See through aggregates in GVN
This PR is extracted from https://github.com/rust-lang/rust/pull/111344
The first 2 commit are cleanups to avoid repeated work. I propose to stop removing useless assignments as part of this pass, and let a later `SimplifyLocals` do it. This makes tests easier to read (among others).
The next 3 commits add a constant folding mechanism to the GVN pass, presented in https://github.com/rust-lang/rust/pull/116012. ~This pass is designed to only use global allocations, to avoid any risk of accidental modification of the stored state.~
The following commits implement opportunistic simplifications, in particular:
- projections of aggregates: `MyStruct { x: a }.x` gets replaced by `a`, works with enums too;
- projections of arrays: `[a, b][0]` becomes `a`;
- projections of repeat expressions: `[a; N][x]` becomes `a`;
- transform arrays of equal operands into a repeat rvalue.
Fixes https://github.com/rust-lang/miri/issues/3090
r? `@oli-obk`
Implement `gen` blocks in the 2024 edition
Coroutines tracking issue https://github.com/rust-lang/rust/issues/43122
`gen` block tracking issue https://github.com/rust-lang/rust/issues/117078
This PR implements `gen` blocks that implement `Iterator`. Most of the logic with `async` blocks is shared, and thus I renamed various types that were referring to `async` specifically.
An example usage of `gen` blocks is
```rust
fn foo() -> impl Iterator<Item = i32> {
gen {
yield 42;
for i in 5..18 {
if i.is_even() { continue }
yield i * 2;
}
}
}
```
The limitations (to be resolved) of the implementation are listed in the tracking issue
Fix ICE: Restrict param constraint suggestion
When encountering an associated item with a type param that could be constrained, do not look at the parent item if the type param comes from the associated item.
Fix#117209, fix#89868.
Stash and cancel cycle errors for auto trait leakage in opaques
We don't need to emit a traditional cycle error when we have a selection error that explains what's going on but in more detail.
We may want to augment this error to actually point out the cycle, now that the cycle error is not being emitted. We could do that by storing the set of opaques that was in the `CyclePlaceholder` that gets returned from `type_of_opaque`.
r? `@oli-obk` cc `@estebank` #117235
Rework negative coherence to properly consider impls that only partly overlap
This PR implements a modified negative coherence that handles impls that only have partial overlap.
It does this by:
1. taking both impl trait refs, instantiating them with infer vars
2. equating both trait refs
3. taking the equated trait ref (which represents the two impls' intersection), and resolving any vars
4. plugging all remaining infer vars with placeholder types
these placeholder-plugged trait refs can then be used normally with the new trait solver, since we no longer have to worry about the issue with infer vars in param-envs.
We use the **new trait solver** to reason correctly about unnormalized trait refs (due to deferred projection equality), since this avoid having to normalize anything under param-envs with infer vars in them.
This PR then additionally:
* removes the `FnPtr` knowable hack by implementing proper negative `FnPtr` trait bounds for rigid types.
---
An example:
Consider these two partially overlapping impls:
```
impl<T, U> PartialEq<&U> for &T where T: PartialEq<U> {}
impl<F> PartialEq<F> for F where F: FnPtr {}
```
Under the old algorithm, we would take one of these impls and replace it with infer vars, then try unifying it with the other impl under identity substitutions. This is not possible in either direction, since it either sets `T = U`, or tries to equate `F = &?0`.
Under the new algorithm, we try to unify `?0: PartialEq<?0>` with `&?1: PartialEq<&?2>`. This gives us `?0 = &?1 = &?2` and thus `?1 = ?2`. The intersection of these two trait refs therefore looks like: `&?1: PartialEq<&?1>`. After plugging this with placeholders, we get a trait ref that looks like `&!0: PartialEq<&!0>`, with the first impl having substs `?T = ?U = !0` and the second having substs `?F = &!0`[^1].
Then we can take the param-env from the first impl, and try to prove the negated where clause of the second.
We know that `&!0: !FnPtr` never holds, since it's a rigid type that is also not a fn ptr, we successfully detect that these impls may never overlap.
[^1]: For the purposes of this example, I just ignored lifetimes, since it doesn't really matter.
Rename AsyncCoroutineKind to CoroutineSource
pulled out of https://github.com/rust-lang/rust/pull/116447
Also refactors the printing infra of `CoroutineSource` to be ready for easily extending it with a `Gen` variant for `gen` blocks
Uplift `Canonical` to `rustc_type_ir`
I plan on moving the new trait solver's canonicalizer into either `rustc_type_ir` or a child crate. One dependency on this is lifting `Canonical<V>` to `rustc_type_ir` so we can actually name the canonicalized values.
I may also later lift `CanonicalVarInfo` into the new trait solver. I can't really tell what other changes need to be done, but I'm just putting this up sooner than later since I'm almost certain it'll need to be done regardless of other design choices.
There are a couple of warts introduced by this PR, since we no longer can define inherent `Canonical` impls in `rustc_middle` -- see the changes to:
* `compiler/rustc_trait_selection/src/traits/query/normalize.rs`
* `compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs`
r? lcnr
Uplift `ClauseKind` and `PredicateKind` into `rustc_type_ir`
Uplift `ClauseKind` and `PredicateKind` into `rustc_type_ir`.
Blocked on #116951
r? `@ghost`
Get rid of `'tcx` lifetime on `ConstVid`, `EffectVid`
These are simply newtyped numbers, so don't really have a reason (per se) to have a lifetime -- `TyVid` and `RegionVid` do not, for example.
The only consequence of this is that we need to use a new key type for `UnifyKey` that mentions `'tcx`. This is already done for `RegionVid`, with `RegionVidKey<'tcx>`, but this `UnifyKey` trait implementation may have been the original reason to give `ConstVid` a lifetime. See the changes to `compiler/rustc_middle/src/infer/unify_key.rs` specifically.
I consider the code cleaner this way, though -- we removed quite a few unnecessary `'tcx` in the process. This also makes it easier to uplift these two ids to `rustc_type_ir`, which I plan on doing in a follow-up PR.
r? `@BoxyUwU`
`OptWithInfcx` naming nits, trait bound simplifications
* Use an associated type `Interner` on `InferCtxtLike` to remove a redundant interner parameter (`I: Interner, Infcx: InferCtxtLike<I>` -> `Infcx: InferCtxtLike`).
* Remove double-`Option` between `infcx: Option<Infcx>` and `fn universe_of_ty(&self, ty: ty::InferTy) -> Option<ty::UniverseIndex>`. We don't need the infcx to be optional if we can provide a "noop" (`NoInfcx`) implementation that just always returns `None` for universe index.
* Also removes the `core::convert::Infallible` implementation which I found a bit weird...
* Some naming nits with params.
* I found `InferCtxt` + `InfCtx` and `Infcx` to be a lot of different ways to spell "inference context", so I got rid of the `InfCtx` type parameter name in favor of `Infcx` which is a more standard name.
* I found `OptWithInfcx` to be a bit redundant -> `WithInfcx`.
I'm making these changes because I intend to reuse the `InferCtxtLike` trait for uplifting the canonicalizer into a new trait -- conveniently, the information I need for uplifting the canonicalizer also is just the universe information of a type var, so it's super convenient 😸
r? `@BoxyUwU` or `@lcnr`
Rollup of 6 pull requests
Successful merges:
- #107159 (rand use getrandom for freebsd (available since 12.x))
- #116859 (Make `ty::print::Printer` take `&mut self` instead of `self`)
- #117046 (return unfixed len if pat has reported error)
- #117070 (rustdoc: wrap Type with Box instead of Generics)
- #117074 (Remove smir from triage and add me to stablemir)
- #117086 (Update .mailmap to promote my livename)
r? `@ghost`
`@rustbot` modify labels: rollup
Make `ty::print::Printer` take `&mut self` instead of `self`
based on #116815
This simplifies the code by removing all the `self` assignments and
makes the flow of data clearer - always into the printer.
Especially in v0 mangling, which already used `&mut self` in some
places, it gets a lot more uniform.
report `unused_import` for empty reexports even it is pub
Fixes#116032
An easy fix. r? `@petrochenkov`
(Discovered this issue while reviewing #115993.)
Implement jump threading MIR opt
This pass is an attempt to generalize `ConstGoto` and `SeparateConstSwitch` passes into a more complete jump threading pass.
This pass is rather heavy, as it performs a truncated backwards DFS on MIR starting from each `SwitchInt` terminator. This backwards DFS remains very limited, as it only walks through `Goto` terminators.
It is build to support constants and discriminants, and a propagating through a very limited set of operations.
The pass successfully manages to disentangle the `Some(x?)` use case and the DFA use case. It still needs a few tests before being ready.
Avoid a `track_errors` by bubbling up most errors from `check_well_formed`
I believe `track_errors` is mostly papering over issues that a sufficiently convoluted query graph can hit. I made this change, while the actual change I want to do is to stop bailing out early on errors, and instead use this new `ErrorGuaranteed` to invoke `check_well_formed` for individual items before doing all the `typeck` logic on them.
This works towards resolving https://github.com/rust-lang/rust/issues/97477 and various other ICEs, as well as allowing us to use parallel rustc more (which is currently rather limited/bottlenecked due to the very sequential nature in which we do `rustc_hir_analysis::check_crate`)
cc `@SparrowLii` `@Zoxc` for the new `try_par_for_each_in` function
coverage: Emit mappings for unused functions without generating stubs
For a while I've been annoyed by the fact that generating coverage maps for unused functions involves generating a stub function at the LLVM level.
As I suspected, generating that stub function isn't actually necessary, as long as we specifically tell LLVM about the symbol names of all the functions that have coverage mappings but weren't codegenned (due to being unused).
---
There is some helper code that gets moved around in the follow-up patches, so look at the first patch to see the most important functional changes.
---
`@rustbot` label +A-code-coverage
This simplifies the code by removing all the `self` assignments and
makes the flow of data clearer - always into the printer.
Especially in v0 mangling, which already used `&mut self` in some
places, it gets a lot more uniform.
