Mention `into_iter` on borrow errors suggestions when appropriate
If we encounter a borrow error on `vec![1, 2, 3].iter()`, suggest `into_iter`.
Fix#68445.
docs: add Rust logo to more compiler crates
c6e6ecb1af added it to some of the compiler's crates, but avoided adding it to all of them to reduce bit-rot. This commit adds to more.
r? `@GuillaumeGomez`
Use structured suggestion for #113174
When encountering a for loop that is rejected by the borrow checker because it is being advanced within its body, provide a structured suggestion for `while let Some(pat) = iter.next()`.
When encountering a for loop that is rejected by the borrow checker
because it is being advanced within its body, provide a structured
suggestion for `while let Some(pat) = iter.next()`.
Compute NLL loan scopes using the polonius model
For a *location-insensitive* analysis (that is, without expressiveness improvements for users yet), this PR implements loans going out of scope using reachability and liveness, rather than checking if the issuing region's values contain a given CFG point. This is equivalent to NLL scopes and computes the same data.
r? `@matthewjasper`
A couple of notes:
- there are some assumptions about SCC representatives, placeholders, free regions, and member constraints that I believe hold, and they're documented in the code
- this passes all the UI tests with `-Zpolonius=next` -- the perf is [not terrible](https://github.com/rust-lang/rust/pull/112432#issuecomment-1749685862) and there are a bunch of ways to improve it in the future.
- there's a fixme left, hopefully Matthew you know a clean way to get the information it mentions.
Show more information when multiple `impl`s apply
- When there are `impl`s without type params, show only those (to avoid showing overly generic `impl`s).
```
error[E0283]: type annotations needed
--> $DIR/multiple-impl-apply.rs:34:9
|
LL | let y = x.into();
| ^ ---- type must be known at this point
|
note: multiple `impl`s satisfying `_: From<Baz>` found
--> $DIR/multiple-impl-apply.rs:14:1
|
LL | impl From<Baz> for Bar {
| ^^^^^^^^^^^^^^^^^^^^^^
...
LL | impl From<Baz> for Foo {
| ^^^^^^^^^^^^^^^^^^^^^^
= note: required for `Baz` to implement `Into<_>`
help: consider giving `y` an explicit type
|
LL | let y: /* Type */ = x.into();
| ++++++++++++
```
- Lower the importance of `T: Sized`, `T: WellFormed` and coercion errors, to prioritize more relevant errors. The pre-existing deduplication logic deals with hiding redundant errors better that way, and we show errors with more metadata that is useful to the user.
- Show `<SelfTy as Trait>::assoc_fn` suggestion in more cases.
```
error[E0790]: cannot call associated function on trait without specifying the corresponding `impl` type
--> $DIR/cross-return-site-inference.rs:38:16
|
LL | return Err(From::from("foo"));
| ^^^^^^^^^^ cannot call associated function of trait
|
help: use a fully-qualified path to a specific available implementation
|
LL | return Err(</* self type */ as From>::from("foo"));
| +++++++++++++++++++ +
```
Fix#88284.
In `report_fullfillment_errors` push back `T: Sized`, `T: WellFormed`
and coercion errors to the end of the list. The pre-existing
deduplication logic eliminates redundant errors better that way, keeping
the resulting output with fewer errors than before, while also having
more detail.
Don't store lazyness in `DefKind::TyAlias`
1. Don't store lazyness of a type alias in its `DefKind`, but instead via a query.
2. This allows us to treat type aliases as lazy if `#[feature(lazy_type_alias)]` *OR* if the alias contains a TAIT, rather than having checks for both in separate parts of the codebase.
r? `@oli-obk` cc `@fmease`
rename mir::Constant -> mir::ConstOperand, mir::ConstKind -> mir::Const
Also, be more consistent with the `to/eval_bits` methods... we had some that take a type and some that take a size, and then sometimes the one that takes a type is called `bits_for_ty`.
Turns out that `ty::Const`/`mir::ConstKind` carry their type with them, so we don't need to even pass the type to those `eval_bits` functions at all.
However this is not properly consistent yet: in `ty` we have most of the methods on `ty::Const`, but in `mir` we have them on `mir::ConstKind`. And indeed those two types are the ones that correspond to each other. So `mir::ConstantKind` should actually be renamed to `mir::Const`. But what to do with `mir::Constant`? It carries around a span, that's really more like a constant operand that appears as a MIR operand... it's more suited for `syntax.rs` than `consts.rs`, but the bigger question is, which name should it get if we want to align the `mir` and `ty` types? `ConstOperand`? `ConstOp`? `Literal`? It's not a literal but it has a field called `literal` so it would at least be consistently wrong-ish...
``@oli-obk`` any ideas?
It's easier to pass it in to the one method that needs it
(`highlighting_region_vid`) than to store it in the type. This means
`RegionHighlightMode` can impl `Default`.
Bubble up opaque <eq> opaque operations instead of picking an order
In case we are in `Bubble` mode (meaning every opaque type that is defined in the current crate is treated as if it were in its defining scope), we don't try to register an opaque type as the hidden type of another opaque type, but instead bubble up an obligation to equate them at the query caller site. Usually that means we have a `DefiningAnchor::Bind` and thus can reliably figure out whether an opaque type is in its defining scope. Where we can't, we'll error out, so the default is sound.
With this change we start using `AliasTyEq` predicates in the old solver, too.
fixes https://github.com/rust-lang/rust/issues/108498
But also regresses `tests/ui/impl-trait/anon_scope_creep.rs`. Our use of `Bubble` for `check_opaque_type_well_formed` is going to keep biting us.
r? `@lcnr` `@compiler-errors`
Fix incorrect mutable suggestion information for binding in ref pattern like: `let &b = a;`
fixes#114896
I find we have to get pat_span but not local_decl.source_info.span for suggestion. In `let &b = a;` pat_span is &b. I think check `let &b = a` in hir to make sure it is hir::Node::Local(hir::Local {pat: hir::Pat{kind: hir::PatKind::Ref(....... can distinguish it from other situation, but I'm not sure.
If my processing method is not accurate, please guide me to modify it, thank you.
r? `@davidtwco`
The `Debug` impl for `Ty` just calls the `Display` impl for `Ty`. This
is surprising and annoying. In particular, it means `Debug` doesn't show
as much information as `Debug` for `TyKind` does. And `Debug` is used in
some user-facing error messages, which seems bad.
This commit changes the `Debug` impl for `Ty` to call the `Debug` impl
for `TyKind`. It also does a number of follow-up changes to preserve
existing output, many of which involve inserting
`with_no_trimmed_paths!` calls. It also adds `Display` impls for
`UserType` and `Canonical`.
Some tests have changes to expected output:
- Those that use the `rustc_abi(debug)` attribute.
- Those that use the `EMIT_MIR` annotation.
In each case the output is slightly uglier than before. This isn't
ideal, but it's pretty weird (particularly for the attribute) that the
output is using `Debug` in the first place. They're fairly obscure
attributes (I hadn't heard of them) so I'm not worried by this.
For `async-is-unwindsafe.stderr`, there is one line that now lacks a
full path. This is a consistency improvement, because all the other
mentions of `Context` in this test lack a path.
Don't report any errors in `lower_intrinsics`.
Intrinsics should have been type checked earlier.
This is part of moving all mir-opt diagnostics early enough so that they are reliably emitted even in check builds: https://github.com/rust-lang/rust/issues/49292#issuecomment-1692212095
This was backfilling causes for new universes that may have been created
by an op, when there was no error info to use for improved
diagnostics. We don't need to do that anymore: `other()` is the default when
there is no registered universe cause.
This was pre-filling causes for universes that could already exist in
the InferCtxt. We don't need to do that anymore: `other()` is the default when
there is no registered universe cause.
This was backfilling causes for the new universes that can be created by
the InferCtxt. We don't need to do that anymore: `other()` is the default when
there is no registered universe cause.
Suggest mutable borrow on read only for-loop that should be mutable
```
error[E0596]: cannot borrow `*test` as mutable, as it is behind a `&` reference
--> $DIR/suggest-mut-iterator.rs:22:9
|
LL | for test in &tests {
| ------ this iterator yields `&` references
LL | test.add(2);
| ^^^^ `test` is a `&` reference, so the data it refers to cannot be borrowed as mutable
|
help: use a mutable iterator instead
|
LL | for test in &mut tests {
| +++
```
Fix#114311.
```
error[E0596]: cannot borrow `*test` as mutable, as it is behind a `&` reference
--> $DIR/suggest-mut-iterator.rs:22:9
|
LL | for test in &tests {
| ------ this iterator yields `&` references
LL | test.add(2);
| ^^^^ `test` is a `&` reference, so the data it refers to cannot be borrowed as mutable
|
help: use a mutable iterator instead
|
LL | for test in &mut tests {
| +++
```
Address #114311.
Store the laziness of type aliases in their `DefKind`
Previously, we would treat paths referring to type aliases as *lazy* type aliases if the current crate had lazy type aliases enabled independently of whether the crate which the alias was defined in had the feature enabled or not.
With this PR, the laziness of a type alias depends on the crate it is defined in. This generally makes more sense to me especially if / once lazy type aliases become the default in a new edition and we need to think about *edition interoperability*:
Consider the hypothetical case where the dependency crate has an older edition (and thus eager type aliases), it exports a type alias with bounds & a where-clause (which are void but technically valid), the dependent crate has the latest edition (and thus lazy type aliases) and it uses that type alias. Arguably, the bounds should *not* be checked since at any time, the dependency crate should be allowed to change the bounds at will with a *non*-major version bump & without negatively affecting downstream crates.
As for the reverse case (dependency: lazy type aliases, dependent: eager type aliases), I guess it rules out anything from slight confusion to mild annoyance from upstream crate authors that would be caused by the compiler ignoring the bounds of their type aliases in downstream crates with older editions.
---
This fixes#114468 since before, my assumption that the type alias associated with a given weak projection was lazy (and therefore had its variances computed) did not necessarily hold in cross-crate scenarios (which [I kinda had a hunch about](https://github.com/rust-lang/rust/pull/114253#discussion_r1278608099)) as outlined above. Now it does hold.
`@rustbot` label F-lazy_type_alias
r? `@oli-obk`
Improve spans for indexing expressions
fixes#114388
Indexing is similar to method calls in having an arbitrary left-hand-side and then something on the right, which is the main part of the expression. Method calls already have a span for that right part, but indexing does not. This means that long method chains that use indexing have really bad spans, especially when the indexing panics and that span in coverted into a panic location.
This does the same thing as method calls for the AST and HIR, storing an extra span which is then put into the `fn_span` field in THIR.
r? compiler-errors
Indexing is similar to method calls in having an arbitrary
left-hand-side and then something on the right, which is the main part
of the expression. Method calls already have a span for that right part,
but indexing does not. This means that long method chains that use
indexing have really bad spans, especially when the indexing panics and
that span in coverted into a panic location.
This does the same thing as method calls for the AST and HIR, storing an
extra span which is then put into the `fn_span` field in THIR.
Perform OpaqueCast field projection on HIR, too.
fixes#105819
This is necessary for closure captures in 2021 edition, as they capture individual fields, not the full mentioned variables. So it may try to capture a field of an opaque (because the hidden type is known to be something with a field).
See https://github.com/rust-lang/rust/pull/99806 for when and why we added OpaqueCast to MIR.
It lints against features that are inteded to be internal to the
compiler and standard library. Implements MCP #596.
We allow `internal_features` in the standard library and compiler as those
use many features and this _is_ the standard library from the "internal to the compiler and
standard library" after all.
Marking some features as internal wasn't exactly the most scientific approach, I just marked some
mostly obvious features. While there is a categorization in the macro,
it's not very well upheld (should probably be fixed in another PR).
We always pass `-Ainternal_features` in the testsuite
About 400 UI tests and several other tests use internal features.
Instead of throwing the attribute on each one, just always allow them.
There's nothing wrong with testing internal features^^
Rollup of 6 pull requests
Successful merges:
- #114178 (Account for macros when suggesting a new let binding)
- #114199 (Don't unsize coerce infer vars in select in new solver)
- #114301 (Don't check unnecessarily that impl trait is RPIT)
- #114314 (Tweaks to `adt_sized_constraint`)
- #114322 (Fix invalid slice coercion suggestion reported in turbofish)
- #114340 ([rustc_attr][nit] Replace `filter` + `is_some` with `map_or`.)
r? `@ghost`
`@rustbot` modify labels: rollup
Account for macros when suggesting a new let binding
Provide a structured suggestion when the expression comes from a macro expansion:
```
error[E0716]: temporary value dropped while borrowed
--> $DIR/borrowck-let-suggestion.rs:2:17
|
LL | let mut x = vec![1].iter();
| ^^^^^^^ - temporary value is freed at the end of this statement
| |
| creates a temporary value which is freed while still in use
LL |
LL | x.use_mut();
| - borrow later used here
|
= note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider using a `let` binding to create a longer lived value
|
LL ~ let binding = vec![1];
LL ~ let mut x = binding.iter();
|
```
Double check that hidden types match the expected hidden type
Fixes https://github.com/rust-lang/rust/issues/113278 specifically, but I left a TODO for where we should also add some hardening.
It feels a bit like papering over the issue, but at least this way we don't get unsoundness, but just surprising errors. Errors will be improved and given spans before this PR lands.
r? `@compiler-errors` `@lcnr`
During borrowck, the `MultiSpan` from a buffered diagnostic is cloned and
used to emit a delayed bug indicating a diagnostic was buffered - when
the buffered diagnostic is translated, then the cloned `MultiSpan` may
contain labels which can only render with the diagnostic's arguments, but
the delayed bug being emitted won't have those arguments. Adds a function
which clones `MultiSpan` without also cloning the contained labels, and
use this function when creating the buffered diagnostic delayed bug.
Signed-off-by: David Wood <david@davidtw.co>
Use maybe_body_owned_by for multiple suggestions
This is a continued work from https://github.com/rust-lang/rust/pull/113567
We have several other suggestions not working for closure, this PR use `maybe_body_owned_by` to fix them and add test cases for them.
(re-)tighten sourceinfo span of adjustments in MIR
Diagnostics rely on the spans of MIR statements being (approximately) correct in order to give suggestions relative to that span (i.e. `shrink_to_hi` and `shrink_to_lo`).
I discovered that we're *intentionally* lowering THIR exprs with their parent expr's span if they come from adjustments that are due to a parent expression. While I understand why that may be desirable to demonstrate the relationship of an adjustment and the expression that requires it, it leads to
1. very verbose borrowck output
2. incorrect spans for suggestions
Some diagnostics get around that by giving suggestions relative to other spans we've collected during MIR lowering, such as the span of the method's identifier (e.g. `name` in `.name()`), but this doesn't work too well when things come from desugaring.
I assume it also has lead to numerous tweaks and complications to diagnostics code down the road, which this PR doesn't necessarily aim to fix but may open the gates to fixing later... The last three commits are simplifications due to the fact that we can assume that the move span actually points to what is being moved (and a test).
This regressed in #89110, which was debated somewhat in #90286. cc `@Aaron1011` who originally made this change.
r? diagnostics
Fixes#113547Fixes#111016
Rewrite `UnDerefer`, again
This PR is intended to improve the perf regression introduced by #112882.
`UnDerefer` has been separated out again for borrowck reasons. It was a bit overzealous to remove it in the previous PR.
r? `@oli-obk`
It makes it sound like the `ExprKind` and `Rvalue` are supposed to represent all pointer related
casts, when in reality their just used to share a some enum variants. Make it clear there these
are only coercion to make it clear why only some pointer related "casts" are in the enum.
Rewrite `UnDerefer`
Currently, `UnDerefer` is used by drop elaboration to undo the effects of the `Derefer` pass. However, it just recreates the original places with derefs in the middle of the projection. Because `ProjectionElem::Deref` is intended to be removed completely in the future, this will not work forever.
This PR introduces a `deref_chain` method that returns the places behind `DerefTemp` locals in a place and rewrites the move path code to use this. In the process, `UnDerefer` was merged into `MovePathLookup`. Now that move paths use the same places as in the MIR, the other uses of `UnDerefer` no longer require it.
See #98145
cc `@ouz-a`
r? `@oli-obk`
suggest `slice::swap` for `mem::swap(&mut x[0], &mut x[1])` borrowck error
Recently saw someone ask why this code (example slightly modified):
```rs
fn main() {
let mut foo = [1, 2];
std::mem::swap(&mut foo[0], &mut foo[1]);
}
```
triggers this error and how to fix it:
```
error[E0499]: cannot borrow `foo[_]` as mutable more than once at a time
--> src/main.rs:4:33
|
4 | std::mem::swap(&mut foo[0], &mut foo[1]);
| -------------- ----------- ^^^^^^^^^^^ second mutable borrow occurs here
| | |
| | first mutable borrow occurs here
| first borrow later used by call
|
= help: consider using `.split_at_mut(position)` or similar method to obtain two mutable non-overlapping sub-slices
```
The current help message is nice and goes in the right direction, but I think we can do better for this specific instance and suggest `slice::swap`, which makes this compile
Migrate `TyCtxt::predicates_of` and `ParamEnv::caller_bounds` to `Clause`
The last big change in the series.
I will follow-up with additional filed issues once this PR lands:
- [ ] Investigate making `TypeFoldable<TyCtxt<'tcx>> for ty::Clause<'tcx>` implementation less weird: 2efe091705/compiler/rustc_middle/src/ty/structural_impls.rs (L672)
- [ ] Clean up the elaborator since it should only be emitting child clauses, not predicates
- [ ] Rename identifiers like `pred` and `predicates` to `clause` if they're actually clauses around the codebase
- [ ] Validate that all of the `ToPredicate` impls are acutally still needed, or prune them if they're not
r? `@ghost` until the other branch lands
[-Ztrait-solver=next, mir-typeck] instantiate hidden types in the root universe
Fixes an ICE in the test `member-constraints-in-root-universe`.
Main motivation is to make #112691 pass under the new solver.
r? ``@compiler-errors``
Migrate `item_bounds` to `ty::Clause`
Should be simpler than the next PR that's coming up. Last three commits are the relevant ones.
r? ``@oli-obk`` or ``@lcnr``
Add a fully fledged `Clause` type, rename old `Clause` to `ClauseKind`
Does two basic things before I put up a more delicate set of PRs (along the lines of #112714, but hopefully much cleaner) that migrate existing usages of `ty::Predicate` to `ty::Clause` (`predicates_of`/`item_bounds`/`ParamEnv::caller_bounds`).
1. Rename `Clause` to `ClauseKind`, so it's parallel with `PredicateKind`.
2. Add a new `Clause` type which is parallel to `Predicate`.
* This type exposes `Clause::kind(self) -> Binder<'tcx, ClauseKind<'tcx>>` which is parallel to `Predicate::kind` 😸
The new `Clause` type essentially acts as a newtype wrapper around `Predicate` that asserts that it is specifically a `PredicateKind::Clause`. Turns out from experimentation[^1] that this is not negative performance-wise, which is wonderful, since this a much simpler design than something that requires encoding the discriminant into the alignment bits of a predicate kind, or something else like that...
r? ``@lcnr`` or ``@oli-obk``
[^1]: https://github.com/rust-lang/rust/pull/112714#issuecomment-1595653910
Don't consider TAIT normalizable to hidden ty if it would result in impossible item bounds
See test for example where we shouldn't consider it possible to alias-relate a TAIT and hidden type.
r? `@lcnr`
Take MIR dataflow analyses by mutable reference
The main motivation here is any analysis requiring dynamically sized scratch memory to work. One concrete example would be pointer target tracking, where tracking the results of a dereference can result in multiple possible targets. This leads to processing multi-level dereferences requiring the ability to handle a changing number of potential targets per step. A (simplified) function for this would be `fn apply_deref(potential_targets: &mut Vec<Target>)` which would use the scratch space contained in the analysis to send arguments and receive the results.
The alternative to this would be to wrap everything in a `RefCell`, which is what `MaybeRequiresStorage` currently does. This comes with a small perf cost and loses the compiler's guarantee that we don't try to take multiple borrows at the same time.
For the implementation:
* `AnalysisResults` is an unfortunate requirement to avoid an unconstrained type parameter error.
* `CloneAnalysis` could just be `Clone` instead, but that would result in more work than is required to have multiple cursors over the same result set.
* `ResultsVisitor` now takes the results type on in each function as there's no other way to have access to the analysis without cloning it. This could use an associated type rather than a type parameter, but the current approach makes it easier to not care about the type when it's not necessary.
* `MaybeRequiresStorage` now no longer uses a `RefCell`, but the graphviz formatter now does. It could be removed, but that would require even more changes and doesn't really seem necessary.
Add `-Ztrait-solver=next-coherence`
Flag that conditionally uses the trait solver *only* during coherence, for more testing and/or eventual partial-migration onto the trait solver (in the medium- to long-term).
* This still uses the selection context in some of the coherence methods I think, so it's not "complete". Putting this up for review and/or for further work in-tree.
* I probably need to spend a bit more time making sure that we don't sneakily create any other infcx's during coherence that also need the new solver enabled.
r? `@lcnr`
