the behavior of the type system not only depends on the current
assumptions, but also the currentnphase of the compiler. This is
mostly necessary as we need to decide whether and how to reveal
opaque types. We track this via the `TypingMode`.
`suggest_borrow_generic_arg`: instantiate clauses properly
This simplifies and fixes the way `suggest_borrow_generic_arg` instantiates callees' predicates when testing them to see if a moved argument can instead be borrowed. Previously, it would ICE if the moved argument's type included a region variable, since it was getting passed to a call of `EarlyBinder::instantiate`. This makes the instantiation much more straightforward, which also fixes the ICE.
Fixes#133118
This also modifies `tests/ui/moves/moved-value-on-as-ref-arg.rs` to have more useful bounds on the tests for suggestions to borrow `Borrow` and `BorrowMut` arguments. With its old tautological `T: BorrowMut<T>` bound, this fix would make it suggest a shared borrow for that argument.
Fixes issue 133118.
This also modifies `tests/ui/moves/moved-value-on-as-ref-arg.rs` to have more
useful bounds on the tests for suggestions to borrow `Borrow` and `BorrowMut`
arguments. With its old tautological `T: BorrowMut<T>` bound, this fix would
make it suggest a shared borrow for that argument.
This subsumes the suggestions to borrow arguments with `AsRef`/`Borrow` bounds and those to borrow
arguments with `Fn` and `FnMut` bounds. It works for other traits implemented on references as well,
such as `std::io::Read`, `std::io::Write`, and `core::fmt::Write`.
Incidentally, by making the logic for suggesting borrowing closures general, this removes some
spurious suggestions to mutably borrow `FnMut` closures in assignments, as well as an unhelpful
suggestion to add a `Clone` constraint to an `impl Fn` argument.
This is setup for unifing the logic for suggestions to borrow arguments in generic positions.
As of this commit, it's still special cases for `AsRef`/`Borrow`-like traits and `Fn`-like traits.
This also downgrades its applicability to MaybeIncorrect. Its suggestion can result in ill-typed
code when the type parameter it suggests providing a different generic argument for appears
elsewhere in the callee's signature or predicates.
Remove unnecessary pub enum glob-imports from `rustc_middle::ty`
We used to have an idiom in the compiler where we'd prefix or suffix all the variants of an enum, for example `BoundRegionKind`, with something like `Br`, and then *glob-import* that enum variant directly.
`@noratrieb` brought this up, and I think that it's easier to read when we just use the normal style `EnumName::Variant`.
This PR is a bit large, but it's just naming.
The only somewhat opinionated change that this PR does is rename `BorrowKind::Imm` to `BorrowKind::Immutable` and same for the other variants. I think these enums are used sparingly enough that the extra length is fine.
r? `@noratrieb` or reassign
Now that `Results` is the only impl of `ResultsVisitable`, the trait can
be removed. This simplifies things by removining unnecessary layers of
indirection and abstraction.
- `ResultsVisitor` is simpler.
- Its type parameter changes from `R` (an analysis result) to the
simpler `A` (an analysis).
- It no longer needs the `Domain` associated type, because it can use
`A::Domain`.
- Occurrences of `R` become `Results<'tcx, A>`, because there is now
only one kind of analysis results.
- `save_as_intervals` also changes type parameter from `R` to `A`.
- The `results.reconstruct_*` method calls are replaced with
`results.analysis.apply_*` method calls, which are equivalent.
- `Direction::visit_results_in_block` is simpler, with a single generic
param (`A`) instead of two (`D` and `R`/`F`, with a bound connecting
them). Likewise for `visit_results`.
- The `ResultsVisitor` impls for `MirBorrowCtxt` and
`StorageConflictVisitor` are now specific about the type of the
analysis results they work with. They both used to have a type param
`R` but they weren't genuinely generic. In both cases there was only a
single results type that made sense to instantiate them with.
The results of most analyses end up in a `Results<'tcx, A>`, where `A`
is the analysis. It's then possible to traverse the results via a
`ResultsVisitor`, which relies on the `ResultsVisitable` trait. (That
trait ends up using the same `apply_*` methods that were used when
computing the analysis, albeit indirectly.)
This pattern of "compute analysis results, then visit them" is common.
But there is one exception. For borrow checking we compute three
separate analyses (`Borrows`, `MaybeUninitializedPlaces`, and
`EverInitializedPlaces`), combine them into a single `BorrowckResults`,
and then do a single visit of that `BorrowckResults` with
`MirBorrowckResults`. `BorrowckResults` is just different enough from
`Results` that it requires the existence of `ResultsVisitable`, which
abstracts over the traversal differences between `Results` and
`BorrowckResults`.
This commit changes things by introducing `Borrowck` and bundling the
three borrowck analysis results into a standard `Results<Borrowck>`
instead of the exceptional `BorrowckResults`. Once that's done, the
results can be visited like any other analysis results.
`BorrowckResults` is removed, as is `impl ResultsVisitable for
BorrowckResults`. (It's instructive to see how similar the added `impl
Analysis for Borrowck` is to the removed `impl ResultsVisitable for
BorrowckResults`. They're both doing exactly the same things.)
Overall this increases the number of lines of code and might not seem
like a win. But it enables the removal of `ResultsVisitable` in the next
commit, which results in many simplifications.
- Store a mut ref to a `BorrowckDiags` in `MirBorrowckCtxt` instead of
owning it, to save having to pass ownership in and out of
`promoted_mbcx`.
- Use `buffer_error` in a couple of suitable places.
Because there is no real reason for it to be a separate struct.
- It has no methods.
- It's easy to confuse with the nearby `BorrowckInferContext` (which
does have methods).
- The `mut` ref to it in `TypeChecker` makes it seem like any of the
fields within might be mutable, but only two (`all_facts` and
`constraints`) actually are.
- Two of the fields are `pub(crate)` but can be private.
This change makes a lot of code more concise and readable.
It's strange to have a struct that contains a single anonymous field
that is an enum. This commit merges them. This does require increasing
the visibility of `TypeOfInfo` to `pub(crate)`, but that seems
worthwhile.
Remove region from adjustments
It's not necessary to store this region, because it's only used in THIR and MemCat/ExprUse, both of which already basically only deal with erased regions anyways.
This is a standard pattern:
```
MyAnalysis.into_engine(tcx, body).iterate_to_fixpoint()
```
`into_engine` and `iterate_to_fixpoint` are always called in pairs, but
sometimes with a builder-style `pass_name` call between them. But a
builder-style interface is overkill here. This has been bugging me a for
a while.
This commit:
- Merges `Engine::new` and `Engine::iterate_to_fixpoint`. This removes
the need for `Engine` to have fields, leaving it as a trivial type
that the next commit will remove.
- Renames `Analysis::into_engine` as `Analysis::iterate_to_fixpoint`,
gives it an extra argument for the optional pass name, and makes it
call `Engine::iterate_to_fixpoint` instead of `Engine::new`.
This turns the pattern from above into this:
```
MyAnalysis.iterate_to_fixpoint(tcx, body, None)
```
which is shorter at every call site, and there's less plumbing required
to support it.
Deeply normalize `TypeTrace` when reporting type error in new solver
Normalize the values that come from the `TypeTrace` for various type mismatches.
Side-note: We can't normalize the `TypeError` itself bc it may come from instantiated binders, so it may reference values from within the probe...
r? lcnr
Continue to get rid of `ty::Const::{try_}eval*`
This PR mostly does:
* Removes all of the `try_eval_*` and `eval_*` helpers from `ty::Const`, and replace their usages with `try_to_*`.
* Remove `ty::Const::eval`.
* Rename `ty::Const::normalize` to `ty::Const::normalize_internal`. This function is still used in the normalization code itself.
* Fix some weirdness around the `TransmuteFrom` goal.
I'm happy to split it out further; for example, I could probably land the first part which removes the helpers, or the changes to codegen which are more obvious than the changes to tools.
r? BoxyUwU
Part of https://github.com/rust-lang/rust/issues/130704
Remove `GenKillAnalysis`
There are two kinds of dataflow analysis in the compiler: `Analysis`, which is the basic kind, and `GenKillAnalysis`, which is a more specialized kind for gen/kill analyses that is intended as an optimization. However, it turns out that `GenKillAnalysis` is actually a pessimization! It's faster (and much simpler) to do all the gen/kill analyses via `Analysis`. This lets us remove `GenKillAnalysis`, and `GenKillSet`, and a few other things, and also merge `AnalysisDomain` into `Analysis`. The PR removes 500 lines of code and improves performance.
r? `@tmiasko`
Use `ThinVec` for PredicateObligation storage
~~I noticed while profiling clippy on a project that a large amount of time is being spent allocating `Vec`s for `PredicateObligation`, and the `Vec`s are often quite small. This is an attempt to optimise this by using SmallVec to avoid heap allocations for these common small Vecs.~~
This PR turns all the `Vec<PredicateObligation>` into a single type alias while avoiding referring to `Vec` around it, then swaps the type over to `ThinVec<PredicateObligation>` and fixes the fallout. This also contains an implementation of `ThinVec::extract_if`, copied from `Vec::extract_if` and currently being upstreamed to https://github.com/Gankra/thin-vec/pull/66.
This leads to a small (0.2-0.7%) performance gain in the latest perf run.
