Revert #104269 (to avoid spurious hang/test failure in CI)
Causes hangs/memory overflows in the test suite apparently 😢Reopens#104225Fixes#104957
r? ``@lcnr``
`mk_const(ty::ConstKind::X(...), ty)` can now be simplified to
`mk_cosnt(..., ty)`.
I searched with the following regex: \mk_const\([\n\s]*(ty::)?ConstKind\
I've left `ty::ConstKind::{Bound, Error}` as-is, they seem clearer this
way.
Remove `SelectionContext::infcx()` in favor of field access
Encapsulation doesn't seem particularly important here, and having two choices is always more confusing than having one.
r? types
Prefer doc comments over `//`-comments in compiler
Doc comments are generally nicer: they show up in the documentation, they are shown in IDEs when you hover other mentions of items, etc. Thus it makes sense to use them instead of `//`-comments.
Pretty-print generators with their `generator_kind`
After removing `GenFuture`, I special-cased async generators to pretty-print as `impl Future<Output = X>` mainly to avoid too much diagnostics changes originally.
This now reverses that change so that async fn/blocks are pretty-printed as `[$async-type@$source-position]` in various diagnostics, and updates the tests that this touches.
After removing `GenFuture`, I special-cased async generators to pretty-print as `impl Future<Output = X>` mainly to avoid too much diagnostics changes originally.
This now reverses that change so that async fn/blocks are pretty-printed as `[$movability `async` $something@$source-position]` in various diagnostics, and updates the tests that this touches.
Add `ConstKind::Expr`
Starting to implement `ty::ConstKind::Abstract`, most of the match cases are stubbed out, some I was unsure what to add, others I didn't want to add until a more complete implementation was ready.
r? `@lcnr`
Initial pass at expr/abstract const/s
Address comments
Switch to using a list instead of &[ty::Const], rm `AbstractConst`
Remove try_unify_abstract_consts
Update comments
Add edits
Recurse more
More edits
Prevent equating associated consts
Move failing test to ui
Changes this test from incremental to ui, and mark it as failing and a known bug.
Does not cause the compiler to ICE, so should be ok.
Avoid `GenFuture` shim when compiling async constructs
Previously, async constructs would be lowered to "normal" generators, with an additional `from_generator` / `GenFuture` shim in between to convert from `Generator` to `Future`.
The compiler will now special-case these generators internally so that async constructs will *directly* implement `Future` without the need to go through the `from_generator` / `GenFuture` shim.
The primary motivation for this change was hiding this implementation detail in stack traces and debuginfo, but it can in theory also help the optimizer as there is less abstractions to see through.
---
Given this demo code:
```rust
pub async fn a(arg: u32) -> Backtrace {
let bt = b().await;
let _arg = arg;
bt
}
pub async fn b() -> Backtrace {
Backtrace::force_capture()
}
```
I would get the following with the latest stable compiler (on Windows):
```
4: async_codegen:🅱️:async_fn$0
at .\src\lib.rs:10
5: core::future::from_generator::impl$1::poll<enum2$<async_codegen:🅱️:async_fn_env$0> >
at /rustc/897e37553bba8b42751c67658967889d11ecd120\library\core\src\future\mod.rs:91
6: async_codegen:🅰️:async_fn$0
at .\src\lib.rs:4
7: core::future::from_generator::impl$1::poll<enum2$<async_codegen:🅰️:async_fn_env$0> >
at /rustc/897e37553bba8b42751c67658967889d11ecd120\library\core\src\future\mod.rs:91
```
whereas now I get a much cleaner stack trace:
```
3: async_codegen:🅱️:async_fn$0
at .\src\lib.rs:10
4: async_codegen:🅰️:async_fn$0
at .\src\lib.rs:4
```
Previously, async constructs would be lowered to "normal" generators,
with an additional `from_generator` / `GenFuture` shim in between to
convert from `Generator` to `Future`.
The compiler will now special-case these generators internally so that
async constructs will *directly* implement `Future` without the need
to go through the `from_generator` / `GenFuture` shim.
The primary motivation for this change was hiding this implementation
detail in stack traces and debuginfo, but it can in theory also help
the optimizer as there is less abstractions to see through.
Properly handle `Pin<&mut dyn* Trait>` receiver in codegen
This ensures we can actually await a `dyn* Future`, which seems important for async fn in dyn trait.
Also, disable `dyn*` trait upcasting. It's not exactly complete right now, and can cause strange ICEs for no reason -- nobody's using it either. I thought it was cute to implement when I did it, but I didn't think about how it interacts structurally with `CoerceUnsized` correctly.
Fixes#104794, presumably removing `dyn*` upcasting and its `CoerceUnsized` issues does the trick.
Use `as_deref` in compiler (but only where it makes sense)
This simplifies some code :3
(there are some changes that are not exacly `as_deref`, but more like "clever `Option`/`Result` method use")
Fix hang in where-clause suggestion with `predicate_can_apply`
Using `predicate_may_hold` during error reporting causes an evaluation overflow, which (because we use `evaluate_obligation_no_overflow`) then causes the predicate to need to be re-evaluated locally, which results in a hang.
... but since the "add a where clause" suggestion is best-effort, just throw any overflow errors. No need for 100% accuracy.
r? `@lcnr` who has been thinking about overflows... Let me know if you want more context about this issue, and as always, feel free to reassign.
Fixes#104225
Rollup of 11 pull requests
Successful merges:
- #103396 (Pin::new_unchecked: discuss pinning closure captures)
- #104416 (Fix using `include_bytes` in pattern position)
- #104557 (Add a test case for async dyn* traits)
- #104559 (Split `MacArgs` in two.)
- #104597 (Probe + better error messsage for `need_migrate_deref_output_trait_object`)
- #104656 (Move tests)
- #104657 (Do not check transmute if has non region infer)
- #104663 (rustdoc: factor out common button CSS)
- #104666 (Migrate alias search result to CSS variables)
- #104674 (Make negative_impl and negative_impl_exists take the right types)
- #104692 (Update test's cfg-if dependency to 1.0)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Probe + better error messsage for `need_migrate_deref_output_trait_object`
1. Use `InferCtxt::probe` in `need_migrate_deref_output_trait_object` -- that normalization *could* technically do type inference as a side-effect, and this is a lint, so it should have no side-effects.
2. Return the trait-ref so we format the error message correctly. See the UI test change -- `(dyn A + 'static)` is not a trait.
Add `PolyExistentialPredicate` type alias
Wrapping `ExistentialPredicate`s in a binder is very common, and this alias already exists for the `PolyExistential{TraitRef,Projection}` types.
Improve spans for RPITIT object-safety errors
No reason why we can't point at the `impl Trait` that causes the object-safety violation.
Also [drive-by: Add is_async fn to hir::IsAsync](c4165f3a96), which touches clippy too.
Make "long type" printing type aware and trim types in E0275
Instead of simple string cutting, use a custom printer to hide parts of long printed types.
On E0275, check for type length before printing.
Revert "Normalize opaques with escaping bound vars"
This caused a perf regression in #103423, cc `@skyzh` this should fix#103423.
reverts #100980
r? `@oli-obk`
Use `ErrorGuaranteed::unchecked_claim_error_was_emitted` less
there are only like 3 or 4 call sites left after this but it wasnt obvious to me how to remove them
nll: correctly deal with bivariance
fixes#104409
when in a bivariant context, relating stuff should always trivially succeed. Also changes the mir validator to correctly deal with higher ranked regions.
r? types cc ``@RalfJung``
Rollup of 8 pull requests
Successful merges:
- #102977 (remove HRTB from `[T]::is_sorted_by{,_key}`)
- #103378 (Fix mod_inv termination for the last iteration)
- #103456 (`unchecked_{shl|shr}` should use `u32` as the RHS)
- #103701 (Simplify some pointer method implementations)
- #104047 (Diagnostics `icu4x` based list formatting.)
- #104338 (Enforce that `dyn*` coercions are actually pointer-sized)
- #104498 (Edit docs for `rustc_errors::Handler::stash_diagnostic`)
- #104556 (rustdoc: use `code-header` class to format enum variants)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Don't allow `CoerceUnsized` into `dyn*` (except for trait upcasting)
This makes sure we don't accidentally allow coercions like `Box<T>` -> `Box<dyn* Trait>`, or in the case of this ICE, `&T` to `&dyn* Trait`. These coercions don't make sense, at least not via the `CoerceUnsized` trait.
Fixes#102172Fixes#102429
Convert predicates into Predicate in the Obligation constructor
instead of having almost all callers do that.
This reduces a bit of boilerplate, and also paves the way for my work towards https://github.com/rust-lang/compiler-team/issues/531 (as it makes it easier to accept both goals and clauses where right now it only accepts predicates).
Record `LocalDefId` in HIR nodes instead of a side table
This is part of an attempt to remove the `HirId -> LocalDefId` table from HIR.
This attempt is a prerequisite to creation of `LocalDefId` after HIR lowering (https://github.com/rust-lang/rust/pull/96840), by controlling how `def_id` information is accessed.
This first part adds the information to HIR nodes themselves instead of a table.
The second part is https://github.com/rust-lang/rust/pull/103902
The third part will be to make `hir::Visitor::visit_fn` take a `LocalDefId` as last parameter.
The fourth part will be to completely remove the side table.
Don't print full paths in overlap errors
We don't print the full path in other diagnostics -- I don't think it particularly helps with the error message. I also delayed the printing until actually needing to render the error message.
r? diagnostics
Use `TraitEngine` in more places, restrict visibility of `FulfillmentCtxt` constructor
Most places that are constructing a `FulfillmentContext` should be constructing a `TraitEngine` generically, so later on if/when we're transitioning it'll be easier.
Logical extension of #99746
Some diagnostic-related nits
1. Use `&mut Diagnostic` instead of `&mut DiagnosticBuilder<'_, T>`
2. Make `diag.span_suggestions` take an `IntoIterator` instead of `Iterator`, just to remove some `.into_iter` calls on the caller.
idk if I should add a lint to make sure people use `&mut Diagnostic` instead of `&mut DiagnosticBuilder<'_, T>` in cases where we're just, e.g., adding subdiagnostics to the diagnostic... maybe a followup.
Cleanups in autoderef impl
Just something I noticed. Turns out the `overloaded_span` is not actually used separately from the main span, so I merged them.
Remove allow(rustc::potential_query_instability) in rustc_trait_selection
Related to https://github.com/rust-lang/rust/issues/84447
This PR needs to be benchmarked to check for regressions.
Rollup of 7 pull requests
Successful merges:
- #100508 (avoid making substs of type aliases late bound when used as fn args)
- #101381 (Test that target feature mix up with homogeneous floats is sound)
- #103353 (Fix Access Violation when using lld & ThinLTO on windows-msvc)
- #103521 (Avoid possible infinite loop when next_point reaching the end of file)
- #103559 (first move on a nested span_label)
- #103778 (Update several crates for improved support of the new targets)
- #103827 (Properly remap and check for substs compatibility in `confirm_impl_trait_in_trait_candidate`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Better error for HRTB error from generator interior
cc #100013
This is just a first pass at an error. It could be better, and shouldn't really be emitted in the first place. But this is better than what was being emitted before.
Make InferCtxtExt use a FxIndexMap
This should be faster, because the map is only being used to iterate,
which is supposed to be faster with the IndexMap
Make the user_computed_preds use an IndexMap
It is being used mostly for iteration, so the change shouldn't result in
a perf hit
Make the RegionDeps fields use an IndexMap
This change could be a perf hit. Both `larger` and `smaller` are used
for iteration, but they are also used for insertions.
Make types_without_default_bounds use an IndexMap
It uses extend, but it also iterates and removes items. Not sure if
this will be a perf hit.
Make InferTtxt.reported_trait_errors use an IndexMap
This change brought a lot of other changes. The map seems to have been
mostly used for iteration, so the performance shouldn't suffer.
Add FIXME to change ProvisionalEvaluationCache.map to use an IndexMap
Right now this results in a perf hit. IndexMap doesn't have
the `drain_filter` API, so in `on_completion` we now need to iterate two
times over the map.
Implement `std::marker::Tuple`, use it in `extern "rust-call"` and `Fn`-family traits
Implements rust-lang/compiler-team#537
I made a few opinionated decisions in this implementation, specifically:
1. Enforcing `extern "rust-call"` on fn items during wfcheck,
2. Enforcing this for all functions (not just ones that have bodies),
3. Gating this `Tuple` marker trait behind its own feature, instead of grouping it into (e.g.) `unboxed_closures`.
Still needing to be done:
1. Enforce that `extern "rust-call"` `fn`-ptrs are well-formed only if they have 1/2 args and the second one implements `Tuple`. (Doing this would fix ICE in #66696.)
2. Deny all explicit/user `impl`s of the `Tuple` trait, kinda like `Sized`.
3. Fixing `Tuple` trait built-in impl for chalk, so that chalkification tests are un-broken.
Open questions:
1. Does this need t-lang or t-libs signoff?
Fixes#99820
Track where diagnostics were created.
This implements the `-Ztrack-diagnostics` flag, which uses `#[track_caller]` to track where diagnostics are created. It is meant as a debugging tool much like `-Ztreat-err-as-bug`.
For example, the following code...
```rust
struct A;
struct B;
fn main(){
let _: A = B;
}
```
...now emits the following error message:
```
error[E0308]: mismatched types
--> src\main.rs:5:16
|
5 | let _: A = B;
| - ^ expected struct `A`, found struct `B`
| |
| expected due to this
-Ztrack-diagnostics: created at compiler\rustc_infer\src\infer\error_reporting\mod.rs:2275:31
```
(almost) Always use `ObligationCtxt` when dealing with canonical queries
Hope this is a step in the right direction. cc rust-lang/types-team#50.
r? `@lcnr`
Accept `TyCtxt` instead of `TyCtxtAt` in `Ty::is_*` functions
Functions in answer:
- `Ty::is_freeze`
- `Ty::is_sized`
- `Ty::is_unpin`
- `Ty::is_copy_modulo_regions`
This allows to remove a lot of useless `.at(DUMMY_SP)`, making the code a bit nicer :3
r? `@compiler-errors`
spastorino noticed some silly expressions like `item_id.def_id.def_id`.
This commit renames several `def_id: OwnerId` fields as `owner_id`, so
those expressions become `item_id.owner_id.def_id`.
`item_id.owner_id.local_def_id` would be even clearer, but the use of
`def_id` for values of type `LocalDefId` is *very* widespread, so I left
that alone.
Flatten diagnostic slug modules
This makes it easier to grep for the slugs in the code.
See https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Localization.20infra.20interferes.20with.20grepping.20for.20error for more discussion about it.
This was mostly done with a few regexes and a bunch of manual work. This also exposes a pretty annoying inconsistency for the extra labels. Some of the extra labels are defined as additional properties in the fluent message (which makes them not prefixed with the crate name) and some of them are new fluent messages themselves (which makes them prefixed with the crate name). I don't know whether we want to clean this up at some point but it's useful to know.
r? `@davidtwco`
Delay ambiguity span bug in normalize query iff not rustdoc
Oli and I decided that the compiler debt of adding another usage of `tcx.sess.opts.actually_rustdoc` is fine, because we don't really want to add more complexity to the normalize query, and moving rustdoc to use fulfill normalization (`fully_normalize`, i.e. not use the normalize query) is unnecessary overhead given that it's skipping binders and stuff.
r? oli-obk
Fixes#102827Fixes#103181
Do not suggest trivially false const predicates
Pass through constness to `predicate_can_apply` and don't suggest other impls if it's satisfied but not const.
Fixes#103267
stop using `ty::UnevaluatedConst` directly
best reviewed commit by commit.
simplifies #99798 because we now don't have to expand `ty::UnevaluatedConst` to `ty::Const`.
I also remember some other places where using `ty::UnevaluatedConst` directly was annoying and caused issues, though I don't quite remember what they were rn '^^
r? `@oli-obk` cc `@JulianKnodt`
Make diagnostic for unsatisfied `Termination` bounds more precise
Don't blindly emit a diagnostic claiming that “*`main` has an invalid return type*” if we encounter a type that should but doesn't implement `std::process::Termination` and isn't actually the return type of the program entry `main`.
Fixes#103052.
``@rustbot`` label A-diagnostics T-compiler T-libs
r? diagnostics
Rollup of 4 pull requests
Successful merges:
- #102454 (Suggest parentheses for possible range method calling)
- #102466 (only allow `ConstEquate` with `feature(gce)`)
- #102945 (Do not register placeholder `RegionOutlives` obligations when `considering_regions` is false)
- #103091 (rustdoc: remove unused HTML class `sidebar-title`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Do not register placeholder `RegionOutlives` obligations when `considering_regions` is false
**NOTE:** I'm kinda just putting this up for discussion. I'm not certain this is correct...?
This was introduced in [`608625d`](608625dae9 (diff-6e54b18681342ec725d75591dbf384ad08cd73df29db00485fe51b4e90f76ff7R361)).
Interestingly, we only check `data.has_placeholders()` for `RegionOutlives`, and not for `TypeOutlives`... why? For the record, that different treatment between `RegionOutlives` and `TypeOutlives` is why the fix "The compiling succeeds when all `'a : 'b` are replaced with `&'a () : 'b`" in #100689 _"works"_, but it seems like an implementation detail considering this.
Also, why do we care about placeholder regions being registered if `considering_regions` is false? It doesn't seem to affect any UI tests, for example.
r? `@lcnr`
Fixes#102899Fixes#100689
Fix subst issues with return-position `impl Trait` in trait
1. Fix an issue where we were rebase impl substs onto trait method substs, instead of trait substs
2. Fix an issue where early-bound regions aren't being mapped correctly for RPITIT hidden types
Fixes#102301Fixes#102310Fixes#102334Fixes#102918
More dupe word typos
I only picked those changes (from the regex search) that I am pretty certain doesn't change meaning and is just a typo fix. Do correct me if any fix is undesirable and I can revert those. Thanks.
Support default-body trait functions with return-position `impl Trait` in traits
Introduce a new `Trait` candidate kind for the `ImplTraitInTrait` projection candidate, which just projects an RPITIT down to its opaque type form.
This is a hack until we lower RPITITs to regular associated types, after which we will need to rework how these default bodies are type-checked, so comments are left in a few places for us to clean up later.
Fixes#101665
Elaborate trait ref to compute object safety.
instead of building them manually from supertraits and associated items.
This allows to have the correct substs for GATs.
Fixes https://github.com/rust-lang/rust/issues/102751
rename `ImplItemKind::TyAlias` to `ImplItemKind::Type`
The naming of this variant seems inconsistent given that this is not really a "type alias", and the associated type variant for `TraitItemKind` is just called `Type`.
Remove `DefId` from some `SelectionCandidate` variants
They are both from `obligation.predicate.def_id()`, which do not need to be on the `SelectionCandidate`.
cc ````@lcnr```` ````@compiler-errors````
Rewrite representability
* Improve placement of `Box` in the suggestion
* Multiple items in a cycle emit 1 error instead of an error for each item in the cycle
* Introduce `representability` query to avoid traversing an item every time it is used.
* Also introduce `params_in_repr` query to avoid traversing generic items every time it is used.
Rollup of 6 pull requests
Successful merges:
- #102300 (Use a macro to not have to copy-paste `ConstFnMutClosure::new(&mut fold, NeverShortCircuit::wrap_mut_2_imp)).0` everywhere)
- #102475 (unsafe keyword: trait examples and unsafe_op_in_unsafe_fn update)
- #102760 (Avoid repeated re-initialization of the BufReader buffer)
- #102764 (Check `WhereClauseReferencesSelf` after all other object safety checks)
- #102779 (Fix `type_of` ICE)
- #102780 (run Miri CI when std::sys changes)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
It's not about types or consts, but the lack of regions
pulled out of https://github.com/rust-lang/rust/pull/101900 which adds a fourth kind of non-lifetime generic parameter, and the naming of these methods would get ridiculous.
Fix ICE #101739
Fixes a part of #101739
This cannot cover the following case. It causes `too many args provided` error and obligation does not have references error. I want your advice to solve the following cases as well in this pull request or a follow-up.
```rust
#![crate_type = "lib"]
#![feature(transmutability)]
#![allow(dead_code, incomplete_features, non_camel_case_types)]
mod assert {
use std::mem::BikeshedIntrinsicFrom;
pub fn is_transmutable<
Src,
Dst,
Context,
const ASSUME_ALIGNMENT: bool,
const ASSUME_LIFETIMES: bool,
const ASSUME_VALIDITY: bool,
const ASSUME_VISIBILITY: bool,
>()
where
Dst: BikeshedIntrinsicFrom<
Src,
Context,
ASSUME_ALIGNMENT,
ASSUME_LIFETIMES,
ASSUME_VALIDITY,
ASSUME_VISIBILITY,
>,
{}
}
fn via_const() {
struct Context;
#[repr(C)] struct Src;
#[repr(C)] struct Dst;
const FALSE: bool = false;
assert::is_transmutable::<Src, Dst, Context, FALSE, FALSE, FALSE, FALSE>();
}
```
Move lint level source explanation to the bottom
So, uhhhhh
r? `@estebank`
## User-facing change
"note: `#[warn(...)]` on by default" and such are moved to the bottom of the diagnostic:
```diff
- = note: `#[warn(unsupported_calling_conventions)]` on by default
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #87678 <https://github.com/rust-lang/rust/issues/87678>
+ = note: `#[warn(unsupported_calling_conventions)]` on by default
```
Why warning is enabled is the least important thing, so it shouldn't be the first note the user reads, IMO.
## Developer-facing change
`struct_span_lint` and similar methods have a different signature.
Before: `..., impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>)`
After: `..., impl Into<DiagnosticMessage>, impl for<'a, 'b> FnOnce(&'b mut DiagnosticBuilder<'a, ()>) -> &'b mut DiagnosticBuilder<'a, ()>`
The reason for this is that `struct_span_lint` needs to edit the diagnostic _after_ `decorate` closure is called. This also makes lint code a little bit nicer in my opinion.
Another option is to use `impl for<'a> FnOnce(LintDiagnosticBuilder<'a, ()>) -> DiagnosticBuilder<'a, ()>` altough I don't _really_ see reasons to do `let lint = lint.build(message)` everywhere.
## Subtle problem
By moving the message outside of the closure (that may not be called if the lint is disabled) `format!(...)` is executed earlier, possibly formatting `Ty` which may call a query that trims paths that crashes the compiler if there were no warnings...
I don't think it's that big of a deal, considering that we move from `format!(...)` to `fluent` (which is lazy by-default) anyway, however this required adding a workaround which is unfortunate.
## P.S.
I'm sorry, I do not how to make this PR smaller/easier to review. Changes to the lint API affect SO MUCH 😢
remove the unused :: between trait and type to give user correct diag…
…nostic information
modified: compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
new file: src/test/ui/type/issue-101866.rs
new file: src/test/ui/type/issue-101866.stderr
remove outdated coherence hack
we have a more precise detection for downstream conflicts in candidate assembly: the `is_knowable` check in `candidate_from_obligation_no_cache`.
r? types cc `@nikomatsakis`
modified: compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
new file: src/test/ui/type/issue-101866.rs
new file: src/test/ui/type/issue-101866.stderr
implied_bounds: deal with inference vars
fixes#101951
while computing implied bounds for `<<T as ConstructionFirm>::Builder as BuilderFn<'_>>::Output` normalization replaces a projection with an inference var (adding a `Projection` obligation). Until we prove that obligation, this inference var remains unknown, which caused us to miss an implied bound necessary to prove that the unnormalized projection from the trait method signature is wf.
r? types
fix a ui test
use `into`
fix clippy ui test
fix a run-make-fulldeps test
implement `IntoQueryParam<DefId>` for `OwnerId`
use `OwnerId` for more queries
change the type of `ParentOwnerIterator::Item` to `(OwnerId, OwnerNode)`
Introduce mir::Unevaluated
Previously the distinction between unevaluated constants in the type-system and in mir was not explicit and a little confusing. Probably better to introduce its own type for that.
r? `@lcnr`
Rollup of 8 pull requests
Successful merges:
- #101598 (Update rustc's information on Android's sanitizers)
- #102036 (Remove use of `io::ErrorKind::Other` in std)
- #102037 (Make cycle errors recoverable)
- #102069 (Skip `Equate` relation in `handle_opaque_type`)
- #102076 (rustc_transmute: fix big-endian discriminants)
- #102107 (Add missing space between notable trait tooltip and where clause)
- #102119 (Fix a typo “pararmeter” in error message)
- #102131 (Added which number is computed in compute_float.)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Make cycle errors recoverable
In particular, this allows rustdoc to recover from cycle errors when normalizing associated types for documentation.
In the past, ```@jackh726``` has said we need to be careful about overflow errors: https://github.com/rust-lang/rust/pull/91430#issuecomment-983997013
> Off the top of my head, we definitely should be careful about treating overflow errors the same as
"not implemented for some reason" errors. Otherwise, you could end up with behavior that is
different depending on recursion depth. But, that might be context-dependent.
But cycle errors should be safe to unconditionally report; they don't depend on the recursion depth, they will always be an error whenever they're encountered.
Helps with https://github.com/rust-lang/rust/issues/81091.
r? ```@lcnr``` cc ```@matthewjasper```
Normalize opaques w/ bound vars
First, we reenable normalization of opaque types with escaping late bound regions to fix rust-lang/miri#2433. This essentially reverts #89285.
Second, we mitigate the perf regression found in #88862 by simplifying the way that we relate (sub and eq) GeneratorWitness types.
This relies on the fact that we construct these GeneratorWitness types somewhat particularly (with all free regions found in the witness types replaced with late bound regions) -- but those bound regions really should be treated as existential regions, not universal ones. Those two facts leads me to believe that we do not need to use the full `higher_ranked_sub` machinery to relate two generator witnesses. I'm pretty confident that this is correct, but I'm glad to discuss this further.
FIX - ambiguous Diagnostic link in docs
UPDATE - rename diagnostic_items to IntoDiagnostic and AddToDiagnostic
[Gardening] FIX - formatting via `x fmt`
FIX - rebase conflicts. NOTE: Confirm wheather or not we want to handle TargetDataLayoutErrorsWrapper this way
DELETE - unneeded allow attributes in Handler method
FIX - broken test
FIX - Rebase conflict
UPDATE - rename residual _SessionDiagnostic and fix LintDiag link
a fn pointer doesn't implement `Fn`/`FnMut`/`FnOnce` if its return type isn't sized
I stumbled upon #83915 which hasn't received much attention recently, and I wanted to revive it since this is one existing soundness hole that seems pretty easy to fix.
I'm not actually sure that the [alternative approach described here](https://github.com/rust-lang/rust/pull/83915#issuecomment-823643322) is sufficient, given the `src/test/ui/function-pointer/unsized-ret.rs` example I provided below. Rebasing the branch mentioned in that comment and testing that UI test, it seems that we actually end up only observing that `str: !Sized` during monomorphization, whereupon we ICE. Even if we were to fix that ICE, ideally we'd be raising an error that a fn pointer is being used badly during _typecheck_ instead of monomorphization, hence adapting the original approach in #83915.
I am happy to close this if people would prefer we rebase the original PR and land that -- I am partly opening to be annoying and get people thinking about this unsoundness again ❤️😸
cc: `@estebank` and `@nikomatsakis`
r? types
Here's a link to the thread: https://rust-lang.zulipchat.com/#narrow/stream/144729-t-types/topic/PR.20.2383915/near/235421351 for more context.
In particular, this allows rustdoc to recover from cycle errors when normalizing associated types for documentation.
In the past, `@jackh726` has said we need to be careful about overflow errors:
> Off the top of my head, we definitely should be careful about treating overflow errors the same as
"not implemented for some reason" errors. Otherwise, you could end up with behavior that is
different depending on recursion depth. But, that might be context-dependent.
But cycle errors should be safe to unconditionally report; they don't depend on the recursion depth, they will always be an error whenever they're encountered.
`EarlyBinder` prevent misuse
folding a type before substituting is pretty much always wrong and could happen by accident, e.g. see https://github.com/rust-lang/rust/pull/99798#discussion_r968666538
this PR removes the `TypeFoldable` and `TypeVisitable` impl from `EarlyBinder`.
r? types cc `@jackh726`
On later stages, the feature is already stable.
Result of running:
rg -l "feature.let_else" compiler/ src/librustdoc/ library/ | xargs sed -s -i "s#\\[feature.let_else#\\[cfg_attr\\(bootstrap, feature\\(let_else\\)#"
Initial implementation of dyn*
This PR adds extremely basic and incomplete support for [dyn*](https://smallcultfollowing.com/babysteps//blog/2022/03/29/dyn-can-we-make-dyn-sized/). The goal is to get something in tree behind a flag to make collaboration easier, and also to make sure the implementation so far is not unreasonable. This PR does quite a few things:
* Introduce `dyn_star` feature flag
* Adds parsing for `dyn* Trait` types
* Defines `dyn* Trait` as a sized type
* Adds support for explicit casts, like `42usize as dyn* Debug`
* Including const evaluation of such casts
* Adds codegen for drop glue so things are cleaned up properly when a `dyn* Trait` object goes out of scope
* Adds codegen for method calls, at least for methods that take `&self`
Quite a bit is still missing, but this gives us a starting point. Note that this is never intended to become stable surface syntax for Rust, but rather `dyn*` is planned to be used as an implementation detail for async functions in dyn traits.
Joint work with `@nikomatsakis` and `@compiler-errors.`
r? `@bjorn3`
Stabilize generic associated types
Closes#44265
r? `@nikomatsakis`
# ⚡ Status of the discussion ⚡
* [x] There have been several serious concerns raised, [summarized here](https://github.com/rust-lang/rust/pull/96709#issuecomment-1129311660).
* [x] There has also been a [deep-dive comment](https://github.com/rust-lang/rust/pull/96709#issuecomment-1167220240) explaining some of the "patterns of code" that are enabled by GATs, based on use-cases posted to this thread or on the tracking issue.
* [x] We have modeled some aspects of GATs in [a-mir-formality](https://github.com/nikomatsakis/a-mir-formality) to give better confidence in how they will be resolved in the future. [You can read a write-up here](https://github.com/rust-lang/types-team/blob/master/minutes/2022-07-08-implied-bounds-and-wf-checking.md).
* [x] The major points of the discussion have been [summarized on the GAT initiative repository](https://rust-lang.github.io/generic-associated-types-initiative/mvp.html).
* [x] [FCP has been proposed](https://github.com/rust-lang/rust/pull/96709#issuecomment-1129311660) and we are awaiting final decisions and discussion amidst the relevant team members.
# Stabilization proposal
This PR proposes the stabilization of `#![feature(generic_associated_types)]`. While there a number of future additions to be made and bugs to be fixed (both discussed below), properly doing these will require significant language design and will ultimately likely be backwards-compatible. Given the overwhelming desire to have some form of generic associated types (GATs) available on stable and the stability of the "simple" uses, stabilizing the current subset of GAT features is almost certainly the correct next step.
Tracking issue: #44265
Initiative: https://rust-lang.github.io/generic-associated-types-initiative/
RFC: https://github.com/rust-lang/rfcs/blob/master/text/1598-generic_associated_types.md
Version: 1.65 (2022-08-22 => beta, 2022-11-03 => stable).
## Motivation
There are a myriad of potential use cases for GATs. Stabilization unblocks probable future language features (e.g. async functions in traits), potential future standard library features (e.g. a `LendingIterator` or some form of `Iterator` with a lifetime generic), and a plethora of user use cases (some of which can be seen just by scrolling through the tracking issue and looking at all the issues linking to it).
There are a myriad of potential use cases for GATs. First, there are many users that have chosen to not use GATs primarily because they are not stable (some of which can be seen just by scrolling through the tracking issue and looking at all the issues linking to it). Second, while language feature desugaring isn't *blocked* on stabilization, it gives more confidence on using the feature. Likewise, library features like `LendingIterator` are not necessarily blocked on stabilization to be implemented unstably; however few, if any, public-facing APIs actually use unstable features.
This feature has a long history of design, discussion, and developement - the RFC was first introduced roughly 6 years ago. While there are still a number of features left to implement and bugs left to fix, it's clear that it's unlikely those will have backwards-incompatibility concerns. Additionally, the bugs that do exist do not strongly impede the most-common use cases.
## What is stabilized
The primary language feature stabilized here is the ability to have generics on associated types, as so. Additionally, where clauses on associated types will now be accepted, regardless if the associated type is generic or not.
```rust
trait ATraitWithGATs {
type Assoc<'a, T> where T: 'a;
}
trait ATraitWithoutGATs<'a, T> {
type Assoc where T: 'a;
}
```
When adding an impl for a trait with generic associated types, the generics for the associated type are copied as well. Note that where clauses are allowed both after the specified type and before the equals sign; however, the latter is a warn-by-default deprecation.
```rust
struct X;
struct Y;
impl ATraitWithGATs for X {
type Assoc<'a, T> = &'a T
where T: 'a;
}
impl ATraitWithGATs for Y {
type Assoc<'a, T>
where T: 'a
= &'a T;
}
```
To use a GAT in a function, generics are specified on the associated type, as if it was a struct or enum. GATs can also be specified in trait bounds:
```rust
fn accepts_gat<'a, T>(t: &'a T) -> T::Assoc<'a, T>
where for<'x> T: ATraitWithGATs<Assoc<'a, T> = &'a T> {
...
}
```
GATs can also appear in trait methods. However, depending on how they are used, they may confer where clauses on the associated type definition. More information can be found [here](https://github.com/rust-lang/rust/issues/87479). Briefly, where clauses are required when those bounds can be proven in the methods that *construct* the GAT or other associated types that use the GAT in the trait. This allows impls to have maximum flexibility in the types defined for the associated type.
To take a relatively simple example:
```rust
trait Iterable {
type Item<'a>;
type Iterator<'a>: Iterator<Item = Self::Item<'a>>;
fn iter<'x>(&'x self) -> Self::Iterator<'x>;
//^ We know that `Self: 'a` for `Iterator<'a>`, so we require that bound on `Iterator`
// `Iterator` uses `Self::Item`, so we also require a `Self: 'a` on `Item` too
}
```
A couple well-explained examples are available in a previous [blog post](https://blog.rust-lang.org/2021/08/03/GATs-stabilization-push.html).
## What isn't stabilized/implemented
### Universal type/const quantification
Currently, you can write a bound like `X: for<'a> Trait<Assoc<'a> = &'a ()>`. However, you cannot currently write `for<T> X: Trait<Assoc<T> = T>` or `for<const N> X: Trait<Assoc<N> = [usize; N]>`.
Here is an example where this is needed:
```rust
trait Foo {}
trait Trait {
type Assoc<F: Foo>;
}
trait Trait2: Sized {
fn foo<F: Foo, T: Trait<Assoc<F> = F>>(_t: T);
}
```
In the above example, the *caller* must specify `F`, which is likely not what is desired.
### Object-safe GATs
Unlike non-generic associated types, traits with GATs are not currently object-safe. In other words the following are not allowed:
```rust
trait Trait {
type Assoc<'a>;
}
fn foo(t: &dyn for<'a> Trait<Assoc<'a> = &'a ()>) {}
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not allowed
let ty: Box<dyn for<'a> Trait<Assoc<'a> = &'a ()>>;
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not allowed
```
### Higher-kinded types
You cannot write currently (and there are no current plans to implement this):
```rust
struct Struct<'a> {}
fn foo(s: for<'a> Struct<'a>) {}
```
## Tests
There are many tests covering GATs that can be found in `src/test/ui/generic-associated-types`. Here, I'll list (in alphanumeric order) tests highlight some important behavior or contain important patterns.
- `./parse/*`: Parsing of GATs in traits and impls, and the trait path with GATs
- `./collections-project-default.rs`: Interaction with associated type defaults
- `./collections.rs`: The `Collection` pattern
- `./const-generics-gat-in-trait-return-type-*.rs`: Const parameters
- `./constraint-assoc-type-suggestion.rs`: Emit correct syntax in suggestion
- `./cross-crate-bounds.rs`: Ensure we handles bounds across crates the same
- `./elided-in-expr-position.rs`: Disallow lifetime elision in return position
- `./gat-in-trait-path-undeclared-lifetime.rs`: Ensure we error on undeclared lifetime in trait path
- `./gat-in-trait-path.rs`: Base trait path case
- `./gat-trait-path-generic-type-arg.rs`: Don't allow shadowing of parameters
- `./gat-trait-path-parenthesised-args.rs`: Don't allow paranthesized args in trait path
- `./generic-associated-types-where.rs`: Ensure that we require where clauses from trait to be met on impl
- `./impl_bounds.rs`: Check that the bounds on GATs in an impl are checked
- `./issue-76826.rs`: `Windows` pattern
- `./issue-78113-lifetime-mismatch-dyn-trait-box.rs`: Implicit 'static diagnostics
- `./issue-84931.rs`: Ensure that we have a where clause on GAT to ensure trait parameter lives long enough
- `./issue-87258_a.rs`: Unconstrained opaque type with TAITs
- `./issue-87429-2.rs`: Ensure we can use bound vars in the bounds
- `./issue-87429-associated-type-default.rs`: Ensure bounds hold with associated type defaults, for both trait and impl
- `./issue-87429-specialization.rs`: Check that bounds hold under specialization
- `./issue-88595.rs`: Under the outlives lint, we require a bound for both trait and GAT lifetime when trait lifetime is used in function
- `./issue-90014.rs`: Lifetime bounds are checked with TAITs
- `./issue-91139.rs`: Under migrate mode, but not NLL, we don't capture implied bounds from HRTB lifetimes used in a function and GATs
- `./issue-91762.rs`: We used to too eagerly pick param env candidates when normalizing with GATs. We now require explicit parameters specified.
- `./issue-95305.rs`: Disallow lifetime elision in trait paths
- `./iterable.rs`: `Iterable` pattern
- `./method-unsatified-assoc-type-predicate.rs`: Print predicates with GATs correctly in method resolve error
- `./missing_lifetime_const.rs`: Ensure we must specify lifetime args (not elidable)
- `./missing-where-clause-on-trait.rs`: Ensure we don't allow stricter bounds on impl than trait
- `./parameter_number_and_kind_impl.rs`: Ensure paramters on GAT in impl match GAT in trait
- `./pointer_family.rs`: `PointerFamily` pattern
- `./projection-bound-cycle.rs`: Don't allow invalid cycles to prove bounds
- `./self-outlives-lint.rs`: Ensures that an e.g. `Self: 'a` is written on the traits GAT if that bound can be implied from the GAT usage in the trait
- `./shadowing.rs`: Don't allow lifetime shadowing in params
- `./streaming_iterator.rs`: `StreamingIterator`(`LendingIterator`) pattern
- `./trait-objects.rs`: Disallow trait objects for traits with GATs
- `./variance_constraints.rs`: Require that GAT substs be invariant
## Remaining bugs and open issues
A full list of remaining open issues can be found at: https://github.com/rust-lang/rust/labels/F-generic_associated_types
There are some `known-bug` tests in-tree at `src/test/ui/generic-associated-types/bugs`.
Here I'll categorize most of those that GAT bugs (or involve a pattern found more with GATs), but not those that include GATs but not a GAT issue in and of itself. (I also won't include issues directly for things listed elsewhere here.)
Using the concrete type of a GAT instead of the projection type can give errors, since lifetimes are chosen to be early-bound vs late-bound.
- #85533
- #87803
In certain cases, we can run into cycle or overflow errors. This is more generally a problem with associated types.
- #87755
- #87758
Bounds on an associatd type need to be proven by an impl, but where clauses need to be proven by the usage. This can lead to confusion when users write one when they mean the other.
- #87831
- #90573
We sometimes can't normalize closure signatures fully. Really an asociated types issue, but might happen a bit more frequently with GATs, since more obvious place for HRTB lifetimes.
- #88382
When calling a function, we assign types to parameters "too late", after we already try (and fail) to normalize projections. Another associated types issue that might pop up more with GATs.
- #88460
- #96230
We don't fully have implied bounds for lifetimes appearing in GAT trait paths, which can lead to unconstrained type errors.
- #88526
Suggestion for adding lifetime bounds can suggest unhelpful fixes (`T: 'a` instead of `Self: 'a`), but the next compiler error after making the suggested change is helpful.
- #90816
- #92096
- #95268
We can end up requiring that `for<'a> I: 'a` when we really want `for<'a where I: 'a> I: 'a`. This can leave unhelpful errors than effectively can't be satisfied unless `I: 'static`. Requires bigger changes and not only GATs.
- #91693
Unlike with non-generic associated types, we don't eagerly normalize with param env candidates. This is intended behavior (for now), to avoid accidentaly stabilizing picking arbitrary impls.
- #91762
Some Iterator adapter patterns (namely `filter`) require Polonius or unsafe to work.
- #92985
## Potential Future work
### Universal type/const quantification
No work has been done to implement this. There are also some questions around implied bounds.
### Object-safe GATs
The intention is to make traits with GATs object-safe. There are some design work to be done around well-formedness rules and general implementation.
### GATified std lib types
It would be helpful to either introduce new std lib traits (like `LendingIterator`) or to modify existing ones (adding a `'a` generic to `Iterator::Item`). There also a number of other candidates, like `Index`/`IndexMut` and `Fn`/`FnMut`/`FnOnce`.
### Reduce the need for `for<'a>`
Seen [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-2611378730). One possible syntax:
```rust
trait Iterable {
type Iter<'a>: Iterator<Item = Self::Item<'a>>;
}
fn foo<T>() where T: Iterable, T::Item<let 'a>: Display { } //note the `let`!
```
### Better implied bounds on higher-ranked things
Currently if we have a `type Item<'a> where self: 'a`, and a `for<'a> T: Iterator<Item<'a> = &'a ()`, this requires `for<'a> Self: 'a`. Really, we want `for<'a where T: 'a> ...`
There was some mentions of this all the back in the RFC thread [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-264340514).
## Alternatives
### Make generics on associated type in bounds a binder
Imagine the bound `for<'a> T: Trait<Item<'a>= &'a ()>`. It might be that `for<'a>` is "too large" and it should instead be `T: Trait<for<'a> Item<'a>= &'a ()>`. Brought up in RFC thread [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-229443863) and in a few places since.
Another related question: Is `for<'a>` the right syntax? Maybe `where<'a>`? Also originally found in RFC thread [here](https://github.com/rust-lang/rfcs/pull/1598#issuecomment-261639969).
### Stabilize lifetime GATs first
This has been brought up a few times. The idea is to only allow GATs with lifetime parameters to in initial stabilization. This was probably most useful prior to actual implementation. At this point, lifetimes, types, and consts are all implemented and work. It feels like an arbitrary split without strong reason.
## History
* On 2016-04-30, [RFC opened](https://github.com/rust-lang/rfcs/pull/1598)
* On 2017-09-02, RFC merged and [tracking issue opened](https://github.com/rust-lang/rust/issues/44265)
* On 2017-10-23, [Move Generics from MethodSig to TraitItem and ImplItem](https://github.com/rust-lang/rust/pull/44766)
* On 2017-12-01, [Generic Associated Types Parsing & Name Resolution](https://github.com/rust-lang/rust/pull/45904)
* On 2017-12-15, [https://github.com/rust-lang/rust/pull/46706](https://github.com/rust-lang/rust/pull/46706)
* On 2018-04-23, [Feature gate where clauses on associated types](https://github.com/rust-lang/rust/pull/49368)
* On 2018-05-10, [Extend tests for RFC1598 (GAT)](https://github.com/rust-lang/rust/pull/49423)
* On 2018-05-24, [Finish implementing GATs (Chalk)](https://github.com/rust-lang/chalk/pull/134)
* On 2019-12-21, [Make GATs less ICE-prone](https://github.com/rust-lang/rust/pull/67160)
* On 2020-02-13, [fix lifetime shadowing check in GATs](https://github.com/rust-lang/rust/pull/68938)
* On 2020-06-20, [Projection bound validation](https://github.com/rust-lang/rust/pull/72788)
* On 2020-10-06, [Separate projection bounds and predicates](https://github.com/rust-lang/rust/pull/73905)
* On 2021-02-05, [Generic associated types in trait paths](https://github.com/rust-lang/rust/pull/79554)
* On 2021-02-06, [Trait objects do not work with generic associated types](https://github.com/rust-lang/rust/issues/81823)
* On 2021-04-28, [Make traits with GATs not object safe](https://github.com/rust-lang/rust/pull/84622)
* On 2021-05-11, [Improve diagnostics for GATs](https://github.com/rust-lang/rust/pull/82272)
* On 2021-07-16, [Make GATs no longer an incomplete feature](https://github.com/rust-lang/rust/pull/84623)
* On 2021-07-16, [Replace associated item bound vars with placeholders when projecting](https://github.com/rust-lang/rust/pull/86993)
* On 2021-07-26, [GATs: Decide whether to have defaults for `where Self: 'a`](https://github.com/rust-lang/rust/issues/87479)
* On 2021-08-25, [Normalize projections under binders](https://github.com/rust-lang/rust/pull/85499)
* On 2021-08-03, [The push for GATs stabilization](https://blog.rust-lang.org/2021/08/03/GATs-stabilization-push.html)
* On 2021-08-12, [Detect stricter constraints on gats where clauses in impls vs trait](https://github.com/rust-lang/rust/pull/88336)
* On 2021-09-20, [Proposal: Change syntax of where clauses on type aliases](https://github.com/rust-lang/rust/issues/89122)
* On 2021-11-06, [Implementation of GATs outlives lint](https://github.com/rust-lang/rust/pull/89970)
* On 2021-12-29. [Parse and suggest moving where clauses after equals for type aliases](https://github.com/rust-lang/rust/pull/92118)
* On 2022-01-15, [Ignore static lifetimes for GATs outlives lint](https://github.com/rust-lang/rust/pull/92865)
* On 2022-02-08, [Don't constrain projection predicates with inference vars in GAT substs](https://github.com/rust-lang/rust/pull/92917)
* On 2022-02-15, [Rework GAT where clause check](https://github.com/rust-lang/rust/pull/93820)
* On 2022-02-19, [Only mark projection as ambiguous if GAT substs are constrained](https://github.com/rust-lang/rust/pull/93892)
* On 2022-03-03, [Support GATs in Rustdoc](https://github.com/rust-lang/rust/pull/94009)
* On 2022-03-06, [Change location of where clause on GATs](https://github.com/rust-lang/rust/pull/90076)
* On 2022-05-04, [A shiny future with GATs blog post](https://jackh726.github.io/rust/2022/05/04/a-shiny-future-with-gats.html)
* On 2022-05-04, [Stabilization PR](https://github.com/rust-lang/rust/pull/96709)
Adjust and slightly generalize operator error suggestion
(in no particular order)
* Stop passing around a whole extra `ProjectionPredicate`
* Add spaces around `=` in `Trait<..., Output = Ty>` suggestion
* Some code clean-ups, including
* add `lang_item_for_op` to turn a `Op` into a `DefId`
* avoid `SourceMap` because we don't really need to render an expr
* Remove `TypeParamVisitor` in favor of just checking `ty.has_param_types_or_consts` -- this acts a bit differently, but shouldn't cause erroneous suggestions (actually might generalize them a bit)
* We now suggest `Output = Ty` in the `where` clause suggestion when we fail to add `Struct<T>` and `T`.
I can split this out into more PRs if needed, but they're all just miscellaneous generalizations, changes, and nitpicks I saw when messing with this operator code.
const_generics: correctly deal with bound variables
removes the hack in `resolve` which was needed because we evaluated constants without caring about their bound variables.
Each commit should be fairly self-contained, even if they build on each other
r? `@jackh726`
rustc: Parameterize `ty::Visibility` over used ID
It allows using `LocalDefId` instead of `DefId` when possible, and also encode cheaper `Visibility<DefIndex>` into metadata.
Update `SessionDiagnostic::into_diagnostic` to take `Handler` instead of `ParseSess`
Suggested by the team in [this Zulip Topic](https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/.23100717.20SessionDiagnostic.20on.20Handler).
`Handler` already has almost all the capabilities of `ParseSess` when it comes to diagnostic emission, in this migration we only needed to add the ability to access `source_map` from the emitter in order to get a `Snippet` and the `start_point`. Not sure if adding these two methods [`span_to_snippet_from_emitter` and `span_start_point_from_emitter`] is the best way to address this gap.
P.S. If this goes in the right direction, then we probably may want to move `SessionDiagnostic` to `rustc_errors` and rename it to `DiagnosticHandler` or something similar.
r? `@davidtwco`
r? `@compiler-errors`
Point out when a callable is not actually callable because its return is not sized
Fixes#100755
I didn't add a UI test for that one because it's equivalent to the UI test that already exists in the suite.
`BindingAnnotation` refactor
* `ast::BindingMode` is deleted and replaced with `hir::BindingAnnotation` (which is moved to `ast`)
* `BindingAnnotation` is changed from an enum to a tuple struct e.g. `BindingAnnotation(ByRef::No, Mutability::Mut)`
* Associated constants added for convenience `BindingAnnotation::{NONE, REF, MUT, REF_MUT}`
One goal is to make it more clear that `BindingAnnotation` merely represents syntax `ref mut` and not the actual binding mode. This was especially confusing since we had `ast::BindingMode`->`hir::BindingAnnotation`->`thir::BindingMode`.
I wish there were more symmetry between `ByRef` and `Mutability` (variant) naming (maybe `Mutable::Yes`?), and I also don't love how long the name `BindingAnnotation` is, but this seems like the best compromise. Ideas welcome.
Suggested by the team in this Zulip Topic https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/.23100717.20SessionDiagnostic.20on.20Handler
Handler already has almost all the capabilities of ParseSess when it comes to diagnostic emission, in this migration we only needed to add the ability to access source_map from the emitter in order to get a Snippet and the start_point. Not sure if this is the best way to address this gap
safe transmute: use `Assume` struct to provide analysis options
This task was left as a TODO in #92268; resolving it brings [`BikeshedIntrinsicFrom`](https://doc.rust-lang.org/nightly/core/mem/trait.BikeshedIntrinsicFrom.html) more in line with the API defined in [MCP411](https://github.com/rust-lang/compiler-team/issues/411).
**Before:**
```rust
pub unsafe trait BikeshedIntrinsicFrom<
Src,
Context,
const ASSUME_ALIGNMENT: bool,
const ASSUME_LIFETIMES: bool,
const ASSUME_VALIDITY: bool,
const ASSUME_VISIBILITY: bool,
> where
Src: ?Sized,
{}
```
**After:**
```rust
pub unsafe trait BikeshedIntrinsicFrom<Src, Context, const ASSUME: Assume = { Assume::NOTHING }>
where
Src: ?Sized,
{}
```
`Assume::visibility` has also been renamed to `Assume::safety`, as library safety invariants are what's actually being assumed; visibility is just the mechanism by which it is currently checked (and that may change).
r? `@oli-obk`
---
Related:
- https://github.com/rust-lang/compiler-team/issues/411
- https://github.com/rust-lang/rust/issues/99571
Attempt to normalize `FnDef` signature in `InferCtxt::cmp`
Stashes a normalization callback in `InferCtxt` so that the signature we get from `tcx.fn_sig(..).subst(..)` in `InferCtxt::cmp` can be properly normalized, since we cannot expect for it to have normalized types since it comes straight from astconv.
This is kind of a hack, but I will say that `@jyn514` found the fact that we present unnormalized types to be very confusing in real life code, and I agree with that feeling. Though altogether I am still a bit unsure about whether this PR is worth the effort, so I'm open to alternatives and/or just closing it outright.
On the other hand, this isn't a ridiculously heavy implementation anyways -- it's less than a hundred lines of changes, and half of that is just miscellaneous cleanup.
This is stacked onto #100471 which is basically unrelated, and it can be rebased off of that when that lands or if needed.
---
The code:
```rust
trait Foo { type Bar; }
impl<T> Foo for T {
type Bar = i32;
}
fn foo<T>(_: <T as Foo>::Bar) {}
fn needs_i32_ref_fn(f: fn(&'static i32)) {}
fn main() {
needs_i32_ref_fn(foo::<()>);
}
```
Before:
```
= note: expected fn pointer `fn(&'static i32)`
found fn item `fn(<() as Foo>::Bar) {foo::<()>}`
```
After:
```
= note: expected fn pointer `fn(&'static i32)`
found fn item `fn(i32) {foo::<()>}`
```
Rollup of 9 pull requests
Successful merges:
- #95376 (Add `vec::Drain{,Filter}::keep_rest`)
- #100092 (Fall back when relating two opaques by substs in MIR typeck)
- #101019 (Suggest returning closure as `impl Fn`)
- #101022 (Erase late bound regions before comparing types in `suggest_dereferences`)
- #101101 (interpret: make read-pointer-as-bytes a CTFE-only error with extra information)
- #101123 (Remove `register_attr` feature)
- #101175 (Don't --bless in pre-push hook)
- #101176 (rustdoc: remove unused CSS selectors for `.table-display`)
- #101180 (Add another MaybeUninit array test with const)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Avoid reporting overflow in `is_impossible_method`
Fixes#100620
We're evaluating a new predicate in a different param-env than it was checked during typeck, so be more careful about handling overflow errors. Instead of using `FulfillmentCtxt`, using `InferCtxt::evaluate_obligation` by itself will give us back the overflow error, so we can throw it away properly.
This may give us more false-positives, but it doesn't regress the `<HashMap as Iterator>::rev` example that originally motivated adding `is_impossible_method` in the first place.
Coherence negative impls implied bounds
Fixes#93875
This PR is rebased on top of #100789 and it would need to include that one which is already r+ed.
r? ``@nikomatsakis``
cc ``@lcnr`` (which I've talked about 3222f420d9, I guess after you finish your reordering of modules and work with OutlivesEnvironmentEnv this commit can just be reverted).
InferCtxt tainted_by_errors_flag should be Option<ErrorGuaranteed>
Fixes#100321.
Use Cell<Option<ErrorGuaranteed>> to guarantee that we emit an error when that flag is set.
Use separate infcx to solve obligations during negative coherence
I feel like I fixed this already but I may have fixed it then forgot to push the branch...
Also fixes up some redundant param-envs being passed around (since they're already passed around in the `Obligation`)
Fixes#99662
r? ``@spastorino``
implied bounds: explicitly state which types are assumed to be wf
Adds a new query which maps each definition to the types which that definition assumes to be well formed. The intent is to make it easier to reason about implied bounds.
This change should not influence the user-facing behavior of rustc. Notably, `borrowck` still only assumes that the function signature of associated functions is well formed while `wfcheck` assumes that the both the function signature and the impl trait ref is well formed. Not sure if that by itself can trigger UB or whether it's just annoying.
As a next step, we can add `WellFormed` predicates to `predicates_of` of these items and can stop adding the wf bounds at each place which uses them. I also intend to move the computation from `assumed_wf_types` to `implied_bounds` into the `param_env` computation. This requires me to take a deeper look at `compare_predicate_entailment` which is currently somewhat weird wrt implied bounds so I am not touching this here.
r? `@nikomatsakis`
Refactor: remove unnecessary string searchings
This patch removes unnecessary string searchings for checking if function arguments have `&` and `&mut`.
Revert "Rollup merge of #97346 - JohnTitor:remove-back-compat-hacks, …
…r=oli-obk"
This reverts commit c703d11dcc, reversing
changes made to 64eb9ab869.
it didn't apply cleanly, so now it works the same for RPIT and for TAIT instead of just working for RPIT, but we should keep those in sync anyway. It also exposed a TAIT bug (see the feature gated test that now ICEs).
r? `@pnkfelix`
fixes#99536
orphan check: rationalize our handling of constants
cc `@rust-lang/types` `@rust-lang/project-const-generics` on whether you agree with this reasoning.
r? types
Keep going if normalized projection has unevaluated consts in `QueryNormalizer`
#100312 was the wrong approach, I think this is the right one.
When normalizing a type, if we see that it's a projection, we currently defer to `tcx.normalize_projection_ty`, which normalizes the projections away but doesn't touch the unevaluated constants. So now we just continue to fold the type if it has unevaluated constants so we make sure to evaluate those too, if we can.
Fixes#100217Fixes#83972Fixes#84669Fixes#86710Fixes#82268Fixes#73298
consider unnormalized types for implied bounds
extracted, and slightly modified, from #98900
The idea here is that generally, rustc is split into things which can assume its inputs are well formed[^1], and things which have verify that themselves.
Generally most predicates should only deal with well formed inputs, e.g. a `&'a &'b (): Trait` predicate should be able to assume that `'b: 'a` holds. Normalization can loosen wf requirements (see #91068) and must therefore not be used in places which still have to check well formedness. The only such place should hopefully be `WellFormed` predicates
fixes#87748 and #98543
r? `@jackh726` cc `@rust-lang/types`
[^1]: These places may still encounter non-wf inputs and have to deal with them without causing an ICE as we may check for well formedness out of order.
Don't document impossible to call default trait items on impls
Closes#100176
This only skips documenting _default_ trait items on impls, not ones that are written inside the impl block. This is a conservative approach, since I think we should document all items written in an impl block (I guess unless hidden or whatever), but the existence of this new query I added makes this easy to extend to other rustdoc cases.
Delay a bug when failed to normalize trait ref during specialization
The error messages still kinda suck here but they don't ICE anymore...
Fixes#45814Fixes#43037
r? types
Use `TraitEngine` in more places that don't specifically need `FulfillmentContext::new_in_snapshot`
Not sure if this change is worthwhile, but couldn't hurt re: chalkification
r? types
remove `commit_unconditionally`
`commit_unconditionally` is a noop unless we somehow inspect the current state of our snapshot. The only thing which does that is the leak check which was only used in one place where `commit_if_ok` is probably at least as, or even more, correct.
r? rust-lang/types
Always include a position span in `rustc_parse_format::Argument`
Moves the spans from the `Position` enum to always be included in the `Argument` struct. Doesn't make any changes to use it in rustc, but it will be useful for some upcoming Clippy lints
make `PlaceholderConst` not store the type of the const
Currently the `Placeholder` variant on `ConstKind` is 28 bytes when with this PR its 8 bytes, i am not sure this is really useful at all rn since `Unevaluated` and `Value` variants are huge still but eventually it should be possible to get both down to 16 bytes 🤔. Mostly opening this to see if this change has any perf impact when done before it can make `ConstKind`/`ConstS` smaller
`codegen_fulfill_obligation` expect erased regions
it's a query, so by erasing regions before calling it, we get better caching.
This doesn't actually change anything as its already the status quo.
Improve type mismatch w/ function signatures
This PR makes use of `note: expected/found` (instead of labeling types in labels) in type mismatch with function signatures. Pros: it's easier to compare the signatures, cons: the error is a little more verbose now.
This is especially nice when
- The signatures differ in a small subset of parameters (same parameters are elided)
- The difference is in details, for example `isize` vs `usize` (there is a better chance that the types align)
Also this PR fixes the inconsistency in variable names in the edited code (`expected` and `found`).
A zulip thread from which this pr started: [[link]](https://rust-lang.zulipchat.com/#narrow/stream/147480-t-compiler.2Fwg-diagnostics/topic/Type.20error.20regression.3F.2E.2E.2E/near/289756602).
An example diagnostic:
<table>
<tr>
<th>this pr</th>
<th>nightly</th>
</tr>
<tr>
<td>
```text
error[E0631]: type mismatch in function arguments
--> ./t.rs:4:12
|
4 | expect(&f);
| ------ ^^ expected due to this
| |
| required by a bound introduced by this call
...
10 | fn f(_: isize, _: u8, _: Vec<u32>) {}
| ---------------------------------- found signature defined here
|
= note: expected function signature `fn(usize, _, Vec<u64>) -> _`
found function signature `fn(isize, _, Vec<u32>) -> _`
note: required because of the requirements on the impl of `Trait` for `fn(isize, u8, Vec<u32>) {f}`
--> ./t.rs:8:9
|
8 | impl<F> Trait for F where F: Fn(usize, u8, Vec<u64>) -> u8 {}
| ^^^^^ ^
= note: required for the cast from `fn(isize, u8, Vec<u32>) {f}` to the object type `dyn Trait`
```
</td>
<td>
```text
error[E0631]: type mismatch in function arguments
--> ./t.rs:4:12
|
4 | expect(&f);
| ------ ^^ expected signature of `fn(usize, u8, Vec<u64>) -> _`
| |
| required by a bound introduced by this call
...
10 | fn f(_: isize, _: u8, _: Vec<u32>) {}
| ---------------------------------- found signature of `fn(isize, u8, Vec<u32>) -> _`
|
note: required because of the requirements on the impl of `Trait` for `fn(isize, u8, Vec<u32>) {f}`
--> ./t.rs:8:9
|
8 | impl<F> Trait for F where F: Fn(usize, u8, Vec<u64>) -> u8 {}
| ^^^^^ ^
= note: required for the cast to the object type `dyn Trait`
```
</td>
</tr>
</table>
<details><summary>code</summary>
<p>
```rust
fn main() {
fn expect(_: &dyn Trait) {}
expect(&f);
}
trait Trait {}
impl<F> Trait for F where F: Fn(usize, u8, Vec<u64>) -> u8 {}
fn f(_: isize, _: u8, _: Vec<u32>) {}
```
</p>
</details>
r? `@compiler-errors`
use `check_region_obligations_and_report_errors` to avoid ICEs
If we don't call `process_registered_region_obligations` before `resolve_regions_and_report_errors` then we'll ICE if we have any region obligations, and `check_region_obligations_and_report_errors` just does both of these for us in a nice convenient function.
Fixes#53475
r? types
Generate correct suggestion with named arguments used positionally
Address issue #99265 by checking each positionally used argument
to see if the argument is named and adding a lint to use the name
instead. This way, when named arguments are used positionally in a
different order than their argument order, the suggested lint is
correct.
For example:
```
println!("{b} {}", a=1, b=2);
```
This will now generate the suggestion:
```
println!("{b} {a}", a=1, b=2);
```
Additionally, this check now also correctly replaces or inserts
only where the positional argument is (or would be if implicit).
Also, width and precision are replaced with their argument names
when they exists.
Since the issues were so closely related, this fix for issue #99265
also fixes issue #99266.
Fixes#99265Fixes#99266
This initial implementation handles transmutations between types with specified layouts, except when references are involved.
Co-authored-by: Igor null <m1el.2027@gmail.com>
Deeply deny fn and raw ptrs in const generics
I think this is right -- just because we wrap a fn ptr in a wrapper type does not mean we should allow it in a const parameter.
We now reject both of these in the same way:
```
#![feature(adt_const_params)]
#[derive(Eq, PartialEq)]
struct Wrapper();
fn foo<const W: Wrapper>() {}
fn foo2<const F: fn()>() {}
```
This does regress one test (`src/test/ui/consts/refs_check_const_eq-issue-88384.stderr`), but I'm not sure it should've passed in the first place.
cc: ``@b-naber`` who introduced that test^
fixes#99641
Restore `Opaque` behavior to coherence check
Fixes#99663.
This broke in 84c3fcd2a0. I'm not exactly certain that adding this behavior back is necessarily correct, but at least the UI test I provided may stimulate some thoughts.
I think delaying a bug here is certainly not correct in the case of opaques -- if we want to change coherence behavior for opaques, then we should at least be emitting a new error.
r? ``@lcnr``
handle consts with param/infer in `const_eval_resolve` better
This PR addresses [this thread here](https://github.com/rust-lang/rust/pull/99449#discussion_r924141230). Was this the change you were looking for ``@lcnr?``
Interestingly, one test has begun to pass. Was that expected?
r? ``@lcnr``
Address issue #99265 by checking each positionally used argument
to see if the argument is named and adding a lint to use the name
instead. This way, when named arguments are used positionally in a
different order than their argument order, the suggested lint is
correct.
For example:
```
println!("{b} {}", a=1, b=2);
```
This will now generate the suggestion:
```
println!("{b} {a}", a=1, b=2);
```
Additionally, this check now also correctly replaces or inserts
only where the positional argument is (or would be if implicit).
Also, width and precision are replaced with their argument names
when they exists.
Since the issues were so closely related, this fix for issue #99265
also fixes issue #99266.
Fixes#99265Fixes#99266
Do not resolve associated const when there is no provided value
Fixes#98629, since now we just delay a bug when we're not able to evaluate a const item due to the value not actually being provided by anything. This means compilation proceeds forward to where the "missing item in impl" error is emitted.
----
The root issue here is that when we're looking for the defining `LeafDef` in `resolve_associated_item`, we end up getting the trait's AssocItem instead of the impl's AssocItem (which does not exist). This resolution "succeeds" even if the trait's item has no default value, and then since this item has no value to evaluate, it turns into a const eval error.
This root issue becomes problematic (as in #98629) when this const eval error happens in wfcheck (for example, due to normalizing the param-env of something that references this const). Since this happens sooner than the check that an impl actually provides all of the items that a trait requires (which happens during later typecheck), we end up aborting compilation early with only this un-informative message.
I'm not exactly sure _why_ this bug arises due to #96591 -- perhaps valtrees are evaluated more eagerly than in the old system?
r? ``@oli-obk`` or ``@lcnr`` since y'all are familiar with const eval and reviewed #96591, though feel free to reassign.
This is a regression from stable to beta, so I would be open to considering this for beta backport. It seems correct to me, especially given the improvements in the other UI tests this PR touches, but may have some side-effects that I'm unaware of...?
Fix hack that remaps env constness.
WARNING: might have perf implications.
Are there any more problems with having a constness in the `ParamEnv` now? :)
r? `@oli-obk`
Improve suggestions for returning binding
Fixes#99525
Also reworks the cause codes for match and if a bit, I think cleaning them up in a positive way.
We no longer need to call `could_remove_semicolon` in successful code, which might save a few cycles?
move `considering_regions` to the infcx
it seems weird to prove some obligations which constrain inference vars while ignoring regions in a context which considers regions. This is especially weird because even for a fulfillment context with ignored regions, we still added region outlives bounds when directly relating regions.
tbh our handling of regions is still very weird, but at least this is a step in the right direction imo.
r? rust-lang/types
Add E0790 as more specific variant of E0283
Fixes#81701
I think this should be good to go, there are only two things where I am somewhat unsure:
- Is there a better way to get the fully-qualified path for the suggestion? I tried `self.tcx.def_path_str`, but that didn't seem to always give a correct path for the context.
- Should all this be extracted into it's own method or is it fine where it is?
r? `@estebank`
`replace_bound_vars` fast path: check predicates, don't check consts
split out from #98900
`ty::Const` doesn't have precomputed type flags, so
computing `has_vars_bound_at_or_above` for constants
requires us to visit the const and its contained types
and constants. A noop fold should be pretty much equally as
fast so removing it prevents us from walking the constant twice
in case it contains bound vars.
r? `@jackh726`
`arena > Rc` for query results
The `Rc`s have to live for the whole duration as their count cannot go below 1 while stored as part of the query results.
By storing them in an arena we should save a bit of memory because we don't have as many independent allocations and also don't have to clone the `Rc` anymore.
Don't pass InferCtxt to WfPredicates
Simple cleanup. Infer vars will get passed up as obligations and shallowed resolved later. This actually improves one test output.
Revert "Highlight conflicting param-env candidates"
This reverts #98794, commit 08135254dc.
Seems to have caused an incremental compilation bug. The root cause of the incr comp bug is somewhat unrelated but is triggered by this PR, so I don't feel comfortable with having this PR in the codebase until it can be investigated further. Fixes#99233.
Better error message for generic_const_exprs inference failure
Fixes#90531
This code:
```rs
#![feature(generic_const_exprs)]
fn foo<const N: usize>(_arr: [u64; N + 1]) where [u64; N + 1]: {}
fn main() {
let arr = [5; 5];
foo(arr);
}
```
Will now emit the following error:
```rs
warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
--> test.rs:1:12
|
1 | #![feature(generic_const_exprs)]
| ^^^^^^^^^^^^^^^^^^^
|
= note: `#[warn(incomplete_features)]` on by default
= note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
error[E0284]: type annotations needed
--> test.rs:8:7
|
8 | foo(arr);
| ^^^ cannot infer the value of the const parameter `N` declared on the function `foo`
|
note: required by a bound in `foo`
--> test.rs:3:56
|
3 | fn foo<const N: usize>(_arr: [u64; N + 1]) where [u64; N + 1]: {}
| ^^^^^ required by this bound in `foo`
help: consider specifying the generic argument
|
8 | foo::<N>(arr);
| +++++
error: aborting due to previous error; 1 warning emitted
```
cc: `@lcnr` thanks a lot again for the help on this
Move abstract const to middle
Moves AbstractConst (and all associated methods) to rustc middle for use in `rustc_infer`.
This allows for const resolution in infer to use abstract consts to walk consts and check if
they are resolvable.
This attempts to resolve the issue where `Foo<{ concrete const }, generic T>` is incorrectly marked as conflicting, and is independent from the other issue where nested abstract consts must be resolved.
r? `@lcnr`
`ty::Const` doesn't have precomputed type flags, so
computing `has_vars_bound_at_or_above` for constants
requires us to visit the const and its contained types
and constants. A noop fold should be pretty much equally as
fast so removing it prevents us from walking the constant twice
in case it contains bound vars.
Implement `for<>` lifetime binder for closures
This PR implements RFC 3216 ([TI](https://github.com/rust-lang/rust/issues/97362)) and allows code like the following:
```rust
let _f = for<'a, 'b> |a: &'a A, b: &'b B| -> &'b C { b.c(a) };
// ^^^^^^^^^^^--- new!
```
cc ``@Aaron1011`` ``@cjgillot``
Lower let-else in MIR
This MR will switch to lower let-else statements in MIR building instead.
To lower let-else in MIR, we build a mini-switch two branches. One branch leads to the matching case, and the other leads to the `else` block. This arrangement will allow temporary lifetime analysis running as-is so that the temporaries are properly extended according to the same rule applied to regular `let` statements.
cc https://github.com/rust-lang/rust/issues/87335Fix#98672
Fix duplicated type annotation suggestion
Before, there was more or less duplicated suggestions to add type hints.
Fix by clearing more generic suggestions when a more specific suggestion
is possible.
This fixes#93506 .
There are several indications that we should not ZST as a ScalarInt:
- We had two ways to have ZST valtrees, either an empty `Branch` or a `Leaf` with a ZST in it.
`ValTree::zst()` used the former, but the latter could possibly arise as well.
- Likewise, the interpreter had `Immediate::Uninit` and `Immediate::Scalar(Scalar::ZST)`.
- LLVM codegen already had to special-case ZST ScalarInt.
So instead add new ZST variants to those types that did not have other variants
which could be used for this purpose.
Before, there was more or less duplicated suggestions to add type hints.
Fix by clearing more generic suggestions when a more specific suggestion
is possible.
This fixes#93506 .
Track implicit `Sized` obligations in type params
When we evaluate `ty::GenericPredicates` we introduce the implicit
`Sized` predicate of type params, but we do so with only the `Predicate`
its `Span` as context, we don't have an `Obligation` or
`ObligationCauseCode` we could influence. To try and carry this
information through, we add a new field to `ty::GenericPredicates` that
tracks both which predicates come from a type param and whether that
param has any bounds already (to use in suggestions).
We also suggest adding a `?Sized` bound if appropriate on E0599.
Address part of #98539.
don't succeed `evaluate_obligation` query if new opaque types were registered
fixes#98608fixes#98604
The root cause of all this is that in type flag computation we entirely ignore nongeneric things like struct fields and the signature of function items. So if a flag had to be set for a struct if it is set for a field, that will only happen if the field is generic, as only the generic parameters are checked.
I now believe we cannot use type flags to handle opaque types. They seem like the wrong tool for this.
Instead, this PR replaces the previous logic by adding a new variant of `EvaluatedToOk`: `EvaluatedToOkModuloOpaqueTypes`, which says that there were some opaque types that got hidden types bound, but that binding may not have been legal (because we don't know if the opaque type was in its defining scope or not).
Highlight conflicting param-env candidates
This could probably be further improved by noting _why_ equivalent param-env candidates (modulo regions) leads to ambiguity.
Fixes#98786
macros: `LintDiagnostic` derive
- Move `LintDiagnosticBuilder` into `rustc_errors` so that a diagnostic derive can refer to it.
- Introduce a `DecorateLint` trait, which is equivalent to `SessionDiagnostic` or `AddToDiagnostic` but for lints. Necessary without making more changes to the lint infrastructure as `DecorateLint` takes a `LintDiagnosticBuilder` and re-uses all of the existing logic for determining what type of diagnostic a lint should be emitted as (e.g. error/warning).
- Various refactorings of the diagnostic derive machinery (extracting `build_field_mapping` helper and moving `sess` field out of the `DiagnosticDeriveBuilder`).
- Introduce a `LintDiagnostic` derive macro that works almost exactly like the `SessionDiagnostic` derive macro except that it derives a `DecorateLint` implementation instead. A new derive is necessary for this because `SessionDiagnostic` is intended for when the generated code creates the diagnostic. `AddToDiagnostic` could have been used but it would have required more changes to the lint machinery.
~~At time of opening this pull request, ignore all of the commits from #98624, it's just the last few commits that are new.~~
r? `@oli-obk`
Avoid some `&str` to `String` conversions with `MultiSpan::push_span_label`
This patch removes some`&str` to `String` conversions with `MultiSpan::push_span_label`.
Erase regions in New Abstract Consts
When an abstract const is constructed, we previously included lifetimes in the set of substitutes, so it was not able to unify two abstract consts if their lifetimes did not match but the values did, despite the values not depending on the lifetimes. This caused code that should have compiled to not compile.
Fixes#98452
r? ```@lcnr```
Currently, `search_for_structural_match_violation` constructs an `infcx`
from a `tcx` and then only uses the `tcx` within the `infcx`. This is
wasteful because `infcx` is a big type.
This commit changes it to use the `tcx` directly. When compiling
`pest-2.1.3`, this changes the memcpy stats reported by DHAT for a `check full`
build from this:
```
433,008,916 bytes (100%, 99,787.93/Minstr) in 2,148,668 blocks (100%, 495.17/Minstr), avg size 201.52 bytes
```
to this:
```
101,422,347 bytes (99.98%, 25,243.59/Minstr) in 1,318,407 blocks (99.96%, 328.15/Minstr), avg size 76.93 bytes
```
This translates to a 4.3% reduction in instruction counts.
Reverse folder hierarchy
#91318 introduced a trait for infallible folders distinct from the fallible version. For some reason (completely unfathomable to me now that I look at it with fresh eyes), the infallible trait was a supertrait of the fallible one: that is, all fallible folders were required to also be infallible. Moreover the `Error` associated type was defined on the infallible trait! It's so absurd that it has me questioning whether I was entirely sane.
This trait reverses the hierarchy, so that the fallible trait is a supertrait of the infallible one: all infallible folders are required to also be fallible (which is a trivial blanket implementation). This of course makes much more sense! It also enables the `Error` associated type to sit on the fallible trait, where it sensibly belongs.
There is one downside however: folders expose a `tcx` accessor method. Since the blanket fallible implementation for infallible folders only has access to a generic `F: TypeFolder`, we need that trait to expose such an accessor to which we can delegate. Alternatively it's possible to extract that accessor into a separate `HasTcx` trait (or similar) that would then be a supertrait of both the fallible and infallible folder traits: this would ensure that there's only one unambiguous `tcx` method, at the cost of a little additional boilerplate. If desired, I can submit that as a separate PR.
r? ````@jackh726````
Greatly improve error reporting for futures and generators in `note_obligation_cause_code`
Most futures don't go through this code path, because they're caught by
`maybe_note_obligation_cause_for_async_await`. But all generators do,
and `maybe_note` is imperfect and doesn't catch all futures. Improve the error message for those it misses.
At some point, we may want to consider unifying this with the code for `maybe_note_async_await`,
so that `async_await` notes all parent constraints, and `note_obligation` can point to yield points.
But both functions are quite complicated, and it's not clear to me how to combine them;
this seems like a good incremental improvement.
Helps with https://github.com/rust-lang/rust/issues/97332.
r? ``@estebank`` cc ``@eholk`` ``@compiler-errors``
#91318 introduced a trait for infallible folders distinct from the fallible version. For some reason (completely unfathomable to me now that I look at it with fresh eyes), the infallible trait was a supertrait of the fallible one: that is, all fallible folders were required to also be infallible. Moreover the `Error` associated type was defined on the infallible trait! It's so absurd that it has me questioning whether I was entirely sane.
This trait reverses the hierarchy, so that the fallible trait is a supertrait of the infallible one: all infallible folders are required to also be fallible (which is a trivial blanket implementation). This of course makes much more sense! It also enables the `Error` associated type to sit on the fallible trait, where it sensibly belongs.
There is one downside however: folders expose a `tcx` accessor method. Since the blanket fallible implementation for infallible folders only has access to a generic `F: TypeFolder`, we need that trait to expose such an accessor to which we can delegate. Alternatively it's possible to extract that accessor into a separate `HasTcx` trait (or similar) that would then be a supertrait of both the fallible and infallible folder traits: this would ensure that there's only one unambiguous `tcx` method, at the cost of a little additional boilerplate. If desired, I can submit that as a separate PR.
r? @jackh726
Add proper tracing spans to rustc_trait_selection::traits::error_reporting
While I was trying to figure out #97704 I did some of this to make the logs more legible, so I figured I'd do the whole module and open a PR with it. afaict this is an ongoing process in the compiler from the log->tracing transition? but lmk if there was a reason for the more verbose forms of logging as they are.
Also, for some of the functions with only one log in them, I put the function name as a message for that log instead of `#[instrument]`-ing the whole function with a span? but maybe the latter would actually be preferable, I'm not actually sure.
Most futures don't go through this code path, because they're caught by
`maybe_note_obligation_cause_for_async_await`. But all generators do,
and `maybe_note` is imperfect and doesn't catch all futures. Improve the error message for those it misses.
At some point, we may want to consider unifying this with the code for `maybe_note_async_await`,
so that `async_await` notes all parent constraints, and `note_obligation` can point to yield points.
But both functions are quite complicated, and it's not clear to me how to combine them;
this seems like a good incremental improvement.
Rename `impl_constness` to `constness`
The current code is a basis for `is_const_fn_raw`, and `impl_constness`
is no longer a valid name, which is previously used for determining the
constness of impls, and not items in general.
r? `@oli-obk`
The current code is a basis for `is_const_fn_raw`, and `impl_constness`
is no longer a valid name, which is previously used for determining the
constness of impls, and not items in general.
Make `ExprKind::Closure` a struct variant.
Simple refactor since we both need it to introduce additional fields in `ExprKind::Closure`.
r? ``@Aaron1011``
Rename the `ConstS::val` field as `kind`.
And likewise for the `Const::val` method.
Because its type is called `ConstKind`. Also `val` is a confusing name
because `ConstKind` is an enum with seven variants, one of which is
called `Value`. Also, this gives consistency with `TyS` and `PredicateS`
which have `kind` fields.
The commit also renames a few `Const` variables from `val` to `c`, to
avoid confusion with the `ConstKind::Value` variant.
r? `@BoxyUwU`
Remove RegionckMode in favor of calling new skip_region_resolution
Simple cleanup. We can skip a bunch of stuff for places where NLL does the region checking, so skip earlier.
r? rust-lang/types
And likewise for the `Const::val` method.
Because its type is called `ConstKind`. Also `val` is a confusing name
because `ConstKind` is an enum with seven variants, one of which is
called `Value`. Also, this gives consistency with `TyS` and `PredicateS`
which have `kind` fields.
The commit also renames a few `Const` variables from `val` to `c`, to
avoid confusion with the `ConstKind::Value` variant.
Remove unwrap from get_vtable
This avoids ICE on issue #97381 I think the bug is a bit deeper though, it compiles fine when `v` is `&v` which makes me think `Deref` is causing some issue with borrowck but it's fine I guess since this thing crashes since `nightly-2020-09-17` 😅
This commit makes type folding more like the way chalk does it.
Currently, `TypeFoldable` has `fold_with` and `super_fold_with` methods.
- `fold_with` is the standard entry point, and defaults to calling
`super_fold_with`.
- `super_fold_with` does the actual work of traversing a type.
- For a few types of interest (`Ty`, `Region`, etc.) `fold_with` instead
calls into a `TypeFolder`, which can then call back into
`super_fold_with`.
With the new approach, `TypeFoldable` has `fold_with` and
`TypeSuperFoldable` has `super_fold_with`.
- `fold_with` is still the standard entry point, *and* it does the
actual work of traversing a type, for all types except types of
interest.
- `super_fold_with` is only implemented for the types of interest.
Benefits of the new model.
- I find it easier to understand. The distinction between types of
interest and other types is clearer, and `super_fold_with` doesn't
exist for most types.
- With the current model is easy to get confused and implement a
`super_fold_with` method that should be left defaulted. (Some of the
precursor commits fixed such cases.)
- With the current model it's easy to call `super_fold_with` within
`TypeFolder` impls where `fold_with` should be called. The new
approach makes this mistake impossible, and this commit fixes a number
of such cases.
- It's potentially faster, because it avoids the `fold_with` ->
`super_fold_with` call in all cases except types of interest. A lot of
the time the compile would inline those away, but not necessarily
always.
Do `suggest_await_before_try` with infer variables in self, and clean up binders
Fixes#97704
Also cleans up binders in this fn, since everything is a `Poly*` and we really shouldn't have stray escaping late-bound regions everywhere. That's why the function changed so much. This isn't necessary, so I can revert if necessary.
Because it really has two halves:
- A read-only part that checks if further work is needed.
- The further work part, which is much less hot.
This makes things a bit clearer and nicer.
Replace `&Vec<_>`s with `&[_]`s
It's generally preferable to use `&[_]` since it's one less indirection and it can be created from types other that `Vec`.
I've left `&Vec` in some locals where it doesn't really matter, in cases where `TypeFoldable` is expected (`TypeFoldable: Clone` so slice can't implement it) and in cases where it's `&TypeAliasThatIsActiallyVec`. Nothing important, really, I was just a little annoyed by `visit_generic_param_vec` :D
r? `@compiler-errors`
Finish bumping stage0
It looks like the last time had left some remaining cfg's -- which made me think
that the stage0 bump was actually successful. This brings us to a released 1.62
beta though.
This now brings us to cfg-clean, with the exception of check-cfg-features in bootstrap;
I'd prefer to leave that for a separate PR at this time since it's likely to be more tricky.
cc https://github.com/rust-lang/rust/pull/97147#issuecomment-1132845061
r? `@pietroalbini`
It looks like the last time had left some remaining cfg's -- which made me think
that the stage0 bump was actually successful. This brings us to a released 1.62
beta though.
Move various checks to typeck so them failing causes the typeck result to get tainted
Fixes#69487fixes#79047
cc `@RalfJung` this gets rid of the `Transmute` invalid program error variant
Output correct type responsible for structural match violation
Previously we included the outermost type that caused a structural match violation in the error message and stated that that type must be annotated with `#[derive(Eq, PartialEq)]` even if it already had that annotation. This PR outputs the correct type in the error message.
Fixes https://github.com/rust-lang/rust/issues/97278
RFC3239: Implement `cfg(target)` - Part 2
This pull-request implements the compact `cfg(target(..))` part of [RFC 3239](https://github.com/rust-lang/rust/issues/96901).
I recommend reviewing this PR on a per commit basics, because of some moving parts.
cc `@GuillaumeGomez`
r? `@petrochenkov`
add a deep fast_reject routine
continues the work on #97136.
r? `@nnethercote`
Actually agree with you on the match structure 😆 let's see how that impacted perf 😅
`match_impl` has two call sites. For one of them (within `rematch_impl`)
the fast reject test isn't necessary, because any rejection would
represent a compiler bug.
This commit moves the fast reject test to the other `match_impl` call
site, in `assemble_candidates_from_impls`. This lets us move the fast
reject test outside the `probe` call in that function. This avoids the
taking of useless snapshots when the fast reject test succeeds, which
gives a performance win when compiling the `bitmaps` and `nalgebra`
crates.
Co-authored-by: name <n.nethercote@gmail.com>
Move a bunch of branches together into one if block, for easier reading.
Resolve comments
Attempt to make some branches unreachable [tmp]
Revert unreachable branches
`simplify_type` improvements and cursed docs
the existing `TreatParams` enum pretty much mixes everything up. Not sure why this looked right to me in #94057
This also includes two changes which impact perf:
- `ty::Projection` with inference vars shouldn't be treated as a rigid type, even if fully normalized
- `ty::Placeholder` only unifies with itself, so actually return `Some` for them
r? `@nikomatsakis`
Clean fix for #96223
Okay, so here we are (hopefully) 👍Closes#96223
Thanks a lot to `@jackh726` for your help and explanation 🙏
- Modified `InferCtxt::mk_trait_obligation_with_new_self_ty` to take as argument a `Binder<(TraitPredicate, Ty)>` instead of a `Binder<TraitPredicate>` and a separate `Ty` with no bound vars.
- Modified all call places to avoid calling `Binder::no_bounds_var` or `Binder::skip_binder` when it is not safe.
r? `@jackh726`
- Modified `InferCtxt::mk_trait_obligation_with_new_self_ty` to take as
argument a `Binder<(TraitPredicate, Ty)>` instead of a
`Binder<TraitPredicate>` and a separate `Ty` with no bound vars.
- Modified all call places to avoid calling `Binder::no_bounds_var` or
`Binder::skip_binder` when it is not safe.
Add EarlyBinder
Chalk has no concept of `Param` (e0ade19d13/chalk-ir/src/lib.rs (L579)) or `ReEarlyBound` (e0ade19d13/chalk-ir/src/lib.rs (L1308)). Everything is just "bound" - the equivalent of rustc's late-bound. It's not completely clear yet whether to move everything to the same time of binder in rustc or add `Param` and `ReEarlyBound` in Chalk.
Either way, tracking when we have or haven't already substituted out these in rustc can be helpful.
As a first step, I'm just adding a `EarlyBinder` newtype that is required to call `subst`. I also add a couple "transparent" `bound_*` wrappers around a couple query that are often immediately substituted.
r? `@nikomatsakis`
don't encode only locally used attrs
Part of https://github.com/rust-lang/compiler-team/issues/505.
We now filter builtin attributes before encoding them in the crate metadata in case they should only be used in the local crate. To prevent accidental misuse `get_attrs` now requires the caller to state which attribute they are interested in. For places where that isn't trivially possible, I've added a method `fn get_attrs_unchecked` which I intend to remove in a followup PR.
After this pull request landed, we can then slowly move all attributes to only be used in the local crate while being certain that we don't accidentally try to access them from extern crates.
cc https://github.com/rust-lang/rust/pull/94963#issuecomment-1082924289
Check hidden types for well formedness at the definition site instead of only at the opaque type itself
work towards #90409 . We'll need to look into closure and generator bodies of closures and generators nested inside the hidden type in order to fix that. In hindsight this PR is not necessary for that, but it may be a bit easier with it and we'll get better diagnostics from it on its own.
Fortify handing of where bounds on trait & trait alias definitions
Closes https://github.com/rust-lang/rust/issues/96664
Closes https://github.com/rust-lang/rust/issues/96665
Since https://github.com/rust-lang/rust/pull/93803, when listing all bounds and predicates we now need to account for the possible presence of predicates on any of the generic parameters. Both bugs were hidden by the special handling of bounds at the generic parameter declaration position.
Trait alias expansion used to confuse predicates on `Self` and where predicates.
Exiting too late when listing all the bounds caused a cycle error.
Begin fixing all the broken doctests in `compiler/`
Begins to fix#95994.
All of them pass now but 24 of them I've marked with `ignore HELP (<explanation>)` (asking for help) as I'm unsure how to get them to work / if we should leave them as they are.
There are also a few that I marked `ignore` that could maybe be made to work but seem less important.
Each `ignore` has a rough "reason" for ignoring after it parentheses, with
- `(pseudo-rust)` meaning "mostly rust-like but contains foreign syntax"
- `(illustrative)` a somewhat catchall for either a fragment of rust that doesn't stand on its own (like a lone type), or abbreviated rust with ellipses and undeclared types that would get too cluttered if made compile-worthy.
- `(not-rust)` stuff that isn't rust but benefits from the syntax highlighting, like MIR.
- `(internal)` uses `rustc_*` code which would be difficult to make work with the testing setup.
Those reason notes are a bit inconsistently applied and messy though. If that's important I can go through them again and try a more principled approach. When I run `rg '```ignore \(' .` on the repo, there look to be lots of different conventions other people have used for this sort of thing. I could try unifying them all if that would be helpful.
I'm not sure if there was a better existing way to do this but I wrote my own script to help me run all the doctests and wade through the output. If that would be useful to anyone else, I put it here: https://github.com/Elliot-Roberts/rust_doctest_fixing_tool
Fixes#96319
The logic around handling co-inductive cycles in the evaluation cache
is confusing and error prone. Fortunately, a perf run showed that it
doesn't actually appear to improve performance, so we can simplify
this code (and eliminate a source of ICEs) by just skipping caching
the evaluation results for co-inductive cycle participants.
This commit makes no changes to any of the other logic around
co-inductive cycle handling. Thus, while this commit could
potentially expose latent bugs that were being hidden by
caching, it should not introduce any new bugs.
