Jacob Pratt ea8bc3b4be Rollup merge of #134600 - dtolnay:chainedcomparison, r=oli-obk ... Fix parenthesization of chained comparisons by pretty-printer Example: ```rust macro_rules! repro { () => { 1 < 2 }; } fn main() { let _ = repro!() == false; } ``` Previously `-Zunpretty=expanded` would pretty-print this syntactically invalid output: `fn main() { let _ = 1 < 2 == false; }` ```console error: comparison operators cannot be chained --> <anon>:8:23 | 8 | fn main() { let _ = 1 < 2 == false; } | ^ ^^ | help: parenthesize the comparison | 8 | fn main() { let _ = (1 < 2) == false; } | + + ``` With the fix, it will print `fn main() { let _ = (1 < 2) == false; }`. Making `-Zunpretty=expanded` consistently produce syntactically valid Rust output is important because that is what makes it possible for `cargo expand` to format and perform filtering on the expanded code. ## Review notes According to `rg '\.fixity\(\)' compiler/` the `fixity` function is called only 3 places: - 13170cd787/compiler/rustc_ast_pretty/src/pprust/state/expr.rs (L283-L287) - 13170cd787/compiler/rustc_hir_pretty/src/lib.rs (L1295-L1299) - 13170cd787/compiler/rustc_parse/src/parser/expr.rs (L282-L289) The 2 pretty printers definitely want to treat comparisons using `Fixity::None`. That's the whole bug being fixed. Meanwhile, the parser's `Fixity::None` codepath is previously unreachable as indicated by the comment, so as long as `Fixity::None` here behaves exactly the way that `Fixity::Left` used to behave, you can tell that this PR definitely does not constitute any behavior change for the parser. My guess for why comparison operators were set to `Fixity::Left` instead of `Fixity::None` is that it's a very old workaround for giving a good chained comparisons diagnostic (like what I pasted above). Nowadays that is handled by a different dedicated codepath.		2024-12-21 01:18:43 -05:00
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src	Rollup merge of #134600 - dtolnay:chainedcomparison, r=oli-obk	2024-12-21 01:18:43 -05:00
Cargo.toml	Update unicode-width to 0.2.0	2024-10-12 21:57:50 +00:00
messages.ftl	Introduce default_field_values feature	2024-12-09 21:55:01 +00:00