From d65f1316bba2b3cdccce3f0d7d3e2eb27b5fbe49 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=E8=AE=B8=E6=9D=B0=E5=8F=8B=20Jieyou=20Xu=20=28Joe=29?= Date: Fri, 9 Aug 2024 05:48:52 +0000 Subject: [PATCH] parser: ensure let stmt compound assignment removal suggestion respect codepoint boundaries MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Previously we would try to issue a suggestion for `let x = 1`, i.e. a compound assignment within a `let` binding, to remove the ``. The suggestion code unfortunately incorrectly assumed that the `` is an exactly-1-byte ASCII character, but this assumption is incorrect because we also recover Unicode-confusables like `➖=` as `-=`. In this example, the suggestion code used a `+ BytePos(1)` to calculate the span of the `` codepoint that looks like `-` but the mult-byte Unicode look-alike would cause the suggested removal span to be inside a multi-byte codepoint boundary, triggering a codepoint boundary assertion. Issue: --- compiler/rustc_parse/src/parser/stmt.rs | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/compiler/rustc_parse/src/parser/stmt.rs b/compiler/rustc_parse/src/parser/stmt.rs index b3efb87a4a26a..a3b782d651d3f 100644 --- a/compiler/rustc_parse/src/parser/stmt.rs +++ b/compiler/rustc_parse/src/parser/stmt.rs @@ -408,10 +408,14 @@ impl<'a> Parser<'a> { fn parse_initializer(&mut self, eq_optional: bool) -> PResult<'a, Option>> { let eq_consumed = match self.token.kind { token::BinOpEq(..) => { - // Recover `let x = 1` as `let x = 1` + // Recover `let x = 1` as `let x = 1` We must not use `+ BytePos(1)` here + // because `` can be a multi-byte lookalike that was recovered, e.g. `➖=` (the + // `➖` is a U+2796 Heavy Minus Sign Unicode Character) that was recovered as a + // `-=`. + let extra_op_span = self.psess.source_map().start_point(self.token.span); self.dcx().emit_err(errors::CompoundAssignmentExpressionInLet { span: self.token.span, - suggestion: self.token.span.with_hi(self.token.span.lo() + BytePos(1)), + suggestion: extra_op_span, }); self.bump(); true