diff options
Diffstat (limited to 'src/libsyntax/parse')
| -rw-r--r-- | src/libsyntax/parse/diagnostics.rs | 87 |
1 files changed, 49 insertions, 38 deletions
diff --git a/src/libsyntax/parse/diagnostics.rs b/src/libsyntax/parse/diagnostics.rs index 0e3d873b252..584c7c2ded5 100644 --- a/src/libsyntax/parse/diagnostics.rs +++ b/src/libsyntax/parse/diagnostics.rs @@ -560,6 +560,7 @@ impl<'a> Parser<'a> { ); match lhs.kind { ExprKind::Binary(op, _, _) if op.node.is_comparison() => { + // Respan to include both operators. let op_span = op.span.to(self.prev_span); let mut err = self.struct_span_err( @@ -573,63 +574,54 @@ impl<'a> Parser<'a> { let msg = "use `::<...>` instead of `<...>` if you meant to specify type \ arguments"; if *outer_op == AssocOp::Less { - // if self.look_ahead(1, |t| t.kind == token::Lt || t.kind == token::ModSep) { let snapshot = self.clone(); self.bump(); - // So far we have parsed `foo<bar<` - let mut acc = 1; - while acc > 0 { - match &self.token.kind { - token::Lt => { - acc += 1; - } - token::Gt => { - acc -= 1; - } - token::BinOp(token::Shr) => { - acc -= 2; - } - token::Eof => { - break; - } - _ => {} - } - self.bump(); - } + // So far we have parsed `foo<bar<`, consume the rest of the type params + let modifiers = vec![ + (token::Lt, 1), + (token::Gt, -1), + (token::BinOp(token::Shr), -2), + ]; + let early_return = vec![token::Eof]; + self.consume_tts(1, &modifiers[..], &early_return[..]); + if self.token.kind != token::OpenDelim(token::Paren) { + // We don't have `foo< bar >(`, so we rewind the parser and bail out. mem::replace(self, snapshot.clone()); } } if self.token.kind == token::OpenDelim(token::Paren) { + // We have high certainty that this was a bad turbofish at this point. + // `foo< bar >(` err.span_suggestion( op_span.shrink_to_lo(), msg, "::".to_string(), Applicability::MaybeIncorrect, ); + let snapshot = self.clone(); - self.bump(); - let mut acc = 1; - while acc > 0 { - match &self.token.kind { - token::OpenDelim(token::Paren) => { - acc += 1; - } - token::CloseDelim(token::Paren) => { - acc -= 1; - } - token::Eof => { - break; - } - _ => {} - } - self.bump(); - } + + // Consume the fn call arguments. + let modifiers = vec![ + (token::OpenDelim(token::Paren), 1), + (token::CloseDelim(token::Paren), -1), + ]; + let early_return = vec![token::Eof]; + self.bump(); // `(` + self.consume_tts(1, &modifiers[..], &early_return[..]); + if self.token.kind == token::Eof { + // Not entirely sure now, but we bubble the error up with the + // suggestion. mem::replace(self, snapshot); return Err(err); } else { + // 99% certain that the suggestion is correct, continue parsing. err.emit(); + // FIXME: actually check that the two expressions in the binop are + // paths and resynthesize new fn call expression instead of using + // `ExprKind::Err` placeholder. return Ok(Some(self.mk_expr( lhs.span.to(self.prev_span), ExprKind::Err, @@ -637,6 +629,8 @@ impl<'a> Parser<'a> { ))); } } else { + // All we know is that this is `foo < bar >` and *nothing* else. Try to + // be helpful, but don't attempt to recover. err.help(msg); err.help("or use `(...)` if you meant to specify fn arguments"); // These cases cause too many knock-down errors, bail out (#61329). @@ -1424,6 +1418,23 @@ impl<'a> Parser<'a> { err } + fn consume_tts( + &mut self, + mut acc: i64, + modifier: &[(token::TokenKind, i64)], // Not using FxHasMap and FxHashSet due to + early_return: &[token::TokenKind], // `token::TokenKind: !Eq + !Hash`. + ) { + while acc > 0 { + if let Some((_, val)) = modifier.iter().filter(|(t, _)| *t == self.token.kind).next() { + acc += *val; + } + if early_return.contains(&self.token.kind) { + break; + } + self.bump(); + } + } + /// Replace duplicated recovered parameters with `_` pattern to avoid unecessary errors. /// /// This is necessary because at this point we don't know whether we parsed a function with |