diff --git a/src/librustc_parse/parser/diagnostics.rs b/src/librustc_parse/parser/diagnostics.rs index e27bbc532cfc4..16a118cb48c91 100644 --- a/src/librustc_parse/parser/diagnostics.rs +++ b/src/librustc_parse/parser/diagnostics.rs @@ -376,7 +376,14 @@ impl<'a> Parser<'a> { /// let _ = vec![1, 2, 3].into_iter().collect::>>>(); /// ^^ help: remove extra angle brackets /// ``` - pub(super) fn check_trailing_angle_brackets(&mut self, segment: &PathSegment, end: TokenKind) { + /// + /// If `true` is returned, then trailing brackets were recovered, tokens were consumed + /// up until one of the tokens in 'end' was encountered, and an error was emitted. + pub(super) fn check_trailing_angle_brackets( + &mut self, + segment: &PathSegment, + end: &[&TokenKind], + ) -> bool { // This function is intended to be invoked after parsing a path segment where there are two // cases: // @@ -409,7 +416,7 @@ impl<'a> Parser<'a> { parsed_angle_bracket_args, ); if !parsed_angle_bracket_args { - return; + return false; } // Keep the span at the start so we can highlight the sequence of `>` characters to be @@ -447,18 +454,18 @@ impl<'a> Parser<'a> { number_of_gt, number_of_shr, ); if number_of_gt < 1 && number_of_shr < 1 { - return; + return false; } // 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 + end.contains(&&t.kind) }) { // 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]); + self.eat_to_tokens(end); let span = lo.until(self.token.span); let total_num_of_gt = number_of_gt + number_of_shr * 2; @@ -473,7 +480,9 @@ impl<'a> Parser<'a> { Applicability::MachineApplicable, ) .emit(); + return true; } + false } /// Check to see if a pair of chained operators looks like an attempt at chained comparison, diff --git a/src/librustc_parse/parser/expr.rs b/src/librustc_parse/parser/expr.rs index 49a5c8801766c..abb444933536f 100644 --- a/src/librustc_parse/parser/expr.rs +++ b/src/librustc_parse/parser/expr.rs @@ -867,7 +867,7 @@ impl<'a> Parser<'a> { let fn_span_lo = self.token.span; let segment = self.parse_path_segment(PathStyle::Expr)?; - self.check_trailing_angle_brackets(&segment, token::OpenDelim(token::Paren)); + self.check_trailing_angle_brackets(&segment, &[&token::OpenDelim(token::Paren)]); if self.check(&token::OpenDelim(token::Paren)) { // Method call `expr.f()` diff --git a/src/librustc_parse/parser/item.rs b/src/librustc_parse/parser/item.rs index 6f13d7994d17d..5923a185dcf93 100644 --- a/src/librustc_parse/parser/item.rs +++ b/src/librustc_parse/parser/item.rs @@ -9,7 +9,7 @@ use rustc_ast::ast::{AssocItem, AssocItemKind, ForeignItemKind, Item, ItemKind, use rustc_ast::ast::{Async, Const, Defaultness, IsAuto, Mutability, Unsafe, UseTree, UseTreeKind}; use rustc_ast::ast::{BindingMode, Block, FnDecl, FnSig, Param, SelfKind}; use rustc_ast::ast::{EnumDef, Generics, StructField, TraitRef, Ty, TyKind, Variant, VariantData}; -use rustc_ast::ast::{FnHeader, ForeignItem, PathSegment, Visibility, VisibilityKind}; +use rustc_ast::ast::{FnHeader, ForeignItem, Path, PathSegment, Visibility, VisibilityKind}; use rustc_ast::ast::{MacArgs, MacCall, MacDelimiter}; use rustc_ast::ptr::P; use rustc_ast::token::{self, TokenKind}; @@ -1262,6 +1262,25 @@ impl<'a> Parser<'a> { sp, &format!("expected `,`, or `}}`, found {}", super::token_descr(&self.token)), ); + + // Try to recover extra trailing angle brackets + let mut recovered = false; + if let TyKind::Path(_, Path { segments, .. }) = &a_var.ty.kind { + if let Some(last_segment) = segments.last() { + recovered = self.check_trailing_angle_brackets( + last_segment, + &[&token::Comma, &token::CloseDelim(token::Brace)], + ); + if recovered { + // Handle a case like `Vec>,` where we can continue parsing fields + // after the comma + self.eat(&token::Comma); + // `check_trailing_angle_brackets` already emitted a nicer error + err.cancel(); + } + } + } + if self.token.is_ident() { // This is likely another field; emit the diagnostic and keep going err.span_suggestion( @@ -1271,6 +1290,14 @@ impl<'a> Parser<'a> { Applicability::MachineApplicable, ); err.emit(); + recovered = true; + } + + if recovered { + // Make sure an error was emitted (either by recovering an angle bracket, + // or by finding an identifier as the next token), since we're + // going to continue parsing + assert!(self.sess.span_diagnostic.has_errors()); } else { return Err(err); } diff --git a/src/librustc_parse/parser/path.rs b/src/librustc_parse/parser/path.rs index 5210614548da3..67e9b3af4a8cf 100644 --- a/src/librustc_parse/parser/path.rs +++ b/src/librustc_parse/parser/path.rs @@ -169,7 +169,7 @@ impl<'a> Parser<'a> { // `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); + self.check_trailing_angle_brackets(&segment, &[&token::ModSep]); } segments.push(segment); diff --git a/src/test/ui/parser/recover-field-extra-angle-brackets.rs b/src/test/ui/parser/recover-field-extra-angle-brackets.rs new file mode 100644 index 0000000000000..5e0e00bcb5e8d --- /dev/null +++ b/src/test/ui/parser/recover-field-extra-angle-brackets.rs @@ -0,0 +1,14 @@ +// Tests that we recover from extra trailing angle brackets +// in a struct field + +struct BadStruct { + first: Vec>, //~ ERROR unmatched angle bracket + second: bool +} + +fn bar(val: BadStruct) { + val.first; + val.second; +} + +fn main() {} diff --git a/src/test/ui/parser/recover-field-extra-angle-brackets.stderr b/src/test/ui/parser/recover-field-extra-angle-brackets.stderr new file mode 100644 index 0000000000000..318e55f6e99ac --- /dev/null +++ b/src/test/ui/parser/recover-field-extra-angle-brackets.stderr @@ -0,0 +1,8 @@ +error: unmatched angle bracket + --> $DIR/recover-field-extra-angle-brackets.rs:5:19 + | +LL | first: Vec>, + | ^ help: remove extra angle bracket + +error: aborting due to previous error +