diff options
Diffstat (limited to 'compiler/rustc_parse/src/parser/ty.rs')
| -rw-r--r-- | compiler/rustc_parse/src/parser/ty.rs | 147 |
1 files changed, 80 insertions, 67 deletions
diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs index 290f0a440af..899a43955ab 100644 --- a/compiler/rustc_parse/src/parser/ty.rs +++ b/compiler/rustc_parse/src/parser/ty.rs @@ -308,11 +308,11 @@ impl<'a> Parser<'a> { // Function pointer type or bound list (trait object type) starting with a poly-trait. // `for<'lt> [unsafe] [extern "ABI"] fn (&'lt S) -> T` // `for<'lt> Trait1<'lt> + Trait2 + 'a` - let (lifetime_defs, _) = self.parse_late_bound_lifetime_defs()?; + let (bound_vars, _) = self.parse_higher_ranked_binder()?; if self.check_fn_front_matter(false, Case::Sensitive) { self.parse_ty_fn_ptr( lo, - lifetime_defs, + bound_vars, Some(self.prev_token.span.shrink_to_lo()), recover_return_sign, )? @@ -326,7 +326,7 @@ impl<'a> Parser<'a> { let path = self.parse_path(PathStyle::Type)?; let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus(); let kind = self.parse_remaining_bounds_path( - lifetime_defs, + bound_vars, path, lo, parse_plus, @@ -359,7 +359,7 @@ impl<'a> Parser<'a> { let path = self.parse_path(PathStyle::Type)?; let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus(); self.parse_remaining_bounds_path( - lifetime_defs, + bound_vars, path, lo, parse_plus, @@ -443,7 +443,7 @@ impl<'a> Parser<'a> { let ty = ts.into_iter().next().unwrap(); let maybe_bounds = allow_plus == AllowPlus::Yes && self.token.is_like_plus(); match ty.kind { - // `(TY_BOUND_NOPAREN) + BOUND + ...`. + // `"(" BareTraitBound ")" "+" Bound "+" ...`. TyKind::Path(None, path) if maybe_bounds => self.parse_remaining_bounds_path( ThinVec::new(), path, @@ -853,10 +853,13 @@ impl<'a> Parser<'a> { Ok(TyKind::ImplTrait(ast::DUMMY_NODE_ID, bounds)) } - fn parse_precise_capturing_args( - &mut self, - ) -> PResult<'a, (ThinVec<PreciseCapturingArg>, Span)> { - let lo = self.token.span; + /// Parse a use-bound aka precise capturing list. + /// + /// ```ebnf + /// UseBound = "use" "<" (PreciseCapture ("," PreciseCapture)* ","?)? ">" + /// PreciseCapture = "Self" | Ident | Lifetime + /// ``` + fn parse_use_bound(&mut self, lo: Span, parens: ast::Parens) -> PResult<'a, GenericBound> { self.expect_lt()?; let (args, _, _) = self.parse_seq_to_before_tokens( &[exp!(Gt)], @@ -882,7 +885,13 @@ impl<'a> Parser<'a> { }, )?; self.expect_gt()?; - Ok((args, lo.to(self.prev_token.span))) + + if let ast::Parens::Yes = parens { + self.expect(exp!(CloseParen))?; + self.report_parenthesized_bound(lo, self.prev_token.span, "precise capturing lists"); + } + + Ok(GenericBound::Use(args, lo.to(self.prev_token.span))) } /// Is a `dyn B0 + ... + Bn` type allowed here? @@ -940,9 +949,10 @@ impl<'a> Parser<'a> { self.parse_generic_bounds_common(AllowPlus::Yes) } - /// Parses bounds of a type parameter `BOUND + BOUND + ...`, possibly with trailing `+`. + /// Parse generic bounds. /// - /// See `parse_generic_bound` for the `BOUND` grammar. + /// Only if `allow_plus` this parses a `+`-separated list of bounds (trailing `+` is admitted). + /// Otherwise, this only parses a single bound or none. fn parse_generic_bounds_common(&mut self, allow_plus: AllowPlus) -> PResult<'a, GenericBounds> { let mut bounds = Vec::new(); @@ -988,48 +998,56 @@ impl<'a> Parser<'a> { || self.check_keyword(exp!(Use)) } - /// Parses a bound according to the grammar: + /// Parse a bound. + /// /// ```ebnf - /// BOUND = TY_BOUND | LT_BOUND + /// Bound = LifetimeBound | UseBound | TraitBound /// ``` fn parse_generic_bound(&mut self) -> PResult<'a, GenericBound> { - let lo = self.token.span; let leading_token = self.prev_token; + let lo = self.token.span; + + // We only admit parenthesized *trait* bounds. However, we want to gracefully recover from + // other kinds of parenthesized bounds, so parse the opening parenthesis *here*. + // + // In the future we might want to lift this syntactic restriction and + // introduce "`GenericBound::Paren(Box<GenericBound>)`". let parens = if self.eat(exp!(OpenParen)) { ast::Parens::Yes } else { ast::Parens::No }; - let bound = if self.token.is_lifetime() { - self.parse_generic_lt_bound(lo, parens)? + if self.token.is_lifetime() { + self.parse_lifetime_bound(lo, parens) } else if self.eat_keyword(exp!(Use)) { - // parse precise captures, if any. This is `use<'lt, 'lt, P, P>`; a list of - // lifetimes and ident params (including SelfUpper). These are validated later - // for order, duplication, and whether they actually reference params. - let use_span = self.prev_token.span; - let (args, args_span) = self.parse_precise_capturing_args()?; - GenericBound::Use(args, use_span.to(args_span)) + self.parse_use_bound(lo, parens) } else { - self.parse_generic_ty_bound(lo, parens, &leading_token)? - }; - - Ok(bound) + self.parse_trait_bound(lo, parens, &leading_token) + } } - /// Parses a lifetime ("outlives") bound, e.g. `'a`, according to: + /// Parse a lifetime-bound aka outlives-bound. + /// /// ```ebnf - /// LT_BOUND = LIFETIME + /// LifetimeBound = Lifetime /// ``` - fn parse_generic_lt_bound( - &mut self, - lo: Span, - parens: ast::Parens, - ) -> PResult<'a, GenericBound> { + fn parse_lifetime_bound(&mut self, lo: Span, parens: ast::Parens) -> PResult<'a, GenericBound> { let lt = self.expect_lifetime(); - let bound = GenericBound::Outlives(lt); + if let ast::Parens::Yes = parens { - // FIXME(Centril): Consider not erroring here and accepting `('lt)` instead, - // possibly introducing `GenericBound::Paren(Box<GenericBound>)`? - self.recover_paren_lifetime(lo)?; + self.expect(exp!(CloseParen))?; + self.report_parenthesized_bound(lo, self.prev_token.span, "lifetime bounds"); } - Ok(bound) + + Ok(GenericBound::Outlives(lt)) + } + + fn report_parenthesized_bound(&self, lo: Span, hi: Span, kind: &str) -> ErrorGuaranteed { + let mut diag = + self.dcx().struct_span_err(lo.to(hi), format!("{kind} may not be parenthesized")); + diag.multipart_suggestion( + "remove the parentheses", + vec![(lo, String::new()), (hi, String::new())], + Applicability::MachineApplicable, + ); + diag.emit() } /// Emits an error if any trait bound modifiers were present. @@ -1074,27 +1092,17 @@ impl<'a> Parser<'a> { unreachable!("lifetime bound intercepted in `parse_generic_ty_bound` but no modifiers?") } - /// Recover on `('lifetime)` with `(` already eaten. - fn recover_paren_lifetime(&mut self, lo: Span) -> PResult<'a, ()> { - self.expect(exp!(CloseParen))?; - let span = lo.to(self.prev_token.span); - let sugg = errors::RemoveParens { lo, hi: self.prev_token.span }; - - self.dcx().emit_err(errors::ParenthesizedLifetime { span, sugg }); - Ok(()) - } - /// Parses the modifiers that may precede a trait in a bound, e.g. `?Trait` or `[const] Trait`. /// /// If no modifiers are present, this does not consume any tokens. /// /// ```ebnf - /// CONSTNESS = [["["] "const" ["]"]] - /// ASYNCNESS = ["async"] - /// POLARITY = ["?" | "!"] + /// Constness = ("const" | "[" "const" "]")? + /// Asyncness = "async"? + /// Polarity = ("?" | "!")? /// ``` /// - /// See `parse_generic_ty_bound` for the complete grammar of trait bound modifiers. + /// See `parse_trait_bound` for more context. fn parse_trait_bound_modifiers(&mut self) -> PResult<'a, TraitBoundModifiers> { let modifier_lo = self.token.span; let constness = self.parse_bound_constness()?; @@ -1187,20 +1195,21 @@ impl<'a> Parser<'a> { }) } - /// Parses a type bound according to: + /// Parse a trait bound. + /// /// ```ebnf - /// TY_BOUND = TY_BOUND_NOPAREN | (TY_BOUND_NOPAREN) - /// TY_BOUND_NOPAREN = [for<GENERIC_PARAMS> CONSTNESS ASYNCNESS | POLARITY] SIMPLE_PATH + /// TraitBound = BareTraitBound | "(" BareTraitBound ")" + /// BareTraitBound = + /// (HigherRankedBinder Constness Asyncness | Polarity) + /// TypePath /// ``` - /// - /// For example, this grammar accepts `for<'a: 'b> [const] ?m::Trait<'a>`. - fn parse_generic_ty_bound( + fn parse_trait_bound( &mut self, lo: Span, parens: ast::Parens, leading_token: &Token, ) -> PResult<'a, GenericBound> { - let (mut lifetime_defs, binder_span) = self.parse_late_bound_lifetime_defs()?; + let (mut bound_vars, binder_span) = self.parse_higher_ranked_binder()?; let modifiers_lo = self.token.span; let modifiers = self.parse_trait_bound_modifiers()?; @@ -1223,11 +1232,11 @@ impl<'a> Parser<'a> { // e.g. `T: for<'a> 'a` or `T: [const] 'a`. if self.token.is_lifetime() { let _: ErrorGuaranteed = self.error_lt_bound_with_modifiers(modifiers, binder_span); - return self.parse_generic_lt_bound(lo, parens); + return self.parse_lifetime_bound(lo, parens); } - if let (more_lifetime_defs, Some(binder_span)) = self.parse_late_bound_lifetime_defs()? { - lifetime_defs.extend(more_lifetime_defs); + if let (more_bound_vars, Some(binder_span)) = self.parse_higher_ranked_binder()? { + bound_vars.extend(more_bound_vars); self.dcx().emit_err(errors::BinderBeforeModifiers { binder_span, modifiers_span }); } @@ -1287,7 +1296,7 @@ impl<'a> Parser<'a> { }; if self.may_recover() && self.token == TokenKind::OpenParen { - self.recover_fn_trait_with_lifetime_params(&mut path, &mut lifetime_defs)?; + self.recover_fn_trait_with_lifetime_params(&mut path, &mut bound_vars)?; } if let ast::Parens::Yes = parens { @@ -1310,7 +1319,7 @@ impl<'a> Parser<'a> { } let poly_trait = - PolyTraitRef::new(lifetime_defs, path, modifiers, lo.to(self.prev_token.span), parens); + PolyTraitRef::new(bound_vars, path, modifiers, lo.to(self.prev_token.span), parens); Ok(GenericBound::Trait(poly_trait)) } @@ -1349,8 +1358,12 @@ impl<'a> Parser<'a> { } } - /// Optionally parses `for<$generic_params>`. - pub(super) fn parse_late_bound_lifetime_defs( + /// Parse an optional higher-ranked binder. + /// + /// ```ebnf + /// HigherRankedBinder = ("for" "<" GenericParams ">")? + /// ``` + pub(super) fn parse_higher_ranked_binder( &mut self, ) -> PResult<'a, (ThinVec<GenericParam>, Option<Span>)> { if self.eat_keyword(exp!(For)) { |