Add support for `const unsafe? extern fn`
This works just as you might expect - an `const extern fn` is a `const fn` that is callable from foreign code.
Currently, panicking is not allowed in `const`s. When https://github.com/rust-lang/rfcs/pull/2345 (https://github.com/rust-lang/rust/issues/51999) is stabilized, then panicking in an `const extern 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.
Tracking issue: https://github.com/rust-lang/rust/issues/64926.
This commit improves the suggestions provided when function parameters
do not have types:
- A new suggestion is added for arbitrary self types, which suggests
adding `self: ` before the type.
- Existing suggestions are now provided when a `<` is found where a `:`
was expected (previously only `,` and `)` or trait items), this gives
suggestions in the case where the unnamed parameter type is generic
in a free function.
- The suggestion that a type name be provided (e.g. `fn foo(HashMap<u32>)`
-> `fn foo(HashMap: TypeName<u32>)`) will no longer occur when a `<` was
found instead of `:`.
- The ident will not be used for recovery when a `<` was found instead
of `:`.
Signed-off-by: David Wood <david@davidtw.co>
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: 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
