If a BCB has more than one code region, those extra regions can now all be
stored in the same coverage statement, instead of being stored in additional
statements.
We're stabilizing `async fn` in trait (AFIT), but we have some
reservations about how people might use this in the definitions of
publicly-visible traits, so we're going to lint about that.
This is a bit of an odd lint for `rustc`. We normally don't lint just
to have people confirm that they understand how Rust works. But in
this one exceptional case, this seems like the right thing to do as
compared to the other plausible alternatives.
In this commit, we describe the nature of this odd lint.
Cleanup number handling in match exhaustiveness
Doing a little bit of cleanup; handling number constants was somewhat messy. In particular, this:
- evals float consts once instead of repetitively
- reduces `Constructor` from 88 bytes to 56 (`mir::Const` is big!)
The `fast_try_eval_bits` function was mostly constructed from inlining existing code but I don't fully understand it; I don't follow how consts work and are evaluated very well.
coverage: Regression test for functions with unreachable bodies
This is a regression test for the coverage issue that was addressed temporarily by #116166, and is tracked by #116171.
---
If we instrument a function for coverage, but all of its counter-increment statements are removed by MIR optimizations, LLVM will think it isn't instrumented and it will disappear from coverage maps and coverage reports.
Most MIR opts won't cause this because they tend not to remove statements from bb0, but `UnreachablePropagation` can do so if it sees that bb0 ends with `TerminatorKind::Unreachable`.
Currently we have worked around this by turning off `UnreachablePropagation` when coverage instrumentation is enabled, which is why this test is able to pass.
---
`@rustbot` label +A-code-coverage
resolve: skip underscore character during candidate lookup
Fixes#116164
In use statement, an underscore is merely a placeholder symbol and does not bind to any name. Therefore, it can be safely ignored.
Previously, any associated function could have `~const` trait bounds on
generic parameters, which could lead to ICEs when these bounds were used
on associated functions of non-`#[const_trait] trait` or
non-`impl const` blocks.
Includes changes as per @fee1-dead's comments in #116210.
Prototype using const generic for simd_shuffle IDX array
cc https://github.com/rust-lang/rust/issues/85229
r? `@workingjubilee` on the design
TLDR: there is now a `fn simd_shuffle_generic<T, U, const IDX: &'static [u32]>(x: T, y: T) -> U;` intrinsic that allows replacing
```rust
simd_shuffle(a, b, const { stuff })
```
with
```rust
simd_shuffle_generic::<_, _, {&stuff}>(a, b)
```
which makes the compiler implementations much simpler, if we manage to at some point eliminate `simd_shuffle`.
There are some issues with this today though (can't do math without bubbling it up in the generic arguments). With this change, we can start porting the simple cases and get better data on the others.
More fixes for running the test suite on a bare metal target
This PR adds more fixes needed to run the test suite on bare metal targets (in this case, without unwinding and with static relocations). There is no CI job exercising tests without unwinds, but I can confirm this worked in Ferrocene's CI.
fix(suggestion): insert projection to associated types
Fixes#98562
This PR has fixed some help suggestions for unsupported syntax, such as `fn f<T>(_:T) where T: IntoIterator, std::iter::IntoIterator::Item = () {}` to `fn f<T: IntoIterator<Item = ()>>(_T) {}`.
stabilize combining +bundle and +whole-archive link modifiers
Per discussion on https://github.com/rust-lang/rust/issues/108081 combining +bundle and +whole-archive already works and can be stabilized independently of other aspects of the packed_bundled_libs feature. There is no risk of regression because this was not previously allowed.
r? `@petrochenkov`
Reveal opaque types before drop elaboration
fixes https://github.com/rust-lang/rust/issues/113594
r? `@cjgillot`
cc `@JakobDegen`
This pass was introduced in https://github.com/rust-lang/rust/pull/110714
I moved it before drop elaboration (which only cares about the hidden types of things, not the opaque TAIT or RPIT type) and set it to run unconditionally (instead of depending on the optimization level and whether the inliner is active)
Make `adt_const_params` feature suggestion consistent with other features and improve when it is emitted
Makes the suggestion to add `adt_const_params` formatted like every other feature gate (notably this makes it such that the playground recognizes it). Additionally improves the situations in which that help is emitted so that it's only emitted when the type would be valid or the type *could* be valid (using a slightly incorrect heuristic that favors suggesting the feature over not) instead of, for example, implying that adding the feature would allow the use of `String`.
Also adds the "the only supported types are integers, `bool` and `char`" note to the errors on fn and raw pointers.
r? `@compiler-errors`
Fix `noop_method_call` detection
This needs to be merged before #116198 can compile. The error occurs before the compiler is built so this needs to be a separate PR.
new solver: remove provisional cache
The provisional cache is a performance optimization if there are large, interleaving cycles. Such cycles generally do not exist. It is incredibly complex and unsound in all trait solvers which have one: the old solver, chalk, and the new solver ([link](https://github.com/rust-lang/rust/blob/master/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.rs)).
Given the assumption that it is not perf-critical and also incredibly complex, remove it from the new solver, only checking whether a goal is on the stack. While writing this, I uncovered two additional soundness bugs, see the inline comments for them.
r? `@compiler-errors`
Stabilize `impl_trait_projections`
Closes#115659
## TL;DR:
This allows us to mention `Self` and `T::Assoc` in async fn and return-position `impl Trait`, as you would expect you'd be able to.
Some examples:
```rust
#![feature(return_position_impl_trait_in_trait, async_fn_in_trait)]
// (just needed for final tests below)
// ---------------------------------------- //
struct Wrapper<'a, T>(&'a T);
impl Wrapper<'_, ()> {
async fn async_fn() -> Self {
//^ Previously rejected because it returns `-> Self`, not `-> Wrapper<'_, ()>`.
Wrapper(&())
}
fn impl_trait() -> impl Iterator<Item = Self> {
//^ Previously rejected because it mentions `Self`, not `Wrapper<'_, ()>`.
std::iter::once(Wrapper(&()))
}
}
// ---------------------------------------- //
trait Trait<'a> {
type Assoc;
fn new() -> Self::Assoc;
}
impl Trait<'_> for () {
type Assoc = ();
fn new() {}
}
impl<'a, T: Trait<'a>> Wrapper<'a, T> {
async fn mk_assoc() -> T::Assoc {
//^ Previously rejected because `T::Assoc` doesn't mention `'a` in the HIR,
// but ends up resolving to `<T as Trait<'a>>::Assoc`, which does rely on `'a`.
// That's the important part -- the elided trait.
T::new()
}
fn a_few_assocs() -> impl Iterator<Item = T::Assoc> {
//^ Previously rejected for the same reason
[T::new(), T::new(), T::new()].into_iter()
}
}
// ---------------------------------------- //
trait InTrait {
async fn async_fn() -> Self;
fn impl_trait() -> impl Iterator<Item = Self>;
}
impl InTrait for &() {
async fn async_fn() -> Self { &() }
//^ Previously rejected just like inherent impls
fn impl_trait() -> impl Iterator<Item = Self> {
//^ Previously rejected just like inherent impls
[&()].into_iter()
}
}
```
## Technical:
Lifetimes in return-position `impl Trait` (and `async fn`) are duplicated as early-bound generics local to the opaque in order to make sure we are able to substitute any late-bound lifetimes from the function in the opaque's hidden type. (The [dev guide](https://rustc-dev-guide.rust-lang.org/return-position-impl-trait-in-trait.html#aside-opaque-lifetime-duplication) has a small section about why this is necessary -- this was written for RPITITs, but it applies to all RPITs)
Prior to #103491, all of the early-bound lifetimes not local to the opaque were replaced with `'static` to avoid issues where relating opaques caused their *non-captured* lifetimes to be related. This `'static` replacement led to strange and possibly unsound behaviors (https://github.com/rust-lang/rust/issues/61949#issuecomment-508836314) (https://github.com/rust-lang/rust/issues/53613) when referencing the `Self` type alias in an impl or indirectly referencing a lifetime parameter via a projection type (via a `T::Assoc` projection without an explicit trait), since lifetime resolution is performed on the HIR, when neither `T::Assoc`-style projections or `Self` in impls are expanded.
Therefore an error was implemented in #62849 to deny this subtle behavior as a known limitation of the compiler. It was attempted by `@cjgillot` to fix this in #91403, which was subsequently unlanded. Then it was re-attempted to much success (🎉) in #103491, which is where we currently are in the compiler.
The PR above (#103491) fixed this issue technically by *not* replacing the opaque's parent lifetimes with `'static`, but instead using variance to properly track which lifetimes are captured and are not. The PR gated any of the "side-effects" of the PR behind a feature gate (`impl_trait_projections`) presumably to avoid having to involve T-lang or T-types in the PR as well. `@cjgillot` can clarify this if I'm misunderstanding what their intention was with the feature gate.
Since we're not replacing (possibly *invariant*!) lifetimes with `'static` anymore, there are no more soundness concerns here. Therefore, this PR removes the feature gate.
Tests:
* `tests/ui/async-await/feature-self-return-type.rs`
* `tests/ui/impl-trait/feature-self-return-type.rs`
* `tests/ui/async-await/issues/issue-78600.rs`
* `tests/ui/impl-trait/capture-lifetime-not-in-hir.rs`
---
r? cjgillot on the impl (not much, just removing the feature gate)
I'm gonna mark this as FCP for T-lang and T-types.
Simplify some of the logic in the `invalid_reference_casting` lint
This PR simplifies 2 areas of the logic for the `invalid_reference_casting` lint:
- The init detection: we now use the newly added `expr_or_init` function instead of a manual detection
- The ref-to-mut-ptr casting detection logic: I simplified this logic by caring less hardly about the order of the casting operations
Those two simplifications permits us to detect more cases, as can be seen in the test output changes.
Implement a global value numbering MIR optimization
The aim of this pass is to avoid repeated computations by reusing past assignments. It is based on an analysis of SSA locals, in order to perform a restricted form of common subexpression elimination.
By opportunity, this pass allows for some simplifications by combining assignments. For instance, this pass could be able to see through projections of aggregates to directly reuse the aggregate field (not in this PR).
We handle references by assigning a different "provenance" index to each `Ref`/`AddressOf` rvalue. This ensure that we do not spuriously merge borrows that should not be merged. Meanwhile, we consider all the derefs of an immutable reference to a freeze type to give the same value:
```rust
_a = *_b // _b is &Freeze
_c = *_b // replaced by _c = _a
```
Anonymize binders for `refining_impl_trait` check
We're naively using the equality impl for `ty::Clause` in the refinement check, which is okay *except* for binders, which carry some information about where they come from in the AST. Those locations are not gonna be equal between traits and impls, so anonymize those clauses so that this doesn't matter.
Fixes#116135
Split out the stable part of smir into its own crate to prevent accidental usage of forever unstable things
Some groundwork for being able to work on https://github.com/rust-lang/project-stable-mir/issues/27 at all
r? `@spastorino`
Don't store lazyness in `DefKind::TyAlias`
1. Don't store lazyness of a type alias in its `DefKind`, but instead via a query.
2. This allows us to treat type aliases as lazy if `#[feature(lazy_type_alias)]` *OR* if the alias contains a TAIT, rather than having checks for both in separate parts of the codebase.
r? `@oli-obk` cc `@fmease`
Only prevent field projections into opaque types, not types containing opaque types
fixes https://github.com/rust-lang/rust/issues/115778
I did not think that original condition through properly... I'll also need to check the similar check around the other `ProjectionKind::OpaqueCast` creation site (this one is in hir, the other one is in mir), but I'll do that change in another PR that doesn't go into a beta backport.
Gate and validate `#[rustc_safe_intrinsic]`
Copied over from #116159:
> This was added as ungated in https://github.com/rust-lang/rust/pull/100719/files#diff-09c366d3ad3ec9a42125253b610ca83cad6b156aa2a723f6c7e83eddef7b1e8fR502, probably because the author looked at the surrounding attributes, which are ungated because they are gated specially behind the staged_api feature.
>
> I don't think we need to crater this, the attribute is entirely useless without the intrinsics feature, which is already unstable..
r? ``@Nilstrieb``
lint towards rejecting consts in patterns that do not implement PartialEq
I think we definitely don't want to allow such consts, so even while the general plan around structural matching is up in the air, we can start the process of getting non-PartialEq matches out of the ecosystem.
ConstParamTy: require Eq as supertrait
As discussed with `@BoxyUwu` [on Zulip](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/.60ConstParamTy.60.20and.20.60Eq.60).
We want to say that valtree equality on const generic params agrees with `==`, but that only makes sense if `==` actually exists, hence we should have an appropriate bound. Valtree equality is an equivalence relation, so such a type can always be `Eq` and not just `PartialEq`.
Properly print cstr literals in `proc_macro::Literal::to_string`
Previously we printed the contents of the string, rather than the actual string literal (e.g. `the c string` instead of `c"the c string"`).
Fixes#112820
cc #105723
Use placeholders to prevent using inferred RPITIT types to imply their own well-formedness
The issue here is that we use the same signature to do RPITIT inference as we do to compute implied bounds. To fix this, when gathering the assumed wf types for the method, we replace all of the infer vars (that will be eventually used to infer RPITIT types) with type placeholders, which imply nothing about lifetime bounds.
This solution kind of sucks, but I'm not certain there's another feasible way to fix this. If anyone has a better solution, I'd be glad to hear it.
My naive first solution was, instead of using placeholders, to replace the signature with the RPITIT projections that it originally started out with. But turns out that we can't just use the unnormalized signature of the trait method in `implied_outlives_bounds` since we normalize during WF computation -- that would cause a query cycle in `collect_return_position_impl_trait_in_trait_tys`.
idk who to request review...
r? `@lcnr` or `@aliemjay` i guess.
Fixes#116060
Point at more causes of expectation of break value when possible
Follow up to #116071.
r? `@compiler-errors`
Disregard the first commit, which is in the other PR.
Don't ICE when no bound vars found while doing closure hir type check
The problem was that we were not visiting the const generic default argument in a bound where predicate when the HIR gets traversed in hir_analysis -> collect -> resolve_bound_vars.
Fixes [112574](https://github.com/rust-lang/rust/issues/112574)
