This commit buffers the errors output by the `rustc_dump_user_substs`
attribute so that they can be output in order of span and would
therefore be consistent.
This commit stops well-formedness checking applying to unreachable code
and therefore stops some of the ICEs that the intended solution taken by
this PR causes.
By disabling these checks, we can land the other fixes and larger
refactors that this PR includes.
This commit moves well-formedness check for the
`UserTypeAnnotation::Ty(..)` case from always running to only when the
code is reachable. This solves the ICE that resulted from
`src/test/ui/issue-54943-1.rs` (a minimal repro of `dropck-eyepatch`
run-pass tests that failed).
The main well-formedness check that was intended to be run despite
unreachable code still is, that being the
`UserTypeAnnotation::TypeOf(..)` case. Before this PR, the other case
wasn't being checked at all.
It is possible to fix this ICE while still always checking
well-formedness for the `UserTypeAnnotation::Ty(..)` case but that
solution will ICE in unreachable code for that case, the diff for
that change [can be found here](0).
[0]: https://gist.github.com/davidtwco/f9751ffd9c0508f7251c0f17adc3af53
This commit adds support for user type annotations in variables declared
using `ref` bindings. When a variable declared using a `ref` binding,
then the `LocalDecl` has the type `&T` where the `&` was introduced by
the `ref` binding but the canonicalized type annotation has only a
`T` since the reference is implicit with the `ref` binding.
Therefore, to support type annotations, the canonicalized type
annotation either needs wrapped in a reference, or the `LocalDecl` type
must have a wrapped reference removed for comparison. It is easier to
remove the outer reference from the `LocalDecl` for the purpose of
comparison, so that is the approach this commit takes.
This commit uses the map introduced by the previous commit to ensure
that types are always checked for well-formedness by the NLL type check.
Previously, without the map introduced by the previous commit, types
would not be checked for well-formedness if the `AscribeUserType`
statement that would trigger that check was removed as unreachable code.
This commit refactors the `UserTypeAnnotation` type to be referred to by
an index within `UserTypeProjection`. `UserTypeAnnotation` is instead
kept in an `IndexVec` within the `Mir` struct.
Further, instead of `UserTypeAnnotation` containing canonicalized types,
it now contains normal types and the entire `UserTypeAnnotation` is
canonicalized. To support this, the type was moved from the `rustc::mir`
module to `rustc::ty` module.
resolve: Fix one more ICE in import validation
So if you have an unresolved import
```rust
mod m {
use foo::bar;
}
```
error recovery will insert a special item with `Def::Err` definition into module `m`, so other things depending on `bar` won't produce extra errors.
The issue was that erroneous `bar` was overwriting legitimate `bar`s coming from globs, e.g.
```rust
mod m {
use baz::*; // imports real existing `bar`
use foo::bar;
}
```
causing some unwanted diagnostics talking about "unresolved items", and producing inconsistent resolutions like https://github.com/rust-lang/rust/issues/57015.
This PR stops overwriting real successful resolutions with `Def::Err`s.
Fixes https://github.com/rust-lang/rust/issues/57015
Implement RFC 2338, "Type alias enum variants"
This PR implements [RFC 2338](https://github.com/rust-lang/rfcs/pull/2338), allowing one to write code like the following.
```rust
#![feature(type_alias_enum_variants)]
enum Foo {
Bar(i32),
Baz { i: i32 },
}
type Alias = Foo;
fn main() {
let t = Alias::Bar(0);
let t = Alias::Baz { i: 0 };
match t {
Alias::Bar(_i) => {}
Alias::Baz { i: _i } => {}
}
}
```
Since `Self` can be considered a type alias in this context, it also enables using `Self::Variant` as both a constructor and pattern.
Fixes issues #56199 and #56611.
N.B., after discussing the syntax for type arguments on enum variants with @petrochenkov and @eddyb (there are also a few comments on the [tracking issue](https://github.com/rust-lang/rust/issues/49683)), the consensus seems to be treat the syntax as follows, which ought to be backwards-compatible.
```rust
Option::<u8>::None; // OK
Option::None::<u8>; // OK, but lint in near future (hard error next edition?)
Alias::<u8>::None; // OK
Alias::None::<u8>; // Error
```
I do not know if this will need an FCP, but let's start one if so.
resolve: Fix another ICE in import validation
Imports are allowed to have ambiguous resolutions as long as all of them have same `Def`.
As it turned out, it's possible for different `Module`s to have same `Def` when `extern crate` items are involved.
Fixes https://github.com/rust-lang/rust/issues/56596
Resolve `$crate`s for pretty-printing at more appropriate time
Doing it in `BuildReducedGraphVisitor` wasn't a good idea, identifiers wasn't actually visited half of the time.
As a result some `$crate`s weren't resolved and were therefore pretty-printed as `$crate` literally, which turns into two tokens during re-parsing of the pretty-printed text.
Now we are visiting and resolving `$crate` identifiers in an item right before sending that item to a proc macro attribute or derive.
Fixes https://github.com/rust-lang/rust/issues/57089
AST/HIR: Introduce `ExprKind::Err` for better error recovery in the front-end
This way we can avoid aborting compilation if expansion produces errors and generate `ExprKind::Err`s instead.
