Use hir::Node helper methods instead of repeating the same impl multiple times
I wanted to do something entirely different and stumbled upon a bunch of cleanups
Fix representation when printing abstract consts
Previously, when printing a const generic expr, it would only display it as `{{const expr}}`. This allows for a more legible representation when printing these out.
I also zipped the types with their constants for abstract consts that contain function calls when using type annotations, eg: `foo(S: usize, true: bool) -> usize` insteaad of `foo(S, true): fn(usize, bool) -> usize` for conciseness.
Remove some only- clauses from mir-opt tests
Derived from https://github.com/rust-lang/rust/pull/122295
Many of these tests were originally codegen tests, and MIR is more trivially portable than LLVM IR. We simply don't need to restrict the platform in most cases.
r? Nadrieril
There are many cases where, due to codegen or a massively unruly codebase,
a deeply nested call(call(call(call(call(call(call(call(call(f())))))))))
can happen. This is a spot where it would be good to grow our stack, so that
we can survive to tell the programmer their code is dubiously written.
For ref pattern in func param, the mutability suggestion has to apply to the binding.
For example: `fn foo(&x: &i32)` -> `fn foo(&(mut x): &i32)`
fixes#122415
clean up `Sized` checking
This PR cleans up `sized_constraint` and related functions to make them simpler and faster. This should not make more or less code compile, but it can change error output in some rare cases.
## enums and unions are `Sized`, even if they are not WF
The previous code has some special handling for enums, which made them sized if and only if the last field of each variant is sized. For example given this definition (which is not WF)
```rust
enum E<T1: ?Sized, T2: ?Sized, U1: ?Sized, U2: ?Sized> {
A(T1, T2),
B(U1, U2),
}
```
the enum was sized if and only if `T2` and `U2` are sized, while `T1` and `T2` were ignored for `Sized` checking. After this PR this enum will always be sized.
Unsized enums are not a thing in Rust and removing this special case allows us to return an `Option<Ty>` from `sized_constraint`, rather than a `List<Ty>`.
Similarly, the old code made an union defined like this
```rust
union Union<T: ?Sized, U: ?Sized> {
head: T,
tail: U,
}
```
sized if and only if `U` is sized, completely ignoring `T`. This just makes no sense at all and now this union is always sized.
## apply the "perf hack" to all (non-error) types, instead of just type parameters
This "perf hack" skips evaluating `sized_constraint(adt): Sized` if `sized_constraint(adt): Sized` exactly matches a predicate defined on `adt`, for example:
```rust
// `Foo<T>: Sized` iff `T: Sized`, but we know `T: Sized` from a predicate of `Foo`
struct Foo<T /*: Sized */>(T);
```
Previously this was only applied to type parameters and now it is applied to every type. This means that for example this type is now always sized:
```rust
// Note that this definition is WF, but the type `S<T>` not WF in the global/empty ParamEnv
struct S<T>([T]) where [T]: Sized;
```
I don't anticipate this to affect compile time of any real-world program, but it makes the code a bit nicer and it also makes error messages a bit more consistent if someone does write such a cursed type.
## tuples are sized if the last type is sized
The old solver already has this behavior and this PR also implements it for the new solver and `is_trivially_sized`. This makes it so that tuples work more like a struct defined like this:
```rust
struct TupleN<T1, T2, /* ... */ Tn: ?Sized>(T1, T2, /* ... */ Tn);
```
This might improve the compile time of programs with large tuples a little, but is mostly also a consistency fix.
## `is_trivially_sized` for more types
This function is used post-typeck code (borrowck, const eval, codegen) to skip evaluating `T: Sized` in some cases. It will now return `true` in more cases, most notably `UnsafeCell<T>` and `ManuallyDrop<T>` where `T.is_trivially_sized`.
I'm anticipating that this change will improve compile time for some real world programs.
CFI: Break tests into smaller files
Break type metadata identifiers tests into smaller set of tests/files, and move CFI (and KCFI) codegen tests to a cfi (and kcfi) subdirectory,
Stabilize associated type bounds (RFC 2289)
This PR stabilizes associated type bounds, which were laid out in [RFC 2289]. This gives us a shorthand to express nested type bounds that would otherwise need to be expressed with nested `impl Trait` or broken into several `where` clauses.
### What are we stabilizing?
We're stabilizing the associated item bounds syntax, which allows us to put bounds in associated type position within other bounds, i.e. `T: Trait<Assoc: Bounds...>`. See [RFC 2289] for motivation.
In all position, the associated type bound syntax expands into a set of two (or more) bounds, and never anything else (see "How does this differ[...]" section for more info).
Associated type bounds are stabilized in four positions:
* **`where` clauses (and APIT)** - This is equivalent to breaking up the bound into two (or more) `where` clauses. For example, `where T: Trait<Assoc: Bound>` is equivalent to `where T: Trait, <T as Trait>::Assoc: Bound`.
* **Supertraits** - Similar to above, `trait CopyIterator: Iterator<Item: Copy> {}`. This is almost equivalent to breaking up the bound into two (or more) `where` clauses; however, the bound on the associated item is implied whenever the trait is used. See #112573/#112629.
* **Associated type item bounds** - This allows constraining the *nested* rigid projections that are associated with a trait's associated types. e.g. `trait Trait { type Assoc: Trait2<Assoc2: Copy>; }`.
* **opaque item bounds (RPIT, TAIT)** - This allows constraining associated types that are associated with the opaque without having to *name* the opaque. For example, `impl Iterator<Item: Copy>` defines an iterator whose item is `Copy` without having to actually name that item bound.
The latter three are not expressible in surface Rust (though for associated type item bounds, this will change in #120752, which I don't believe should block this PR), so this does represent a slight expansion of what can be expressed in trait bounds.
### How does this differ from the RFC?
Compared to the RFC, the current implementation *always* desugars associated type bounds to sets of `ty::Clause`s internally. Specifically, it does *not* introduce a position-dependent desugaring as laid out in [RFC 2289], and in particular:
* It does *not* desugar to anonymous associated items in associated type item bounds.
* It does *not* desugar to nested RPITs in RPIT bounds, nor nested TAITs in TAIT bounds.
This position-dependent desugaring laid out in the RFC existed simply to side-step limitations of the trait solver, which have mostly been fixed in #120584. The desugaring laid out in the RFC also added unnecessary complication to the design of the feature, and introduces its own limitations to, for example:
* Conditionally lowering to nested `impl Trait` in certain positions such as RPIT and TAIT means that we inherit the limitations of RPIT/TAIT, namely lack of support for higher-ranked opaque inference. See this code example: https://github.com/rust-lang/rust/pull/120752#issuecomment-1979412531.
* Introducing anonymous associated types makes traits no longer object safe, since anonymous associated types are not nameable, and all associated types must be named in `dyn` types.
This last point motivates why this PR is *not* stabilizing support for associated type bounds in `dyn` types, e.g, `dyn Assoc<Item: Bound>`. Why? Because `dyn` types need to have *concrete* types for all associated items, this would necessitate a distinct lowering for associated type bounds, which seems both complicated and unnecessary compared to just requiring the user to write `impl Trait` themselves. See #120719.
### Implementation history:
Limited to the significant behavioral changes and fixes and relevant PRs, ping me if I left something out--
* #57428
* #108063
* #110512
* #112629
* #120719
* #120584Closes#52662
[RFC 2289]: https://rust-lang.github.io/rfcs/2289-associated-type-bounds.html
Fix heading anchors in doc pages.
This fixes the heading anchors on the standalone doc pages (the index, releases, etc.) so that the § symbol is only shown when the user hovers over the heading. This was changed in https://github.com/rust-lang/rust/pull/117662, but this CSS was not updated.
`NormalizesTo`: return nested goals to caller
Fixes the regression of `paperclip-core`. see https://hackmd.io/IsVAafiOTAaPIFcUxRJufw for more details.
r? ```@compiler-errors```
core: document default attribute stabilization
As of now, the first release which stabilized the `#[default]` macro for the deriving the `Default` trait for enus is not documented.
I have had to search the [`RELEASES.md`](https://github.com/rust-lang/rust/blob/master/RELEASES.md) when making sure my code would be accepted by an older Rust compiler.
I just added a line in the doc comment since, as far as I know, there's no option to pass to the `#[stable()]` attribute.
I am open to improvements in the wording.
Provide structured suggestion for `#![feature(foo)]`
```
error: `S2<'_>` is forbidden as the type of a const generic parameter
--> $DIR/lifetime-in-const-param.rs:5:23
|
LL | struct S<'a, const N: S2>(&'a ());
| ^^
|
= note: the only supported types are integers, `bool` and `char`
help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
|
LL + #![feature(adt_const_params)]
|
```
Fix#55941.
never patterns: suggest `!` patterns on non-exhaustive matches
When a match is non-exhaustive we now suggest never patterns whenever it makes sense.
r? ``@compiler-errors``
Reject overly generic assoc const binding types
Split off from #119385 to make #119385 easier to review.
---
In the *instantiated* type of assoc const bindings
1. reject **early-bound generic params**
* Provide a rich error message instead of ICE'ing ([#108271](https://github.com/rust-lang/rust/issues/108271)).
* This is a temporary and semi-artificial restriction until the arrival of *generic const generics*.
* It's quite possible that rustc could already perfectly support this subset of generic const generics if we just removed some checks (some `.no_bound_vars().expect(…)`) but even if that was the case, I'd rather gate it behind a new feature flag. Reporting an error instead of ICE'ing is a good first step towards an eventual feature gate error.
2. reject **escaping late-bound generic params**
* They lead to ICEs before & I'm pretty sure that they remain incorrect even in a world with *generic const generics*
---
Together with #118668 & #119385, this supersedes #118360.
Fixes#108271.
