diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs index 798f14dcba955..af521848e9057 100644 --- a/src/libsyntax/ast.rs +++ b/src/libsyntax/ast.rs @@ -140,6 +140,20 @@ pub enum GenericArgs { } impl GenericArgs { + pub fn is_parenthesized(&self) -> bool { + match *self { + Parenthesized(..) => true, + _ => false, + } + } + + pub fn is_angle_bracketed(&self) -> bool { + match *self { + AngleBracketed(..) => true, + _ => false, + } + } + pub fn span(&self) -> Span { match *self { AngleBracketed(ref data) => data.span, diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index 5e73230b4038c..c7e33a1656428 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -2188,7 +2188,27 @@ 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::>::Qux` + // ^ here + // + // As opposed to the below highlight (if we had only finished the first + // recursion): + // + // `Foo::>::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(()); @@ -2821,6 +2841,8 @@ impl<'a> Parser<'a> { // Assuming we have just parsed `.`, continue parsing into an expression. fn parse_dot_suffix(&mut self, self_arg: P, lo: Span) -> PResult<'a, P> { let segment = self.parse_path_segment(PathStyle::Expr, true)?; + self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren)); + Ok(match self.token { token::OpenDelim(token::Paren) => { // Method call `expr.f()` @@ -2848,6 +2870,116 @@ impl<'a> Parser<'a> { }) } + /// This function checks if there are trailing angle brackets and produces + /// a diagnostic to suggest removing them. + /// + /// ```ignore (diagnostic) + /// let _ = vec![1, 2, 3].into_iter().collect::>>>(); + /// ^^ help: remove extra angle brackets + /// ``` + 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: + // + // 1. A specific token is expected after the path segment. + // eg. `x.foo(`, `x.foo::(` (parenthesis - method call), + // `Foo::`, or `Foo::::` (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 the token `end` (if + // present). This includes any angle bracket arguments, such as `.foo::` or + // `Foo::`. + + // 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 + // removed in this case: + // + // `x.foo >> (3)` (where `x.foo` is a `u32` for example) + // + // This case is particularly tricky as we won't notice it just looking at the tokens - + // it will appear the same (in terms of upcoming tokens) as below (since the `::` will + // have already been parsed): + // + // `x.foo::>>(3)` + let parsed_angle_bracket_args = segment.args + .as_ref() + .map(|args| args.is_angle_bracketed()) + .unwrap_or(false); + + debug!( + "check_trailing_angle_brackets: parsed_angle_bracket_args={:?}", + parsed_angle_bracket_args, + ); + if !parsed_angle_bracket_args { + return; + } + + // Keep the span at the start so we can highlight the sequence of `>` characters to be + // removed. + let lo = self.span; + + // We need to look-ahead to see if we have `>` characters without moving the cursor forward + // (since we might have the field access case and the characters we're eating are + // actual operators and not trailing characters - ie `x.foo >> 3`). + let mut position = 0; + + // 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; + 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, then we have nothing to error about. + debug!( + "check_trailing_angle_brackets: number_of_gt={:?} number_of_shr={:?}", + number_of_gt, number_of_shr, + ); + if number_of_gt < 1 && number_of_shr < 1 { + return; + } + + // 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(&[&end]); + let span = lo.until(self.span); + + let plural = number_of_gt > 1 || number_of_shr >= 1; + self.diagnostic() + .struct_span_err( + span, + &format!("unmatched angle bracket{}", if plural { "s" } else { "" }), + ) + .span_suggestion_with_applicability( + span, + &format!("remove extra angle bracket{}", if plural { "s" } else { "" }), + String::new(), + Applicability::MachineApplicable, + ) + .emit(); + } + } + fn parse_dot_or_call_expr_with_(&mut self, e0: P, lo: Span) -> PResult<'a, P> { let mut e = e0; let mut hi; diff --git a/src/test/ui/issues/issue-54521-1.rs b/src/test/ui/issues/issue-54521-1.rs new file mode 100644 index 0000000000000..d6a14a6e11f67 --- /dev/null +++ b/src/test/ui/issues/issue-54521-1.rs @@ -0,0 +1,16 @@ +// compile-pass + +// This test checks that the `remove extra angle brackets` error doesn't happen for some +// potential edge-cases.. + +struct X { + len: u32, +} + +fn main() { + let x = X { len: 3 }; + + let _ = x.len > (3); + + let _ = x.len >> (3); +} diff --git a/src/test/ui/issues/issue-54521-2.fixed b/src/test/ui/issues/issue-54521-2.fixed new file mode 100644 index 0000000000000..a91c4fe43ea46 --- /dev/null +++ b/src/test/ui/issues/issue-54521-2.fixed @@ -0,0 +1,22 @@ +// run-rustfix + +// This test checks that the following error is emitted and the suggestion works: +// +// ``` +// let _ = Vec::>>::new(); +// ^^ help: remove extra angle brackets +// ``` + +fn main() { + let _ = Vec::::new(); + //~^ ERROR unmatched angle bracket + + let _ = Vec::::new(); + //~^ ERROR unmatched angle bracket + + let _ = Vec::::new(); + //~^ ERROR unmatched angle bracket + + let _ = Vec::::new(); + //~^ ERROR unmatched angle bracket +} diff --git a/src/test/ui/issues/issue-54521-2.rs b/src/test/ui/issues/issue-54521-2.rs new file mode 100644 index 0000000000000..3639aac87ee7f --- /dev/null +++ b/src/test/ui/issues/issue-54521-2.rs @@ -0,0 +1,22 @@ +// run-rustfix + +// This test checks that the following error is emitted and the suggestion works: +// +// ``` +// let _ = Vec::>>::new(); +// ^^ help: remove extra angle brackets +// ``` + +fn main() { + let _ = Vec::>>>>::new(); + //~^ ERROR unmatched angle bracket + + let _ = Vec::>>>::new(); + //~^ ERROR unmatched angle bracket + + let _ = Vec::>>::new(); + //~^ ERROR unmatched angle bracket + + let _ = Vec::>::new(); + //~^ ERROR unmatched angle bracket +} diff --git a/src/test/ui/issues/issue-54521-2.stderr b/src/test/ui/issues/issue-54521-2.stderr new file mode 100644 index 0000000000000..9556b83b730a4 --- /dev/null +++ b/src/test/ui/issues/issue-54521-2.stderr @@ -0,0 +1,26 @@ +error: unmatched angle brackets + --> $DIR/issue-54521-2.rs:11:25 + | +LL | let _ = Vec::>>>>::new(); + | ^^^^ help: remove extra angle brackets + +error: unmatched angle brackets + --> $DIR/issue-54521-2.rs:14:25 + | +LL | let _ = Vec::>>>::new(); + | ^^^ help: remove extra angle brackets + +error: unmatched angle brackets + --> $DIR/issue-54521-2.rs:17:25 + | +LL | let _ = Vec::>>::new(); + | ^^ help: remove extra angle brackets + +error: unmatched angle bracket + --> $DIR/issue-54521-2.rs:20:25 + | +LL | let _ = Vec::>::new(); + | ^ help: remove extra angle bracket + +error: aborting due to 4 previous errors + diff --git a/src/test/ui/issues/issue-54521.fixed b/src/test/ui/issues/issue-54521.fixed new file mode 100644 index 0000000000000..84ab6866cf133 --- /dev/null +++ b/src/test/ui/issues/issue-54521.fixed @@ -0,0 +1,22 @@ +// run-rustfix + +// This test checks that the following error is emitted and the suggestion works: +// +// ``` +// let _ = vec![1, 2, 3].into_iter().collect::>>>(); +// ^^ help: remove extra angle brackets +// ``` + +fn main() { + let _ = vec![1, 2, 3].into_iter().collect::>(); + //~^ ERROR unmatched angle bracket + + let _ = vec![1, 2, 3].into_iter().collect::>(); + //~^ ERROR unmatched angle bracket + + let _ = vec![1, 2, 3].into_iter().collect::>(); + //~^ ERROR unmatched angle bracket + + let _ = vec![1, 2, 3].into_iter().collect::>(); + //~^ ERROR unmatched angle bracket +} diff --git a/src/test/ui/issues/issue-54521.rs b/src/test/ui/issues/issue-54521.rs new file mode 100644 index 0000000000000..f1d6850417880 --- /dev/null +++ b/src/test/ui/issues/issue-54521.rs @@ -0,0 +1,22 @@ +// run-rustfix + +// This test checks that the following error is emitted and the suggestion works: +// +// ``` +// let _ = vec![1, 2, 3].into_iter().collect::>>>(); +// ^^ help: remove extra angle brackets +// ``` + +fn main() { + let _ = vec![1, 2, 3].into_iter().collect::>>>>>(); + //~^ ERROR unmatched angle bracket + + let _ = vec![1, 2, 3].into_iter().collect::>>>>(); + //~^ ERROR unmatched angle bracket + + let _ = vec![1, 2, 3].into_iter().collect::>>>(); + //~^ ERROR unmatched angle bracket + + let _ = vec![1, 2, 3].into_iter().collect::>>(); + //~^ ERROR unmatched angle bracket +} diff --git a/src/test/ui/issues/issue-54521.stderr b/src/test/ui/issues/issue-54521.stderr new file mode 100644 index 0000000000000..ffefbfd0348a8 --- /dev/null +++ b/src/test/ui/issues/issue-54521.stderr @@ -0,0 +1,26 @@ +error: unmatched angle brackets + --> $DIR/issue-54521.rs:11:60 + | +LL | let _ = vec![1, 2, 3].into_iter().collect::>>>>>(); + | ^^^^ help: remove extra angle brackets + +error: unmatched angle brackets + --> $DIR/issue-54521.rs:14:60 + | +LL | let _ = vec![1, 2, 3].into_iter().collect::>>>>(); + | ^^^ help: remove extra angle brackets + +error: unmatched angle brackets + --> $DIR/issue-54521.rs:17:60 + | +LL | let _ = vec![1, 2, 3].into_iter().collect::>>>(); + | ^^ help: remove extra angle brackets + +error: unmatched angle bracket + --> $DIR/issue-54521.rs:20:60 + | +LL | let _ = vec![1, 2, 3].into_iter().collect::>>(); + | ^ help: remove extra angle bracket + +error: aborting due to 4 previous errors +