`c_variadic`: make `VaList` abi-compatible with C
tracking issue: https://github.com/rust-lang/rust/issues/44930
related PR: rust-lang/rust#144529
On some platforms, the C `va_list` type is actually a single-element array of a struct (on other platforms it is just a pointer). In C, arrays passed as function arguments expirience array-to-pointer decay, which means that C will pass a pointer to the array in the caller instead of the array itself, and modifications to the array in the callee will be visible to the caller (this does not match Rust by-value semantics). However, for `va_list`, the C standard explicitly states that it is undefined behaviour to use a `va_list` after it has been passed by value to a function (in Rust parlance, the `va_list` is moved, not copied). This matches Rust's pass-by-value semantics, meaning that when the C `va_list` type is a single-element array of a struct, the ABI will match C as long as the Rust type is always be passed indirectly.
In the old implementation, this ABI was achieved by having two separate types: `VaList` was the type that needed to be used when passing a `VaList` as a function parameter, whereas `VaListImpl` was the actual `va_list` type that was correct everywhere else. This however is quite confusing, as there are lots of footguns: it is easy to cause bugs by mixing them up (e.g. the C function `void foo(va_list va)` was equivalent to the Rust `fn foo(va: VaList)` whereas the C function `void bar(va_list* va)` was equivalent to the Rust `fn foo(va: *mut VaListImpl)`, not `fn foo(va: *mut VaList)` as might be expected); also converting from `VaListImpl` to `VaList` with `as_va_list()` had platform specific behaviour: on single-element array of a struct platforms it would return a `VaList` referencing the original `VaListImpl`, whereas on other platforms it would return a cioy,
In this PR, there is now just a single `VaList` type (renamed from `VaListImpl`) which represents the C `va_list` type and will just work in all positions. Instead of having a separate type just to make the ABI work, rust-lang/rust#144529 adds a `#[rustc_pass_indirectly_in_non_rustic_abis]` attribute, which when applied to a struct will force the struct to be passed indirectly by non-Rustic calling conventions. This PR then implements the `VaList` rework, making use of the new attribute on all platforms where the C `va_list` type is a single-element array of a struct.
Cleanup of the `VaList` API and implementation is also included in this PR: since it was decided it was OK to experiment with Rust requiring that not calling `va_end` is not undefined behaviour (https://github.com/rust-lang/rust/issues/141524#issuecomment-3028383594), I've removed the `with_copy` method as it was redundant to the `Clone` impl (the `Drop` impl of `VaList` is a no-op as `va_end` is a no-op on all known platforms).
Previous discussion: rust-lang/rust#141524 and [t-compiler > c_variadic API and ABI](https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/c_variadic.20API.20and.20ABI)
Tracking issue: https://github.com/rust-lang/rust/issues/44930
r? `@joshtriplett`
Add perma-unstable `--print=backend-has-zstd` for use by compiletest
Tests for `-Zdebuginfo-compression=zstd` need to be skipped if LLVM was built without support for zstd compression.
Currently, compiletest relies on messy and fragile heuristics to detect whether the compiler's LLVM was built with zstd support. But the compiler itself already knows whether LLVM has zstd or not, so it's easier for compiletest to just ask the compiler.
---
Originally I was intending for this to be a `--print=debuginfo-compression` flag that would print out a list of values supported by `-Zdebuginfo-compression=`. I got that working locally, but it was more complex than I was happy with (in both rustc and compiletest), so I decided to cut scope and instead add a very narrow perma-unstable print request instead.
There is always a circularity hazard whenever we ask the compiler-under-test for information about how to test it. But in this case, the underlying compiler code is fairly simple, whereas the previous heuristics were inherently messy and unreliable anyway.
Add regression test for 141845
close: rust-lang/rust#141845
I saw the `tests/ui/associated-inherent-types` directory, but I felt the current location was a better fit.
Check identifiers defined in macros when suggesting identifiers hidden by hygiene
Fixrust-lang/rust#149604
r? `@JonathanBrouwer` (Since you reviewed the other one related to this)
Generate delegation error body when delegation is not resolved
This PR relates to the delegation feature rust-lang/rust#118212, it fixesrust-lang/rust#144594 ICE.
r? `@petrochenkov`
library: Rename `IterRange*` to `Range*Iter`
There is a weak convention in the ecosystem that `IterFoos` is an iterator yielding items of type `Foo` (e.g. `bitflags` `IterNames`, `hashbrown` `IterBuckets`), while `FooIter` is an iterator over `Foo` from an `.iter()` or `.into_iter()` method (e.g. `memchr` `OneIter`, `regex` `SetMatchesIter`). Rename `IterRange`, `IterRangeInclusive`, and `IterRangeFrom` to `RangeIter`, `RangeInclusiveIter`, and `RangeInclusiveIter` to match this.
Tracking issue: https://github.com/rust-lang/rust/issues/125687 (`new_range_api`)
misc coercion cleanups and handle safety correctly
r? lcnr
### "remove normalize call"
Fixesrust-lang/rust#132765
If the normalization fails we would sometimes get a `TypeError` containing inference variables created inside of the probe used by coercion. These would then get leaked out causing ICEs in diagnostics logic
### "leak check and lub for closure<->closure coerce-lubs of same defids"
Fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/233
```rust
fn peculiar() -> impl Fn(u8) -> u8 {
return |x| x + 1
}
```
the `|x| x + 1` expr has a type of `Closure(?31t)` which we wind up inferring the RPIT to. The `CoerceMany` `ret_coercion` for the whole `peculiar` typeck has an expected type of `RPIT` (unnormalized). When we type check the `return |x| x + 1` expr we go from the never type to `Closure(?31t)` which then participates in the `ret_coercion` giving us a `coerce-lub(RPIT, Closure(?31t))`.
Normalizing `RPIT` gives us some `Closure(?50t)` where `?31t` and `?50t` have been unified with `?31t` as the root var. `resolve_vars_if_possible` doesn't resolve infer vars to their roots so these wind up with different structural identities so the fast path doesn't apply and we fall back to coercing to a `fn` ptr. cc rust-lang/rust#147193 which also fixes this
New solver probably just gets more inference variables here because canonicalization + generally different approach to normalization of opaques. Idk :3
### FCP worthy stuffy
there are some other FCP worthy things but they're in my FCP comment which also contains some analysis of the breaking nature of the previously listed changes in this PR: https://github.com/rust-lang/rust/pull/148602#issuecomment-3503497467
Tests for `-Zdebuginfo-compression=zstd` need to be skipped if LLVM was built
without support for zstd compression.
Currently, compiletest relies on messy and fragile heuristics to detect whether
the compiler's LLVM was built with zstd support. But the compiler itself
already knows whether LLVM has zstd or not, so it's easier for compiletest to
just ask the compiler.
Rollup of 9 pull requests
Successful merges:
- rust-lang/rust#147224 (Emscripten: Turn wasm-eh on by default)
- rust-lang/rust#149405 (Recover on misspelled item keyword)
- rust-lang/rust#149443 (Tidying up UI tests [6/N])
- rust-lang/rust#149524 (Move attribute safety checking to attribute parsing)
- rust-lang/rust#149593 (powf, powi: point out SNaN non-determinism)
- rust-lang/rust#149605 (Use branch name instead of HEAD when unshallowing)
- rust-lang/rust#149612 (Apply the `bors` environment also to the `outcome` job)
- rust-lang/rust#149623 (Don't require a normal tool build of clippy/rustfmt when running their test steps)
- rust-lang/rust#149627 (Point to the item that is incorrectly annotated with `#[diagnostic::on_const]`)
r? `@ghost`
`@rustbot` modify labels: rollup
Move attribute safety checking to attribute parsing
This PR moves attribute safety checking to be done during attribute parsing. The `cfg` and `cfg_attr` attribute no longer need special-cased safety checking, yay!
This PR is a part 1 of 2, in the second part I'd like to define attribute safety in the attribute parsers rather than getting the information from BUILTIN_ATTRIBUTE_MAP, but to keep PRs reviewable lets do that separately.
Fixes https://github.com/rust-lang/rust/issues/148453 by reordering the diagnostics. The "cannot find attribute" diagnostic now appears first, but both diagnostics still appear.
r? `@jdonszelmann`
Tidying up UI tests [6/N]
> [!NOTE]
> Intermediate commits are intended to help review, but will be squashed add comment commit prior to merge.
part of rust-lang/rust#133895
removed directory `tests/ui/trait-objects`, `tests/ui/for`, `tests/ui/warnings`
`trait-objects` -> `traits/object`
`for` -> `for-loop-while` (except `for/issue-20605.rs` test. this relocated to `traits/dyn-iterator-deref-in-for-loop.rs`)
`warnings` -> `resolve`, `entry-point`
r? Kivooeo
Recover on misspelled item keyword
the title says everything. first commit adds a test that shows how current `main` behaves on misspelled item keyword. second commit adds the recovery, which allows to emit many more errors.
This removes variance information from some diagnostics. However,
that variance information is not actually relevant here. Casting
`*const dyn Cat<'a>` to `*const S<dyn Cat<'static>>` is an error
regardless of whether `S` requires its argument to be invariant.
Wide-pointer casts always require the trait object arguments to be
invariant.
Tidying up `tests/ui/issues` tests [2/N]
> [!NOTE]
> Intermediate commits are intended to help review, but will be squashed add comment commit prior to merge.
part of rust-lang/rust#133895
reword error for invalid range patterns
For half-open ranges, specifies that the upper bound cannot be the minimum.
Also specify that this only applies to range patterns and not also expressions.
Fixesrust-lang/rust#149165
CTFE: avoid emitting a hard error on generic normalization failures
Fixesrust-lang/rust#149081.
The fix is quite unsatisfying and should not be necessary, cc rust-lang/rust#149283. That change is significantly more involved. This temporary fix introduces some unnecessary complexity and may hide other type system bugs.
cc ````@rust-lang/types```` I think we should try to fix issue rust-lang/rust#149283 in the near future and then remove this hack again.
I originally intended a more targeted fix. I wanted to skip evaluating constants in MIR opts if their body was polymorphic and the current generic arguments still reference generic parameters. Notes from looking into this:
- we only fetch the MIR in the `eval_to_allocation_raw` query
- figuring out which MIR to use is hard
- dealing with trivial consts is annoying
- need to resolve instances for associated consts
- implementing this by hand is hard
- inlining handles this issue by bailing on literally all normalization failures, even the ones that imply an unsoundness
- `try_normalize_after_erasing_regions` generally does two things
- deal with ambiguity after inlining
- deal with error tainting issues (please don't, we should stop doing that)
- CTFE could be changed to always silently ignore normalization failures if we're in a generic body
- hides actual bugs <- went with this option
r? types
Fix ICE when applying test macro to crate root
This PR does a couple of things. First of all, I found [an ICE](https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=a733a7f3d223e1a9712e44b571f3e5cf) that happens when applying `#![core::prelude::v1::test]` to the crate root. This is caused by the test macro not expanding to an item when `--test` isn't applied. For the crate root, that means it deletes the crate....
The fix now first does target checking, and only if the target is valid discards the item when `--test` isn't applied. The discarding is, I think, important for perf.
The problem with this PR is that it means that `#[test]` applied to structs previously would give no errors unless `--test` is applied! That sounds like a bug to me, but maybe we should crater run it just in case, since technically that's a breaking change. Errors in such items wouldn't be reported previously.
Also fixed a smol diagnostics bug with `#[bench]`'s error messages refering to `#[test]` accidentally.
r? noratrieb (since I already explained you a bunch, feel free to re-assign)
Fixes https://github.com/rust-lang/rust/issues/114920
bors