Avoid ICE when referencing desugared local binding in borrow error
To avoid leaking the names of local bindings from expressions like for loops, #60984 explicitly ignored them, but an assertion that `LocalKind::Var` *must* have a name would trigger an ICE.
Before this change, the binding generated by desugaring the for loop would leak into the diagnostic (#63027):
```
error[E0515]: cannot return value referencing local variable `__next`
--> return-local-binding-from-desugaring.rs:LL:CC
|
LL | for ref x in xs {
| ----- `__next` is borrowed here
...
LL | result
| ^^^^^^ returns a value referencing data owned by the current function
```
Ideally `LocalKind` would carry more information to more accurately explain the problem, but for now, in order to avoid the ICE (fix#63026), we accept `LocalKind::Var` without a name and produce the following output:
```
error[E0515]: cannot return value referencing local binding
--> $DIR/return-local-binding-from-desugaring.rs:30:5
|
LL | for ref x in xs {
| -- local binding introduced here
...
LL | result
| ^^^^^^ returns a value referencing data owned by the current function
```
Implement RFC 2707 + Parser recovery for range patterns
Implement https://github.com/rust-lang/rfcs/pull/2707.
- Add a new basic syntactic pattern form `ast::PatKind::Rest` (parsed as `..` or `DOTDOT`) and simplify `ast::PatKind::{Slice, Tuple, TupleStruct}` as a result.
- Lower `ast::PatKind::Rest` in combination with the aforementioned `PatKind` variants as well as `PatKind::Ident`. The HIR remains unchanged for now (may be advisable to make slight adjustments later).
- Refactor `parser.rs` wrt. parsing sequences and lists of things in the process.
- Add parser recovery for range patterns of form `X..`, `X..=`, `X...`, `..Y`, `..=Y`, and `...Y`.
This should make it easy to actually support these patterns semantically later if we so desire.
cc https://github.com/rust-lang/rust/issues/62254
r? @petrochenkov
Allow lifetime elision in `Pin<&(mut) Self>`
This PR changes `self: &(mut) S` elision rules to instead visit the type of `self` and look for `&(mut) S` (where `is_self_ty(S)`) within it
Replaces #60944Closes#52675
r? @eddyb
cc @cramertj @Centril @withoutboats @scottmcm
Stop bare trait lint applying to macro call sites
Fixes#61963. Apologies for the delay with in fixing this. If anyone has a better idea how to detect this macro call site case, I'd be happy to fix this in a more robust, less hacky way.
r? @estebank
Fix cycle error with existential types
Fixes#61863
We now allow uses of `existential type`'s that aren't defining uses - that is, uses which don't constrain the underlying concrete type.
To make this work correctly, we also modify `eq_opaque_type_and_type` to not try to apply additional constraints to an opaque type. If we have code like this:
```rust
existential type Foo;
fn foo1() -> Foo { ... }
fn foo2() -> Foo { foo1() }
```
then `foo2` doesn't end up constraining `Foo`, which means that `foo2` will end up using the type `Foo` internally - that is, an actual `TyKind::Opaque`. We don't want to equate this to the underlying concrete type - we just need to enforce the basic equality constraint between the two types (here, the return type of `foo1` and the return type of `foo2`)
Define built-in macros through libcore
This PR defines built-in macros through libcore using a scheme similar to lang items (attribute `#[rustc_builtin_macro]`).
All the macro properties (stability, visibility, etc.) are taken from the source code in libcore, with exception of the expander function transforming input tokens/AST into output tokens/AST, which is still provided by the compiler.
The macros are made available to user code through the standard library prelude (`{core,std}::prelude::v1`), so they are still always in scope.
As a result **built-in macros now have stable absolute addresses in the library**, like `core::prelude::v1::line!()`, this is an insta-stable change.
Right now `prelude::v1` is the only publicly available absolute address for these macros, but eventually they can be moved into more appropriate locations with library team approval (e.g. `Clone` derive -> `core::clone::Clone`).
Now when built-in macros have canonical definitions they can be imported or reexported without issues (https://github.com/rust-lang/rust/issues/61687).
Other changes:
- You can now define a derive macro with a name matching one of the built-in derives (https://github.com/rust-lang/rust/issues/52269). This was an artificial restriction that could be worked around with import renaming anyway.
Known regressions:
- Empty library crate with a crate-level `#![test]` attribute no longer compiles without `--test`. Previously it didn't compile *with* `--test` or with the bin crate type.
Fixes https://github.com/rust-lang/rust/issues/61687
Fixes https://github.com/rust-lang/rust/issues/61804
r? @eddyb
