Use identifiers more in diagnostics code
This should make the diagnostics code slightly more correct when rendering idents in mixed crate edition situations. Kinda a no-op, but a cleanup regardless.
r? oli-obk or reassign
Add a workaround for parallel rustc crashing when there are delayed bugs
This doesn't fix the root cause of this crash, but at least stops it from happening for the time being.
Workaround for https://github.com/rust-lang/rust/issues/135870
- `check-pass` test for a MRE of #135020
- fail test for #135138
- switch to `TooGeneric` for checking CMSE fn signatures
- switch to `TooGeneric` for compute `SizeSkeleton` (for transmute)
- fix broken tests
Get rid of `mir::Const::from_ty_const`
This function is strange, because it turns valtrees into `mir::Const::Value`, but the rest of the const variants stay as type system consts.
All of the callsites except for one in `instsimplify` (array length simplification of `ptr_metadata` call) just go through the valtree arm of the function, so it's easier to just create a `mir::Const` directly for those.
For the instsimplify case, if we have a type system const we should *keep* having a type system const, rather than turning it into a `mir::Const::Value`; it doesn't really matter in practice, though, bc `usize` has no padding, but it feels more principled.
Expand polonius MIR dump
This PR starts expanding the polonius MIR:
- switches to an HTML file, to show graphs in the same document as the MIR dump, share them more easily since it's a single file that can be hosted as a gist, and also to allow for interactivity in the near future.
- adds the regular NLL MIR + polonius constraints
- embeds a mermaid version of the CFG, similar to the graphviz one, but that needs a smaller js than `dot`'s emscripten js from graphvizonline
[Here's an example](https://gistpreview.github.io/?0c18f2a59b5e24ac0f96447aa34ffe00) of how it looks.
---
In future PRs: mermaid graphs of the NLL region graph, of the NLL SCCs, of the polonius localized outlives constraints, and the interactive polonius MIR dump.
r? ```@matthewjasper```
for cases where we want to dump the MIR to a given writer instead of a
new file as the default does.
this will be used when dumping the MIR to a buffer to process
differently, e.g. post-process to escape for an HTML dump.
Add `#[optimize(none)]`
cc #54882
This extends the `optimize` attribute to add `none`, which corresponds to the LLVM `OptimizeNone` attribute.
Not sure if an MCP is required for this, happy to file one if so.
coverage: Prepare for upcoming changes to counter creation
This is a collection of smaller changes to coverage instrumentation code that have been extracted from a larger PR that I'm still working on, in order to hopefully make review easier.
Each individual change should hopefully be mostly self-explanatory. One of the big goals of the upcoming PR will be to defer certain parts of counter-creation until codegen, via the query system, so that ends up being a recurring theme in these changes. Several of the changes are follow-ups to #135481.
There should be no observable change in compiler output.
Forbid usage of `hir` `Infer` const/ty variants in ambiguous contexts
The feature `generic_arg_infer` allows providing `_` as an argument to const generics in order to infer them. This introduces a syntactic ambiguity as to whether generic arguments are type or const arguments. In order to get around this we introduced a fourth `GenericArg` variant, `Infer` used to represent `_` as an argument to generic parameters when we don't know if its a type or a const argument.
This made hir visitors that care about `TyKind::Infer` or `ConstArgKind::Infer` very error prone as checking for `TyKind::Infer`s in `visit_ty` would find *some* type infer arguments but not *all* of them as they would sometimes be lowered to `GenericArg::Infer` instead.
Additionally the `visit_infer` method would previously only visit `GenericArg::Infer` not *all* infers (e.g. `TyKind::Infer`), this made it very easy to override `visit_infer` and expect it to visit all infers when in reality it would only visit *some* infers.
---
This PR aims to fix those issues by making the `TyKind` and `ConstArgKind` types generic over whether the infer types/consts are represented by `Ty/ConstArgKind::Infer` or out of line (e.g. by a `GenericArg::Infer` or accessible by overiding `visit_infer`). We then make HIR Visitors convert all const args and types to the versions where infer vars are stored out of line and call `visit_infer` in cases where a `Ty`/`Const` would previously have had a `Ty/ConstArgKind::Infer` variant:
API Summary
```rust
enum AmbigArg {}
enum Ty/ConstArgKind<Unambig = ()> {
...
Infer(Unambig),
}
impl Ty/ConstArg {
fn try_as_ambig_ty/ct(self) -> Option<Ty/ConstArg<AmbigArg>>;
}
impl Ty/ConstArg<AmbigArg> {
fn as_unambig_ty/ct(self) -> Ty/ConstArg;
}
enum InferKind {
Ty(Ty),
Const(ConstArg),
Ambig(InferArg),
}
trait Visitor {
...
fn visit_ty/const_arg(&mut self, Ty/ConstArg<AmbigArg>) -> Self::Result;
fn visit_infer(&mut self, id: HirId, sp: Span, kind: InferKind) -> Self::Result;
}
// blanket impl'd, not meant to be overriden
trait VisitorExt {
fn visit_ty/const_arg_unambig(&mut self, Ty/ConstArg) -> Self::Result;
}
fn walk_unambig_ty/const_arg(&mut V, Ty/ConstArg) -> Self::Result;
fn walk_ty/const_arg(&mut V, Ty/ConstArg<AmbigArg>) -> Self::Result;
```
The end result is that `visit_infer` visits *all* infer args and is also the *only* way to visit an infer arg, `visit_ty` and `visit_const_arg` can now no longer encounter a `Ty/ConstArgKind::Infer`. Representing this in the type system means that it is now very difficult to mess things up, either accessing `TyKind::Infer` "just works" and you won't miss *some* type infers- or it doesn't work and you have to look at `visit_infer` or some `GenericArg::Infer` which forces you to think about the full complexity involved.
Unfortunately there is no lint right now about explicitly matching on uninhabited variants, I can't find the context for why this is the case 🤷♀️
I'm not convinced the framing of un/ambig ty/consts is necessarily the right one but I'm not sure what would be better. I somewhat like calling them full/partial types based on the fact that `Ty<Partial>`/`Ty<Full>` directly specifies how many of the type kinds are actually represented compared to `Ty<Ambig>` which which leaves that to the reader to figure out based on the logical consequences of it the type being in an ambiguous position.
---
tool changes have been modified in their own commits for easier reviewing by anyone getting cc'd from subtree changes. I also attempted to split out "bug fixes arising from the refactoring" into their own commit so they arent lumped in with a big general refactor commit
Fixes#112110
This reflects the fact that we can't compute meaningful info for a function
that wasn't instrumented and therefore doesn't have `function_coverage_info`.
These types are unlikely to ever contain type information in the foreseeable
future, so excluding them from TypeFoldable/TypeVisitable avoids some unhelpful
derive boilerplate.
Properly record metavar spans for other expansions other than TT
This properly records metavar spans for nonterminals other than tokentree. This means that we operations like `span.to(other_span)` work correctly for macros. As you can see, other diagnostics involving metavars have improved as a result.
Fixes#132908
Alternative to #133270
cc `@ehuss`
cc `@petrochenkov`
remove support for the (unstable) #[start] attribute
As explained by `@Noratrieb:`
`#[start]` should be deleted. It's nothing but an accidentally leaked implementation detail that's a not very useful mix between "portable" entrypoint logic and bad abstraction.
I think the way the stable user-facing entrypoint should work (and works today on stable) is pretty simple:
- `std`-using cross-platform programs should use `fn main()`. the compiler, together with `std`, will then ensure that code ends up at `main` (by having a platform-specific entrypoint that gets directed through `lang_start` in `std` to `main` - but that's just an implementation detail)
- `no_std` platform-specific programs should use `#![no_main]` and define their own platform-specific entrypoint symbol with `#[no_mangle]`, like `main`, `_start`, `WinMain` or `my_embedded_platform_wants_to_start_here`. most of them only support a single platform anyways, and need cfg for the different platform's ways of passing arguments or other things *anyways*
`#[start]` is in a super weird position of being neither of those two. It tries to pretend that it's cross-platform, but its signature is a total lie. Those arguments are just stubbed out to zero on ~~Windows~~ wasm, for example. It also only handles the platform-specific entrypoints for a few platforms that are supported by `std`, like Windows or Unix-likes. `my_embedded_platform_wants_to_start_here` can't use it, and neither could a libc-less Linux program.
So we have an attribute that only works in some cases anyways, that has a signature that's a total lie (and a signature that, as I might want to add, has changed recently, and that I definitely would not be comfortable giving *any* stability guarantees on), and where there's a pretty easy way to get things working without it in the first place.
Note that this feature has **not** been RFCed in the first place.
*This comment was posted [in May](https://github.com/rust-lang/rust/issues/29633#issuecomment-2088596042) and so far nobody spoke up in that issue with a usecase that would require keeping the attribute.*
Closes https://github.com/rust-lang/rust/issues/29633
try-job: x86_64-gnu-nopt
try-job: x86_64-msvc-1
try-job: x86_64-msvc-2
try-job: test-various
Get rid of `ToPolyTraitRef`
It's generally a footgun, since it throws away `PredicatePolarity`.
This PR doesn't attempt to fix any related bugs having to do with binders or polarity; it just tries to pass through `TraitPredicate`s around instead of `TraitRef`s. There should be basically no functional changes.
Making these separate types from `CovTerm` and `Expression` was historically
very helpful, but now that most of the counter-creation work is handled by
`node_flow` they are no longer needed.
Add gpu-kernel calling convention
The amdgpu-kernel calling convention was reverted in commit f6b21e90d1 (#120495 and https://github.com/rust-lang/rust-analyzer/pull/16463) due to inactivity in the amdgpu target.
Introduce a `gpu-kernel` calling convention that translates to `ptx_kernel` or `amdgpu_kernel`, depending on the target that rust compiles for.
Tracking issue: #135467
amdgpu target tracking issue: #135024
Use trait definition cycle detection for trait alias definitions, too
fixes#133901
In general doing this for `All` is not right, but this code path is specifically for traits and trait aliases, and there we only ever use `All` for trait aliases.
The amdgpu-kernel calling convention was reverted in commit
f6b21e90d1 due to inactivity in the amdgpu
target.
Introduce a `gpu-kernel` calling convention that translates to
`ptx_kernel` or `amdgpu_kernel`, depending on the target that rust
compiles for.
deprecate `std::intrinsics::transmute` etc, use `std::mem::*` instead
The `rustc_allowed_through_unstable_modules` attribute lets users call `std::mem::transmute` as `std::intrinsics::transmute`. The former is a reexport of the latter, and for a long time we didn't properly check stability for reexports, so making this a hard error now would be a breaking change for little gain. But at the same time, `std::intrinsics::transmute` is not the intended path for this function, so I think it is a good idea to show a deprecation warning when that path is used. This PR implements that, for all the functions in `std::intrinsics` that carry the attribute.
I assume this will need ``@rust-lang/libs-api`` FCP.
Treat safe target_feature functions as unsafe by default [less invasive variant]
This unblocks
* #134090
As I stated in https://github.com/rust-lang/rust/pull/134090#issuecomment-2541332415 I think the previous impl was too easy to get wrong, as by default it treated safe target feature functions as safe and had to add additional checks for when they weren't. Now the logic is inverted. By default they are unsafe and you have to explicitly handle safe target feature functions.
This is the less (imo) invasive variant of #134317, as it doesn't require changing the Safety enum, so it only affects FnDefs and nothing else, as it should.
Exclude dependencies of `std` for diagnostics
Currently crates in the sysroot can show up in diagnostic suggestions, such as in https://github.com/rust-lang/rust/issues/135232. To prevent this, duplicate `all_traits` into `visible_traits` which only shows traits in non-private crates.
Setting `#![feature(rustc_private)]` overrides this and makes items in private crates visible as well, since `rustc_private` enables use of `std`'s private dependencies.
This may be reviewed per-commit.
Fixes: https://github.com/rust-lang/rust/issues/135232
Add an alternative to `tcx.all_traits()` that only shows traits that the
user might be able to use, for diagnostic purposes. With this available,
make use of it for diagnostics including associated type errors, which
is part of the problem with [1].
Includes a few comment updates for related API.
[1]: https://github.com/rust-lang/rust/issues/135232
Really this is always-visible override only needs to happen when the
crate is a dependency of itself. However, this is a very internal
feature, so it doesn't seem worth doing any additional filtering here.
Remove code duplication when hashing query result and interning node
Refactored the duplicated code into a function.
`with_feed_task` currently passes the query key to `debug_assert!`. I believe that's a mistake, since `with_task` prints the `DepNode` which is more sensible, so this commit changes that, so it debug prints the `DepNode`.
Fix cycle error only occurring with -Zdump-mir
fixes#134205
During mir dumping, we evaluate static items to render their allocations. If a static item refers to itself, its own MIR will have a reference to itself, so during mir dumping we end up evaluating the static again, causing us to try to build MIR again (mir dumping happens during MIR building).
Thus I disabled evaluation of statics during MIR dumps in case the MIR body isn't far enough along yet to be able to be guaranteed cycle free.
Refactored the duplicated code into a function.
`with_feed_task` currently passes the query key to `debug_assert!`.
This commit changes that, so it debug prints the `DepNode`, as in
`with_task`.
Assert that `Instance::try_resolve` is only used on body-like things
`Instance::resolve` is not set up to resolve items that are not body-like things. The logic in `resolve_associated_item` very much encodes this assumption:
e7ad3ae331/compiler/rustc_ty_utils/src/instance.rs (L96-L386)
However, some diagnostics were using `Instance::resolve` on an associated type, and it was simply a lucky coicidence that nothing went wrong.
This PR adds an assertion to make sure we won't do this again in the future, and fixes two callsites:
1. `call_kind` which returns a `CallKind` enum to categorize what a call in MIR comes from, and was using `Instance::resolve` to point at the associated type `Deref::Target` for a specific self ty.
2. `MirBorrowckCtxt::explain_deref_coercion`, which was doing the same thing.
The logic was replaced with `specialization_graph::assoc_def`, which is the proper way of fetching the right `AssocItem` for a given impl.
r? `@lcnr` or re-roll :)
Depth limit const eval query
Currently the const-eval query doesn't have a recursion limit or timeout, causing the complier to freeze in an infinite loop, see #125718. This PR depth limits the `eval_to_const_value_raw` query (with the [`recursion_limit`](https://doc.rust-lang.org/reference/attributes/limits.html) attribute) and improves the diagnostics for query overflow errors, so spans are reported for other dep kinds than `layout_of` (e.g. `eval_to_const_value_raw`).
fixes#125718fixes#114192
De-abstract tagged ptr and make it covariant
In #135272 I needed to use a tagged ptr in `hir::TyKind` in order to not regress hir type sizes. Unfortunately the existing `CopyTaggedPtr` abstraction is insufficient as it makes the `'hir` lifetime invariant.
I spent some time trying to keep existing functionality while making it covariant but in the end I realised that actually we dont use *any* of this code *anywhere* in rustc, so I've just removed everything and replaced it with a much less general abstraction that is suitable for what I need in #135272.
Idk if anyone has a preference for just keeping all the abstractions here in case anyone needs them in the future 🤷♀️
Remove a bunch of diagnostic stashing that doesn't do anything
#121669 removed a bunch of conditional diagnostic stashing/canceling, but left around the `steal` calls which just emitted the error eagerly instead of canceling the diagnostic. I think that these no-op `steal` calls don't do much and are confusing to encounter, so let's remove them.
The net effect is:
1. We emit more duplicated errors, since stashing has the side effect of duplicating diagnostics. This is not a big deal, since outside of `-Zdeduplicate-diagnostics=no`, the errors are already being deduplicated by the compiler.
2. It changes the order of diagnostics, since we're no longer stashing and then later stealing the errors. I don't think this matters much for the changes that the UI test suite manifests, and it makes these errors less order dependent.
Eagerly collect mono items for non-generic closures
This allows users to use `-Zprint-mono-items=eager` to eagerly monomorphize closures and coroutine bodies, in case they want to inspect the LLVM or ASM for those items.
`-Zprint-mono-items`, which used to be called `-Zprint-trans-items`, was originally added in https://github.com/rust-lang/rust/pull/30900:
> Eager mode is meant to be used in conjunction with incremental compilation
> where a stable set of translation items is more important than a minimal
> one. Thus, eager mode will instantiate drop-glue for every drop-able type
> in the crate, even of no drop call for that type exists (yet). It will
> also instantiate default implementations of trait methods, something that
> otherwise is only done on demand.
Although it remains an unstable option, its purpose has somewhat expanded since then, and as far as I can tell it's generally useful for cases when you want to monomorphize as many items as possible, even if they're unreachable. Specifically, it's useful for debugging since you can look at the codegen'd body of a function, since we don't emit items that are not reachable in monomorphization.
And even more specifically, it would be very to monomorphize the coroutine body of an async fn, since those you can't easily call those without a runtime. This PR enables this usecase since we now monomorphize `DefKind::Closure`.
Adds `#[rustc_force_inline]` which is similar to always inlining but
reports an error if the inlining was not possible, and which always
attempts to inline annotated items, regardless of optimisation levels.
It can only be applied to free functions to guarantee that the MIR
inliner will be able to resolve calls.
`-Zrandomize-layout` harder. `Foo<T> != Foo<U>`
Tracking issue: #106764
Previously randomize-layout only used a deterministic shuffle based on the seed stored in an Adt's ReprOptions, meaning that `Foo<T>` and `Foo<U>` were shuffled by the same seed. This change adds a similar seed to each calculated LayoutData so that a struct can be randomized both based on the layout of its fields and its per-type seed.
Primitives start with simple seed derived from some of their properties. Though some types can no longer be distinguished at that point, e.g. usize and u64 will still be treated the same.
previously field ordering was using the same seed for all instances of Foo,
now we pass seed values through the layout tree so that not only
the struct itself affects layout but also its fields
`Ty::new` wasn't used anywhere outside this module
`Ty::new_adt` shouldn't ever be used for anything but adts. This hasn't caught any bugs, but seems good to check anyway
Implement `const Destruct` in old solver
Self-explanatory. Not totally settled that this is the best structure for built-in trait impls for effect goals in the new solver, but it's almost certainly the simplest.
r? lcnr or re-roll
Suggest Replacing Comma with Semicolon in Incorrect Repeat Expressions
Fixes#80173
This PR detects typos in repeat expressions like `["_", 10]` and `vec![String::new(), 10]` and suggests replacing comma with semicolon.
Also, improves code in other place by adding doc comments and making use of a helper function to check if a type implements `Clone`.
References:
1. For `vec![T; N]`: https://doc.rust-lang.org/std/macro.vec.html
2. For `[T; N]`: https://doc.rust-lang.org/std/primitive.array.html
Exhaustively handle expressions in patterns
We currently have this invariant in HIR that a `PatKind::Lit` or a `PatKind::Range` only contains
* `ExprKind::Lit`
* `ExprKind::UnOp(Neg, ExprKind::Lit)`
* `ExprKind::Path`
* `ExprKind::ConstBlock`
So I made `PatKind::Lit` and `PatKind::Range` stop containing `Expr`, and instead created a `PatLit` type whose `kind` enum only contains those variants.
The only place code got more complicated was in clippy, as it couldn't share as much anymore with `Expr` handling
It may be interesting on merging `ExprKind::{Path,Lit,ConstBlock}` in the future and using the same `PatLit` type (under a new name).
Then it should also be easier to eliminate any and all `UnOp(Neg, Lit) | Lit` matching that we have across the compiler. Some day we should fold the negation into the literal itself and just store it on the numeric literals
`best_blame_constraint`: Blame better constraints when the region graph has cycles from invariance or `'static`
This fixes#132749 by changing which constraint is blamed for region errors in several cases. `best_blame_constraint` had a heuristic that tried to pinpoint the constraint causing an error by filtering out any constraints where the outliving region is unified with the ultimate target region being outlived. However, it used the SCCs of the region graph to do this, which is unreliable; in particular, if the target region is `'static`, or if there are cycles from the presence of invariant types, it was skipping over the constraints it should be blaming. As is the case in that issue, this could lead to confusing diagnostics. The simplest fix seems to work decently, judging by test stderr: this makes `best_blame_constraint` no longer filter constraints by their outliving region's SCC.
There are admittedly some quirks in the test output. In many cases, subdiagnostics that depend on the particular constraint being blamed have either started or stopped being emitted. After starting at this for quite a while, I think anything too fickle about whether it outputs based on the particular constraint being blamed should instead be looking at the constraint path as a whole, similar to what's done for [the placeholder-from-predicate note](https://github.com/rust-lang/rust/compare/master...dianne:rust:better-blame-constraints-for-static#diff-3c0de6462469af483c9ecdf2c4b00cb26192218ef2d5c62a0fde75107a74caaeR506).
Very many tests involving invariant types gained a note pointing out the types' invariance, but in a few cases it was lost. A particularly illustrative example is [tests/ui/lifetimes/copy_modulo_regions.stderr](https://github.com/rust-lang/rust/compare/master...dianne:rust:better-blame-constraints-for-static?expand=1#diff-96e1f8b29789b3c4ce2f77a5e0fba248829b97ef9d1ce39e7d2b4aa57b2cf4f0); I'd argue the new constraint is a better one to blame, but it lacks the variance diagnostic information that's elsewhere in the constraint path. If desired, I can try making that note check the whole path rather than just the blamed constraint.
The subdiagnostic [`BorrowExplanation::add_object_lifetime_default_note`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_borrowck/diagnostics/explain_borrow/enum.BorrowExplanation.html#method.add_object_lifetime_default_note) depends on a `Cast` being blamed, so [a special case](364ca7f99c) was necessary to keep it from disappearing from tests specifically testing for it. However, see the FIXME comment in that commit; I think the special case should be removed once that subdiagnostic works properly, but it's nontrivial enough to warrant a separate PR. Incidentally, this removes the note from a test where it was being added erroneously: in [tests/ui/borrowck/two-phase-surprise-no-conflict.stderr](https://github.com/rust-lang/rust/compare/master...dianne:rust:better-blame-constraints-for-static?expand=1#diff-8cf085af8203677de6575a45458c9e6b03412a927df879412adec7e4f7ff5e14), the object lifetime is explicitly provided and it's not `'static`.
Convert typeck constraints in location-sensitive polonius
In this PR, we do a big chunk of the work of localizing regular outlives constraints.
The slightly annoying thing is handling effectful statements: usually the subset graph propagates loans at a single point between regions, and liveness propagates loans between points within a single region, but some statements have effects applied on exit.
This was also a problem before, in datalog polonius terms and Niko's solution at the time, this is about: the mid-point. The idea was to duplicate all MIR locations into two physical points, and orchestrate the effects with that. Somewhat easier to do, but double the CFG.
We've always believed we didn't _need_ midpoints in principle, as we can represent changes on exit as on happening entry to the successor, but there's some difficulty in tracking the position information at sufficient granularity through outlives relation (especially since we also have bidirectional edges and time-traveling now).
Now, that is surely what we should be doing in the future. In the mean time, I infer this from the kind of statement/terminator where an outlives constraint arose. It's not particularly complicated but some explanation will help clarify the code.
Assignments (in their various forms) are the quintessential example of these crossover cases: loans that would flow into the LHS would not be visible on entry to the point but on exit -- so we'll localize these edges to the successor. Let's look at a real-world example, involving invariance for bidirectional edges:
```rust
let mut _1: HashMap<i32, &'7 i32>;
let mut _3: &'9 mut HashMap<i32, &'10 i32>;
...
/* at bb1[3]: */ _3 = &'3 mut _1;
```
Here, typeck expectedly produces 3 outlives constraints today:
1. `'3 -> '9`
2. `'7 -> '10`
3. `'10 -> '7`
And we localize them like so,
1. `'3 -> '9` flows into the LHS and becomes: `3_bb1_3 -> 9_bb1_4`
2. `'7 -> '10` flows into the LHS and becomes: `7_bb1_3 -> 10_bb1_4`
3. `'10 -> '7` flows from the LHS and becomes: `10_bb1_4 -> 7_bb1_3` (time traveling 👌)
---
r? ``@jackh726``
To keep you entertained during the holidays I also threw in a couple of small changes removing cruft in the borrow checker.
We're actually getting there. The next PR will be the last one needed to get end-to-end tests working.
Use a post-monomorphization typing env when mangling components that come from impls
When mangling associated methods of impls, we were previously using the wrong param-env. Instead of using a fully monomorphized param-env like we usually do in codegen, we were taking the post-analysis param-env, and treating it as an early binder to *re-substitute* the impl args. I've pointed out the problematic old code in an inline comment.
This would give us param-envs with possibly trivial predicates that would prevent normalization via param-env shadowing.
In the example test linked below, `tests/ui/symbol-names/normalize-in-param-env.rs`, this happens when we mangle the impl `impl<P: Point2> MyFrom<P::S> for P` with the substitution `P = Vec2`. Because the where clause of the impl is `P: Point2`, which elaborates to `[P: Point2, P: Point, <P as Point>::S projects-to <P as Point2>::S2]` and the fact that `impl Point2 for Vec2` normalizes `Vec2::S2` to `Vec2::S`, this causes a cycle.
The proper fix here is to use a fully monomorphized param-env for the case where the impl is properly substituted.
Fixes#135143
While #134081 uncovered this bug for legacy symbol mangling, it was preexisting for v0 symbol mangling. This PR fixes both. The test requires a "hack" because we strip the args of the instance we're printing for legacy symbol mangling except for drop glue, so we box a closure to ensure we generate drop glue.
r? oli-obk
A few borrowck tweaks to improve 2024 edition migration lints
See first two commits' changes to test outputs. Test coverage in this area is kinda weak, but I think it affects more cases than this (like the craters that will begin to trigger the `tail_expr_drop_order` tests in #134523).
Third commit is a drive-by change that removes a deref hack from `UseSpans` which doesn't really improve diagnostics much.
Add a notion of "some ABIs require certain target features"
I think I finally found the right shape for the data and checks that I recently added in https://github.com/rust-lang/rust/pull/133099, https://github.com/rust-lang/rust/pull/133417, https://github.com/rust-lang/rust/pull/134337: we have a notion of "this ABI requires the following list of target features, and it is incompatible with the following list of target features". Both `-Ctarget-feature` and `#[target_feature]` are updated to ensure we follow the rules of the ABI. This removes all the "toggleability" stuff introduced before, though we do keep the notion of a fully "forbidden" target feature -- this is needed to deal with target features that are actual ABI switches, and hence are needed to even compute the list of required target features.
We always explicitly (un)set all required and in-conflict features, just to avoid potential trouble caused by the default features of whatever the base CPU is. We do this *before* applying `-Ctarget-feature` to maintain backward compatibility; this poses a slight risk of missing some implicit feature dependencies in LLVM but has the advantage of not breaking users that deliberately toggle ABI-relevant target features. They get a warning but the feature does get toggled the way they requested.
For now, our logic supports x86, ARM, and RISC-V (just like the previous logic did). Unsurprisingly, RISC-V is the nicest. ;)
As a side-effect this also (unstably) allows *enabling* `x87` when that is harmless. I used the opportunity to mark SSE2 as required on x86-64, to better match the actual logic in LLVM and because all x86-64 chips do have SSE2. This infrastructure also prepares us for requiring SSE on x86-32 when we want to use that for our ABI (and for float semantics sanity), see https://github.com/rust-lang/rust/issues/133611, but no such change is happening in this PR.
r? `@workingjubilee`
rustc_intrinsic: support functions without body
We synthesize a HIR body `loop {}` but such bodyless intrinsics.
Most of the diff is due to turning `ItemKind::Fn` into a brace (named-field) enum variant, because it carries a `bool`-typed field now. This is to remember whether the function has a body. MIR building panics to avoid ever translating the fake `loop {}` body, and the intrinsic logic uses the lack of a body to implicitly mark that intrinsic as must-be-overridden.
I first tried actually having no body rather than generating the fake body, but there's a *lot* of code that assumes that all function items have HIR and MIR, so this didn't work very well. Then I noticed that even `rustc_intrinsic_must_be_overridden` intrinsics have MIR generated (they are filled with an `Unreachable` terminator) so I guess I am not the first to discover this. ;)
r? `@oli-obk`
Project to `TyKind::Error` when there are unconstrained non-lifetime (ty/const) impl params
It splits the `enforce_impl_params_are_constrained` function into lifetime/non-lifetime, and queryfies the latter. We can then use the result of the latter query (`Result<(), ErrorGuaranteed>`) to intercept projection and constrain the projected type to `TyKind::Error`, which ensures that we leak no ty or const vars to places that don't expect them, like `normalize_erasing_regions`.
The reason we split `enforce_impl_params_are_constrained` into two parts is because we only error for *lifetimes* if the lifetime ends up showing up in any of the associated types of the impl (e.g. we allow `impl<'a> Foo { type Assoc = (); }`). However, in order to compute the `type_of` query for the anonymous associated type of an RPITIT, we need to do trait solving (in `query collect_return_position_impl_trait_in_trait_tys`). That would induce cycles. Luckily, it turns out for lifetimes we don't even care about if they're unconstrained, since they're erased in all contexts that we are trying to fix ICEs. So it's sufficient to keep this check separated out of the query.
I think this is a bit less invasive of an approach compared to #127973. The major difference between this PR and that PR is that we queryify the check instead of merging it into the `explicit_predicates_of` query, and we use the result to taint just projection goals, rather than trait goals too. This doesn't require a lot of new tracking in `ItemCtxt` and `GenericPredicates`, and it also seems to not require any other changes to typeck like that PR did.
Fixes#123141Fixes#125874Fixes#126942Fixes#127804Fixes#130967
r? oli-obk
Improve infer (`_`) suggestions in `const`s and `static`s
Fixes https://github.com/rust-lang/rust/issues/135010.
This PR does a few things to (imo) greatly improve the error message when users write something like `static FOO: [i32; _] = [1, 2, 3]`.
Firstly, it adapts the recovery code for when we encounter `_` in a const/static to work a bit more like `fn foo() -> _`, and removes the somewhat redundant query `diagnostic_only_typeck`.
Secondly, it changes the lowering for `[T; _]` to always lower under the `feature(generic_arg_infer)` logic to `ConstArgKind::Infer`. We still issue the feature error, so it's not doing anything *observable* on the good path, but it does mean that we no longer erroneously interpret `[T; _]`'s array length as a `_` **wildcard expression** (à la destructuring assignment, like `(_, y) = expr`).
Lastly it makes the suggestions verbose and fixes (well, suppresses) a bug with stashing and suggestions.
r? oli-obk
Spruce up the docs of several queries related to the type/trait system and const eval
- Editorial
- Proper rustdoc summary/synopsis line by making use of extra paragraphs: Leads to better rendered output on module pages, in search result lists and overall, too
- Use rustdoc warning blocks for admonitions of the form "do not call / avoid calling this query directly"
- Use intra-doc links of the form ``[`Self::$query`]`` to cross-link queries. Indeed, such links are generally a bit brittle due to the existence of `TyCtxtFeed` which only contains a subset of queries. Therefore the docs of `feedable` queries cannot cross-link to non-`feedable` ones. I'd say it's fine to use intra-doc links despite the potential/unlikely occasional future breakage (if a query with the aforementioned characteristics becomes `feedable`). `Self::` is nicer than `TyCtxt::` (which would be more stable) since it accounts for other contexts like `TyCtxt{Feed,At,Ensure{,WithValue}}`
- Informative
- Generally add, flesh out and correct some doc comments
- Add *Panic* sections (to a few selected queries only). The lists of panics aren't necessarily exhaustive and focus on the more "obvious" or "important" panics.
- Where applicable add a paragraph calling attention to the relevant [`#[rustc_*]` TEST attribute](https://rustc-dev-guide.rust-lang.org/compiler-debugging.html#rustc_-test-attributes)
The one non-doc change (it's internal and not observable):
Be even more defensive in `query constness`'s impl (spiritual follow-up to #134122) (see self review comment).
Fixes#133494.
r\? **any**(compiler-errors, oli-obk)
Begin to implement type system layer of unsafe binders
Mostly TODOs, but there's a lot of match arms that are basically just noops so I wanted to split these out before I put up the MIR lowering/projection part of this logic.
r? oli-obk
Tracking:
- https://github.com/rust-lang/rust/issues/130516
cleanup `TypeVerifier`
We should merge it with the `TypeChecker` as we no longer bail in cases where it encounters an error since #111863.
It's quite inconsistent whether a check lives in the verifier or the `TypeChecker`, so this feels like a quite impactful cleanup. I expect that for this we may want to change the `TypeChecker` to also be a MIR visitor 🤔 this is non-trivial so I didn't fully do it in this PR.
Best reviewed commit by commit.
r? `@compiler-errors` feel free to reassign however
coroutine_clone: add comments
I was very surprised to learn that coroutines can be cloned. This has non-trivial semantic consequences that I do not think have been considered. Lucky enough, it's still unstable. Let's add some comments and pointers so we hopefully become aware when a MIR opt actually is in conflict with this.
Cc `@rust-lang/wg-mir-opt`
Foundations of location-sensitive polonius
I'd like to land the prototype I'm describing in the [polonius project goal](https://github.com/rust-lang/rust-project-goals/issues/118). It still is incomplete and naive and terrible but it's working "well enough" to consider landing.
I'd also like to make review easier by not opening a huge PR, but have a couple small-ish ones (the +/- line change summary of this PR looks big, but >80% is moving datalog to a single place).
This PR starts laying the foundation for that work:
- it refactors and collects 99% of the old datalog fact gen, which was spread around everywhere, into a single dedicated module. It's still present at 3 small places (one of which we should revert anyways) that are kinda deep within localized components and are not as easily extractable into the rest of fact gen, so it's fine for now.
- starts introducing the localized constraints, the building blocks of the naive way of implementing the location-sensitive analysis in-tree, which is roughly sketched out in https://smallcultfollowing.com/babysteps/blog/2023/09/22/polonius-part-1/ and https://smallcultfollowing.com/babysteps/blog/2023/09/29/polonius-part-2/ but with a different vibe than per-point environments described in these posts, just `r1@p: r2@q` constraints.
- sets up the skeleton of generating these localized constraints: converting NLL typeck constraints, and creating liveness constraints
- introduces the polonius dual to NLL MIR to help development and debugging. It doesn't do much currently but is a way to see these localized constraints: it's an NLL MIR dump + a dumb listing of the constraints, that can be dumped with `-Zdump-mir=polonius -Zpolonius=next`. Its current state is not intended to be a long-term thing, just for testing purposes -- I will replace its contents in the future with a different approach (an HTML+js file where we can more easily explore/filter/trace these constraints and loan reachability, have mermaid graphs of the usual graphviz dumps, etc).
I've started documenting the approach in this PR, I'll add more in the future. It's quite simple, and should be very clear when more constraints are introduced anyways.
r? `@matthewjasper`
Best reviewed per commit so that the datalog move is less bothersome to read, but if you'd prefer we separate that into a different PR, I can do that (and michael has offered to review these more mechanical changes if it'd help).
handle member constraints directly in the mir type checker
cleaner, faster, easier to change going forward :> fixes#109654
r? `@oli-obk` `@compiler-errors`
unimplement `PointerLike` for trait objects
Values of type `dyn* PointerLike` or `dyn PointerLike` are not pointer-like so these types should not implement `PointerLike`.
After https://github.com/rust-lang/rust/pull/133226, `PointerLike` allows user implementations, so we can't just mark it with `#[rustc_deny_explicit_impl(implement_via_object = false)]`. Instead, this PR splits the `#[rustc_deny_explicit_impl(implement_via_object = ...)]` attribute into two separate attributes `#[rustc_deny_explicit_impl]` and `#[rustc_do_not_implement_via_object]` so that we opt out of the automatic `impl PointerLike for dyn PointerLike` and still allow user implementations.
For traits that are marked with `#[do_not_implement_via_object]` but not `#[rustc_deny_explicit_impl]` I've also made it possible to add a manual `impl Trait for dyn Trait`. There is no immediate need for this, but it was one line to implement and seems nice to have.
fixes https://github.com/rust-lang/rust/issues/134545
fixes https://github.com/rust-lang/rust/issues/134543
r? `@compiler-errors`
This commit splits the `#[rustc_deny_explicit_impl(implement_via_object = ...)]` attribute
into two attributes `#[rustc_deny_explicit_impl]` and `#[rustc_do_not_implement_via_object]`.
This allows us to have special traits that can have user-defined impls but do not have the
automatic trait impl for trait objects (`impl Trait for dyn Trait`).
Improve dependency_format a bit
* Make `DependencyList` an `IndexVec` rather than emulating one using a `Vec` (which was off-by-one as LOCAL_CRATE was intentionally skipped)
* Update some comments for the fact that we now use `#[global_allocator]` rather than `extern crate alloc_system;`/`extern crate alloc_jemalloc;` for specifying which allocator to use. We still use a similar mechanism for the panic runtime, so refer to the panic runtime in those comments instead.
* An unrelated refactor to `create_and_enter_global_ctxt` I forgot to include in https://github.com/rust-lang/rust/pull/134302. This refactor is too small to be worth it's own PR.
coverage: Store coverage source regions as `Span` until codegen (take 2)
This is an attempt to re-land #133418:
> Historically, coverage spans were converted into line/column coordinates during the MIR instrumentation pass.
> This PR moves that conversion step into codegen, so that coverage spans spend most of their time stored as Span instead.
> In addition to being conceptually nicer, this also reduces the size of coverage mappings in MIR, because Span is smaller than 4x u32.
That PR was reverted by #133608, because in some circumstances not covered by our test suite we were emitting coverage metadata that was causing `llvm-cov` to exit with an error (#133606).
---
The implementation here is *mostly* the same, but adapted for subsequent changes in the relevant code (e.g. #134163).
I believe that the changes in #134163 should be sufficient to prevent the problem that required the original PR to be reverted. But I haven't been able to reproduce the original breakage in a regression test, and the `llvm-cov` error message is extremely unhelpful, so I can't completely rule out the possibility of this breaking again.
r? jieyouxu (reviewer of the original PR)
Some destructor/drop related tweaks
Two random tweaks I got from investigating some stuff around drops in edition 2024:
1. Use the `TypingEnv` of the mir builder, rather than making it over again.
2. Rename the `id` field from `Scope` to `local_id`, to reflect that it's a local id, and remove the `item_local_id()` accessor which just returned the id field.
Variants::Single: do not use invalid VariantIdx for uninhabited enums
~~Stacked on top of https://github.com/rust-lang/rust/pull/133681, only the last commit is new.~~
Currently, `Variants::Single` for an empty enum contains a `VariantIdx` of 0; looking that up in the enum variant list will ICE. That's quite confusing. So let's fix that by adding a new `Variants::Empty` case for types that have 0 variants.
try-job: i686-msvc
cleanup region handling: add `LateParamRegionKind`
The second commit is to enable a split between `BoundRegionKind` and `LateParamRegionKind`, by avoiding `BoundRegionKind` where it isn't necessary.
The third comment then adds `LateParamRegionKind` to avoid having the same late-param region for separate bound regions. This fixes#124021.
r? `@compiler-errors`
-Znext-solver: modify candidate preference rules
This implements the design proposed in the FCP in #132325 and matches the old solver behavior. I hope the inline comments are all sufficiently clear, I personally think this is a fairly clear improvement over the existing approach using `fn discard_impls_shadowed_by_env`. This fixes https://github.com/rust-lang/trait-system-refactor-initiative/issues/96.
This also fixes#133639 which encounters an ICE in negative coherence when evaluating the where-clause. Given the features required to trigger this ICE 🤷
r? ``@compiler-errors``
Clarify the match ergonomics 2024 migration lint's output
This makes a few changes:
- Rather than using the whole pattern as a span for the lint, this collects spans for each problematic default binding mode reset and labels them with why they're problems.
- The lint's suggestions are now verbose-styled, so that it's clear what's being suggested vs. what's problematic.
- The wording is now less technical, and the hard error version of this diagnostic now links to the same reference material as the lint (currently an unwritten page of the edition guide).
I'm not totally confident in the wording or formatting, so I'd appreciate feedback on that in particular. I tried to draw a connection with word choice between the labels and the suggestion, but it might be imprecise, unclear, or cluttered. If so, it might be worth making the labels more terse and adding notes that explain them, but that's harder to read in a way too.
cc ```@Nadrieril``` ```@Jules-Bertholet```
Closes#133854. For reference, the error from that issue becomes:
```
error: pattern uses features incompatible with edition 2024
--> $DIR/remove-me.rs:6:25
|
LL | map.iter().filter(|(&(_x, _y), &_c)| false);
| ^ ^ cannot implicitly match against multiple layers of reference
| |
| cannot implicitly match against multiple layers of reference
|
help: make the implied reference pattern explicit
|
LL | map.iter().filter(|&(&(_x, _y), &_c)| false);
| +
```
