diff options
Diffstat (limited to 'src/libsyntax/parse/parser.rs')
| -rw-r--r-- | src/libsyntax/parse/parser.rs | 94 |
1 files changed, 61 insertions, 33 deletions
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index 6a881eb6241..d380948b891 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -2149,7 +2149,27 @@ impl<'a> Parser<'a> { enable_warning: bool) -> PResult<'a, ()> { loop { - segments.push(self.parse_path_segment(style, enable_warning)?); + let segment = self.parse_path_segment(style, enable_warning)?; + if style == PathStyle::Expr { + // In order to check for trailing angle brackets, we must have finished + // recursing (`parse_path_segment` can indirectly call this function), + // that is, the next token must be the highlighted part of the below example: + // + // `Foo::<Bar as Baz<T>>::Qux` + // ^ here + // + // As opposed to the below highlight (if we had only finished the first + // recursion): + // + // `Foo::<Bar as Baz<T>>::Qux` + // ^ here + // + // `PathStyle::Expr` is only provided at the root invocation and never in + // `parse_path_segment` to recurse and therefore can be checked to maintain + // this invariant. + self.check_trailing_angle_brackets(&segment, token::ModSep); + } + segments.push(segment); if self.is_import_coupler() || !self.eat(&token::ModSep) { return Ok(()); @@ -2757,7 +2777,7 @@ impl<'a> Parser<'a> { // Assuming we have just parsed `.`, continue parsing into an expression. fn parse_dot_suffix(&mut self, self_arg: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> { let segment = self.parse_path_segment(PathStyle::Expr, true)?; - self.check_trailing_angle_brackets(&segment); + self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren)); Ok(match self.token { token::OpenDelim(token::Paren) => { @@ -2793,15 +2813,19 @@ impl<'a> Parser<'a> { /// let _ = vec![1, 2, 3].into_iter().collect::<Vec<usize>>>>(); /// ^^ help: remove extra angle brackets /// ``` - fn check_trailing_angle_brackets(&mut self, segment: &PathSegment) { - // This function is intended to be invoked from `parse_dot_suffix` where there are two + fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: token::Token) { + // This function is intended to be invoked after parsing a path segment where there are two // cases: // - // - A field access (eg. `x.foo`) - // - A method call (eg. `x.foo()`) + // 1. A specific token is expected after the path segment. + // eg. `x.foo(`, `x.foo::<u32>(` (parenthesis - method call), + // `Foo::`, or `Foo::<Bar>::` (mod sep - continued path). + // 2. No specific token is expected after the path segment. + // eg. `x.foo` (field access) // - // This function is called after parsing `.foo` and before parsing any parenthesis (if - // present). This includes any angle bracket arguments, such as `.foo::<u32>`. + // This function is called after parsing `.foo` and before parsing the token `end` (if + // present). This includes any angle bracket arguments, such as `.foo::<u32>` or + // `Foo::<Bar>`. // We only care about trailing angle brackets if we previously parsed angle bracket // arguments. This helps stop us incorrectly suggesting that extra angle brackets be @@ -2836,43 +2860,47 @@ impl<'a> Parser<'a> { // actual operators and not trailing characters - ie `x.foo >> 3`). let mut position = 0; - // The first tokens we will encounter are shift right tokens (`>>`) since pairs of `>` - // characters will have been grouped together by the tokenizer. + // We can encounter `>` or `>>` tokens in any order, so we need to keep track of how + // many of each (so we can correctly pluralize our error messages) and continue to + // advance. let mut number_of_shr = 0; - while self.look_ahead(position, |t| *t == token::BinOp(token::BinOpToken::Shr)) { - number_of_shr += 1; - position += 1; - } - - // Afterwards, there will be at most one `>` character remaining (more than one and it'd - // have shown up as a `>>`). - let encountered_gt = self.look_ahead(position, |t| *t == token::Gt); - if encountered_gt { + let mut number_of_gt = 0; + while self.look_ahead(position, |t| { + trace!("check_trailing_angle_brackets: t={:?}", t); + if *t == token::BinOp(token::BinOpToken::Shr) { + number_of_shr += 1; + true + } else if *t == token::Gt { + number_of_gt += 1; + true + } else { + false + } + }) { position += 1; } - // If we didn't find any trailing `>>` characters or a trailing `>`, then we have - // nothing to error about. + // If we didn't find any trailing `>` characters, then we have nothing to error about. debug!( - "check_trailing_angle_brackets: encountered_gt={:?} number_of_shr={:?}", - encountered_gt, number_of_shr, + "check_trailing_angle_brackets: number_of_gt={:?} number_of_shr={:?}", + number_of_gt, number_of_shr, ); - if !encountered_gt && number_of_shr < 1 { + if number_of_gt < 1 && number_of_shr < 1 { return; } - // Finally, double check that we have a left parenthesis next as otherwise this is the - // field case. - if self.look_ahead(position, |t| *t == token::OpenDelim(token::Paren)) { - // Eat from where we started until the left parenthesis so that parsing can continue + // Finally, double check that we have our end token as otherwise this is the + // second case. + if self.look_ahead(position, |t| { + trace!("check_trailing_angle_brackets: t={:?}", t); + *t == end + }) { + // Eat from where we started until the end token so that parsing can continue // as if we didn't have those extra angle brackets. - self.eat_to_tokens(&[&token::OpenDelim(token::Paren)]); + self.eat_to_tokens(&[&end]); let span = lo.until(self.span); - // We needn't check `encountered_gt` to determine if we should pluralize "bracket". - // `encountered_gt` can only represent a single `>` character, if `number_of_shr >= 1` - // then there is either `>>` or `>>>` - in either case a plural is warranted. - let plural = number_of_shr >= 1; + let plural = number_of_gt > 1 || number_of_shr >= 1; self.diagnostic() .struct_span_err( span, |