Some where clause lowering simplifications
Rename `PredicateFilter::SelfThatDefines` to `PredicateFilter::SelfTraitThatDefines` to make it clear that it's only concerned with converting *traits*, and make it do a bit less work when converting bounds.
Also, make the predicate filter matching in `probe_ty_param_bounds_in_generics` explicit, and simply the args it receives a bit.
Fix validation when lowering `?` trait bounds
Pass the unlowered (`rustc_hir`) polarity to `lower_poly_trait_ref`.
This allows us to actually *validate* that generic args are actually valid on `?Trait` paths. This actually regressed in #113671 because that PR changed the behavior where we were inadvertently re-lowering paths as `BoundPolarity::Positive`, which was also coincidentally the only place we were enforcing the generics on `?Trait` paths were correct.
Try to point out when edition 2024 lifetime capture rules cause borrowck issues
Lifetime capture rules in 2024 are modified to capture more lifetimes, which sometimes lead to some non-local borrowck errors. This PR attempts to link these back together with a useful note pointing out the capture rule changes.
This is not a blocking concern, but I'd appreciate feedback (though, again, I'd like to stress that I don't want to block this PR on this): I'm worried about this note drowning in the sea of other diagnostics that borrowck emits. I was tempted to change the level of the note to `.span_warn` just so it would show up in a different color. Thoughts?
Fixes#130545
Opening as a draft first since it's stacked on #131183.
r? `@ghost`
Make sure `type_param_predicates` resolves correctly for RPITIT
After #132194, we end up lowering the item bounds for an RPITIT in an `ItemCtxt` whose def id is the *synthetic GAT*, not the opaque type from the HIR.
This means that when we're resolving a shorthand projection like `T::Assoc`, we call the `type_param_predicates` function with the `item_def_id` of the *GAT* and not the opaque. That function operates on the HIR, and is not designed to work with the `Node::Synthetic` that gets fed for items synthesized by the compiler...
This PR reuses the trick we use elsewhere in lowering, where we intercept whether an item comes from RPITIT lowering, and forwards the query off to the correct item.
Fixes#132372
Remap impl-trait lifetimes on HIR instead of AST lowering
Current AST->HIR lowering goes out of its way to remap lifetimes for opaque types. This is complicated and leaks into upstream and downstream code.
This PR stops trying to be clever during lowering, and prefers to do this remapping during the HIR->ty lowering. The remapping computation easily fits into the bound var resolution code. Its result can be used in by `generics_of` and `hir_ty_lowering::new_opaque` to add the proper parameters and arguments.
See an example on the doc for query `opaque_captured_lifetimes`.
Based on https://github.com/rust-lang/rust/pull/129244/
Fixes https://github.com/rust-lang/rust/issues/125249
Fixes https://github.com/rust-lang/rust/issues/126850
cc `@compiler-errors` `@spastorino`
r? `@petrochenkov`
The RFC for arbitrary self types v2 declares that we should reject
"generic" self types. This commit does so.
The definition of "generic" was unclear in the RFC, but has been
explored in
https://github.com/rust-lang/rust/issues/129147
and the conclusion is that "generic" means any `self` type which
is a type parameter defined on the method itself, or references
to such a type.
This approach was chosen because other definitions of "generic"
don't work. Specifically,
* we can't filter out generic type _arguments_, because that would
filter out Rc<Self> and all the other types of smart pointer
we want to support;
* we can't filter out all type params, because Self itself is a
type param, and because existing Rust code depends on other
type params declared on the type (as opposed to the method).
This PR decides to make a new error code for this case, instead of
reusing the existing E0307 error. This makes the code a
bit more complex, but it seems we have an opportunity to provide
specific diagnostics for this case so we should do so.
This PR filters out generic self types whether or not the
'arbitrary self types' feature is enabled. However, it's believed
that it can't have any effect on code which uses stable Rust, since
there are no stable traits which can be used to indicate a valid
generic receiver type, and thus it would have been impossible to
write code which could trigger this new error case.
It is however possible that this could break existing code which
uses either of the unstable `arbitrary_self_types` or
`receiver_trait` features. This breakage is intentional; as
we move arbitrary self types towards stabilization we don't want
to continue to support generic such types.
This PR adds lots of extra tests to arbitrary-self-from-method-substs.
Most of these are ways to trigger a "type mismatch" error which
9b82580c73/compiler/rustc_hir_typeck/src/method/confirm.rs (L519)
hopes can be minimized by filtering out generics in this way.
We remove a FIXME from confirm.rs suggesting that we make this change.
It's still possible to cause type mismatch errors, and a subsequent
PR may be able to improve diagnostics in this area, but it's harder
to cause these errors without contrived uses of the turbofish.
This is a part of the arbitrary self types v2 project,
https://github.com/rust-lang/rfcs/pull/3519https://github.com/rust-lang/rust/issues/44874
r? @wesleywiser
TypingMode: merge intercrate, reveal, and defining_opaque_types
This adds `TypingMode` and uses it in most places. We do not yet remove `Reveal` from `param_env`s. This and other future work as tracked in #132279 and via `FIXME`s.
Fetching the `TypingMode` of the `InferCtxt` asserts that the `TypingMode` agrees with `ParamEnv::reveal` to make sure we don't introduce any subtle bugs here. This will be unnecessary once `ParamEnv::reveal` no longer exists.
As the `TypingMode` is now a part of the query input, I've merged the coherence and non-coherence caches for the new solver. I've also enabled the local `infcx` cache during coherence by clearing the cache when forking it with a different `TypingMode`.
#### `TypingMode::from_param_env`
I am using this even in cases where I know that the `param_env` will always be `Reveal::UserFacing`. This is to make it easier to correctly refactor this code in the future, any time we use `Reveal::UserFacing` in a body while not defining its opaque types is incorrect and should use a `TypingMode` which only reveals opaques defined by that body instead, cc #124598
r? ``@compiler-errors``
Collect item bounds for RPITITs from trait where clauses just like associated types
We collect item bounds from trait where clauses for *associated types*, i.e. this:
```rust
trait Foo
where
Self::Assoc: Send
{
type Assoc;
}
```
Becomes this:
```rust
trait Foo {
type Assoc: Send;
}
```
Today, with RPITITs/AFIT and return-type notation, we don't do that, i.e.:
```rust
trait Foo where Self::method(..): Send {
fn method() -> impl Sized;
}
fn is_send(_: impl Send) {}
fn test<T: Foo>() {
is_send(T::method());
}
```
...which fails on nightly today.
Turns out it's super easy to fix this, and we just need to use the `associated_type_bounds` lowering function in `explicit_item_bounds_with_filter`, which has that logic baked in.
Hack out effects support for old solver
Opening this for vibes ✨
Turns out that a basic, somewhat incomplete implementation of host effects is achievable in the old trait solver pretty easily. This should be sufficient for us to use in the standard library itself.
Regarding incompleteness, maybe we should always treat host predicates as ambiguous in intercrate mode (at least in the old solver) to avoid any worries about accidental impl overlap or something.
r? ```@lcnr``` cc ```@fee1-dead```
Add `LayoutS::is_uninhabited` and use it
Use accessors for the things that accessors are good at: reducing everyone's need to be nosy and peek at the internals of every data structure.
compiler: Add rustc_abi dependence to the compiler
Depend on rustc_abi in compiler crates that use it indirectly but have not yet taken on that dependency, and are not *significantly* entangled in my other PRs. This leaves an "excise rustc_target" step after the dust settles.
Remove `ObligationCause::span()` method
I think it's an incredibly confusing footgun to expose both `obligation_cause.span` and `obligation_cause.span()`. Especially because `ObligationCause::span()` (the method) seems to just be hacking around a single quirk in the way we set up obligation causes for match arms.
First commit removes the need for that hack, with only one diagnostic span changing (but IMO not really getting worse -- I'd argue that it was already confusing).
Depend on rustc_abi in compiler crates that use it indirectly but have
not yet taken on that dependency, and are not entangled in my other PRs.
This leaves an "excise rustc_target" step after the dust settles.
Cleanup: Move an impl-Trait check from AST validation to AST lowering
Namely the one that rejects `impl Trait` in qself types and non-final path segments.
There's no good reason to perform this during AST validation.
We have better infrastructure in place in the AST lowerer (`ImplTraitContext`).
This shaves off a lot of code.
We now lower `impl Trait` in bad positions to `{type error}` which allows us to
remove a special case from HIR ty lowering.
Coincidentally fixes#126725. Well, it only *masks* it by passing `{type error}` to HIR analysis instead of a "bad" opaque. I was able to find a new reproducer for it. See the issue.
Simplify param handling in `resolve_bound_vars`
I always found the flow of the `ResolvedArg` constructors to be a bit confusing; turns out they're also kinda redundantly passing around their data, too.
Also, deduplicate some code handling early-bound var to late-bound var conversion between return type notation's two styles: `where <T as Trait>::method(..): Bound` and `where T: Trait<method(..): Bound>`.
Effects cleanup
- removed extra bits from predicates queries that are no longer needed in the new system
- removed the need for `non_erasable_generics` to take in tcx and DefId, removed unused arguments in callers
r? compiler-errors
- removed extra bits from predicates queries that are no longer needed in the new system
- removed the need for `non_erasable_generics` to take in tcx and DefId, removed unused arguments in callers
Then we can rename the _raw functions to drop their suffix, and instead
explicitly use is_stable_const_fn for the few cases where that is really what
you want.
Stabilize shorter-tail-lifetimes
Close#131445
Tracked by #123739
We found a test case `tests/ui/drop/drop_order.rs` that had not been covered by the change. The test fixture is fixed now with the correct expectation.
Deeply normalize `TypeTrace` when reporting type error in new solver
Normalize the values that come from the `TypeTrace` for various type mismatches.
Side-note: We can't normalize the `TypeError` itself bc it may come from instantiated binders, so it may reference values from within the probe...
r? lcnr
Rename Receiver -> LegacyReceiver
As part of the "arbitrary self types v2" project, we are going to replace the current `Receiver` trait with a new mechanism based on a new, different `Receiver` trait.
This PR renames the old trait to get it out the way. Naming is hard. Options considered included:
* HardCodedReceiver (because it should only be used for things in the standard library, and hence is sort-of hard coded)
* LegacyReceiver
* TargetLessReceiver
* OldReceiver
These are all bad names, but fortunately this will be temporary. Assuming the new mechanism proceeds to stabilization as intended, the legacy trait will be removed altogether.
Although we expect this trait to be used only in the standard library, we suspect it may be in use elsehwere, so we're landing this change separately to identify any surprising breakages.
It's known that this trait is used within the Rust for Linux project; a patch is in progress to remove their dependency.
This is a part of the arbitrary self types v2 project,
https://github.com/rust-lang/rfcs/pull/3519https://github.com/rust-lang/rust/issues/44874
r? `@wesleywiser`
Minor tweaks to `compare_impl_item.rs`
1. Stop using the `InstantiatedPredicates` struct for `hybrid_preds` in `compare_impl_item.rs`, since we never actually push anything into the `spans` part of it.
2. Remove redundant impl args and don't do useless identity substitution, prefer calling `instantiate_identity`.
Validate args are correct for `UnevaluatedConst`, `ExistentialTraitRef`/`ExistentialProjection`
For the `Existential*` ones, we have to do some adjustment to the args list to deal with the missing `Self` type, so we introduce a `debug_assert_existential_args_compatible` function to the interner as well.
As part of the "arbitrary self types v2" project, we are going to
replace the current `Receiver` trait with a new mechanism based on a
new, different `Receiver` trait.
This PR renames the old trait to get it out the way. Naming is hard.
Options considered included:
* HardCodedReceiver (because it should only be used for things in the
standard library, and hence is sort-of hard coded)
* LegacyReceiver
* TargetLessReceiver
* OldReceiver
These are all bad names, but fortunately this will be temporary.
Assuming the new mechanism proceeds to stabilization as intended, the
legacy trait will be removed altogether.
Although we expect this trait to be used only in the standard library,
we suspect it may be in use elsehwere, so we're landing this change
separately to identify any surprising breakages.
It's known that this trait is used within the Rust for Linux project; a
patch is in progress to remove their dependency.
This is a part of the arbitrary self types v2 project,
https://github.com/rust-lang/rfcs/pull/3519https://github.com/rust-lang/rust/issues/44874
r? @wesleywiser
make unsupported_calling_conventions a hard error
This has been a future-compat lint (not shown in dependencies) since Rust 1.55, released 3 years ago. Hopefully that was enough time so this can be made a hard error now. Given that long timeframe, I think it's justified to skip the "show in dependencies" stage. There were [not many crates hitting this](https://github.com/rust-lang/rust/pull/86231#issuecomment-866300943) even when the lint was originally added.
This should get cratered, and I assume then it needs a t-compiler FCP. (t-compiler because this looks entirely like an implementation oversight -- for the vast majority of ABIs, we already have a hard error, but some were initially missed, and we are finally fixing that.)
Fixes https://github.com/rust-lang/rust/pull/87678
Rollup of 4 pull requests
Successful merges:
- #126588 (Added more scenarios where comma to be removed in the function arg)
- #131728 (bootstrap: extract builder cargo to its own module)
- #131968 (Rip out old effects var handling code from traits)
- #131981 (Remove the `BoundConstness::NotConst` variant)
r? `@ghost`
`@rustbot` modify labels: rollup
Continue to get rid of `ty::Const::{try_}eval*`
This PR mostly does:
* Removes all of the `try_eval_*` and `eval_*` helpers from `ty::Const`, and replace their usages with `try_to_*`.
* Remove `ty::Const::eval`.
* Rename `ty::Const::normalize` to `ty::Const::normalize_internal`. This function is still used in the normalization code itself.
* Fix some weirdness around the `TransmuteFrom` goal.
I'm happy to split it out further; for example, I could probably land the first part which removes the helpers, or the changes to codegen which are more obvious than the changes to tools.
r? BoxyUwU
Part of https://github.com/rust-lang/rust/issues/130704
Get rid of `OnlySelfBounds`
We turn `PredicateFilter` into a newtyped bool called `OnlySelfBounds`. There's no reason to lose the information of the `PredicateFilter`, so let's just pass it all the way through.
Don't report bivariance error when nesting a struct with field errors into another struct
We currently have logic to avoid reporting lifetime bivariance ("lifetime parameter ... is never used") errors when a struct has field resolution errors. However, this doesn't apply transitively. This PR implements a simple visitor to do so.
This was reported [here](https://twitter.com/fasterthanlime/status/1846257921086165033) since a `derive(Deserialize, Serialize)` ends up generating helper structs which have bivariant lifetimes due to containing the offending struct (that's being derived on).
Use `ThinVec` for PredicateObligation storage
~~I noticed while profiling clippy on a project that a large amount of time is being spent allocating `Vec`s for `PredicateObligation`, and the `Vec`s are often quite small. This is an attempt to optimise this by using SmallVec to avoid heap allocations for these common small Vecs.~~
This PR turns all the `Vec<PredicateObligation>` into a single type alias while avoiding referring to `Vec` around it, then swaps the type over to `ThinVec<PredicateObligation>` and fixes the fallout. This also contains an implementation of `ThinVec::extract_if`, copied from `Vec::extract_if` and currently being upstreamed to https://github.com/Gankra/thin-vec/pull/66.
This leads to a small (0.2-0.7%) performance gain in the latest perf run.
Rollup of 9 pull requests
Successful merges:
- #122670 (Fix bug where `option_env!` would return `None` when env var is present but not valid Unicode)
- #131095 (Use environment variables instead of command line arguments for merged doctests)
- #131339 (Expand set_ptr_value / with_metadata_of docs)
- #131652 (Move polarity into `PolyTraitRef` rather than storing it on the side)
- #131675 (Update lint message for ABI not supported)
- #131681 (Fix up-to-date checking for run-make tests)
- #131702 (Suppress import errors for traits that couldve applied for method lookup error)
- #131703 (Resolved python deprecation warning in publish_toolstate.py)
- #131710 (Remove `'apostrophes'` from `rustc_parse_format`)
r? `@ghost`
`@rustbot` modify labels: rollup
Remove unnecessary sorts in `rustc_hir_analysis`
A follow-up after #131140. Here the related objects are `IndexSet` so do not require a sort to stay stable. And they don't need to be `mut` anymore.
r? ```@compiler-errors```
Update lint message for ABI not supported
Tracking issue: #130260
As requested in https://github.com/rust-lang/rust/pull/128784#pullrequestreview-2364026550 I updated the error message.
I could also change it to be the same message as if it was a hard error on a normal function:
> "`{abi}` is not a supported ABI for the current target"
Or would that get confusing when people try to google the error message?
r? compiler-errors
Check ABI target compatibility for function pointers
Tracking issue: https://github.com/rust-lang/rust/issues/130260
Related tracking issue: #87678
Compatibility of an ABI for a target was previously only performed on function definitions and `extern` blocks. This PR adds it also to function pointers to be consistent.
This might have broken some of the `tests/ui/` depending on the platform, so a try run seems like a good idea.
Also this might break existing code, because we now emit extra errors. Does this require a crater run?
# Example
```rust
// build with: --target=x86_64-unknown-linux-gnu
// These raise E0570
extern "thiscall" fn foo() {}
extern "thiscall" { fn bar() }
// This did not raise any error
fn baz(f: extern "thiscall" fn()) { f() }
```
# Open Questions
* [x] Should this report a future incompatibility warning like #87678 ?
* [ ] Is this the best place to perform the check?
Add intrinsics `fmuladd{f16,f32,f64,f128}`. This computes `(a * b) +
c`, to be fused if the code generator determines that (i) the target
instruction set has support for a fused operation, and (ii) that the
fused operation is more efficient than the equivalent, separate pair
of `mul` and `add` instructions.
https://llvm.org/docs/LangRef.html#llvm-fmuladd-intrinsic
MIRI support is included for f32 and f64.
The codegen_cranelift uses the `fma` function from libc, which is a
correct implementation, but without the desired performance semantic. I
think this requires an update to cranelift to expose a suitable
instruction in its IR.
I have not tested with codegen_gcc, but it should behave the same
way (using `fma` from libc).
Retire the `unnamed_fields` feature for now
`#![feature(unnamed_fields)]` was implemented in part in #115131 and #115367, however work on that feature has (afaict) stalled and in the mean time there have been some concerns raised (e.g.[^1][^2]) about whether `unnamed_fields` is worthwhile to have in the language, especially in its current desugaring. Because it represents a compiler implementation burden including a new kind of anonymous ADT and additional complication to field selection, and is quite prone to bugs today, I'm choosing to remove the feature.
However, since I'm not one to really write a bunch of words, I'm specifically *not* going to de-RFC this feature. This PR essentially *rolls back* the state of this feature to "RFC accepted but not yet implemented"; however if anyone wants to formally unapprove the RFC from the t-lang side, then please be my guest. I'm just not totally willing to summarize the various language-facing reasons for why this feature is or is not worthwhile, since I'm coming from the compiler side mostly.
Fixes#117942Fixes#121161Fixes#121263Fixes#121299Fixes#121722Fixes#121799Fixes#126969Fixes#131041
Tracking:
* https://github.com/rust-lang/rust/issues/49804
[^1]: https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Unnamed.20struct.2Funion.20fields
[^2]: https://github.com/rust-lang/rust/issues/49804#issuecomment-1972619108
Compiler & its UI tests: Rename remaining occurrences of "object safe" to "dyn compatible"
Follow-up to #130826.
Part of #130852.
1. 1st commit: Fix stupid oversights. Should've been part of #130826.
2. 2nd commit: Rename the unstable feature `object_safe_for_dispatch` to `dyn_compatible_for_dispatch`. Might not be worth the churn, you decide.
3. 3rd commit: Apply the renaming to all UI tests (contents and paths).
Make opaque types regular HIR nodes
Having opaque types as HIR owner introduces all sorts of complications. This PR proposes to make them regular HIR nodes instead.
I haven't gone through all the test changes yet, so there may be a few surprises.
Many thanks to `@camelid` for the first draft.
Fixes https://github.com/rust-lang/rust/issues/129023Fixes#129099Fixes#125843Fixes#119716Fixes#121422
Account for `impl Trait {` when `impl Trait for Type {` was intended
On editions where bare traits are never allowed, detect if the user has written `impl Trait` with no type, silence any dyn-compatibility errors, and provide a structured suggestion for the potentially missing type:
```
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/missing-for-type-in-impl.rs:8:6
|
LL | impl Foo<i64> {
| ^^^^^^^^
|
help: add `dyn` keyword before this trait
|
LL | impl dyn Foo<i64> {
| +++
help: you might have intended to implement this trait for a given type
|
LL | impl Foo<i64> for /* Type */ {
| ++++++++++++++
```
CC #131051.
Check elaborated projections from dyn don't mention unconstrained late bound lifetimes
Check that the projections that are *not* explicitly written but which we deduce from elaborating the principal of a `dyn` *also* do not reference unconstrained late-bound lifetimes, just like the ones that the user writes by hand.
That is to say, given:
```
trait Foo<T>: Bar<Assoc = T> {}
trait Bar {
type Assoc;
}
```
The type `dyn for<'a> Foo<&'a T>` (basically) elaborates to `dyn for<'a> Foo<&'a T> + for<'a> Bar<Assoc = &'a T>`[^1]. However, the `Bar` projection predicate is not well-formed, since `'a` must show up in the trait's arguments to be referenced in the term of a projection. We must error in this situation[^well], or else `dyn for<'a> Foo<&'a T>` is unsound.
We already detect this for user-written projections during HIR->rustc_middle conversion, so this largely replicates that logic using the helper functions that were already conveniently defined.
---
I'm cratering this first to see the fallout; if it's minimal or zero, then let's land it as-is. If not, the way that this is implemented is very conducive to an FCW.
---
Fixes#130347
[^1]: We don't actually elaborate it like that in rustc; we only keep the principal trait ref `Foo<&'a T>` and the projection part of `Bar<Assoc = ...>`, but it's useful to be a bit verbose here for the purpose of explaining the issue.
[^well]: Well, we could also make `dyn for<'a> Foo<&'a T>` *not* implement `for<'a> Bar<Assoc = &'a T>`, but this is inconsistent with the case where the user writes `Assoc = ...` in the type itself, and it overly complicates the implementation of trait objects' built-in impls.
On editions where bare traits are never allowed, detect if the user has
written `impl Trait` with no type, silence any dyn-compatibility errors,
and provide a structured suggestion for the potentially missing type:
```
error[E0782]: trait objects must include the `dyn` keyword
--> $DIR/missing-for-type-in-impl.rs:8:6
|
LL | impl Foo<i64> {
| ^^^^^^^^
|
help: add `dyn` keyword before this trait
|
LL | impl dyn Foo<i64> {
| +++
help: you might have intended to implement this trait for a given type
|
LL | impl Foo<i64> for /* Type */ {
| ++++++++++++++
```
Stabilize the `map`/`value` methods on `ControlFlow`
And fix the stability attribute on the `pub use` in `core::ops`.
libs-api in https://github.com/rust-lang/rust/issues/75744#issuecomment-2231214910 seemed reasonably happy with naming for these, so let's try for an FCP.
Summary:
```rust
impl<B, C> ControlFlow<B, C> {
pub fn break_value(self) -> Option<B>;
pub fn map_break<T>(self, f: impl FnOnce(B) -> T) -> ControlFlow<T, C>;
pub fn continue_value(self) -> Option<C>;
pub fn map_continue<T>(self, f: impl FnOnce(C) -> T) -> ControlFlow<B, T>;
}
```
Resolves#75744
``@rustbot`` label +needs-fcp +t-libs-api -t-libs
---
Aside, in case it keeps someone else from going down the same dead end: I looked at the `{break,continue}_value` methods and tried to make them `const` as part of this, but that's disallowed because of not having `const Drop`, so put it back to not even unstably-const.
Refactoring to `OpaqueTyOrigin`
Pulled out of a larger PR that uses these changes to do cross-crate encoding of opaque origin, so we can use them for edition 2024 migrations. These changes should be self-explanatory on their own, tho 😄
Fix `adt_const_params` leaking `{type error}` in error msg
Fixes the confusing diagnostic described in #118179. (users would see `{type error}` in some situations, which is pretty weird)
`adt_const_params` tracking issue: #95174
properly elaborate effects implied bounds for super traits
Summary: This PR makes it so that we elaborate `<T as Tr>::Fx: EffectsCompat<somebool>` into `<T as SuperTr>::Fx: EffectsCompat<somebool>` when we know that `trait Tr: ~const SuperTr`.
Some discussion at https://github.com/rust-lang/project-const-traits/issues/2.
r? project-const-traits
`@rust-lang/project-const-traits:` how do we feel about this approach?
Assert that `explicit_super_predicates_of` and `explicit_item_super_predicates` truly only contains bounds for the type itself
We distinguish _implied_ predicates (anything that is implied from elaborating a trait bound) from _super_ predicates, which are are the subset of implied predicates that share the same self type as the trait predicate we're elaborating. This was originally done in #107614, which fixed a large class of ICEs and strange errors where the compiler expected the self type of a trait predicate not to change when elaborating super predicates.
Specifically, super predicates are special for various reasons: they're the valid candidates for trait upcasting, are the only predicates we elaborate when doing closure signature inference, etc. So making sure that we get this list correct and don't accidentally "leak" any other predicates into this list is quite important.
This PR adds some debug assertions that we're in fact not doing so, and it fixes an oversight in the effect desugaring rework.
Implement Return Type Notation (RTN)'s path form in where clauses
Implement return type notation (RTN) in path position for where clauses. We already had RTN in associated type position ([e.g.](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=627a4fb8e2cb334863fbd08ed3722c09)), but per [the RFC](https://rust-lang.github.io/rfcs/3654-return-type-notation.html#where-rtn-can-be-used-for-now):
> As a standalone type, RTN can only be used as the Self type of a where-clause [...]
Specifically, in order to enable code like:
```rust
trait Foo {
fn bar() -> impl Sized;
}
fn is_send(_: impl Send) {}
fn test<T>()
where
T: Foo,
T::bar(..): Send,
{
is_send(T::bar());
}
```
* In the resolver, when we see a `TyKind::Path` whose final segment is `GenericArgs::ParenthesizedElided` (i.e. `(..)`), resolve that path in the *value* namespace, since we're looking for a method.
* When lowering where clauses in HIR lowering, we first try to intercept an RTN self type via `lower_ty_maybe_return_type_notation`. If we find an RTN type, we lower it manually in a way that respects its higher-ranked-ness (see below) and resolves to the corresponding RPITIT. Anywhere else, we'll emit the same "return type notation not allowed in this position yet" error we do when writing RTN in every other position.
* In `resolve_bound_vars`, we add some special treatment for RTN types in where clauses. Specifically, we need to add new lifetime variables to our binders for the early- and late-bound vars we encounter on the method. This implements the higher-ranked desugaring [laid out in the RFC](https://rust-lang.github.io/rfcs/3654-return-type-notation.html#converting-to-higher-ranked-trait-bounds).
This PR also adds a bunch of tests, mostly negative ones (testing error messages).
In a follow-up PR, I'm going to mark RTN as no longer incomplete, since this PR basically finishes the impl surface that we should initially stabilize, and the RFC was accepted.
cc [RFC 3654](https://github.com/rust-lang/rfcs/pull/3654) and https://github.com/rust-lang/rust/issues/109417
Correct outdated object size limit
The comment here about 48 bit addresses being enough was written in 2016 but was made incorrect in 2019 by 5-level paging, and then persisted for another 5 years before being noticed and corrected.
The bolding of the "exclusive" part is merely to call attention to something I missed when reading it and doublechecking the math.
try-job: i686-msvc
try-job: test-various
When we have two types with the same name, one without type parameters and the other with type parameters and a derive macro, we were before incorrectly suggesting to remove type parameters from the former, which ICEd because we were suggesting to remove nothing. We now gate against this.
The output is still not perfect. E0107 should explicitly detect this case and provide better context, but for now let's avoid the ICE.
Implement a Method to Seal `DiagInner`'s Suggestions
This PR adds a method on `DiagInner` called `.seal_suggestions()` to prevent new suggestions from being added while preserving existing suggestions.
This is useful because currently there is no way to prevent new suggestions from being added to a diagnostic. `.disable_suggestions()` is the closest but it gets rid of all suggestions before and after the call.
Therefore, `.seal_suggestions()` can be used when, for example, misspelled keyword is detected and reported. In such cases, we may want to prevent other suggestions from being added to the diagnostic, as they would likely be meaningless once the misspelled keyword is identified. For context: https://github.com/rust-lang/rust/pull/129899#discussion_r1741307132
To store an additional state, the type of the `suggestions` field in `DiagInner` was changed into a three variant enum. While this change affects files across different crates, care was taken to preserve the existing code's semantics. This is validated by the fact that all UI tests pass without any modifications.
r? chenyukang
Rollup of 4 pull requests
Successful merges:
- #123436 (linker: Allow MSVC to use import libraries following the Meson/MinGW convention)
- #130410 (Don't ICE when generating `Fn` shim for async closure with borrowck error)
- #130412 (Don't ICE when RPITIT captures more method args than trait definition)
- #130436 (Ignore reduce-fadd-unordered on SGX platform)
r? `@ghost`
`@rustbot` modify labels: rollup
Rescope temp lifetime in if-let into IfElse with migration lint
Tracking issue #124085
This PR shortens the temporary lifetime to cover only the pattern matching and consequent branch of a `if let`.
At the expression location, means that the lifetime is shortened from previously the deepest enclosing block or statement in Edition 2021. This warrants an Edition change.
Coming with the Edition change, this patch also implements an edition lint to warn about the change and a safe rewrite suggestion to preserve the 2021 semantics in most cases.
Related to #103108.
Related crater runs: https://github.com/rust-lang/rust/pull/129466.
Fix `clippy::useless_conversion`
Self-explanatory. Probably the last clippy change I'll actually put up since this is the only other one I've actually seen in the wild.
Simplify some nested `if` statements
Applies some but not all instances of `clippy::collapsible_if`. Some ended up looking worse afterwards, though, so I left those out. Also applies instances of `clippy::collapsible_else_if`
Review with whitespace disabled please.
Correctly handle stability of `#[diagnostic]` attributes
This commit changes the way we treat the stability of attributes in the
`#[diagnostic]` namespace. Instead of relaying on ad-hoc checks to
ensure at call side that a certain attribute is really usable at that
location it centralises the logic to one place. For diagnostic
attributes comming from other crates it just skips serializing
attributes that are not stable and that do not have the corresponding
feature enabled. For attributes from the current crate we can just use
the feature information provided by `TyCtx`.
r? `@compiler-errors`
Arbitrary self types v2: pointers feature gate.
The main `arbitrary_self_types` feature gate will shortly be reused for a new version of arbitrary self types which we are amending per [this RFC](https://github.com/rust-lang/rfcs/blob/master/text/3519-arbitrary-self-types-v2.md). The main amendments are:
* _do_ support `self` types which can't safely implement `Deref`
* do _not_ support generic `self` types
* do _not_ support raw pointers as `self` types.
This PR relates to the last of those bullet points: this strips pointer support from the current `arbitrary_self_types` feature. We expect this to cause some amount of breakage for crates using this unstable feature to allow raw pointer self types. If that's the case, we want to know about it, and we want crate authors to know of the upcoming changes.
For now, this can be resolved by adding the new
`arbitrary_self_types_pointers` feature to such crates. If we determine that use of raw pointers as self types is common, then we may maintain that as an unstable feature even if we come to stabilize the rest of the `arbitrary_self_types` support in future. If we don't hear that this PR is causing breakage, then perhaps we don't need it at all, even behind an unstable feature gate.
[Tracking issue](https://github.com/rust-lang/rust/issues/44874)
This is [step 4 of the plan outlined here](https://github.com/rust-lang/rust/issues/44874#issuecomment-2122179688)
Suggest `impl Trait` for References to Bare Trait in Function Header
Fixes#125139
This PR suggests `impl Trait` when `&Trait` is found as a function parameter type or return type. This makes use of existing diagnostics by adding `peel_refs()` when checking for type equality.
Additionaly, it makes a few other improvements:
1. Checks if functions inside impl blocks have bare trait in their headers.
2. Introduces a trait `NextLifetimeParamName` similar to the existing `NextTypeParamName` for suggesting a lifetime name. Also, abstracts out the common logic between the two trait impls.
### Related Issues
I ran into a bunch of related diagnostic issues but couldn't fix them within the scope of this PR. So, I have created the following issues:
1. [Misleading Suggestion when Returning a Reference to a Bare Trait from a Function](https://github.com/rust-lang/rust/issues/127689)
2. [Verbose Error When a Function Takes a Bare Trait as Parameter](https://github.com/rust-lang/rust/issues/127690)
3. [Incorrect Suggestion when Returning a Bare Trait from a Function](https://github.com/rust-lang/rust/issues/127691)
r? ```@estebank``` since you implemented #119148
Remove `#[macro_use] extern crate tracing`, round 4
Because explicit importing of macros via use items is nicer (more standard and readable) than implicit importing via #[macro_use]. Continuing the work from #124511, #124914, and #125434. After this PR no `rustc_*` crates use `#[macro_use] extern crate tracing` except for `rustc_codegen_gcc` which is a special case and I will do separately.
r? ```@jieyouxu```
Get rid of `predicates_defined_on`
This is the uncontroversial part of #129532. This simply inlines the `predicates_defined_on` into into `predicates_of`. Nothing should change here logically.
Stop storing a special inner body for the coroutine by-move body for async closures
...and instead, just synthesize an item which is treated mostly normally by the MIR pipeline.
This PR does a few things:
* We synthesize a new `DefId` for the by-move body of a closure, which has its `mir_built` fed with the output of the `ByMoveBody` MIR transformation, and some other relevant queries.
* This has the `DefKind::ByMoveBody`, which we use to distinguish it from "real" bodies (that come from HIR) which need to be borrowck'd. Introduce `TyCtxt::is_synthetic_mir` to skip over `mir_borrowck` which is called by `mir_promoted`; borrowck isn't really possible to make work ATM since it heavily relies being called on a body generated from HIR, and is redundant by the construction of the by-move-body.
* Remove the special `PassManager` hacks for handling the inner `by_move_body` stored within the coroutine's mir body. Instead, this body is fed like a regular MIR body, so it's goes through all of the `tcx.*_mir` stages normally (build -> promoted -> ...etc... -> optimized) ✨.
* Remove the `InstanceKind::ByMoveBody` shim, since now we have a "regular" def id, we can just use `InstanceKind::Item`. This also allows us to remove the corresponding hacks from codegen, such as in `fn_sig_for_fn_abi` ✨.
Notable remarks:
* ~~I know it's kind of weird to be using `DefKind::Closure` here, since it's not a distinct closure but just a new MIR body. I don't believe it really matters, but I could also use a different `DefKind`... maybe one that we could use for synthetic MIR bodies in general?~~ edit: We're doing this now.
The main `arbitrary_self_types` feature gate will shortly be reused for
a new version of arbitrary self types which we are amending per [this
RFC](https://github.com/rust-lang/rfcs/blob/master/text/3519-arbitrary-self-types-v2.md).
The main amendments are:
* _do_ support `self` types which can't safely implement `Deref`
* do _not_ support generic `self` types
* do _not_ support raw pointers as `self` types.
This PR relates to the last of those bullet points: this strips pointer
support from the current `arbitrary_self_types` feature.
We expect this to cause some amount of breakage for crates using this
unstable feature to allow raw pointer self types. If that's the case, we
want to know about it, and we want crate authors to know of the upcoming
changes.
For now, this can be resolved by adding the new
`arbitrary_self_types_pointers` feature to such crates. If we determine
that use of raw pointers as self types is common, then we may maintain
that as an unstable feature even if we come to stabilize the rest of the
`arbitrary_self_types` support in future. If we don't hear that this PR
is causing breakage, then perhaps we don't need it at all, even behind
an unstable feature gate.
[Tracking issue](https://github.com/rust-lang/rust/issues/44874)
This is [step 4 of the plan outlined here](https://github.com/rust-lang/rust/issues/44874#issuecomment-2122179688)
Remove redundant flags from `lower_ty_common` that can be inferred from the HIR
...and then get rid of `lower_ty_common`.
r? ``@fmease`` or re-roll if you're busy!
Print the generic parameter along with the variance in dumps.
This allows to make sure we are testing what we think we are testing.
While the tests are correct, I discovered that opaque duplicated args are in the reverse declaration order.
Given `trait Any: 'static` and a `struct` with a `Box<dyn Any + 'a>` field, point at the `'static` bound in `Any` to explain why `'a: 'static`.
```
error[E0478]: lifetime bound not satisfied
--> f202.rs:2:12
|
2 | value: Box<dyn std::any::Any + 'a>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: lifetime parameter instantiated with the lifetime `'a` as defined here
--> f202.rs:1:14
|
1 | struct Hello<'a> {
| ^^
note: but lifetime parameter must outlive the static lifetime
--> /home/gh-estebank/rust/library/core/src/any.rs:113:16
|
113 | pub trait Any: 'static {
| ^^^^^^^
```
Partially address #33652.
Use shorthand field initialization syntax more aggressively in the compiler
Caught these when cleaning up #129344 and decided to run clippy to find the rest
Use `bool` in favor of `Option<()>` for diagnostics
We originally only supported `Option<()>` for optional notes/labels, but we now support `bool`. Let's use that, since it usually leads to more readable code.
I'm not removing the support from the derive macro, though I guess we could error on it... 🤔
Minor Refactor: Remove a Redundant Conditional Check
The existing code checks `where_bounds.is_empty()` twice when
it can be combined into one. Now, after combining, the refactored code reads
better and feels straightforward.
The diff doesn't make it clear. So, the current code looks like this:
``` rust
if !where_bounds.is_empty() {
err.help(format!(
"consider introducing a new type parameter `T` and adding `where` constraints:\
\n where\n T: {qself_str},\n{}",
where_bounds.join(",\n"),
));
}
let reported = err.emit();
if !where_bounds.is_empty() {
return Err(reported);
}
```
The proposed changes:
``` rust
if !where_bounds.is_empty() {
err.help(format!(
"consider introducing a new type parameter `T` and adding `where` constraints:\
\n where\n T: {qself_str},\n{}",
where_bounds.join(",\n"),
));
let reported = err.emit();
return Err(reported);
}
err.emit();
```
Shrink `TyKind::FnPtr`.
By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and `FnHeader`, which can be packed more efficiently. This reduces the size of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms. This reduces peak memory usage by a few percent on some benchmarks. It also reduces cache misses and page faults similarly, though this doesn't translate to clear cycles or wall-time improvements on CI.
r? `@compiler-errors`
Store `do_not_recommend`-ness in impl header
Alternative to #128674
It's less flexible, but also less invasive. Hopefully it's also performant. I'd recommend we think separately about the design for how to gate arbitrary diagnostic attributes moving forward.
Differentiate between methods and associated functions in diagnostics
Accurately refer to assoc fn without receiver as assoc fn instead of methods. Add `AssocItem::descr` method to centralize where we call methods and associated functions.
Cache supertrait outlives of impl header for soundness check
This caches the results of computing the transitive supertraits of an impl and filtering it to its outlives obligations. This is purely an optimization to improve https://github.com/rust-lang/rust/pull/124336.
Accurately refer to assoc fn without receiver as assoc fn instead of methods.
Add `AssocItem::descr` method to centralize where we call methods and associated functions.
By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and
`FnHeader`, which can be packed more efficiently. This reduces the size
of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms.
This reduces peak memory usage by a few percent on some benchmarks. It
also reduces cache misses and page faults similarly, though this doesn't
translate to clear cycles or wall-time improvements on CI.
The existing code check for `where_bounds.is_empty()` twice when
it can be combined into one. Moreover, the refactored code reads
better and feels straightforward.
minor `effects` cleanups
* remove the fixme comment about not needing defaults because it turns out we do need defaults (if I made it None instead it would ice a bunch of tests)
* remove the part that special cased trait args when lowering them. This is now historical because effects doesn't add host args to traits anymore (we use associated types now)
Fix ICE Caused by Incorrectly Delaying E0107
Fixes #128249
For the following code:
```rust
trait Foo<T> {}
impl Foo<T: Default> for u8 {}
```
#126054 added some logic to delay emitting E0107 as the names of associated type `T` in the impl header and generic parameter `T` in `trait Foo` match.
But it failed to ensure whether such unexpected associated type bounds are coming from a impl block header. This caused an ICE as the compiler was delaying E0107 for code like:
```rust
trait Trait<Type> {
type Type;
fn method(&self) -> impl Trait<Type: '_>;
}
```
because it assumed the associated type bound `Type: '_` is for the generic parameter `Type` in `trait Trait` since the names are same.
This PR adds a check to ensure that E0107 is delayed only in the context of impl block header.
Tweak type inference for `const` operands in inline asm
Previously these would be treated like integer literals and default to `i32` if a type could not be determined. To allow for forward-compatibility with `str` constants in the future, this PR changes type inference to use an unbound type variable instead.
The actual type checking is deferred until after typeck where we still ensure that the final type for the `const` operand is an integer type.
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turn `invalid_type_param_default` into a `FutureReleaseErrorReportInDeps`
`````@rust-lang/types````` I assume the plan is still to disallow this? It has been a future-compat lint for a long time, seems ripe to go for hard error.
However, turns out that outright removing it right now would lead to [tons of crater regressions](https://github.com/rust-lang/rust/pull/127655#issuecomment-2228285460), so for now this PR just makes this future-compat lint show up in cargo's reports, so people are warned when they use a dependency that is affected by this.
Fixes https://github.com/rust-lang/rust/issues/27336 by removing the feature gate (so there's no way to silence the lint even on nightly)
CC https://github.com/rust-lang/rust/issues/36887
Delegation: support generics for delegation from free functions
(The PR was split from https://github.com/rust-lang/rust/pull/123958, explainer - https://github.com/Bryanskiy/posts/blob/master/delegation%20in%20generic%20contexts.md)
This PR implements generics inheritance from free functions to free functions and trait methods.
#### free functions to free functions:
```rust
fn to_reuse<T: Clone>(_: T) {}
reuse to_reuse as bar;
// desugaring:
fn bar<T: Clone>(x: T) {
to_reuse(x)
}
```
Generics, predicates and signature are simply copied. Generic arguments in paths are ignored during generics inheritance:
```rust
fn to_reuse<T: Clone>(_: T) {}
reuse to_reuse::<u8> as bar;
// desugaring:
fn bar<T: Clone>(x: T) {
to_reuse::<u8>(x) // ERROR: mismatched types
}
```
Due to implementation limitations callee path is lowered without modifications. Therefore, it is a compilation error at the moment.
#### free functions to trait methods:
```rust
trait Trait<'a, A> {
fn foo<'b, B>(&self, x: A, y: B) {...}
}
reuse Trait::foo;
// desugaring:
fn foo<'a, 'b, This: Trait<'a, A>, A, B>(this: &This, x: A, y: B) {
Trait::foo(this, x, y)
}
```
The inheritance is similar to the previous case but with some corrections:
- `Self` parameter converted into `T: Trait`
- generic parameters need to be reordered so that lifetimes go first
Arguments are similarly ignored.
---
In the future, we plan to support generic inheritance for delegating from all contexts to all contexts (from free/trait/impl to free/trait /impl). These cases were considered first as the simplest from the implementation perspective.
Add `select_unpredictable` to force LLVM to use CMOV
Since https://reviews.llvm.org/D118118, LLVM will no longer turn CMOVs into branches if it comes from a `select` marked with an `unpredictable` metadata attribute.
This PR introduces `core::intrinsics::select_unpredictable` which emits such a `select` and uses it in the implementation of `binary_search_by`.
Don't record trait aliases as marker traits
Don't record `#[marker]` on trait aliases, since we use that to check for the (non-presence of) associated types and other things which don't make sense of trait aliases. We already enforce this attr is only applied to a trait.
Also do the same for `#[const_trait]`, which we also enforce is only applied to a trait. This is a drive-by change, but also worthwhile just in case.
Fixes#127222
Since https://reviews.llvm.org/D118118, LLVM will no longer turn CMOVs
into branches if it comes from a `select` marked with an `unpredictable`
metadata attribute.
This PR introduces `core::intrinsics::select_unpredictable` which emits
such a `select` and uses it in the implementation of `binary_search_by`.
Support ?Trait bounds in supertraits and dyn Trait under a feature gate
This patch allows `maybe` polarity bounds under a feature gate. The only language change here is that corresponding hard errors are replaced by feature gates. Example:
```rust
#![feature(allow_maybe_polarity)]
...
trait Trait1 : ?Trait { ... } // ok
fn foo(_: Box<(dyn Trait2 + ?Trait)>) {} // ok
fn bar<T: ?Sized + ?Trait>(_: &T) {} // ok
```
Maybe bounds still don't do anything (except for `Sized` trait), however this patch will allow us to [experiment with default auto traits](https://github.com/rust-lang/rust/pull/120706#issuecomment-1934006762).
This is a part of the [MCP: Low level components for async drop](https://github.com/rust-lang/compiler-team/issues/727)
Make it crystal clear what lint `type_alias_bounds` actually signifies
This is part of my work on https://github.com/rust-lang/rust/labels/F-lazy_type_alias ([tracking issue](#112792)).
---
To recap, the lint `type_alias_bounds` detects bounds on generic parameters and where clauses on (eager) type aliases. These bounds should've never been allowed because they are currently neither enforced[^1] at usage sites of type aliases nor thoroughly checked for correctness at definition sites due to the way type aliases are represented in the compiler. Allowing them was an oversight.
Explicitly label this as a known limitation of the type checker/system and establish the experimental feature `lazy_type_alias` as its eventual proper solution.
Where this becomes a bit tricky (for me as a rustc dev) are the "secondary effects" of these bounds whose existence I sadly can't deny. As a matter of fact, type alias bounds do play some small roles during type checking. However, after a lot of thinking over the last two weeks I've come to the conclusion (not without second-guessing myself though) that these use cases should not trump the fact that these bounds are currently *inherently broken*. Therefore the lint `type_alias_bounds` should and will continue to flag bounds that may have subordinate uses.
The two *known* secondary effects are:
1. They may enable the use of "shorthand" associated type paths `T::Assoc` (as opposed to fully qualified paths `<T as Trait>::Assoc`) where `T` is a type param bounded by some trait `Trait` which defines that assoc ty.
2. They may affect the default lifetime of trait object types passed as a type argument to the type alias. That concept is called (trait) object lifetime default.
The second one is negligible, no question asked. The first one however is actually "kinda nice" (for writability) and comes up in practice from time to time.
So why don't I just special-case trait bounds that "define" shorthand assoc type paths as originally planned in #125709?
1. Starting to permit even a tiny subset of bounds would already be enough to send a signal to users that bounds in type aliases have been legitimized and that they can expect to see type alias bounds in the wild from now on (proliferation). This would be actively misleading and dangerous because those bounds don't behave at all like one would expect, they are *not real*[^2]!
1. Let's take `type A<T: Trait> = T::Proj;` for example. Everywhere else in the language `T: Trait` means `T: Trait + Sized`. For type aliases, that's not the case though: `T: Trait` and `T: Trait + ?Sized` for that matter do neither mean `T: Trait + Sized` nor `T: Trait + ?Sized` (for both!). Instead, whether `T` requires `Sized` or not entirely depends on the definition of `Trait`[^2]. Namely, whether or not it is bounded by `Sized`.
2. Given `type A<T: Trait<AssocA = ()>> = T::AssocB;`, while `X: Trait` gets checked given `A<X>` (by virtue of projection wfchecking post alias expansion[^2]), the associated type constraint `AssocA = ()` gets dropped entirely! While we could choose to warn on such cases, it would inevitably lead to a huge pile of special cases.
3. While it's common knowledge that the body / aliased type / RHS of an (eager) type alias does not get checked for well-formedness, I'm not sure if people would realize that that extends to bounds as well. Namely, `type A<T: Trait<[u8]>> = T::Proj;` compiles even if `Trait`'s generic parameter requires `Sized`. Of course, at usage sites `[u8]: Sized` would still end up getting checked[^2], so it's not a huge problem if you have full control over `A`. However, imagine that `A` was actually part of a public API and was never used inside the defining crate (not unreasonable). In such a scenario, downstream users would be presented with an impossible to use type alias! Remember, bounds may grow arbitrarily complex and nuanced in practice.
4. Even if we allowed trait bounds that "define" shorthand assoc type paths, we would still need to continue to warn in cases where the assoc ty comes from a supertrait despite the fact that the shorthand syntax can be used: `type A<T: Sub> = T::Assoc;` does compile given `trait Sub: Super {}` and `trait Super { type Assoc; }`. However, `A<X>` does not enforce `X: Sub`, only `X: Super`[^2]. All that to say, type alias bounds are simply not real and we shouldn't pretend they are!
5. Summarizing the points above, we would be legitimizing bounds that are completely broken!
2. It's infeasible to implement: Due to the lack of `TypeckResults` in `ItemCtxt` (and a way to propagate it to other parts of the compiler), the resolution of type-dependent paths in non-`Body` items (most notably type aliases) is not recoverable from the HIR alone which would be necessary because the information of whether an associated type path (projection) is a shorthand is only present pre&in-HIR and doesn't survive HIR ty lowering. Of course, I could rerun parts of HIR ty lowering inside the lint `type_alias_bounds` (namely, `probe_single_ty_param_bound_for_assoc_ty` which would need to be exposed or alternatively a stripped-down version of it). This likely has a performance impact and introduces complexity. In short, the "benefits" are not worth the costs.
---
* 3rd commit: Update a diagnostic to avoid suggesting type alias bounds
* 4th commit: Flag type alias bounds even if the RHS contains inherent associated types.
* I started to allow them at some point in the past which was not correct (see commit for details)
* 5th commit: Allow type alias bounds if the RHS contains const projections and GCEs are enabled
* (and add a `FIXME(generic_const_exprs)` to be revisited before (M)GCE's stabilization)
* As a matter of fact type alias bounds are enforced in this case because the contained AnonConsts do get checked for well-formedness and crucially they inherit the generics and predicates of their parent item (here: the type alias)
* Remaining commits: Improve the lint `type_alias_bounds` itself
---
Fixes#125789 (sugg diag fix).
Fixes#125709 (wontfix, acknowledgement, sugg diag applic fix).
Fixes#104918 (sugg diag applic fix).
Fixes#100270 (wontfix, acknowledgement, sugg diag applic fix).
Fixes#94398 (true fix).
r? `@compiler-errors` `@oli-obk`
[^1]: From the perspective of the trait solver.
[^2]: Given `type A<T: Trait> = T::Proj;`, the reason why the trait bound "`T: Trait`" gets *seemingly* enforced at usage sites of the type alias `A` is simply because `A<X>` gets expanded to "`<X as Trait>::Proj`" very early on and it's the *expansion* that gets checked for well-formedness, not the type alias reference.
Graciously handle `Drop` impls introducing more generic parameters than the ADT
Follow up to #110577Fixes#126378Fixes#126889
## Motivation
A current issue with the way we check drop impls do not specialize any of their generic parameters is that when the `Drop` impl introduces *more* generic parameters than are present on the ADT, we fail to prove any bounds involving those parameters. This can be demonstrated with the following [code on stable](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=139b65e4294634d7286a3282bc61e628) which fails due to the fact that `<T as Trait>::Assoc == U` is not present in `Foo`s `ParamEnv` even though arguably there is no reason it cannot compiler:
```rust
struct Foo<T: Trait>(T);
trait Trait {
type Assoc;
}
impl<T: Trait<Assoc = U>, U: ?Sized> Drop for Foo<T> {
//~^ ERROR: `Drop` impl requires `<T as Trait>::Assoc == U` but the struct ...
fn drop(&mut self) {}
}
fn main() {}
```
I think the motivation for supporting this code is somewhat lacking, it might be useful in practice for deeply nested associated types where you might want to be able to write:
`where T: Trait<Assoc: Other<AnotherAssoc: MoreTrait<YetAnotherAssoc: InnerTrait<Final = U>>>>`
in order to be able to just use `U` in the function body instead of writing out the whole nested associated type. Regardless I don't think there is really any reason to *not* support this code and it is relatively easy to support it.
What I find slightly more compelling is the fact that when defining a const parameter `const N: u8` we desugar that to having a where clause requiring the constant `N` is typed as `u8` (`ClauseKind::ConstArgHasType`). As we *always* desugar const parameters to have these bounds, if we attempt to prove that some const parameter `N` is of type `u8` and there is no bound on `N` in the enviroment that generally indicates usage of an incorrect `ParamEnv` (this has caught a bug already).
Given that, if we write the following code:
```rust
#![feature(associated_const_equality)]
struct Foo<T: Trait>(T);
trait Trait {
const ASSOC: usize;
}
impl<T: Trait<ASSOC = N>, const N: usize> Drop for Foo<T> {
fn drop(&mut self) {}
}
fn main() {}
```
The `Drop` impl would have this desugared where clause about `N` being of type `usize`, and if we were to try to prove that where clause in `Foo`'s `ParamEnv` we would ICE as there would not be any `ConstArgHasType` in the environment (which generally indicates improper `ParamEnv` usage. As this is otherwise well formed code (the `T: Trait<ASSOC = N>` causes `N` to be constrained) we have to handle this *somehow* and I believe the only principled way to support this is the changes I have made to `dropck.rs` that would cause these code examples to compiler (Perhaps we could just throw out all `ConstArgHasType` where clauses from the predicates we prove but that makes me nervous even if it might actually be okay).
## The changes
Currently the way `dropck.rs` works is that take the `ParamEnv` of the ADT and instantiate it with the generic arguments used on the self ty of the `impl`. We then instantiate the predicates of the drop impl with the identity params to the impl, e.g. in the original example `<T as Trait>::Assoc == U` stays as `<T as Trait>::Assoc == U`. We then attempt to prove all the where clauses in the instantiated env of the self type ADT.
This PR changes us to first instantiate the impl with infer vars, then we equate the self type (with infer vars as its generic arguments) with the self type as written by the user. This causes all generic parameters on the impl that are constrained via associated type/const equality bounds to be left as inference variables while all other parameters are still `Ty`/`Const`/`Region`
Finally when instantiating the predicates on the impl, instead of using the identity arguments, we use the list of inference variables of which some have been inferred to the impl parameters. In practice this means that we wind up proving `<T as Trait>::Assoc == ?x` which can succeed just fine. In the const generics example we would wind up trying to prove `ConstArgHasType(?x: usize)` instead of `ConstArgHasType(N: usize)` which avoids the ICE as it is expected to encounter goals of the form `?x: usize`.
At a higher level the way I justify/think about this is that as we are proving goals in the environment of the ADT (`Foo` in the above examples), we do not expect to encounter generic parameters from a different environment so we must "deal with them" somehow. In this PR we handle them by replacing them with inference variables as they should either *actually* be unconstrained (and we will error later) or they are constrained to be equal to some associated type/const.
To go along with this it would be nice if we were not instantiating the adt's env with the generic arguments to the ADT in the `Drop` impl as it would make it clearer we are proving bounds in the adt's env instead of the `Drop` impl's. Instead we would map the predicates on the drop impl to be valid in the environment of the adt. In practice this causes diagnostic regressions as all of the generic parameters in errors refer to the ones defined on the adt; attempting to map these back to the ones on the impl, while possible, is involved as writing a `TypeFolder` over `FulfillmentError` is non trivial.
## Edge cases
There are some subtle interactions here:
One is that we should not allow `<T as Trait>::Assoc == U` to be present on the `Drop` if `U` is constrained by the self type of the impl and the bound is not present in the ADT's environment. demonstrated with the [following code](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=af839e2c3e43e03a624825c58af84dff):
```rust
trait Trait {
type Assoc;
}
struct Foo<T: Trait, U: ?Sized>(T, U);
impl<T: Trait<Assoc = U>, U: ?Sized> Drop for Foo<T, U> {
//~^ ERROR: `Drop` impl requires `<T as Trait>::Assoc == U`
fn drop(&mut self) {}
}
fn main() {}
```
This is tested at `tests/ui/dropck/constrained_by_assoc_type_equality_and_self_ty.rs`.
Another weirdness is that we permit the following code to compile now:
```rust
struct Foo<T>(T);
impl<'a, T: 'a> Drop for Foo<T> {
fn drop(&mut self) {}
}
```
This is caused by the fact that we permit unconstrained lifetime parameters in trait implementations as long as they are not used in associated types (so we do not wind up erroring on this code like we perhaps ought to), combined with the fact that as we are now proving `T: '?x` instead of `T: 'a` which allows proving the bound via `'?x= 'empty` wheras previously it would have failed.
This is tested as part of `tests/ui/dropck/reject-specialized-drops-8142.rs`.
---
r? `@compiler-errors`
Previously these would be treated like integer literals and default to
`i32` if a type could not be determined. To allow for
forward-compatibility with `str` constants in the future, this PR
changes type inference to use an unbound type variable instead.
The actual type checking is deferred until after typeck where we still
ensure that the final type for the `const` operand is an integer type.
Uplift most type-system related error reporting from `rustc_infer` to `rustc_trait_selection`
Completes the major part of #127492. The only cleanup that's needed afterwards is to actually use normalization in favor of the callback where needed, and deleting `can_eq_shallow`.
r? lcnr
Sorry for the large diff! Would prefer if comments can be handled in a follow-up (unless they're absolutely dealbreakers) because it seems bitrotty to let this sit.
Just totally fully deny late-bound consts
Kinda don't care about supporting this until we have where clauses on binders. They're super busted and should be reworked in due time, and they are approximately 100% useless until then 😸Fixes#127970Fixes#127009
r? ``@BoxyUwU``
Forbid borrows and unsized types from being used as the type of a const generic under `adt_const_params`
Fixes#112219Fixes#112124Fixes#112125
### Motivation
Currently the `adt_const_params` feature allows writing `Foo<const N: [u8]>` this is entirely useless as it is not possible to write an expression which evaluates to a type that is not `Sized`. In order to actually use unsized types in const generics they are typically written as `const N: &[u8]` which *is* possible to provide a value of.
Unfortunately allowing the types of const parameters to contain references is non trivial (#120961) as it introduces a number of difficult questions about how equality of references in the type system should behave. References in the types of const generics is largely only useful for using unsized types in const generics.
This PR introduces a new feature gate `unsized_const_parameters` and moves support for `const N: [u8]` and `const N: &...` from `adt_const_params` into it. The goal here hopefully is to experiment with allowing `const N: [u8]` to work without references and then eventually completely forbid references in const generics.
Splitting this out into a new feature gate means that stabilization of `adt_const_params` does not have to resolve#120961 which is the only remaining "big" blocker for the feature. Remaining issues after this are a few ICEs and naming bikeshed for `ConstParamTy`.
### Implementation
The implementation is slightly subtle here as we would like to ensure that a stabilization of `adt_const_params` is forwards compatible with any outcome of `unsized_const_parameters`. This is inherently tricky as we do not support unstable trait implementations and we determine whether a type is valid as the type of a const parameter via a trait bound.
There are a few constraints here:
- We would like to *allow for the possibility* of adding a `Sized` supertrait to `ConstParamTy` in the event that we wind up opting to not support unsized types and instead requiring people to write the 'sized version', e.g. `const N: [u8; M]` instead of `const N: [u8]`.
- Crates should be able to enable `unsized_const_parameters` and write trait implementations of `ConstParamTy` for `!Sized` types without downstream crates that only enable `adt_const_params` being able to observe this (required for std to be able to `impl<T> ConstParamTy for [T]`
Ultimately the way this is accomplished is via having two traits (sad), `ConstParamTy` and `UnsizedConstParamTy`. Depending on whether `unsized_const_parameters` is enabled or not we change which trait is used to check whether a type is allowed to be a const parameter.
Long term (when stabilizing `UnsizedConstParamTy`) it should be possible to completely merge these traits (and derive macros), only having a single `trait ConstParamTy` and `macro ConstParamTy`.
Under `adt_const_params` it is now illegal to directly refer to `ConstParamTy` it is only used as an internal impl detail by `derive(ConstParamTy)` and checking const parameters are well formed. This is necessary in order to ensure forwards compatibility with all possible future directions for `feature(unsized_const_parameters)`.
Generally the intuition here should be that `ConstParamTy` is the stable trait that everything uses, and `UnsizedConstParamTy` is that plus unstable implementations (well, I suppose `ConstParamTy` isn't stable yet :P).
Avoid ref when using format! in compiler
Clean up a few minor refs in `format!` macro, as it has a performance cost. Apparently the compiler is unable to inline `format!("{}", &variable)`, and does a run-time double-reference instead (format macro already does one level referencing). Inlining format args prevents accidental `&` misuse.
See also https://github.com/rust-lang/rust-clippy/issues/10851
Clean up a few minor refs in `format!` macro, as it has a performance cost. Apparently the compiler is unable to inline `format!("{}", &variable)`, and does a run-time double-reference instead (format macro already does one level referencing). Inlining format args prevents accidental `&` misuse.
Lazy type aliases: Diagostics: Detect bivariant ty params that are only used recursively
Follow-up to errs's #127871. Extends the logic to cover LTAs, too, not just ADTs.
This change only takes effect with the next-gen solver enabled as cycle errors like
the one we have here are fatal in the old solver. That's my explanation anyways.
r? compiler-errors
Use structured suggestions for unconstrained generic parameters on impl blocks
I did not deduplicate with `UnusedGenericParameter`, because in contrast to type declarations, just using a generic parameter in an impl isn't enough, it must be used with the right variance and not just as part of a projection.
`C-cmse-nonsecure-call`: improved error messages
tracking issue: #81391
issue for the error messages (partially implemented by this PR): #81347
related, in that it also deals with CMSE: https://github.com/rust-lang/rust/pull/127766
When using the `C-cmse-nonsecure-call` ABI, both the arguments and return value must be passed via registers. Previously, when violating this constraint, an ugly LLVM error would be shown. Now, the rust compiler itself will print a pretty message and link to more information.
Rollup of 7 pull requests
Successful merges:
- #121533 (Handle .init_array link_section specially on wasm)
- #127825 (Migrate `macos-fat-archive`, `manual-link` and `archive-duplicate-names` `run-make` tests to rmake)
- #127891 (Tweak suggestions when using incorrect type of enum literal)
- #127902 (`collect_tokens_trailing_token` cleanups)
- #127928 (Migrate `lto-smoke-c` and `link-path-order` `run-make` tests to rmake)
- #127935 (Change `binary_asm_labels` to only fire on x86 and x86_64)
- #127953 ([compiletest] Search *.a when getting dynamic libraries on AIX)
r? `@ghost`
`@rustbot` modify labels: rollup
Represent type-level consts with new-and-improved `hir::ConstArg`
### Summary
This is a step toward `min_generic_const_exprs`. We now represent all const
generic arguments using an enum that differentiates between const *paths*
(temporarily just bare const params) and arbitrary anon consts that may perform
computations. This will enable us to cleanly implement the `min_generic_const_args`
plan of allowing the use of generics in paths used as const args, while
disallowing their use in arbitrary anon consts. Here is a summary of the salient
aspects of this change:
- Add `current_def_id_parent` to `LoweringContext`
This is needed to track anon const parents properly once we implement
`ConstArgKind::Path` (which requires moving anon const def-creation
outside of `DefCollector`).
- Create `hir::ConstArgKind` enum with `Path` and `Anon` variants. Use it in the
existing `hir::ConstArg` struct, replacing the previous `hir::AnonConst` field.
- Use `ConstArg` for all instances of const args. Specifically, use it instead
of `AnonConst` for assoc item constraints, array lengths, and const param
defaults.
- Some `ast::AnonConst`s now have their `DefId`s created in
rustc_ast_lowering rather than `DefCollector`. This is because in some
cases they will end up becoming a `ConstArgKind::Path` instead, which
has no `DefId`. We have to solve this in a hacky way where we guess
whether the `AnonConst` could end up as a path const since we can't
know for sure until after name resolution (`N` could refer to a free
const or a nullary struct). If it has no chance as being a const
param, then we create a `DefId` in `DefCollector` -- otherwise we
decide during ast_lowering. This will have to be updated once all path
consts use `ConstArgKind::Path`.
- We explicitly use `ConstArgHasType` for array lengths, rather than
implicitly relying on anon const type feeding -- this is due to the
addition of `ConstArgKind::Path`.
- Some tests have their outputs changed, but the changes are for the
most part minor (including removing duplicate or almost-duplicate
errors). One test now ICEs, but it is for an incomplete, unstable
feature and is now tracked at https://github.com/rust-lang/rust/issues/127009.
### Followup items post-merge
- Use `ConstArgKind::Path` for all const paths, not just const params.
- Fix (no github dont close this issue) #127009
- If a path in generic args doesn't resolve as a type, try to resolve as a const
instead (do this in rustc_resolve). Then remove the special-casing from
`rustc_ast_lowering`, so that all params will automatically be lowered as
`ConstArgKind::Path`.
- (?) Consider making `const_evaluatable_unchecked` a hard error, or at least
trying it in crater
r? `@BoxyUwU`
Tweak suggestions when using incorrect type of enum literal
More accurate suggestions when writing wrong style of enum variant literal:
```
error[E0533]: expected value, found struct variant `E::Empty3`
--> $DIR/empty-struct-braces-expr.rs:18:14
|
LL | let e3 = E::Empty3;
| ^^^^^^^^^ not a value
|
help: you might have meant to create a new value of the struct
|
LL | let e3 = E::Empty3 {};
| ++
```
```
error[E0533]: expected value, found struct variant `E::V`
--> $DIR/struct-literal-variant-in-if.rs:10:13
|
LL | if x == E::V { field } {}
| ^^^^ not a value
|
help: you might have meant to create a new value of the struct
|
LL | if x == (E::V { field }) {}
| + +
```
```
error[E0618]: expected function, found enum variant `Enum::Unit`
--> $DIR/suggestion-highlights.rs:15:5
|
LL | Unit,
| ---- enum variant `Enum::Unit` defined here
...
LL | Enum::Unit();
| ^^^^^^^^^^--
| |
| call expression requires function
|
help: `Enum::Unit` is a unit enum variant, and does not take parentheses to be constructed
|
LL - Enum::Unit();
LL + Enum::Unit;
|
```
```
error[E0599]: no variant or associated item named `tuple` found for enum `Enum` in the current scope
--> $DIR/suggestion-highlights.rs:36:11
|
LL | enum Enum {
| --------- variant or associated item `tuple` not found for this enum
...
LL | Enum::tuple;
| ^^^^^ variant or associated item not found in `Enum`
|
help: there is a variant with a similar name
|
LL | Enum::Tuple(/* i32 */);
| ~~~~~~~~~~~~~~~~;
|
```
Tweak "field not found" suggestion when giving struct literal for tuple struct type:
```
error[E0560]: struct `S` has no field named `x`
--> $DIR/nested-non-tuple-tuple-struct.rs:8:19
|
LL | pub struct S(f32, f32);
| - `S` defined here
...
LL | let _x = (S { x: 1.0, y: 2.0 }, S { x: 3.0, y: 4.0 });
| ^ field does not exist
|
help: `S` is a tuple struct, use the appropriate syntax
|
LL | let _x = (S(/* f32 */, /* f32 */), S { x: 3.0, y: 4.0 });
| ~~~~~~~~~~~~~~~~~~~~~~~
Handle .init_array link_section specially on wasm
Given that wasm-ld now has support for [.init_array](8f2bd8ae68/llvm/lib/MC/WasmObjectWriter.cpp (L1852)), it appears we can easily implement that section by falling through to the normal path rather than taking the typical custom_section path for wasm.
The wasm-ld appears to have a bunch of limitations. Only one static with the `link_section` in a crate or else you hit the fatal error in the link above "only one .init_array section fragment supported". They do not get merged.
You can still call multiple constructors by setting it to an array.
```
unsafe extern "C" fn ctor() {
println!("foo");
}
#[used]
#[link_section = ".init_array"]
static FOO: [unsafe extern "C" fn(); 2] = [ctor, ctor];
```
Another issue appears to be that if crate *A* depends on crate *B*, but *A* doesn't call any symbols from *B* and *B* doesn't `#[export_name = ...]` any symbols, then crate *B*'s constructor will not be called. The workaround to this is to provide an exported symbol in crate *B*.
Use more accurate span for `addr_of!` suggestion
Use a multipart suggestion instead of a single whole-span replacement:
```
error[E0796]: creating a shared reference to a mutable static
--> $DIR/reference-to-mut-static-unsafe-fn.rs:10:18
|
LL | let _y = &X;
| ^^ shared reference to mutable static
|
= note: this shared reference has lifetime `'static`, but if the static ever gets mutated, or a mutable reference is created, then any further use of this shared reference is Undefined Behavior
help: use `addr_of!` instead to create a raw pointer
|
LL | let _y = addr_of!(X);
| ~~~~~~~~~ +
```
Mention that type parameters are used recursively on bivariance error
Right now when a type parameter is used recursively, even with indirection (so it has a finite size) we say that the type parameter is unused:
```
struct B<T>(Box<B<T>>);
```
This is confusing, because the type parameter is *used*, it just doesn't have its variance constrained. This PR tweaks that message to mention that it must be used *non-recursively*.
Not sure if we should actually mention "variance" here, but also I'd somewhat prefer we don't keep the power users in the dark w.r.t the real underlying issue, which is that the variance isn't constrained. That technical detail is reserved for a note, though.
cc `@fee1-dead`
Fixes#118976Fixes#26283Fixes#53191Fixes#105740Fixes#110466
Use a multipart suggestion instead of a single whole-span replacement:
```
error[E0796]: creating a shared reference to a mutable static
--> $DIR/reference-to-mut-static-unsafe-fn.rs:10:18
|
LL | let _y = &X;
| ^^ shared reference to mutable static
|
= note: this shared reference has lifetime `'static`, but if the static ever gets mutated, or a mutable reference is created, then any further use of this shared reference is Undefined Behavior
help: use `addr_of!` instead to create a raw pointer
|
LL | let _y = addr_of!(X);
| ~~~~~~~~~ +
```
```
error[E0533]: expected value, found struct variant `E::Empty3`
--> $DIR/empty-struct-braces-expr.rs:18:14
|
LL | let e3 = E::Empty3;
| ^^^^^^^^^ not a value
|
help: you might have meant to create a new value of the struct
|
LL | let e3 = E::Empty3 {};
| ++
```
```
error[E0533]: expected value, found struct variant `E::V`
--> $DIR/struct-literal-variant-in-if.rs:10:13
|
LL | if x == E::V { field } {}
| ^^^^ not a value
|
help: you might have meant to create a new value of the struct
|
LL | if x == (E::V { field }) {}
| + +
```
```
error[E0618]: expected function, found enum variant `Enum::Unit`
--> $DIR/suggestion-highlights.rs:15:5
|
LL | Unit,
| ---- enum variant `Enum::Unit` defined here
...
LL | Enum::Unit();
| ^^^^^^^^^^--
| |
| call expression requires function
|
help: `Enum::Unit` is a unit enum variant, and does not take parentheses to be constructed
|
LL - Enum::Unit();
LL + Enum::Unit;
|
```
```
error[E0599]: no variant or associated item named `tuple` found for enum `Enum` in the current scope
--> $DIR/suggestion-highlights.rs:36:11
|
LL | enum Enum {
| --------- variant or associated item `tuple` not found for this enum
...
LL | Enum::tuple;
| ^^^^^ variant or associated item not found in `Enum`
|
help: there is a variant with a similar name
|
LL | Enum::Tuple(/* i32 */);
| ~~~~~~~~~~~~~~~~;
|
```
More accurate span for type parameter suggestion
After:
```
error[E0229]: associated item constraints are not allowed here
--> $DIR/impl-block-params-declared-in-wrong-spot-issue-113073.rs:3:10
|
LL | impl Foo<T: Default> for String {}
| ^^^^^^^^^^ associated item constraint not allowed here
|
help: declare the type parameter right after the `impl` keyword
|
LL - impl Foo<T: Default> for String {}
LL + impl<T: Default> Foo<T> for String {}
|
```
Before:
```
error[E0229]: associated item constraints are not allowed here
--> $DIR/impl-block-params-declared-in-wrong-spot-issue-113073.rs:3:10
|
LL | impl Foo<T: Default> for String {}
| ^^^^^^^^^^ associated item constraint not allowed here
|
help: declare the type parameter right after the `impl` keyword
|
LL | impl<T: Default> Foo<T> for String {}
| ++++++++++++ ~
```
Fix associated item removal suggestion
We were previously telling people to write what was already there, instead of removal (treating it as a `help`). We now properly suggest to remove the code that needs to be removed.
```
error[E0229]: associated item constraints are not allowed here
--> $DIR/E0229.rs:13:25
|
LL | fn baz<I>(x: &<I as Foo<A = Bar>>::A) {}
| ^^^^^^^ associated item constraint not allowed here
|
help: consider removing this associated item binding
|
LL - fn baz<I>(x: &<I as Foo<A = Bar>>::A) {}
LL + fn baz<I>(x: &<I as Foo>::A) {}
|
```
After:
```
error[E0229]: associated item constraints are not allowed here
--> $DIR/impl-block-params-declared-in-wrong-spot-issue-113073.rs:3:10
|
LL | impl Foo<T: Default> for String {}
| ^^^^^^^^^^ associated item constraint not allowed here
|
help: declare the type parameter right after the `impl` keyword
|
LL - impl Foo<T: Default> for String {}
LL + impl<T: Default> Foo<T> for String {}
|
```
Before:
```
error[E0229]: associated item constraints are not allowed here
--> $DIR/impl-block-params-declared-in-wrong-spot-issue-113073.rs:3:10
|
LL | impl Foo<T: Default> for String {}
| ^^^^^^^^^^ associated item constraint not allowed here
|
help: declare the type parameter right after the `impl` keyword
|
LL | impl<T: Default> Foo<T> for String {}
| ++++++++++++ ~
```
We were previously telling people to write what was already there, instead of removal.
```
error[E0229]: associated item constraints are not allowed here
--> $DIR/E0229.rs:13:25
|
LL | fn baz<I>(x: &<I as Foo<A = Bar>>::A) {}
| ^^^^^^^ associated item constraint not allowed here
|
help: consider removing this associated item binding
|
LL - fn baz<I>(x: &<I as Foo<A = Bar>>::A) {}
LL + fn baz<I>(x: &<I as Foo>::A) {}
|
```
This is a very large commit since a lot needs to be changed in order to
make the tests pass. The salient changes are:
- `ConstArgKind` gets a new `Path` variant, and all const params are now
represented using it. Non-param paths still use `ConstArgKind::Anon`
to prevent this change from getting too large, but they will soon use
the `Path` variant too.
- `ConstArg` gets a distinct `hir_id` field and its own variant in
`hir::Node`. This affected many parts of the compiler that expected
the parent of an `AnonConst` to be the containing context (e.g., an
array repeat expression). They have been changed to check the
"grandparent" where necessary.
- Some `ast::AnonConst`s now have their `DefId`s created in
rustc_ast_lowering rather than `DefCollector`. This is because in some
cases they will end up becoming a `ConstArgKind::Path` instead, which
has no `DefId`. We have to solve this in a hacky way where we guess
whether the `AnonConst` could end up as a path const since we can't
know for sure until after name resolution (`N` could refer to a free
const or a nullary struct). If it has no chance as being a const
param, then we create a `DefId` in `DefCollector` -- otherwise we
decide during ast_lowering. This will have to be updated once all path
consts use `ConstArgKind::Path`.
- We explicitly use `ConstArgHasType` for array lengths, rather than
implicitly relying on anon const type feeding -- this is due to the
addition of `ConstArgKind::Path`.
- Some tests have their outputs changed, but the changes are for the
most part minor (including removing duplicate or almost-duplicate
errors). One test now ICEs, but it is for an incomplete, unstable
feature and is now tracked at #127009.
Automatically taint when reporting errors from ItemCtxt
This isn't very robust yet, as you need to use `itemctxt.dcx()` instead of `tcx.dcx()` for it to take effect, but it's at least more convenient than sprinkling `set_tainted_by_errors` calls in individual places.
based on https://github.com/rust-lang/rust/pull/127357
r? `@fmease`
Move trait selection error reporting to its own top-level module
This effectively moves `rustc_trait_selection::traits::error_reporting` to `rustc_trait_selection::error_reporting::traits`. There are only a couple of actual changes to the code, like moving the `pretty_impl_header` fn out of the specialization module for privacy reasons.
This is quite pointless on its own, but having `error_reporting` as a top-level module in `rustc_trait_selection` is very important to make sure we have a meaningful file structure for when we move **type** error reporting (and region error reporting, with which it's incredibly entangled currently) into `rustc_trait_selection`. I've opened a tracking issue here: #127492
r? lcnr
Uplift elaboration into `rustc_type_ir`
Allows us to deduplicate and consolidate elaboration (including these stupid elaboration duplicate fns i added for pretty printing like 3 years ago) so I'm pretty hyped about this change :3
r? lcnr
Make `can_eq` process obligations (almost) everywhere
Move `can_eq` to an extension trait on `InferCtxt` in `rustc_trait_selection`, and change it so that it processes obligations. This should strengthen it to be more accurate in some cases, but is most important for the new trait solver which delays relating aliases to `AliasRelate` goals. Without this, we always basically just return true when passing aliases to `can_eq`, which can lead to weird errors, for example #127149.
I'm not actually certain if we should *have* `can_eq` be called on the good path. In cases where we need `can_eq`, we probably should just be using a regular probe.
Fixes#127149
r? lcnr
Remove a use of `StructuredDiag`, which is incompatible with automatic error tainting and error translations
fixes#127219
I want to remove all of `StructuredDiag`, but it's a bit more involved as it is also used from the `ItemCtxt`, which doesn't support tainting yet.
Introduce a `rustc_` attribute to dump all the `DefId` parents of a `DefId`
We've run into a bunch of issues with anon consts having the wrong generics and it would have been incredibly helpful to be able to quickly slap a `rustc_` attribute to check what `tcx.parent(` will return on the relevant DefIds.
I wasn't sure of a better way to make this work for anon consts than requiring the attribute to be on the enclosing item and then walking the inside of it to look for any anon consts. This particular method will honestly break at some point when we stop having a `DefId` available for anon consts in hir but that's for another day...
r? ``@compiler-errors``
Rollup of 9 pull requests
Successful merges:
- #123237 (Various rustc_codegen_ssa cleanups)
- #126960 (Improve error message in tidy)
- #127002 (Implement `x perf` as a separate tool)
- #127081 (Add a run-make test that LLD is not being used by default on the x64 beta/stable channel)
- #127106 (Improve unsafe extern blocks diagnostics)
- #127110 (Fix a error suggestion for E0121 when using placeholder _ as return types on function signature.)
- #127114 (fix: prefer `(*p).clone` to `p.clone` if the `p` is a raw pointer)
- #127118 (Show `used attribute`'s kind for user when find it isn't applied to a `static` variable.)
- #127122 (Remove uneccessary condition in `div_ceil`)
r? `@ghost`
`@rustbot` modify labels: rollup
Fix a error suggestion for E0121 when using placeholder _ as return types on function signature.
Recommit after refactoring based on comment:
https://github.com/rust-lang/rust/pull/126017#issuecomment-2189149361
But when changing return type's lifetime to `ReError` will affect the subsequent borrow check process and cause test11 in typeck_type_placeholder_item.rs to lost E0515 message.
```rust
fn test11(x: &usize) -> &_ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
&x //~ ERROR cannot return reference to function parameter(this E0515 msg will disappear)
}
```
fixes#125488
r? ``@pnkfelix``
Implement new effects desugaring
cc `@rust-lang/project-const-traits.` Will write down notes once I have finished.
* [x] See if we want `T: Tr` to desugar into `T: Tr, T::Effects: Compat<true>`
* [x] Fix ICEs on `type Assoc: ~const Tr` and `type Assoc<T: ~const Tr>`
* [ ] add types and traits to minicore test
* [ ] update rustc-dev-guide
Fixes#119717Fixes#123664Fixes#124857Fixes#126148
Recommit after refactoring based on comment:
https://github.com/rust-lang/rust/pull/126017#issuecomment-2189149361
But when changing return type's lifetime to `ReError` will affect the subsequent borrow check process and cause test11 in typeck_type_placeholder_item.rs to lost E0515 message.
```rust
fn test11(x: &usize) -> &_ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
&x //~ ERROR cannot return reference to function parameter(this E0515 msg will disappear)
}
```
Don't ICE during RPITIT refinement checking for resolution errors after normalization
#126670 shows a case where resolution errors after normalization can happen during RPITIT refinement checking. Our tests didn't reach this path before, and we explicitly ICEd until we had a test. We can now delay a bug since we're sure it is reachable and have the test from the isue.
The comment I added likely still needs more expert wordsmithing.
r? ``@compiler-errors`` who's making me work during vacation (j/k).
Fixes#126670
Remove use of const traits (and `feature(effects)`) from stdlib
The current uses are already unsound because they are using non-const impls in const contexts. We can reintroduce them by reverting the commit in this PR, after #120639 lands.
Also, make `effects` an incomplete feature.
cc `@rust-lang/project-const-traits`
r? `@compiler-errors`
Clean up some comments near `use` declarations
#125443 will reformat all `use` declarations in the repository. There are a few edge cases involving comments on `use` declarations that require care. This PR cleans up some clumsy comment cases, taking us a step closer to #125443 being able to merge.
r? ``@lqd``
Actually taint InferCtxt when a fulfillment error is emitted
And avoid checking the global error counter
fixes#122044fixes#123255fixes#123276fixes#125799
Place tail expression behind terminating scope
This PR implements #123739 so that we can do further experiments in nightly.
A little rewrite has been applied to `for await` lowering. It was previously `unsafe { Pin::unchecked_new(into_async_iter(..)) }`. Under the edition 2024 rule, however, `into_async_iter` gets dropped at the end of the `unsafe` block. This presumably the first Edition 2024 migration rule goes by hoisting `into_async_iter(..)` into `match` one level above, so it now looks like the following.
```rust
match into_async_iter($iter_expr) {
ref mut iter => match unsafe { Pin::unchecked_new(iter) } {
...
}
}
```
Add `f16` and `f128` inline ASM support for `x86` and `x86-64`
This PR adds `f16` and `f128` input and output support to inline ASM on `x86` and `x86-64`. `f16` vector sizes are taken from [here](https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html).
Relevant issue: #125398
Tracking issue: #116909
``@rustbot`` label +F-f16_and_f128
`E0229`: Suggest Moving Type Constraints to Type Parameter Declaration
Fixes#113073
This PR suggests `impl<T: Bound> Trait<T> for Foo` when finding `impl Trait<T: Bound> for Foo`. Tangentially, it also improves a handful of other error messages.
It accomplishes this in two steps:
1. Check if constrained arguments and parameter names appear in the same order and delay emitting "incorrect number of generic arguments" error because it can be confusing for the programmer to see `0 generic arguments provided` when there are `n` constrained generic arguments.
2. Inside `E0229`, suggest declaring the type parameter right after the `impl` keyword by finding the relevant impl block's span for type parameter declaration. This also handles lifetime declarations correctly.
Also, the multi part suggestion doesn't use the fluent error mechanism because translating all the errors to fluent style feels outside the scope of this PR. I will handle it in a separate PR if this gets approved.
Fix outdated predacates_of.rs comments
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Provide correct parent for nested anon const
Fixes#126147
99% of this PR is just comments explaining what the issue is.
`tcx.parent(` and `hir().get_parent_item(` give different results as the hir owner for all the hir of anon consts is the enclosing function. I didn't attempt to change that as being a hir owner requires a `DefId` and long term we want to stop creating anon consts' `DefId`s before hir ty lowering.
So i just opted to change `generics_of` to use `tcx.parent` to get the parent for `AnonConst`'s. I'm not entirely sure about this being what we want, it does seem weird that we have two ways of getting the parent of an `AnonConst` and they both give different results.
Alternatively we could just go ahead and make `const_evaluatable_unchecked` a hard error and stop providing generics to repeat exprs. Then this isn't an issue. (The FCW has been around for almost 4 years now)
r? ````@compiler-errors````
Rollup of 16 pull requests
Successful merges:
- #123374 (DOC: Add FFI example for slice::from_raw_parts())
- #124514 (Recommend to never display zero disambiguators when demangling v0 symbols)
- #125978 (Cleanup: HIR ty lowering: Consolidate the places that do assoc item probing & access checking)
- #125980 (Nvptx remove direct passmode)
- #126187 (For E0277 suggest adding `Result` return type for function when using QuestionMark `?` in the body.)
- #126210 (docs(core): make more const_ptr doctests assert instead of printing)
- #126249 (Simplify `[T; N]::try_map` signature)
- #126256 (Add {{target}} substitution to compiletest)
- #126263 (Make issue-122805.rs big endian compatible)
- #126281 (set_env: State the conclusion upfront)
- #126286 (Make `storage-live.rs` robust against rustc internal changes.)
- #126287 (Update a cranelift patch file for formatting changes.)
- #126301 (Use `tidy` to sort crate attributes for all compiler crates.)
- #126305 (Make PathBuf less Ok with adding UTF-16 then `into_string`)
- #126310 (Migrate run make prefer rlib)
- #126314 (fix RELEASES: we do not support upcasting to auto traits)
r? `@ghost`
`@rustbot` modify labels: rollup
Use `tidy` to sort crate attributes for all compiler crates.
We already do this for a number of crates, e.g. `rustc_middle`, `rustc_span`, `rustc_metadata`, `rustc_span`, `rustc_errors`.
For the ones we don't, in many cases the attributes are a mess.
- There is no consistency about order of attribute kinds (e.g. `allow`/`deny`/`feature`).
- Within attribute kind groups (e.g. the `feature` attributes), sometimes the order is alphabetical, and sometimes there is no particular order.
- Sometimes the attributes of a particular kind aren't even grouped all together, e.g. there might be a `feature`, then an `allow`, then another `feature`.
This commit extends the existing sorting to all compiler crates, increasing consistency. If any new attribute line is added there is now only one place it can go -- no need for arbitrary decisions.
Exceptions:
- `rustc_log`, `rustc_next_trait_solver` and `rustc_type_ir_macros`, because they have no crate attributes.
- `rustc_codegen_gcc`, because it's quasi-external to rustc (e.g. it's ignored in `rustfmt.toml`).
r? `@davidtwco`
Cleanup: HIR ty lowering: Consolidate the places that do assoc item probing & access checking
Use `probe_assoc_item` (for hygienically probing an assoc item and checking if it's accessible wrt. visibility and stability) for assoc item constraints, too, not just for assoc type paths and make the privacy error translatable.
We already do this for a number of crates, e.g. `rustc_middle`,
`rustc_span`, `rustc_metadata`, `rustc_span`, `rustc_errors`.
For the ones we don't, in many cases the attributes are a mess.
- There is no consistency about order of attribute kinds (e.g.
`allow`/`deny`/`feature`).
- Within attribute kind groups (e.g. the `feature` attributes),
sometimes the order is alphabetical, and sometimes there is no
particular order.
- Sometimes the attributes of a particular kind aren't even grouped
all together, e.g. there might be a `feature`, then an `allow`, then
another `feature`.
This commit extends the existing sorting to all compiler crates,
increasing consistency. If any new attribute line is added there is now
only one place it can go -- no need for arbitrary decisions.
Exceptions:
- `rustc_log`, `rustc_next_trait_solver` and `rustc_type_ir_macros`,
because they have no crate attributes.
- `rustc_codegen_gcc`, because it's quasi-external to rustc (e.g. it's
ignored in `rustfmt.toml`).
Revert: create const block bodies in typeck via query feeding
as per the discussion in https://github.com/rust-lang/rust/pull/125806#discussion_r1622563948
It was a mistake to try to shoehorn const blocks and some specific anon consts into the same box and feed them during typeck. It turned out not simplifying anything (my hope was that we could feed `type_of` to start avoiding the huge HIR matcher, but that didn't work out), but instead making a few things more fragile.
reverts the const-block-specific parts of https://github.com/rust-lang/rust/pull/124650
`@bors` rollup=never had a small perf impact previously
fixes https://github.com/rust-lang/rust/issues/125846
r? `@compiler-errors`
`ct_infer` and `lower_ty` will correctly result in an error constant or type respectively, as they go through a `HirTyLowerer` method (just like `HirTyLowerer::allow_infer` is a method implemented by both implementors
Silence follow-up errors directly based on error types and regions
During type_of, we used to just return an error type if there were any errors encountered. This is problematic, because it means a struct declared as `struct Foo<'static>` will end up not finding any inherent or trait impls because those impl blocks' `Self` type will be `{type error}` instead of `Foo<'re_error>`. Now it's the latter, silencing nonsensical follow-up errors about `Foo` not having any methods.
Unfortunately that now allows for new follow-up errors, because borrowck treats `'re_error` as `'static`, causing nonsensical errors about non-error lifetimes not outliving `'static`. So what I also did was to just strip all outlives bounds that borrowck found, thus never letting it check them. There are probably more nuanced ways to do this, but I worried there would be other nonsensical errors if some outlives bounds were missing. Also from the test changes, it looked like an improvement everywhere.
Align `Term` methods with `GenericArg` methods, add `Term::expect_*`
* `Term::ty` -> `Term::as_type`.
* `Term::ct` -> `Term::as_const`.
* Adds `Term::expect_type` and `Term::expect_const`, and uses them in favor of `.ty().unwrap()`, etc.
I could also shorten these to `as_ty` and then do `GenericArg::as_ty` as well, but I do think the `as_` is important to signal that this is a conversion method, and not a getter, like `Const::ty` is.
r? types
Make `WHERE_CLAUSES_OBJECT_SAFETY` a regular object safety violation
#### The issue
In #50781, we have known about unsound `where` clauses in function arguments:
```rust
trait Impossible {}
trait Foo {
fn impossible(&self)
where
Self: Impossible;
}
impl Foo for &() {
fn impossible(&self)
where
Self: Impossible,
{}
}
// `where` clause satisfied for the object, meaning that the function now *looks* callable.
impl Impossible for dyn Foo {}
fn main() {
let x: &dyn Foo = &&();
x.impossible();
}
```
... which currently segfaults at runtime because we try to call a method in the vtable that doesn't exist. :(
#### What did u change
This PR removes the `WHERE_CLAUSES_OBJECT_SAFETY` lint and instead makes it a regular object safety violation. I choose to make this into a hard error immediately rather than a `deny` because of the time that has passed since this lint was authored, and the single (1) regression (see below).
That means that it's OK to mention `where Self: Trait` where clauses in your trait, but making such a trait into a `dyn Trait` object will report an object safety violation just like `where Self: Sized`, etc.
```rust
trait Impossible {}
trait Foo {
fn impossible(&self)
where
Self: Impossible; // <~ This definition is valid, just not object-safe.
}
impl Foo for &() {
fn impossible(&self)
where
Self: Impossible,
{}
}
fn main() {
let x: &dyn Foo = &&(); // <~ THIS is where we emit an error.
}
```
#### Regressions
From a recent crater run, there's only one crate that relies on this behavior: https://github.com/rust-lang/rust/pull/124305#issuecomment-2122381740. The crate looks unmaintained and there seems to be no dependents.
#### Further
We may later choose to relax this (e.g. when the where clause is implied by the supertraits of the trait or something), but this is not something I propose to do in this FCP.
For example, given:
```
trait Tr {
fn f(&self) where Self: Blanket;
}
impl<T: ?Sized> Blanket for T {}
```
Proving that some placeholder `S` implements `S: Blanket` would be sufficient to prove that the same (blanket) impl applies for both `Concerete: Blanket` and `dyn Trait: Blanket`.
Repeating here that I don't think we need to implement this behavior right now.
----
r? lcnr
Use parenthetical notation for `Fn` traits
Always use the `Fn(T) -> R` format when printing closure traits instead of `Fn<(T,), Output = R>`.
Address #67100:
```
error[E0277]: expected a `Fn()` closure, found `F`
--> file.rs:6:13
|
6 | call_fn(f)
| ------- ^ expected an `Fn()` closure, found `F`
| |
| required by a bound introduced by this call
|
= note: wrap the `F` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `call_fn`
--> file.rs:1:15
|
1 | fn call_fn<F: Fn() -> ()>(f: &F) {
| ^^^^^^^^^^ required by this bound in `call_fn`
help: consider further restricting this bound
|
5 | fn call_any<F: std::any::Any + Fn()>(f: &F) {
| ++++++
```
Implement `needs_async_drop` in rustc and optimize async drop glue
This PR expands on #121801 and implements `Ty::needs_async_drop` which works almost exactly the same as `Ty::needs_drop`, which is needed for #123948.
Also made compiler's async drop code to look more like compiler's regular drop code, which enabled me to write an optimization where types which do not use `AsyncDrop` can simply forward async drop glue to `drop_in_place`. This made size of the async block from the [async_drop test](67980dd6fb/tests/ui/async-await/async-drop.rs) to decrease by 12%.
Fold item bounds before proving them in `check_type_bounds` in new solver
Vaguely confident that this is sufficient to prevent rust-lang/trait-system-refactor-initiative#46 and rust-lang/trait-system-refactor-initiative#62.
This is not the "correct" solution, but will probably suffice until coinduction, at which point we implement the right solution (`check_type_bounds` must prove `Assoc<...> alias-eq ConcreteType`, normalizing requires proving item bounds).
r? lcnr
Rename HIR `TypeBinding` to `AssocItemConstraint` and related cleanup
Rename `hir::TypeBinding` and `ast::AssocConstraint` to `AssocItemConstraint` and update all items and locals using the old terminology.
Motivation: The terminology *type binding* is extremely outdated. "Type bindings" not only include constraints on associated *types* but also on associated *constants* (feature `associated_const_equality`) and on RPITITs of associated *functions* (feature `return_type_notation`). Hence the word *item* in the new name. Furthermore, the word *binding* commonly refers to a mapping from a binder/identifier to a "value" for some definition of "value". Its use in "type binding" made sense when equality constraints (e.g., `AssocTy = Ty`) were the only kind of associated item constraint. Nowadays however, we also have *associated type bounds* (e.g., `AssocTy: Bound`) for which the term *binding* doesn't make sense.
---
Old terminology (HIR, rustdoc):
```
`TypeBinding`: (associated) type binding
├── `Constraint`: associated type bound
└── `Equality`: (associated) equality constraint (?)
├── `Ty`: (associated) type binding
└── `Const`: associated const equality (constraint)
```
Old terminology (AST, abbrev.):
```
`AssocConstraint`
├── `Bound`
└── `Equality`
├── `Ty`
└── `Const`
```
New terminology (AST, HIR, rustdoc):
```
`AssocItemConstraint`: associated item constraint
├── `Bound`: associated type bound
└── `Equality`: associated item equality constraint OR associated item binding (for short)
├── `Ty`: associated type equality constraint OR associated type binding (for short)
└── `Const`: associated const equality constraint OR associated const binding (for short)
```
r? compiler-errors
Make `body_owned_by` return the `Body` instead of just the `BodyId`
fixes#125677
Almost all `body_owned_by` callers immediately called `body`, too, so just return `Body` directly.
This makes the inline-const query feeding more robust, as all calls to `body_owned_by` will now yield a body for inline consts, too.
I have not yet figured out a good way to make `tcx.hir().body()` return an inline-const body, but that can be done as a follow-up
Always use the `Fn(T) -> R` format when printing closure traits instead of `Fn<(T,), Output = R>`.
Fix#67100:
```
error[E0277]: expected a `Fn()` closure, found `F`
--> file.rs:6:13
|
6 | call_fn(f)
| ------- ^ expected an `Fn()` closure, found `F`
| |
| required by a bound introduced by this call
|
= note: wrap the `F` in a closure with no arguments: `|| { /* code */ }`
note: required by a bound in `call_fn`
--> file.rs:1:15
|
1 | fn call_fn<F: Fn() -> ()>(f: &F) {
| ^^^^^^^^^^ required by this bound in `call_fn`
help: consider further restricting this bound
|
5 | fn call_any<F: std::any::Any + Fn()>(f: &F) {
| ++++++
```
Uplift `EarlyBinder` into `rustc_type_ir`
We also need to give `EarlyBinder` a `'tcx` param, so that we can carry the `Interner` in the `EarlyBinder` too. This is necessary because otherwise we have an unconstrained `I: Interner` parameter in many of the `EarlyBinder`'s inherent impls.
I also generally think that this is desirable to have, in case we later want to track some state in the `EarlyBinder`.
r? lcnr
[perf] Delay the construction of early lint diag structs
Attacks some of the perf regressions from https://github.com/rust-lang/rust/pull/124417#issuecomment-2123700666.
See individual commits for details. The first three commits are not strictly necessary.
However, the 2nd one (06bc4fc671, *Remove `LintDiagnostic::msg`*) makes the main change way nicer to implement.
It's also pretty sweet on its own if I may say so myself.
Remove `DefId` from `EarlyParamRegion`
Currently we represent usages of `Region` parameters via the `ReEarlyParam` or `ReLateParam` variants. The `ReEarlyParam` is effectively equivalent to `TyKind::Param` and `ConstKind::Param` (i.e. it stores a `Symbol` and a `u32` index) however it also stores a `DefId` for the definition of the lifetime parameter.
This was used in roughly two places:
- Borrowck diagnostics instead of threading the appropriate `body_id` down to relevant locations. Interestingly there were already some places that had to pass down a `DefId` manually.
- Some opaque type checking logic was using the `DefId` field to track captured lifetimes
I've split this PR up into a commit for generate rote changes to diagnostics code to pass around a `DefId` manually everywhere, and another commit for the opaque type related changes which likely require more careful review as they might change the semantics of lints/errors.
Instead of manually passing the `DefId` around everywhere I previously tried to bundle it in with `TypeErrCtxt` but ran into issues with some call sites of `infcx.err_ctxt` being unable to provide a `DefId`, particularly places involved with trait solving and normalization. It might be worth investigating adding some new wrapper type to pass this around everywhere but I think this might be acceptable for now.
This pr also has the effect of reducing the size of `EarlyParamRegion` from 16 bytes -> 8 bytes. I wouldn't expect this to have any direct performance improvement however, other variants of `RegionKind` over `8` bytes are all because they contain a `BoundRegionKind` which is, as far as I know, mostly there for diagnostics. If we're ever able to remove this it would shrink the `RegionKind` type from `24` bytes to `12` (and with clever bit packing we might be able to get it to `8` bytes). I am curious what the performance impact would be of removing interning of `Region`'s if we ever manage to shrink `RegionKind` that much.
Sidenote: by removing the `DefId` the `Debug` output for `Region` has gotten significantly nicer. As an example see this opaque type debug print before vs after this PR:
`Opaque(DefId(0:13 ~ impl_trait_captures[aeb9]::foo::{opaque#0}), [DefId(0:9 ~ impl_trait_captures[aeb9]::foo::'a)_'a/#0, T, DefId(0:9 ~ impl_trait_captures[aeb9]::foo::'a)_'a/#0])`
`Opaque(DefId(0:13 ~ impl_trait_captures[aeb9]::foo::{opaque#0}), ['a/#0, T, 'a/#0])`
r? `@compiler-errors` (I would like someone who understands the opaque type setup to atleast review the type system commit, but the rest is likely reviewable by anyone)
Expand `for_loops_over_fallibles` lint to lint on fallibles behind references.
Extends the scope of the (warn-by-default) lint `for_loops_over_fallibles` from just `for _ in x` where `x: Option<_>/Result<_, _>` to also cover `x: &(mut) Option<_>/Result<_>`
```rs
fn main() {
// Current lints
for _ in Some(42) {}
for _ in Ok::<_, i32>(42) {}
// New lints
for _ in &Some(42) {}
for _ in &mut Some(42) {}
for _ in &Ok::<_, i32>(42) {}
for _ in &mut Ok::<_, i32>(42) {}
// Should not lint
for _ in Some(42).into_iter() {}
for _ in Some(42).iter() {}
for _ in Some(42).iter_mut() {}
for _ in Ok::<_, i32>(42).into_iter() {}
for _ in Ok::<_, i32>(42).iter() {}
for _ in Ok::<_, i32>(42).iter_mut() {}
}
```
<details><summary><code>cargo build</code> diff</summary>
```diff
diff --git a/old.out b/new.out
index 84215aa..ca195a7 100644
--- a/old.out
+++ b/new.out
`@@` -1,33 +1,93 `@@`
warning: for loop over an `Option`. This is more readably written as an `if let` statement
--> src/main.rs:3:14
|
3 | for _ in Some(42) {}
| ^^^^^^^^
|
= note: `#[warn(for_loops_over_fallibles)]` on by default
help: to check pattern in a loop use `while let`
|
3 | while let Some(_) = Some(42) {}
| ~~~~~~~~~~~~~~~ ~~~
help: consider using `if let` to clear intent
|
3 | if let Some(_) = Some(42) {}
| ~~~~~~~~~~~~ ~~~
warning: for loop over a `Result`. This is more readably written as an `if let` statement
--> src/main.rs:4:14
|
4 | for _ in Ok::<_, i32>(42) {}
| ^^^^^^^^^^^^^^^^
|
help: to check pattern in a loop use `while let`
|
4 | while let Ok(_) = Ok::<_, i32>(42) {}
| ~~~~~~~~~~~~~ ~~~
help: consider using `if let` to clear intent
|
4 | if let Ok(_) = Ok::<_, i32>(42) {}
| ~~~~~~~~~~ ~~~
-warning: `for-loops-over-fallibles` (bin "for-loops-over-fallibles") generated 2 warnings
- Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.04s
+warning: for loop over a `&Option`. This is more readably written as an `if let` statement
+ --> src/main.rs:7:14
+ |
+7 | for _ in &Some(42) {}
+ | ^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+7 | while let Some(_) = &Some(42) {}
+ | ~~~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+7 | if let Some(_) = &Some(42) {}
+ | ~~~~~~~~~~~~ ~~~
+
+warning: for loop over a `&mut Option`. This is more readably written as an `if let` statement
+ --> src/main.rs:8:14
+ |
+8 | for _ in &mut Some(42) {}
+ | ^^^^^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+8 | while let Some(_) = &mut Some(42) {}
+ | ~~~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+8 | if let Some(_) = &mut Some(42) {}
+ | ~~~~~~~~~~~~ ~~~
+
+warning: for loop over a `&Result`. This is more readably written as an `if let` statement
+ --> src/main.rs:9:14
+ |
+9 | for _ in &Ok::<_, i32>(42) {}
+ | ^^^^^^^^^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+9 | while let Ok(_) = &Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+9 | if let Ok(_) = &Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~ ~~~
+
+warning: for loop over a `&mut Result`. This is more readably written as an `if let` statement
+ --> src/main.rs:10:14
+ |
+10 | for _ in &mut Ok::<_, i32>(42) {}
+ | ^^^^^^^^^^^^^^^^^^^^^
+ |
+help: to check pattern in a loop use `while let`
+ |
+10 | while let Ok(_) = &mut Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~~~~ ~~~
+help: consider using `if let` to clear intent
+ |
+10 | if let Ok(_) = &mut Ok::<_, i32>(42) {}
+ | ~~~~~~~~~~ ~~~
+
+warning: `for-loops-over-fallibles` (bin "for-loops-over-fallibles") generated 6 warnings
+ Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.02s
```
</details>
-----
Question:
* ~~Currently, the article `an` is used for `&Option`, and `&mut Option` in the lint diagnostic, since that's what `Option` uses. Is this okay or should it be changed? (likewise, `a` is used for `&Result` and `&mut Result`)~~ The article `a` is used for `&Option`, `&mut Option`, `&Result`, `&mut Result` and (as before) `Result`. Only `Option` uses `an` (as before).
`@rustbot` label +A-lint
* instead simply set the primary message inside the lint decorator functions
* it used to be this way before [#]101986 which introduced `msg` to prevent
good path delayed bugs (which no longer exist) from firing under certain
circumstances when lints were suppressed / silenced
* this is no longer necessary for various reasons I presume
* it shaves off complexity and makes further changes easier to implement
Pattern types: Prohibit generic args on const params
Addresses https://github.com/rust-lang/rust/pull/123689/files#r1562676629.
NB: Technically speaking, *not* prohibiting generics args on const params is not a bug as `pattern_types` is an *internal* feature and as such any uncaught misuses of it are considered to be the fault of the user. However, permitting this makes me slightly uncomfortable esp. since we might want to make pattern types available to the public at some point and I don't want this oversight to be able to slip into the language (for comparison, ICEs triggered by the use of internal features are like super fine).
Furthermore, this is an ad hoc fix. A more general fix would be changing the representation of the pattern part of pattern types in such a way that it can reuse preexisting lowering routines for exprs / anon consts. See also this [Zulip discussion](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/pattern.20type.20HIR.20nodes/near/432410768) and #124650.
Also note that we currently don't properly typeck the pattern of pat tys. This however is out of scope for this PR.
cc ``@oli-obk``
r? ``@spastorino`` as discussed
Rename Unsafe to Safety
Alternative to #124455, which is to just have one Safety enum to use everywhere, this opens the posibility of adding `ast::Safety::Safe` that's useful for unsafe extern blocks.
This leaves us today with:
```rust
enum ast::Safety {
Unsafe(Span),
Default,
// Safe (going to be added for unsafe extern blocks)
}
enum hir::Safety {
Unsafe,
Safe,
}
```
We would convert from `ast::Safety::Default` into the right Safety level according the context.
Split out `ty::AliasTerm` from `ty::AliasTy`
Splitting out `AliasTerm` (for use in project and normalizes goals) and `AliasTy` (for use in `ty::Alias`)
r? lcnr
Rename some `FulfillmentErrorCode`/`ObligationCauseCode` variants to be less redundant
1. Rename some `FulfillmentErrorCode` variants.
2. Always use `ObligationCauseCode::` to prefix a code, rather than using a glob import and naming them through `traits::`.
3. Rename some `ObligationCauseCode` variants -- I wasn't particularly thorough with thinking of a new names for these, so could workshop them if necessary.
4. Misc stuff from renaming.
r? lcnr
Rename `Generics::params` to `Generics::own_params`
I hope this makes it slightly more obvious that `generics.own_params` is insufficient when considering nested items. I didn't actually audit any of the usages, for the record.
r? lcnr
`InferCtxt::next_{ty,const}_var*` all take an origin, but the
`param_def_id` is almost always `None`. This commit changes them to just
take a `Span` and build the origin within the method, and adds new
methods for the rare cases where `param_def_id` might not be `None`.
This avoids a lot of tedious origin building.
Specifically:
- next_ty_var{,_id_in_universe,_in_universe}: now take `Span` instead of
`TypeVariableOrigin`
- next_ty_var_with_origin: added
- next_const_var{,_in_universe}: takes Span instead of ConstVariableOrigin
- next_const_var_with_origin: added
- next_region_var, next_region_var_in_universe: these are unchanged,
still take RegionVariableOrigin
The API inconsistency (ty/const vs region) seems worth it for the
large conciseness improvements.
The starting point for this was identical comments on two different
fields, in `ast::VariantData::Struct` and `hir::VariantData::Struct`:
```
// FIXME: investigate making this a `Option<ErrorGuaranteed>`
recovered: bool
```
I tried that, and then found that I needed to add an `ErrorGuaranteed`
to `Recovered::Yes`. Then I ended up using `Recovered` instead of
`Option<ErrorGuaranteed>` for these two places and elsewhere, which
required moving `ErrorGuaranteed` from `rustc_parse` to `rustc_ast`.
This makes things more consistent, because `Recovered` is used in more
places, and there are fewer uses of `bool` and
`Option<ErrorGuaranteed>`. And safer, because it's difficult/impossible
to set `recovered` to `Recovered::Yes` without having emitted an error.
Do not ICE on `AnonConst`s in `diagnostic_hir_wf_check`
Fixes#122989
Below is the snippet from #122989 that ICEs:
```rust
trait Traitor<const N: N<2> = 1, const N: N<2> = N> {
fn N(&N) -> N<2> {
M
}
}
trait N<const N: Traitor<2> = 12> {}
```
The `AnonConst` that triggers the ICE is the `2` in the param `const N: N<2> = 1`. The currently existing code in `diagnostic_hir_wf_check` deals only with `AnonConst`s that are default values of some param, but the `2` is not a default value. It is just an `AnonConst` HIR node inside a `TraitRef` HIR node corresponding to `N<2>`. Therefore the existing code cannot handle it and this PR ensures that it does.
Make `Bounds.clauses` private
Construct it through `Bounds::default()`, then consume the clauses via the method `Bounds::clauses()`.
This helps with effects desugaring where `clauses()` is not only the clauses within the `clauses` field.
Some hir cleanups
It seemed odd to not put `AnonConst` in the arena, compared with the other types that we did put into an arena. This way we can also give it a `Span` without growing a lot of other HIR data structures because of the extra field.
r? compiler
