Enforce the shadowing restrictions from RFC 1560 for today's macros
This PR enforces a weakened version of the shadowing restrictions from RFC 1560. More specifically,
- If a macro expansion contains a `macro_rules!` macro definition that is used outside of the expansion, the defined macro may not shadow an existing macro.
- If a macro expansion contains a `#[macro_use] extern crate` macro import that is used outside of the expansion, the imported macro may not shadow an existing macro.
This is a [breaking-change]. For example,
```rust
macro_rules! m { () => {} }
macro_rules! n { () => {
macro_rules! m { () => {} } //< This shadows an existing macro.
m!(); //< This is inside the expansion that generated `m`'s definition, so it is OK.
} }
n!();
m!(); //< This use of `m` is outside the expansion, so it causes the shadowing to be an error.
```
r? @nrc
emit feature help in cheat mode (fix nightlies)
This should fix the `distcheck` failure in the latest nightly.
cc #36539
It's probably not ideal to check the environment that often and the code ist duplicated from `librustc/session/config.rs` but this was the easiest fix I could think of.
A cleaner solution would probably be to move the `unstable_features` from `Options` to `ParseSess` and change the `diag` parameter of `emit_feature_err` to take `ParseSess` instead of a `Handler`.
Adds a `ProcMacro` form of syntax extension
This commit adds syntax extension forms matching the types for procedural macros 2.0 (RFC #1566), these still require the usual syntax extension boiler plate, but this is a first step towards proper implementation and should be useful for macros 1.1 stuff too.
Supports both attribute-like and function-like macros.
Note that RFC #1566 has not been accepted yet, but I think there is consensus that we want to head in vaguely that direction and so this PR will be useful in any case. It is also fairly easy to undo and does not break any existing programs.
This is related to #35957 in that I hope it can be used in the implementation of macros 1.1, however, there is no direct overlap and is more of a complement than a competing proposal. There is still a fair bit of work to do before the two can be combined.
r? @jseyfried
cc @alexcrichton, @cgswords, @eddyb, @aturon
Assign node ids during macro expansion
After this PR,
- The `ExtCtxt` can access `resolve`'s `Resolver` through the trait object `ext::base::Resolver`.
- The `Resolver` trait object can load macros and replaces today's `MacroLoader` trait object.
- The macro expander uses the `Resolver` trait object to resolve macro invocations.
- The macro expander assigns node ids and builds the `Resolver`'s `macros_at_scope` map.
- This is groundwork for merging import resolution and expansion.
- Performance of expansion together with node id assignment improves by ~5%.
**EDIT:** Since Github is reordering the commits, here is `git log`:
- b54e1e3997: Differentiate between monotonic and non-monotonic expansion and only assign node ids during monotonic expansion.
- 78c0039878: Expand generated test harnesses and macro registries.
- f3c2dca353: Remove scope placeholders from the crate root.
- c86c8d41a2: Perform node id assignment and `macros_at_scope` construction during the `InvocationCollector` and `PlaceholderExpander` folds.
- 72a636975f: Move macro resolution into `librustc_resolve`.
- 20b43b2323: Rewrite the unit tests in `ext/expand.rs` as a `compile-fail` test.
- a9821e1658: Refactor `ExtCtxt` to use a `Resolver` instead of a `MacroLoader`.
- 60440b226d: Refactor `noop_fold_stmt_kind` out of `noop_fold_stmt`.
- 50f94f6c95: Avoid needless reexpansions.
r? @nrc
The span labels for associated types and consts were hardcoded to `Foo`
rather than substituting the name of the trait.
This also normalizes the wording for associated methods', traits', and
consts' span labels.
Fixes#36428.
resolve: Suggest `use self` when import resolves
Improves errors messages by replacing "Maybe a missing `extern crate`" messages
with "Did you mean `self::...`" when the `self` import would succeed.
Fixes#34191.
Thank you for the help @jseyfried!
Change E0259 to the new error format
Fixes#35514 as part of #35233.
Sorry about creating a new PR I was having a lot of troubles squashing the commit because I didn't properly branch the new feature.
r? @GuillaumeGomez
Batch up libsyntax breaking changes
Batch of the following syntax-[breaking-change] changes:
- #35591: Add a field `span: Span` to `ast::Generics`.
- #35618: Remove variant `Mod` of `ast::PathListItemKind` and refactor the remaining variant `ast::PathListKind::Ident` to a struct `ast::PathListKind_`.
- #35480: Change uses of `Constness` in the AST to `Spanned<Constness>`.
- c.f. `MethodSig`, `ItemKind`
- #35728: Refactor `cx.pat_enum()` into `cx.pat_tuple_struct()` and `cx.pat_path()`.
- #35850: Generalize the elements of lists in attributes from `MetaItem` to a new type `NestedMetaItem` that can represent a `MetaItem` or a literal.
- #35917: Remove traits `AttrMetaMethods`, `AttributeMethods`, and `AttrNestedMetaItemMethods`.
- Besides removing imports of these traits, this won't cause fallout.
- Add a variant `Union` to `ItemKind` to future proof for `union` (c.f. #36016).
- Remove inherent methods `attrs` and `fold_attrs` of `Annotatable`.
- Use methods `attrs` and `map_attrs` of `HasAttrs` instead.
r? @Manishearth
Refactor `PathListItem`s
This refactors away variant `Mod` of `ast::PathListItemKind` and refactors the remaining variant `Ident` to a struct `ast::PathListItem_`.
* A step towards #34902
* More stable error messages in some places related to crate loading
* Possible slight performance improvements since all `HashMap`s
replaced had small keys where `FnvHashMap` should be faster
(although I didn't measure)
