Implement declarative (`macro_rules!`) attribute macros (RFC 3697)
This implements [RFC 3697](https://github.com/rust-lang/rust/issues/143547), "Declarative (`macro_rules!`) attribute macros".
I would suggest reading this commit-by-commit. This first introduces the
feature gate, then adds parsing for attribute rules (doing nothing with them),
then adds the ability to look up and apply `macro_rules!` attributes by path,
then adds support for local attributes, then adds a test, and finally makes
various improvements to errors.
Add infrastructure to apply an attribute macro given argument tokens and
body tokens.
Teach the resolver to consider `macro_rules` macros when looking for an
attribute via a path.
This does not yet handle local `macro_rules` attributes.
Resolver: introduce a conditionally mutable Resolver for (non-)speculative resolution.
This pr introduces a `CmResolver`, a wrapper around the main resolver which gives out mutable access given a condition.
`CmResolver` only allows mutation when we’re not in speculative import resolution. This ensures we can’t accidentally mutate the resolver during this process, which is important as we move towards a batched resolution algorithm.
This also changes functions that are used during speculative import resolution to take a `CmResolver` instead of a `&mut Resolver`.
Also introduces a new kind of "smart pointer" which has the behaviour described above:
```rust
/// A wrapper around a mutable reference that conditionally allows mutable access.
pub(crate) struct RefOrMut<'a, T> {
p: &'a mut T,
mutable: bool,
}
type CmResolver<'r, 'ra, 'tcx> = RefOrMut<'r, Resolver<'ra, 'tcx>>;
```
r? petrochenkov
resolve: Make disambiguators for underscore bindings module-local (take 2)
The difference with https://github.com/rust-lang/rust/pull/144013 can be seen in the second commit.
Now we just keep a separate disambiguator counter in every `Module`, instead of a global counter in `Resolver`.
This will be ok for parallel import resolution because we'll need to lock the module anyway when updating `resolutions` and other fields in it.
And for external modules the disabmiguator could be just passed as an argument to `define_extern`, without using any cells or locks, once https://github.com/rust-lang/rust/pull/143884 lands.
Unblocks https://github.com/rust-lang/rust/pull/143884.
Rather than adding `get_unused_rule` to the `TTMacroExpander` trait, put
it on the concrete `MacroRulesMacroExpander`, and downcast to that type
via `Any` in order to call it.
Suggested-by: Vadim Petrochenkov <vadim.petrochenkov@gmail.com>
resolve: Make disambiguators for underscore bindings module-local
Disambiguators attached to underscore name bindings (like `const _: u8 = something;`) do not need to be globally unique, they just need to be unique inside the module in which they live, because the bindings in a module are basically kept as `Map<BindingKey, SomeData>`.
Also, the specific values of the disambiguators are not important, so a glob import of `const _` may have a different disambiguator than the original `const _` itself.
So in this PR the disambiguator is just set to the current number of bindings in the module.
This removes one more piece of global mutable state from resolver and unblocks https://github.com/rust-lang/rust/pull/143884.
Split up the `unknown_or_malformed_diagnostic_attributes` lint
This splits up the lint into the following lint group:
- `unknown_diagnostic_attributes` - triggers if the attribute is unknown to the current compiler
- `misplaced_diagnostic_attributes` - triggers if the attribute exists but it is not placed on the item kind it's meant for
- `malformed_diagnostic_attributes` - triggers if the attribute's syntax or options are invalid
- `malformed_diagnostic_format_literals` - triggers if the format string literal is invalid, for example if it has unpaired curly braces or invalid parameters
- this pr doesn't create it, but future lints for things like deprecations can also go here.
This PR does not start emitting lints in places that previously did not.
## Motivation
I want to have finer control over what `unknown_or_malformed_diagnostic_attributes` does
I have a project with fairly low msrv that is/will have a lower msrv than future diagnostic attributes. So lints will be emitted when I or others compile it on a lower msrv.
At this time, there are two options to silence these lints:
- `#[allow(unknown_or_malformed_diagnostic_attributes)]` - this risks diagnostic regressions if I (or others) mess up using the attribute, or if the attribute's syntax ever changes.
- write a build script to detect the compiler version and emit cfgs, and then conditionally enable the attribute:
```rust
#[cfg_attr(rust_version_99, diagnostic::new_attr_in_rust_99(thing = ..))]`
struct Foo;
```
or conditionally `allow` the lint:
```rust
// lib.rs
#![cfg_attr(not(current_rust), allow(unknown_or_malformed_diagnostic_attributes))]
```
I like to avoid using build scripts if I can, so the following works much better for me. That is what this PR will let me do in the future:
```rust
#[allow(unknown_diagnostic_attribute, reason = "attribute came out in rust 1.99 but msrv is 1.70")]
#[diagnostic::new_attr_in_rust_99(thing = ..)]`
struct Foo;
The MBE parser checks rules at initial parse time to see if their RHS
has `compile_error!` in it, and returns a list of rule indexes and LHS
spans that don't map to `compile_error!`, for use in unused macro rule
checking.
Instead, have the unused macro rule reporting ask the macro for the rule
to report, and let the macro check at that time. That avoids checking
rules unless they're unused.
In the process, refactor the data structure used to store macro rules,
to group the LHS and RHS (and LHS span) of each rule together, and
refactor the unused rule tracking to only track rule indexes.
This ends up being a net simplification, and reduction in code size.
Look at proc-macro attributes when encountering unknown attribute
```
error: cannot find attribute `sede` in this scope
--> $DIR/missing-derive-2.rs:22:7
|
LL | #[sede(untagged)]
| ^^^^
|
help: the derive macros `Deserialize` and `Serialize` accept the similarly named `serde` attribute
|
LL | #[serde(untagged)]
| +
error: cannot find attribute `serde` in this scope
--> $DIR/missing-derive-2.rs:16:7
|
LL | #[serde(untagged)]
| ^^^^^
|
note: `serde` is imported here, but it is a crate, not an attribute
--> $DIR/missing-derive-2.rs:5:1
|
LL | extern crate serde;
| ^^^^^^^^^^^^^^^^^^^
help: `serde` is an attribute that can be used by the derive macros `Serialize` and `Deserialize`, you might be missing a `derive` attribute
|
LL + #[derive(Serialize, Deserialize)]
LL | enum B {
|
```
Partially address #47608. This PR doesn't find [macros that haven't yet been imported by name](af945cb86e).
```
error: cannot find attribute `empty_helper` in this scope
--> $DIR/derive-helper-legacy-limits.rs:17:3
|
LL | #[empty_helper]
| ^^^^^^^^^^^^
|
help: `empty_helper` is an attribute that can be used by the derive macro `Empty`, you might be missing a `derive` attribute
|
LL + #[derive(Empty)]
LL | struct S2;
|
```
Look at proc-macro attributes when encountering unknown attribute
```
error: cannot find attribute `sede` in this scope
--> src/main.rs:18:7
|
18 | #[sede(untagged)]
| ^^^^
|
help: the derive macros `Serialize` and `Deserialize` accept the similarly named `serde` attribute
|
18 | #[serde(untagged)]
| ~~~~~
error: cannot find attribute `serde` in this scope
--> src/main.rs:12:7
|
12 | #[serde(untagged)]
| ^^^^^
|
= note: `serde` is in scope, but it is a crate, not an attribute
help: `serde` is an attribute that can be used by the derive macros `Serialize` and `Deserialize`, you might be missing a `derive` attribute
|
10 | #[derive(Serialize, Deserialize)]
|
```
It bugs me when variables of type `Ident` are called `name`. It leads to
silly things like `name.name`. `Ident` variables should be called
`ident`, and `name` should be used for variables of type `Symbol`.
This commit improves things by by doing `s/name/ident/` on a bunch of
`Ident` variables. Not all of them, but a decent chunk.
Visitors track whether an assoc item is in a trait impl or an inherent impl
`AssocCtxt::Impl` now contains an `of_trait` field. This allows ast lowering and nameres to not have to track whether we're in a trait impl or an inherent impl.
This way, `None` represents "crate root without a name" instead of
`kw::Empty`. This changes makes it impossible to forget to handle the
exceptional case.
Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it
Fixes a regression, see issue below. This is a temporary fix, super let is the real solution.
Closes#138596
