Break dependencies between `syntax_ext` and other crates
Move `source_util` macros into `syntax_ext`.
Move other early code generation facilities like standard library injection into `syntax_ext`.
The only crate that depends on `syntax_ext` now is `rustc_interface` which is one of the "final" crates that depend on everything.
Minor: Cleanup dependencies of `rustc_driver`, many of them are no longer used after introduction of `rustc_interface`.
r? @eddyb
Define built-in macros through libcore
This PR defines built-in macros through libcore using a scheme similar to lang items (attribute `#[rustc_builtin_macro]`).
All the macro properties (stability, visibility, etc.) are taken from the source code in libcore, with exception of the expander function transforming input tokens/AST into output tokens/AST, which is still provided by the compiler.
The macros are made available to user code through the standard library prelude (`{core,std}::prelude::v1`), so they are still always in scope.
As a result **built-in macros now have stable absolute addresses in the library**, like `core::prelude::v1::line!()`, this is an insta-stable change.
Right now `prelude::v1` is the only publicly available absolute address for these macros, but eventually they can be moved into more appropriate locations with library team approval (e.g. `Clone` derive -> `core::clone::Clone`).
Now when built-in macros have canonical definitions they can be imported or reexported without issues (https://github.com/rust-lang/rust/issues/61687).
Other changes:
- You can now define a derive macro with a name matching one of the built-in derives (https://github.com/rust-lang/rust/issues/52269). This was an artificial restriction that could be worked around with import renaming anyway.
Known regressions:
- Empty library crate with a crate-level `#![test]` attribute no longer compiles without `--test`. Previously it didn't compile *with* `--test` or with the bin crate type.
Fixes https://github.com/rust-lang/rust/issues/61687
Fixes https://github.com/rust-lang/rust/issues/61804
r? @eddyb
Implement slow-path for FirstSets::first
When 2 or more sequences share the same span, we can't use the precomputed map
for their first set. So we compute it recursively.
Fixes#62831.
add rustc_private as a proper language feature gate
At the moment, `rustc_private` as a (library) feature exists by
accident: `char::is_xid_start`, `char::is_xid_continue` methods in
libcore define it.
cc https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/How.20to.20declare.20new.20langauge.20feature.3F
I don't know if this is at all reasonable, but at least tests seem to pass locally. That probably means that we can remove/rename to something more resonable the feature in libcore in the next release?
move unescape module to rustc_lexer
It makes sense to keep the definition of escape sequences closer to the lexer itself, and it is also a bit of code that I would like to share with rust-analyzer.
r? @petrochenkov
The idea here is to make a reusable library out of the existing
rust-lexer, by separating out pure lexing and rustc-specific concerns,
like spans, error reporting an interning.
So, rustc_lexer operates directly on `&str`, produces simple tokens
which are a pair of type-tag and a bit of original text, and does not
report errors, instead storing them as flags on the token.
Add meta-variable checks in macro definitions
This is an implementation of #61053. It is not sound (some errors are not reported) and not complete (reports may not be actual errors). This is due to the possibility to define macros in macros in indirect ways. See module documentation of `macro_check` for more details.
What remains to be done:
- [x] Migrate from an error to an allow-by-default lint.
- [x] Add more comments in particular for the handling of nested macros.
- [x] Add more tests if needed.
- [x] Try to avoid cloning too much (one idea is to use lists on the stack).
- [ ] Run crater with deny-by-default lint (measure rate of false positives).
- [ ] Remove extra commit for deny-by-default lint
- [x] Create a PR to remove the old `question_mark_macro_sep` lint #62160
This is needed for having complete error messages where reporting macro variable
errors. Here is what they would look like:
error: meta-variable repeats with different kleene operator
--> $DIR/issue-61053-different-kleene.rs:3:57
|
LL | ( $( $i:ident = $($j:ident),+ );* ) => { $( $( $i = $j; )* )* };
| - expected repetition ^^ - conflicting repetition
