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: 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
Propagate spans and attributes from proc macro definitions
Thanks to https://github.com/rust-lang/rust/pull/63269 we now have spans and attributes from proc macro definitions available in metadata.
However, that PR didn't actually put them into use! This PR finishes that work.
Attributes `rustc_macro_transparency`, `allow_internal_unstable`, `allow_internal_unsafe`, `local_inner_macros`, `rustc_builtin_macro`, `stable`, `unstable`, `rustc_deprecated`, `deprecated` now have effect when applied to proc macro definition functions.
From those attributes only `deprecated` is both stable and supposed to be used in new code.
(`#![staged_api]` still cannot be used in proc macro crates for unrelated reasons though.)
`Span::def_site` from the proc macro API now returns the correct location of the proc macro definition.
Also, I made a mistake in https://github.com/rust-lang/rust/pull/63269#discussion_r312702919, loaded proc macros didn't actually use the resolver cache.
This PR fixes the caching issue, now proc macros go through the `Resolver::macro_map` cache as well.
(Also, the first commit turns `proc_macro::quote` into a regular built-in macro to reduce the number of places where `SyntaxExtension`s need to be manually created.)
Rename `ItemKind::Ty` to `ItemKind::TyAlias`
The current name is not entirely clear without context and `TyAlias` is consistent with `ItemKind::TraitAlias`.
