use Scalar return types for Windows shims
I started doing this while working on https://github.com/rust-lang/miri/issues/2595; now I don't need the rest of this patch but this part still makes sense.
Ideas on getting information about borrow stacks during execution
From time to time people ask what some borrow stack looks like in some code. I just know that I am terrible at doing Stacked Borrows by hand, so I always toss together something like this.
I know that Miri has logging, but I've never found it particularly useful because there's just too much output. Also I personally don't think about exactly what the state of a borrow stack is, but this seems to be something that newcomers to Stacked Borrows always want.
Update: This has been sitting as S-waiting-on-author for a long time. I bring it out from time to time to explain Stacked Borrows to people, and just now `@JakobDegen` said
> Can we please merge that btw? It's such a valuable teaching tool
> Interfaces can be fixed later
I'm inclined to trust Jake's judgement here.
nicer errors from assert_unsafe_precondition
This makes the errors shown by cargo-careful nicer, and since `panic_no_unwind` is `nounwind noreturn` it hopefully doesn't have bad codegen impact. Thanks to `@bjorn3` for the hint!
Would be nice if we could somehow supply our own (static) message to print, currently it always prints `panic in a function that cannot unwind`. But still, this is better than before.
Prevent UB in child process after calling libc::fork
After calling libc::fork, the child process tried to access a TLS variable when processing a panic. This caused a memory allocation which is UB in the child.
To prevent this from happening, the panic handler will not access the TLS variable in case `panic::always_abort` was called before.
Fixes#85261 (not only on Android systems, but also on Linux/QNX with TLS disabled, see issue for more details)
Main drawbacks of this fix:
* Panic messages can incorrectly omit `core::panic::PanicInfo` struct in case several panics (of multiple threads) occur at the same time. The handler cannot distinguish between multiple panics in different threads or recursive ones in the same thread, but the message will contain a hint about the uncertainty.
* `panic_count::increase()` will be a bit slower as it has an additional `if`, but this should be irrelevant as it is only called in case of a panic.
rustdoc: remove unused classes from sidebar links
Since 98f05a0282 removed separate colors from the currently-selected item, there's no need to have item classes on sidebar links.
Preview: https://notriddle.com/notriddle-rustdoc-demos/sidebar-link-class/std/vec/struct.Vec.html
While cleaning up the CSS to remove unneeded `.content` selectors, this PR changes the `h1.fqn a` CSS selector to just be `h1 a`, so that the header link color selector is less specific than the typed link at the end. Since https://github.com/rust-lang/rust/pull/89506 made docblocks start at `h2`, the main page link header should be the only h1 in the page now.
unify `IsPattern` and `IsImport` enum in `show_candidates`
Follow-up of #102876
A binding cannot appear in both pattern and import at the same time, so it makes sense to unify them
r? `@compiler-errors`
Check representability in adt_sized_constraint
Now that representability is a query, we can use it to preemptively avoid a cycle in `adt_sized_constraint`.
I moved the representability check into `check_mod_type_wf` to avoid a scenario where rustc quits before checking all the types for representability. This also removes the check from rustdoc, which is alright AFAIK.
r? ``@cjgillot``
Use memset to initialize readbuf
The write loop was found to be slow in #102727
The proper fix is in #102760 but this might still help debug builds and code running under miri by using the write_bytes intrinsic instead of writing one byte at a time.
Use correct location for type tests in promoted constants
Previously we forgot to remap the location in a type test collected when visiting the body of a promoted constant back to the usage location, causing an ICE when trying to get span information for that type test.
Fixes https://github.com/rust-lang/rust/issues/102117
Migrate rustc_passes diagnostics
Picks up abandoned work from https://github.com/rust-lang/rust/pull/100870
I would like to do this collaboratively, as there is a lot of work! Here's the process:
- Comment below that you are willing to help and I will add you as a collaborator to my `rust` fork (that gives you write access)
- Indicate which file/task you would like to work on (so we don't duplicate work) from the list below
- Do the work, push up a commit, comment that you're done with that file/task
- Repeat until done 😄
### Files to Migrate (in `compiler/rustc_passes/src/`)
- [x] check_attr.rs ``@CleanCut``
- [x] check_const.rs ``@CleanCut``
- [x] dead.rs ``@CleanCut``
- [x] debugger_visualizer.rs ``@CleanCut``
- [x] diagnostic_items.rs ``@CleanCut``
- [x] entry.rs ``@CleanCut``
- [x] lang_items.rs ``@CleanCut``
- [x] layout_test.rs ``@CleanCut``
- [x] lib_features.rs ``@CleanCut``
- [x] ~liveness.rs~ ``@CleanCut`` Nothing to do
- [x] loops.rs ``@CleanCut``
- [x] naked_functions.rs ``@CleanCut``
- [x] stability.rs ``@CleanCut``
- [x] weak_lang_items.rs ``@CleanCut``
### Tasks
- [x] Rebase on current `master` ``@CleanCut``
- [x] Review work from [the earlier PR](https://github.com/rust-lang/rust/pull/100870) and make sure it all looks good
- [x] compiler/rustc_error_messages/locales/en-US/passes.ftl ``@CleanCut``
- [x] compiler/rustc_passes/src/check_attr.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/errors.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/lang_items.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/lib.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/weak_lang_items.rs ``@CleanCut``
Remove `TokenStreamBuilder`
`TokenStreamBuilder` is used to combine multiple token streams. It can be removed, leaving the code a little simpler and a little faster.
r? `@Aaron1011`
Interpret EH actions properly
The EH actions stored in the LSDA follows the format of GCC except table (even for LLVM-generated code). An missing action in the table is the encoding for `Terminate`, see https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/libsupc%2B%2B/eh_personality.cc#L522-L526.
The currently code interprets it as `None`, as a workaround for #35011, an issue that seems to occur in LLVM 3.7 and not after 3.9. These are very old versions of LLVM and we don't support them anymore, so remove this workaround and interpret them properly.
Note that LLVM currently does not emit any `Terminate` actions, but GCC does. Although GCC backend currently doesn't do unwinding, removing it preemptively would prevent future developers from wasting time to figure out what's wrong.
``@rustbot`` label: +T-compiler
Migrate `codegen_ssa` to diagnostics structs - [Part 1]
Initial migration of `codegen_ssa`. Going to split this crate migration in at least two PRs in order to avoid a huge PR and to quick off some questions around:
1. Translating messages from "external" crates.
2. Interfacing with OS messages.
3. Adding UI tests while migrating diagnostics.
_See comments below._
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.
