevention, instead of Thursday (T-0). But since the beta
promotion PR is sent at Tuesday evening at UTC, the protection should
include the whole Tuesday as well, meaning the 6-week cycle will start from
Wednesdays.
This will also move the start of the regression protection week one day
earlier.
Rollup of 30 pull requests
Successful merges:
- #52340 (Document From trait implementations for OsStr, OsString, CString, and CStr)
- #52628 (Cleanup some rustdoc code)
- #52732 (Remove unstable and deprecated APIs)
- #52745 (Update clippy to latest master)
- #52771 (Clarify thread::park semantics)
- #52778 (Improve readability of serialize.rs)
- #52810 ([NLL] Don't make "fake" match variables mutable)
- #52821 (pretty print for std::collections::vecdeque)
- #52822 (Fix From<LocalWaker>)
- #52824 (Fix -Wpessimizing-move warnings in rustllvm/PassWrapper)
- #52825 (Make sure #47772 does not regress)
- #52831 (remove references to AUTHORS.txt file)
- #52842 (update comment)
- #52846 (Add timeout to use of `curl` in bootstrap.py.)
- #52851 (Make the tool_lints actually usable)
- #52853 (Improve bootstrap help on stages)
- #52859 (Use Vec::extend in SmallVec::extend when applicable)
- #52861 (Add targets for HermitCore (https://hermitcore.org) to the Rust compiler and port libstd to it.)
- #52867 (releases.md: fix 2 typos)
- #52870 (Implement Unpin for FutureObj and LocalFutureObj)
- #52876 (run-pass/const-endianness: negate before to_le())
- #52878 (Fix wrong issue number in the test name)
- #52883 (Include lifetime in mutability suggestion in NLL messages)
- #52888 (Use suggestions for shell format arguments)
- #52904 (NLL: sort diagnostics by span)
- #52905 (Fix a typo in unsize.rs)
- #52907 (NLL: On "cannot move out of type" error, print original before rewrite)
- #52914 (Only run the sparc-abi test on sparc)
- #52918 (Backport 1.27.2 release notes)
- #52929 (Update compatibility note for 1.28.0 to be correct)
Failed merges:
r? @ghost
Update compatibility note for 1.28.0 to be correct
You can still put implementations on `dyn Trait + Send + Send`, but it'd be the same as putting them on `dyn Trait + Send`. This is why the error is that there are duplicate definitions in the example.
Only run the sparc-abi test on sparc
It is not required for LLVM to have SPARC target support, so it is
necessary to only run this test when LLVM does support SPARC. Sadly, it
isn’t possible to specify exactly this constraint. Instead, we specify
that this test should run on SPARC host only (it surely is sane
assumption to make that compiler running on a SPARC can generate
SPARC, right?)
Since you cannot specify multiple `only-*` to have it run on both 32-bit
and 64-bit SPARC we pick 64-bit SPARC, because it is exactly what is
being tested by this test.
Fixes#52881
NLL: On "cannot move out of type" error, print original before rewrite
NLL: On "cannot move out of type" error, print original source before rewrite.
* Arguably this change is sometimes injecting noise into the output (namely in the cases where the suggested rewrite is inline with the suggestion and we end up highlighting the original source code). I would not be opposed to something more aggressive/dynamic, like revising the suggestion code to automatically print the original source when necessary (e.g. when the error does not have a span that includes the span of the suggestion).
* Also, as another note on this change: The doc comment for `Diagnostic::span_suggestion` says:
```rust
/// The message
///
/// * should not end in any punctuation (a `:` is added automatically)
/// * should not be a question
/// * should not contain any parts like "the following", "as shown"
```
* but the `:` is *not* added when the emitted line appears out-of-line relative to the suggestion. I find that to be an unfortunate UI experience.
----
As a drive-by fix, also changed code to combine multiple suggestions for a pattern into a single multipart suggestion (which vastly improves user experience IMO).
----
Includes the updates to expected NLL diagnostics.
Fix#52877
NLL: sort diagnostics by span
Sorting the output diagnostics by span is a long planned revision to the NLL diagnostics that we hope will yield a less surprising user experience in some case.
Once we got them buffered, it was trivial to implement. (The hard part is skimming the resulting changes to the diagnostics to make sure nothing broke... Note that I largely rubber-stamped the `#[rustc_regions]` output change.)
Fix#51167
