Allow to feed a value in another query's cache and remove `WithOptConstParam`
I used it to remove `WithOptConstParam` queries, as an example.
The idea is that a query (here `typeck(function)`) can write into another query's cache (here `type_of(anon const)`). The dependency node for `type_of` would depend on all the current dependencies of `typeck`.
There is still an issue with cycles: if `type_of(anon const)` is accessed before `typeck(function)`, we will still have the usual cycle. The way around this issue is to `ensure` that `typeck(function)` is called before accessing `type_of(anon const)`.
When replayed, we may the following cases:
- `typeck` is green, in that case `type_of` is green too, and all is right;
- `type_of` is green, `typeck` may still be marked as red (it depends on strictly more things than `type_of`) -> we verify that the saved value and the re-computed value of `type_of` have the same hash;
- `type_of` is red, then `typeck` is red -> it's the caller responsibility to ensure `typeck` is recomputed *before* `type_of`.
As `anon consts` have their own `DefPathData`, it's not possible to have the def-id of the anon-const point to something outside the original function, but the general case may have to be resolved before using this device more broadly.
There is an open question about loading from the on-disk cache. If `typeck` is loaded from the on-disk cache, the side-effect does not happen. The regular `type_of` implementation can go and fetch the correct value from the decoded `typeck` results, and the dep-graph will check that the hashes match, but I'm not sure we want to rely on this behaviour.
I specifically allowed to feed the value to `type_of` from inside a call to `type_of`. In that case, the dep-graph will check that the fingerprints of both values match.
This implementation is still very sensitive to cycles, and requires that we call `typeck(function)` before `typeck(anon const)`. The reason is that `typeck(anon const)` calls `type_of(anon const)`, which calls `typeck(function)`, which feeds `type_of(anon const)`, and needs to build the MIR so needs `typeck(anon const)`. The latter call would not cycle, since `type_of(anon const)` has been set, but I'd rather not remove the cycle check.
Various minor Idx-related tweaks
Nothing particularly exciting here, but a couple of things I noticed as I was looking for more index conversions to simplify.
cc https://github.com/rust-lang/compiler-team/issues/606
r? `@WaffleLapkin`
don't uniquify regions when canonicalizing
uniquifying causes a bunch of issues, most notably it causes `AliasEq(<?x as Trait<'a>>::Assoc, <?x as Trait<'a>>::Assoc)` to result in ambiguity because both `normalizes-to` paths result in ambiguity and substs equate should trivially succeed but doesn't because we uniquified `'a` to two different regions.
I originally added uniquification to make it easier to deal with requirement 6 from the dev-guide: https://rustc-dev-guide.rust-lang.org/solve/trait-solving.html#requirements
> ### 6. Trait solving must be (free) lifetime agnostic
>
> Trait solving during codegen should have the same result as during typeck. As we erase
> all free regions during codegen we must not rely on them during typeck. A noteworthy example
> is special behavior for `'static`.
cc https://github.com/rust-lang/rustc-dev-guide/pull/1671
Relying on regions being identical may cause ICE during MIR typeck, but even without this PR we can end up relying on that as type inference vars can resolve to types which contain an identical region. Let's land this and deal with any ICE that crop up as we go. Will look at this issue again before stabilization.
r? ```@compiler-errors```
Split implied and super predicate queries, then allow elaborator to filter only supertraits
Split the `super_predicates_of` query into a new `implied_predicates_of` query. The former now only returns the *real* supertraits of a trait alias, and the latter now returns the implied predicates (which include all of the `where` clauses of the trait alias). The behavior of these queries is identical for regular traits.
Now that the two queries are split, we can add a new filter method to the elaborator, `filter_only_self()`, which can be used in instances that we need only the *supertrait* predicates, such as during the elaboration used in closure signature deduction. This toggles the usage of `super_predicates_of` instead of `implied_predicates_of` during elaboration of a trait predicate.
This supersedes #104745, and fixes the four independent bugs identified in that PR.
Fixes#104719Fixes#106238Fixes#110023Fixes#109514
r? types
Support safe transmute in new solver
Basically copies the same implementation as the old solver, but instead of looking for param types, we look for type or const placeholders.
Enforce that `PointerLike` requires a pointer-like ABI
At least temporarily, let's ban coercing things that are pointer-sized and pointer-aligned but *not* `Abi::Scalar(..)` into `dyn*`. See: https://github.com/rust-lang/rust/pull/104694#discussion_r1142522073
This can be lifted in the future if we decie that we *want* to be able to coerce something `repr(C)` into a `dyn*`, but we'll have to figure out what to do with Miri and codegen...
r? compiler
Make elaboration generic over input
Combines all the `elaborate_*` family of functions into just one, which is an iterator over the same type that you pass in (e.g. elaborating `Predicate` gives `Predicate`s, elaborating `Obligation`s gives `Obligation`s, etc.)
Implement support for `GeneratorWitnessMIR` in new solver
r? ```@cjgillot```
I mostly want this to cut down the number of failing UI tests when running the UI test suite with `--compare-mode=next-solver`, but there doesn't seem like much reason to block implementing this since it adds minimal complexity to the existing structural traits impl in the new solver.
If others are against adding this for some reason, then maybe we should just make `GeneratorWitnessMIR` return `NoSolution` for these traits. Anything but an ICE please 😸🧊
Update `ty::VariantDef` to use `IndexVec<FieldIdx, FieldDef>`
And while doing the updates for that, also uses `FieldIdx` in `ProjectionKind::Field` and `TypeckResults::field_indices`.
There's more places that could use it (like `rustc_const_eval` and `LayoutS`), but I tried to keep this PR from exploding to *even more* places.
Part 2/? of https://github.com/rust-lang/compiler-team/issues/606
Closures always implement `FnOnce` in new solver
We should process `[closure]: FnOnce(Tys...) -> Ty` obligations *before* fallback and closure analysis. We can do this by taking advantage of the fact that `FnOnce` is always implemented by closures, even before we definitely know the closure kind.
Fixescompiler-errors/next-solver-hir-issues#15
r? ``@oli-obk`` (trying to spread the reviewer load for new trait solver prs, and this one is pretty self-contained, though feel free to reassign 😸)
Freshen normalizes-to hack goal RHS in the evaluate loop
Ensure that we repeatedly equate the unconstrained RHS of the normalizes-to hack goal with the *actual* RHS of the goal, even if the normalizes-to goal loops several times and thus we replace the unconstrained RHS var repeatedly.
Alternative to #109583.
And while doing the updates for that, also uses `FieldIdx` in `ProjectionKind::Field` and `TypeckResults::field_indices`.
There's more places that could use it (like `rustc_const_eval` and `LayoutS`), but I tried to keep this PR from exploding to *even more* places.
Part 2/? of https://github.com/rust-lang/compiler-team/issues/606
Canonicalize float var as float in new solver
Typo in new canonicalizer -- we should be canonicalizing float vars as `CanonicalTyVarKind::Float`, not `CanonicalTyVarKind::Int`.
Fixescompiler-errors/next-solver-hir-issues#9
