fs::get_path solarish version.
similar to linux, albeit there is no /proc/self notion on solaris
based system thus flattening the difference for simplification sake.
Warn about safety of `fetch_update`
Specifically as it relates to the ABA problem.
`fetch_update` is a useful function, and one that isn't provided by, say, C++. However, this does not mean the function is magic. It is implemented in terms of `compare_exchange_weak`, and in particular, suffers from the ABA problem. See the following code, which is a naive implementation of `pop` in a lock-free queue:
```rust
fn pop(&self) -> Option<i32> {
self.front.fetch_update(Ordering::Relaxed, Ordering::Acquire, |front| {
if front == ptr::null_mut() {
None
}
else {
Some(unsafe { (*front).next })
}
}.ok()
}
```
This code is unsound if called from multiple threads because of the ABA problem. Specifically, suppose nodes are allocated with `Box`. Suppose the following sequence happens:
```
Initial: Queue is X -> Y.
Thread A: Starts popping, is pre-empted.
Thread B: Pops successfully, twice, leaving the queue empty.
Thread C: Pushes, and `Box` returns X (very common for allocators)
Thread A: Wakes up, sees the head is still X, and stores Y as the new head.
```
But `Y` is deallocated. This is undefined behaviour.
Adding a note about this problem to `fetch_update` should hopefully prevent users from being misled, and also, a link to this common problem is, in my opinion, an improvement to our docs on atomics.
Check uniqueness of impl items by trait item when applicable.
When checking uniqueness of item names in impl blocks, we currently use the same definition of hygiene as for toplevel items. This means that a plain item and one generated by a macro 2.0 do not collide.
This hygiene rule does not match with how impl items resolve to associated trait items. As a consequence, we misdiagnose the trait impls.
This PR proposes to consider that trait impl items are uses of the corresponding trait items during resolution, instead of checking for duplicates later. An error is emitted when a trait impl item is used twice.
There should be no stable breakage, since macros 2.0 are still unstable.
r? ``@petrochenkov``
cc ``@RalfJung``
Fixes https://github.com/rust-lang/rust/issues/71614.
Since 98f05a0282 and
b5963f07e6 removed color classes from sidebar
items, there's no need for the selectors to be so specific any more.
This commit does have to change `h1.fqn a` to just be `h1 a`, so that the
header link color selector is less specific than the typed link at the end.
Since #89506 made docblocks start at `h2`, the main page link header should
be the only h1 in the page now.
Move lifetime resolution module to rustc_hir_analysis.
Now that lifetime resolution has been removed from it, this file has nothing to do in `rustc_resolve`. It's purpose is to compute Debruijn indices for lifetimes, so let's put it in type collection.
scoped threads: pass closure through MaybeUninit to avoid invalid dangling references
The `main` function defined here looks roughly like this, if it were written as a more explicit stand-alone function:
```rust
// Not showing all the `'lifetime` tracking, the point is that
// this closure might live shorter than `thread`.
fn thread(control: ..., closure: impl FnOnce() + 'lifetime) {
closure();
control.signal_done();
// A lot of time can pass here.
}
```
Note that `thread` continues to run even after `signal_done`! Now consider what happens if the `closure` captures a reference of lifetime `'lifetime`:
- The type of `closure` is a struct (the implicit unnameable closure type) with a `&'lifetime mut T` field. References passed to a function are marked with `dereferenceable`, which is LLVM speak for *this reference will remain live for the entire duration of this function*.
- The closure runs, `signal_done` runs. Then -- potentially -- this thread gets scheduled away and the main thread runs, seeing the signal and returning to the user. Now `'lifetime` ends and the memory the reference points to might be deallocated.
- Now we have UB! The reference that as passed to `thread` with the promise of remaining live for the entire duration of the function, actually got deallocated while the function still runs. Oops.
Long-term I think we should be able to use `ManuallyDrop` to fix this without `unsafe`, or maybe a new `MaybeDangling` type. I am working on an RFC for that. But in the mean time it'd be nice to fix this so that Miri with `-Zmiri-retag-fields` (which is needed for "full enforcement" of all the LLVM flags we generate) stops erroring on scoped threads.
Fixes https://github.com/rust-lang/rust/issues/101983
r? `@m-ou-se`
tools/remote-test-{server,client}: Use /data/local/tmp on Android
The /data/tmp directory does not exist, at least not on recent versions of Android, which currently leads to test failures on that platform. I checked a virtual device running AOSP master and a Nexus 5 running Android Marshmallow and on both devices the /data/tmp directory does not exist and /data/local/tmp does, so let's switch to /data/local/tmp.
Fix the sanitizer_scs_attr_check.rs test
The test is failing when targeting aarch64 Android. The intent appears to have been to look for a function attributes comment (or the absence of one) on the line preceding the function declaration. But this isn't quite possible with FileCheck and the test as written was looking for a line with `no_scs` after a line with `scs`, which doesn't appear in the output. Instead, match on the function attributes comment on the line following the demangled function name comment.
Improve rustdoc-gui search-color test
Thanks to the add of "functions" in `browser-ui-test`, we can start to reduce the size of the scripts. It'll be very useful for all color checks.
r? `@notriddle`
suggest candidates for unresolved import
Currently we prompt suggestion of candidates(help notes of `use xxx::yyy`) for names which cannot be resolved, but we don't do that for import statements themselves that couldn't be resolved. It seems reasonable to add candidate help information for these statements as well.
Fixes#102711
rustdoc: clean up overly complex `.trait-impl` CSS selectors
When added in 45964368f4, these multi-class selectors were present in the initial commit, but no reason was given why the shorter selector wouldn't work.
update to syn-1.0.102
This update removes the only `.gitignore` found in `rustc-src`:
vendor/syn/tests/.gitignore
vendor/syn-1.0.91/tests/.gitignore
vendor/syn-1.0.95/tests/.gitignore
To check-in `rustc-src` for hermetic builds in environments with
restrictive `.gitignore` policies, one has to remove these
`tests/.gitignore` and patch the respective
`.cargo-checksum.json`.`syn` >1.0.101 includes dtolnay/syn@3c49303bed,
which removes its `tests/.gitignore`. Now the `syn` crates.io package
has no `.gitignore`.
[`rustc-src`'s `vendor`][] is produced from the root `Cargo.toml`,
`src/tools/rust-analyzer/Cargo.toml`,
`compiler/rustc_codegen_cranelift/Cargo.toml`, and
`src/bootstrap/Cargo.toml`. `rustc_codegen_cranelift` does not use
`syn`.
[`rustc-src`'s `vendor`]:
https://github.com/rust-lang/rust/blob/c0784109daa0/src/bootstrap/dist.rs#L934-L940
This was produced with:
cargo update --package syn --precise 1.0.102 \
cargo update --package syn --precise 1.0.102 \
--manifest-path src/tools/rust-analyzer/Cargo.toml
cargo update --package syn --precise 1.0.102 \
--manifest-path src/bootstrap/Cargo.toml
Copying the approach of the Unix target, this change uses the standard
`RwLock` to protect against concurrent access of libc's environment.
This locking is only enabled when WebAssembly's `atomics` feature is
also enabled.
The issue #102157 demonstrates how currently the `-Z build-std` option
will fail when re-compiling the standard library with `RUSTFLAGS` like
`RUSTFLAGS="-C target-feature=+atomics,+bulk-memory -C
link-args=--shared-memory"`. This change attempts to resolve those build
issues by depending on the the WebAssembly `futex` module and providing
an implementation for `env_lock`. Fixes#102157.
