This works just as you might expect - an 'extern const fn' is a 'const
fn' that is callable from foreign code.
Currently, panicking is not allowed in consts. When RFC 2345 is
stabilized, then panicking in an 'extern const fn' will produce a
compile-time error when invoked at compile time, and an abort when
invoked at runtime.
Since this is extending the language (we're allowing the `const` keyword
in a new context), I believe that this will need an FCP. However, it's a
very minor change, so I didn't think that filing an RFC was necessary.
This will allow libc (and other FFI crates) to make many functions
`const`, without having to give up on making them `extern` as well.
syntax: cleanup param, method, and misc parsing
Do some misc cleanup of the parser:
- Method and parameter parsing is refactored.
- A parser for `const | mut` is introduced that https://github.com/rust-lang/rust/pull/64588 can reuse.
- Some other misc parsing.
Next up in a different PR:
- ~Implementing https://github.com/rust-lang/rust/issues/64252.~ -- maybe some other time...
- Heavily restructuring up `item.rs` which is a mess (hopefully, no promises ^^).
r? @petrochenkov
A small amount of tidying-up factored out from PR #64648
As requested by @Mark-Simulacrum, I put this in a separate commit to make it easier to review. (As far as I can tell, no violations of the policy here, and they are simply in a separate PR because they're not directly related to the import of that PR.)
r? @Mark-Simulacrum
syntax: recover trailing `|` in or-patterns
Fixes https://github.com/rust-lang/rust/issues/64879.
For example (this also shows that we are sensitive to the typo `||`):
```
error: a trailing `|` is not allowed in an or-pattern
--> $DIR/remove-leading-vert.rs:33:11
|
LL | A || => {}
| - ^^ help: remove the `||`
| |
| while parsing this or-pattern starting here
|
= note: alternatives in or-patterns are separated with `|`, not `||`
```
r? @estebank
syntax: Support modern attribute syntax in the `meta` matcher
Where "modern" means https://github.com/rust-lang/rust/pull/57367:
```
PATH
PATH `(` TOKEN_STREAM `)`
PATH `[` TOKEN_STREAM `]`
PATH `{` TOKEN_STREAM `}`
```
Unfortunately, `meta` wasn't future-proofed using the `FOLLOW` token set like other matchers (https://github.com/rust-lang/rust/issues/34011), so code like `$meta:meta {` or `$meta:meta [` may break, and we need a crater run to find out how often this happens in practice.
Closes https://github.com/rust-lang/rust/issues/49629 (by fully supporting `meta` rather than removing it.)
syntax: fix dropping of attribute on first param of non-method assocated fn
Fixes#64682.
The general idea is that we bake parsing of `self` into `parse_param_general` and then we just use standard list parsing. Overall, this simplifies the parsing and makes it more consistent.
r? @petrochenkov cc @c410-f3r
No StableHasherResult everywhere
This removes the generic parameter on `StableHasher`, instead moving it to the call to `finish`. This has the side-effect of making all `HashStable` impls nicer, since we no longer need the verbose `<W: StableHasherResult>` that previously existed -- often forcing line wrapping.
This is done for two reasons:
* we should avoid false "generic" dependency on the result of StableHasher
* we don't need to codegen two/three copies of all the HashStable impls when they're transitively used to produce a fingerprint, u64, or u128. I haven't measured, but this might actually make our artifacts somewhat smaller too.
* Easier to understand/read/write code -- the result of the stable hasher is irrelevant when writing a hash impl.
Remove redundancy from the implementation of C variadics.
This cleanup was first described in https://github.com/rust-lang/rust/issues/44930#issuecomment-497163539:
* AST doesn't track `c_variadic: bool` anymore, relying solely on a trailing `CVarArgs` type in fn signatures
* HIR doesn't have a `CVarArgs` anymore, relying solely on `c_variadic: bool`
* same for `ty::FnSig` (see tests for diagnostics improvements from that)
* `{hir,mir}::Body` have one extra argument than the signature when `c_variadic == true`
* `rustc_typeck` and `rustc_mir::{build,borrowck}` need to give that argument the right type (which no longer uses a lifetime parameter, but a function-internal scope)
* `rustc_target::abi::call` doesn't need special hacks anymore (since it never sees the `VaListImpl` now, it's all inside the body)
r? @nagisa / @rkruppe cc @dlrobertson @oli-obk
Rename `*.node` to `*.kind`, and `hair::Pattern*` to `hair::Pat*`
In both `ast::Expr` and `hir::Expr`:
- Rename `Expr.node` to `Expr.kind`.
- Rename `Pat.node` to `Pat.kind`.
- Rename `ImplItem.node` to `ImplItem.kind`.
- Rename `Lit.node` to `Lit.kind`.
- Rename `TraitItem.node` to `TraitItem.kind`.
- Rename `Ty.node` to `Ty.kind`.
- Rename `Stmt.node` to `Stmt.kind`.
- Rename `Item.node` to `Item.kind`.
- Rename `ForeignItem.node` to `ForeignItem.kind`.
- Rename `MetaItem.node` to `MetaItem.kind`.
Also:
- Rename `hair::FieldPattern` to `hair::FieldPat`.
- Rename `hair::PatternKind` to `hair::PatKind`.
- Rename `hair::PatternRange` to `hair::PatRange`.
- Rename `PatternContext` to `PatCtxt`.
- Rename `PatternTypeProjection` to `PatTyProj`.
- Rename `hair::Pattern` to `hair::Pat`.
These two sets of changes are grouped together to aid with merging. The only changes are renamings.
r? @petrochenkov
