Remove Nonterminal and TokenKind::Interpolated
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By using `token_descr`, as is done for many other errors, we can get slightly better descriptions in error messages, e.g. "macro expansion ignores token `let` and any following" becomes "macro expansion ignores keyword `let` and any tokens following". This will be more important once invisible delimiters start being mentioned in error messages.
It's not used meaningfully yet, but will be needed to get rid of interpolated tokens.
Pasted metavariables are wrapped in invisible delimiters, which pretty-print as empty strings, and changing that can break some proc macros. But error messages saying "expected identifer, found ``" are bad. So this commit adds support for metavariables in `TokenDescription` so they print as "metavariable" in error messages, instead of "``". It's not used meaningfully yet, but will be needed to get rid of interpolated tokens.
This has no effect right now because invisible delimiters aren't produced by `TokenCursor`, but it will make more sense once invisible delimiter origins are introduced.
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Some changes occurred in src/tools/rustfmt cc @rust-lang/rustfmt |
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Current places where `Interpolated` is used are going to change to instead use invisible delimiters. This prepares for that by adding panics in various places.
We now use invisible delimiters for expanded `vis` fragments, instead of `Token::Interpolated`.
Notes about tests: - tests/ui/parser/macro/trait-object-macro-matcher.rs: the syntax error is duplicated, because it occurs now when parsing the decl macro input, and also when parsing the expanded decl macro. But this won't show up for normal users due to error de-duplication. - tests/ui/associated-consts/issue-93835.rs: ditto.
XXX: tests/ui/macros/trace_faulty_macros.rs regresses because I haven't fixed `expected_expression_found` properly yet.
This involves replacing `nt_pretty_printing_compatibility_hack` with `stream_pretty_printing_compatibility_hack`. The handling of statements in `transcribe` is slightly different to other nonterminal kinds, due to the lack of `from_ast` implementation for empty statements. Notable test changes: - `tests/ui/macros/nonterminal-matching.rs` now passes. Removal of `Token::Interpolated` will remove the "captured metavariables except for `:tt`, `:ident` and `:lifetime` cannot be compared to other tokens" restriction. - `tests/ui/proc-macro/expand-to-derive.rs`: the diff looks large but the only difference is the insertion of a single invisible-delimited group. I hope this doesn't cause any new `ProceduralMasquerade`-type problems.
Note: there was an existing code path involving `Interpolated` in `MetaItem::from_tokens` that was dead. This commit transfers that to the new form, but puts an `unreachable!` call inside it.
Notes about tests:
- tests/ui/macros/stringify.rs: the `c2` macro is no longer needed,
because the TokenStream pretty printer is now used for all cases.
- tests/ui/rfcs/rfc-2294-if-let-guard/feature-gate.rs: some messages are
now duplicated due to repeated parsing.
- tests/ui/rfcs/rfc-2497-if-let-chains/disallowed-positions*.rs: ditto.
Getting a test failure here:
```
Building tool error_index_generator (stage1 -> stage2, x86_64-unknown-linux-gnu)
Compiling cfg-if v1.0.0
...
Compiling mdbook v0.4.37
error: internal compiler error: the following error was constructed but not emitted
error: unexpected token: keyword `self`
--> /home/njn/.cargo/registry/src/index.crates.io-6f17d22bba15001f/mdbook-0.4.37/src/book/summary.rs:280:31
|
280 | ... bail!(self.parse_error("Suffix chapters cannot be followed by a list"));
| ^^^^
thread 'rustc' panicked at /home/njn/dev/rust3/compiler/rustc_errors/src/diagnostic.rs:1375:17:
error was constructed but not emitted
```
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r? @ghost