diff options
Diffstat (limited to 'src/libsyntax/parse/parser.rs')
| -rw-r--r-- | src/libsyntax/parse/parser.rs | 101 |
1 files changed, 64 insertions, 37 deletions
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index 0cdb09a842f..1baf0d1b54c 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -152,6 +152,7 @@ fn maybe_append(mut lhs: Vec<Attribute>, rhs: Option<Vec<Attribute>>) enum PrevTokenKind { DocComment, Comma, + Plus, Interpolated, Eof, Other, @@ -1061,6 +1062,7 @@ impl<'a> Parser<'a> { self.prev_token_kind = match self.token { token::DocComment(..) => PrevTokenKind::DocComment, token::Comma => PrevTokenKind::Comma, + token::BinOp(token::Plus) => PrevTokenKind::Plus, token::Interpolated(..) => PrevTokenKind::Interpolated, token::Eof => PrevTokenKind::Eof, _ => PrevTokenKind::Other, @@ -1354,20 +1356,26 @@ impl<'a> Parser<'a> { break; } } + let trailing_plus = self.prev_token_kind == PrevTokenKind::Plus; self.expect(&token::CloseDelim(token::Paren))?; if ts.len() == 1 && !last_comma { let ty = ts.into_iter().nth(0).unwrap().unwrap(); + let maybe_bounds = allow_plus && self.token == token::BinOp(token::Plus); match ty.node { - // Accept `(Trait1) + Trait2 + 'a` for backward compatibility (#39318). - TyKind::Path(None, ref path) - if allow_plus && self.token == token::BinOp(token::Plus) => { - self.bump(); // `+` - let pt = PolyTraitRef::new(Vec::new(), path.clone(), lo.to(self.prev_span)); - let mut bounds = vec![TraitTyParamBound(pt, TraitBoundModifier::None)]; - bounds.append(&mut self.parse_ty_param_bounds()?); - TyKind::TraitObject(bounds) + // `(TY_BOUND_NOPAREN) + BOUND + ...`. + TyKind::Path(None, ref path) if maybe_bounds => { + self.parse_remaining_bounds(Vec::new(), path.clone(), lo, true)? } + TyKind::TraitObject(ref bounds) + if maybe_bounds && bounds.len() == 1 && !trailing_plus => { + let path = match bounds[0] { + TraitTyParamBound(ref pt, ..) => pt.trait_ref.path.clone(), + _ => self.bug("unexpected lifetime bound"), + }; + self.parse_remaining_bounds(Vec::new(), path, lo, true)? + } + // `(TYPE)` _ => TyKind::Paren(P(ty)) } } else { @@ -1418,11 +1426,8 @@ impl<'a> Parser<'a> { // Just a type path or bound list (trait object type) starting with a trait. // `Type` // `Trait1 + Trait2 + 'a` - if allow_plus && self.eat(&token::BinOp(token::Plus)) { - let poly_trait = PolyTraitRef::new(Vec::new(), path, lo.to(self.prev_span)); - let mut bounds = vec![TraitTyParamBound(poly_trait, TraitBoundModifier::None)]; - bounds.append(&mut self.parse_ty_param_bounds()?); - TyKind::TraitObject(bounds) + if allow_plus && self.check(&token::BinOp(token::Plus)) { + self.parse_remaining_bounds(Vec::new(), path, lo, true)? } else { TyKind::Path(None, path) } @@ -1440,12 +1445,8 @@ impl<'a> Parser<'a> { self.parse_ty_bare_fn(lifetime_defs)? } else { let path = self.parse_path(PathStyle::Type)?; - let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span)); - let mut bounds = vec![TraitTyParamBound(poly_trait, TraitBoundModifier::None)]; - if allow_plus && self.eat(&token::BinOp(token::Plus)) { - bounds.append(&mut self.parse_ty_param_bounds()?) - } - TyKind::TraitObject(bounds) + let parse_plus = allow_plus && self.check(&token::BinOp(token::Plus)); + self.parse_remaining_bounds(lifetime_defs, path, lo, parse_plus)? } } else if self.eat_keyword(keywords::Impl) { // FIXME: figure out priority of `+` in `impl Trait1 + Trait2` (#34511). @@ -1468,6 +1469,17 @@ impl<'a> Parser<'a> { Ok(P(ty)) } + fn parse_remaining_bounds(&mut self, lifetime_defs: Vec<LifetimeDef>, path: ast::Path, + lo: Span, parse_plus: bool) -> PResult<'a, TyKind> { + let poly_trait_ref = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span)); + let mut bounds = vec![TraitTyParamBound(poly_trait_ref, TraitBoundModifier::None)]; + if parse_plus { + self.bump(); // `+` + bounds.append(&mut self.parse_ty_param_bounds()?); + } + Ok(TyKind::TraitObject(bounds)) + } + fn maybe_recover_from_bad_type_plus(&mut self, allow_plus: bool, ty: &Ty) -> PResult<'a, ()> { // Do not add `+` to expected tokens. if !allow_plus || self.token != token::BinOp(token::Plus) { @@ -4070,28 +4082,43 @@ impl<'a> Parser<'a> { // Parse bounds of a type parameter `BOUND + BOUND + BOUND`, possibly with trailing `+`. // BOUND = TY_BOUND | LT_BOUND // LT_BOUND = LIFETIME (e.g. `'a`) - // TY_BOUND = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g. `?for<'a: 'b> m::Trait<'a>`) + // TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN) + // TY_BOUND_NOPAREN = [?] [for<LT_PARAM_DEFS>] SIMPLE_PATH (e.g. `?for<'a: 'b> m::Trait<'a>`) fn parse_ty_param_bounds_common(&mut self, allow_plus: bool) -> PResult<'a, TyParamBounds> { let mut bounds = Vec::new(); loop { - let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None }; - if self.check_lifetime() { - if let Some(question_span) = question { - self.span_err(question_span, - "`?` may only modify trait bounds, not lifetime bounds"); - } - bounds.push(RegionTyParamBound(self.expect_lifetime())); - } else if self.check_keyword(keywords::For) || self.check_path() { - let lo = self.span; - let lifetime_defs = self.parse_late_bound_lifetime_defs()?; - let path = self.parse_path(PathStyle::Type)?; - let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span)); - let modifier = if question.is_some() { - TraitBoundModifier::Maybe + let is_bound_start = self.check_path() || self.check_lifetime() || + self.check(&token::Question) || + self.check_keyword(keywords::For) || + self.check(&token::OpenDelim(token::Paren)); + if is_bound_start { + let has_parens = self.eat(&token::OpenDelim(token::Paren)); + let question = if self.eat(&token::Question) { Some(self.prev_span) } else { None }; + if self.token.is_lifetime() { + if let Some(question_span) = question { + self.span_err(question_span, + "`?` may only modify trait bounds, not lifetime bounds"); + } + bounds.push(RegionTyParamBound(self.expect_lifetime())); } else { - TraitBoundModifier::None - }; - bounds.push(TraitTyParamBound(poly_trait, modifier)); + let lo = self.span; + let lifetime_defs = self.parse_late_bound_lifetime_defs()?; + let path = self.parse_path(PathStyle::Type)?; + let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_span)); + let modifier = if question.is_some() { + TraitBoundModifier::Maybe + } else { + TraitBoundModifier::None + }; + bounds.push(TraitTyParamBound(poly_trait, modifier)); + } + if has_parens { + self.expect(&token::CloseDelim(token::Paren))?; + if let Some(&RegionTyParamBound(..)) = bounds.last() { + self.span_err(self.prev_span, + "parenthesized lifetime bounds are not supported"); + } + } } else { break } |