diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_ast/src/ast.rs | 14 | ||||
| -rw-r--r-- | compiler/rustc_ast/src/visit.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_ast_lowering/src/lib.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_expand/src/build.rs | 1 | ||||
| -rw-r--r-- | compiler/rustc_lint/src/unused.rs | 128 | ||||
| -rw-r--r-- | compiler/rustc_parse/src/parser/ty.rs | 53 | ||||
| -rw-r--r-- | compiler/rustc_resolve/src/late/diagnostics.rs | 1 |
7 files changed, 173 insertions, 27 deletions
diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs index 286bbfb5ae8..3aceec7002a 100644 --- a/compiler/rustc_ast/src/ast.rs +++ b/compiler/rustc_ast/src/ast.rs @@ -1390,6 +1390,7 @@ impl Expr { path.clone(), TraitBoundModifiers::NONE, self.span, + Parens::No, ))), _ => None, } @@ -3366,6 +3367,13 @@ pub struct TraitRef { pub ref_id: NodeId, } +/// Whether enclosing parentheses are present or not. +#[derive(Clone, Encodable, Decodable, Debug)] +pub enum Parens { + Yes, + No, +} + #[derive(Clone, Encodable, Decodable, Debug)] pub struct PolyTraitRef { /// The `'a` in `for<'a> Foo<&'a T>`. @@ -3378,6 +3386,10 @@ pub struct PolyTraitRef { pub trait_ref: TraitRef, pub span: Span, + + /// When `Yes`, the first and last character of `span` are an opening + /// and a closing paren respectively. + pub parens: Parens, } impl PolyTraitRef { @@ -3386,12 +3398,14 @@ impl PolyTraitRef { path: Path, modifiers: TraitBoundModifiers, span: Span, + parens: Parens, ) -> Self { PolyTraitRef { bound_generic_params: generic_params, modifiers, trait_ref: TraitRef { path, ref_id: DUMMY_NODE_ID }, span, + parens, } } } diff --git a/compiler/rustc_ast/src/visit.rs b/compiler/rustc_ast/src/visit.rs index d0c2b2bf68b..867ab7d9478 100644 --- a/compiler/rustc_ast/src/visit.rs +++ b/compiler/rustc_ast/src/visit.rs @@ -1142,7 +1142,7 @@ macro_rules! common_visitor_and_walkers { vis: &mut V, p: &$($lt)? $($mut)? PolyTraitRef, ) -> V::Result { - let PolyTraitRef { bound_generic_params, modifiers, trait_ref, span } = p; + let PolyTraitRef { bound_generic_params, modifiers, trait_ref, span, parens: _ } = p; try_visit!(visit_modifiers(vis, modifiers)); try_visit!(visit_generic_params(vis, bound_generic_params)); try_visit!(vis.visit_trait_ref(trait_ref)); diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index 26d7c0cd6d3..d14e27982ef 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -1209,6 +1209,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> { modifiers: TraitBoundModifiers::NONE, trait_ref: TraitRef { path: path.clone(), ref_id: t.id }, span: t.span, + parens: ast::Parens::No, }, itctx, ); diff --git a/compiler/rustc_expand/src/build.rs b/compiler/rustc_expand/src/build.rs index 14b8cc90d97..a333f2c7cb7 100644 --- a/compiler/rustc_expand/src/build.rs +++ b/compiler/rustc_expand/src/build.rs @@ -195,6 +195,7 @@ impl<'a> ExtCtxt<'a> { }, trait_ref: self.trait_ref(path), span, + parens: ast::Parens::No, } } diff --git a/compiler/rustc_lint/src/unused.rs b/compiler/rustc_lint/src/unused.rs index a206f71e153..0627f70507c 100644 --- a/compiler/rustc_lint/src/unused.rs +++ b/compiler/rustc_lint/src/unused.rs @@ -3,6 +3,7 @@ use std::iter; use rustc_ast::util::{classify, parser}; use rustc_ast::{self as ast, ExprKind, HasAttrs as _, StmtKind}; use rustc_attr_data_structures::{AttributeKind, find_attr}; +use rustc_data_structures::fx::FxHashMap; use rustc_errors::{MultiSpan, pluralize}; use rustc_hir::def::{DefKind, Res}; use rustc_hir::def_id::DefId; @@ -10,6 +11,7 @@ use rustc_hir::{self as hir, LangItem}; use rustc_infer::traits::util::elaborate; use rustc_middle::ty::{self, Ty, adjustment}; use rustc_session::{declare_lint, declare_lint_pass, impl_lint_pass}; +use rustc_span::edition::Edition::Edition2015; use rustc_span::{BytePos, Span, Symbol, kw, sym}; use tracing::instrument; @@ -1034,6 +1036,31 @@ pub(crate) struct UnusedParens { /// `1 as (i32) < 2` parses to ExprKind::Lt /// `1 as i32 < 2` parses to i32::<2[missing angle bracket] parens_in_cast_in_lt: Vec<ast::NodeId>, + /// Ty nodes in this map are in TypeNoBounds position. Any bounds they + /// contain may be ambiguous w/r/t trailing `+` operators. + in_no_bounds_pos: FxHashMap<ast::NodeId, NoBoundsException>, +} + +/// Whether parentheses may be omitted from a type without resulting in ambiguity. +/// +/// ``` +/// type Example = Box<dyn Fn() -> &'static (dyn Send) + Sync>; +/// ``` +/// +/// Here, `&'static (dyn Send) + Sync` is a `TypeNoBounds`. As such, it may not directly +/// contain `ImplTraitType` or `TraitObjectType` which is why `(dyn Send)` is parenthesized. +/// However, an exception is made for `ImplTraitTypeOneBound` and `TraitObjectTypeOneBound`. +/// The following is accepted because there is no `+`. +/// +/// ``` +/// type Example = Box<dyn Fn() -> &'static dyn Send>; +/// ``` +enum NoBoundsException { + /// The type must be parenthesized. + None, + /// The type is the last bound of the containing type expression. If it has exactly one bound, + /// parentheses around the type are unnecessary. + OneBound, } impl_lint_pass!(UnusedParens => [UNUSED_PARENS]); @@ -1277,23 +1304,100 @@ impl EarlyLintPass for UnusedParens { ); } ast::TyKind::Paren(r) => { - match &r.kind { - ast::TyKind::TraitObject(..) => {} - ast::TyKind::BareFn(b) - if self.with_self_ty_parens && b.generic_params.len() > 0 => {} - ast::TyKind::ImplTrait(_, bounds) if bounds.len() > 1 => {} - _ => { - let spans = if !ty.span.from_expansion() { + let unused_parens = match &r.kind { + ast::TyKind::ImplTrait(_, bounds) | ast::TyKind::TraitObject(bounds, _) => { + match self.in_no_bounds_pos.get(&ty.id) { + Some(NoBoundsException::None) => false, + Some(NoBoundsException::OneBound) => bounds.len() <= 1, + None => true, + } + } + ast::TyKind::BareFn(b) => { + !self.with_self_ty_parens || b.generic_params.is_empty() + } + _ => true, + }; + + if unused_parens { + let spans = (!ty.span.from_expansion()) + .then(|| { r.span .find_ancestor_inside(ty.span) .map(|r| (ty.span.with_hi(r.lo()), ty.span.with_lo(r.hi()))) + }) + .flatten(); + + self.emit_unused_delims(cx, ty.span, spans, "type", (false, false), false); + } + + self.with_self_ty_parens = false; + } + ast::TyKind::Ref(_, mut_ty) | ast::TyKind::Ptr(mut_ty) => { + self.in_no_bounds_pos.insert(mut_ty.ty.id, NoBoundsException::OneBound); + } + ast::TyKind::TraitObject(bounds, _) | ast::TyKind::ImplTrait(_, bounds) => { + for i in 0..bounds.len() { + let is_last = i == bounds.len() - 1; + + if let ast::GenericBound::Trait(poly_trait_ref) = &bounds[i] { + let fn_with_explicit_ret_ty = if let [.., segment] = + &*poly_trait_ref.trait_ref.path.segments + && let Some(args) = segment.args.as_ref() + && let ast::GenericArgs::Parenthesized(paren_args) = &**args + && let ast::FnRetTy::Ty(ret_ty) = &paren_args.output + { + self.in_no_bounds_pos.insert( + ret_ty.id, + if is_last { + NoBoundsException::OneBound + } else { + NoBoundsException::None + }, + ); + + true } else { - None + false }; - self.emit_unused_delims(cx, ty.span, spans, "type", (false, false), false); + + // In edition 2015, dyn is a contextual keyword and `dyn::foo::Bar` is + // parsed as a path, so parens are necessary to disambiguate. See + // - tests/ui/lint/unused/unused-parens-trait-obj-e2015.rs and + // - https://doc.rust-lang.org/reference/types/trait-object.html#r-type.trait-object.syntax-edition2018 + let dyn2015_exception = cx.sess().psess.edition == Edition2015 + && matches!(ty.kind, ast::TyKind::TraitObject(..)) + && i == 0 + && poly_trait_ref + .trait_ref + .path + .segments + .first() + .map(|s| s.ident.name == kw::PathRoot) + .unwrap_or(false); + + if let ast::Parens::Yes = poly_trait_ref.parens + && (is_last || !fn_with_explicit_ret_ty) + && !dyn2015_exception + { + let s = poly_trait_ref.span; + let spans = (!s.from_expansion()).then(|| { + ( + s.with_hi(s.lo() + rustc_span::BytePos(1)), + s.with_lo(s.hi() - rustc_span::BytePos(1)), + ) + }); + + self.emit_unused_delims( + cx, + poly_trait_ref.span, + spans, + "type", + (false, false), + false, + ); + } } } - self.with_self_ty_parens = false; } _ => {} } @@ -1303,6 +1407,10 @@ impl EarlyLintPass for UnusedParens { <Self as UnusedDelimLint>::check_item(self, cx, item) } + fn check_item_post(&mut self, _: &EarlyContext<'_>, _: &rustc_ast::Item) { + self.in_no_bounds_pos.clear(); + } + fn enter_where_predicate(&mut self, _: &EarlyContext<'_>, pred: &ast::WherePredicate) { use rustc_ast::{WhereBoundPredicate, WherePredicateKind}; if let WherePredicateKind::BoundPredicate(WhereBoundPredicate { diff --git a/compiler/rustc_parse/src/parser/ty.rs b/compiler/rustc_parse/src/parser/ty.rs index 8221c709027..0c57a8cc5e1 100644 --- a/compiler/rustc_parse/src/parser/ty.rs +++ b/compiler/rustc_parse/src/parser/ty.rs @@ -305,8 +305,13 @@ impl<'a> Parser<'a> { let removal_span = kw.span.with_hi(self.token.span.lo()); 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, path, lo, parse_plus)?; + let kind = self.parse_remaining_bounds_path( + lifetime_defs, + path, + lo, + parse_plus, + ast::Parens::No, + )?; let err = self.dcx().create_err(errors::TransposeDynOrImpl { span: kw.span, kw: kw.name.as_str(), @@ -333,7 +338,13 @@ impl<'a> Parser<'a> { } else { let path = self.parse_path(PathStyle::Type)?; let parse_plus = allow_plus == AllowPlus::Yes && self.check_plus(); - self.parse_remaining_bounds_path(lifetime_defs, path, lo, parse_plus)? + self.parse_remaining_bounds_path( + lifetime_defs, + path, + lo, + parse_plus, + ast::Parens::No, + )? } } } else if self.eat_keyword(exp!(Impl)) { @@ -413,9 +424,13 @@ impl<'a> Parser<'a> { let maybe_bounds = allow_plus == AllowPlus::Yes && self.token.is_like_plus(); match ty.kind { // `(TY_BOUND_NOPAREN) + BOUND + ...`. - TyKind::Path(None, path) if maybe_bounds => { - self.parse_remaining_bounds_path(ThinVec::new(), path, lo, true) - } + TyKind::Path(None, path) if maybe_bounds => self.parse_remaining_bounds_path( + ThinVec::new(), + path, + lo, + true, + ast::Parens::Yes, + ), // For `('a) + …`, we know that `'a` in type position already lead to an error being // emitted. To reduce output, let's indirectly suppress E0178 (bad `+` in type) and // other irrelevant consequential errors. @@ -495,12 +510,14 @@ impl<'a> Parser<'a> { path: ast::Path, lo: Span, parse_plus: bool, + parens: ast::Parens, ) -> PResult<'a, TyKind> { let poly_trait_ref = PolyTraitRef::new( generic_params, path, TraitBoundModifiers::NONE, lo.to(self.prev_token.span), + parens, ); let bounds = vec![GenericBound::Trait(poly_trait_ref)]; self.parse_remaining_bounds(bounds, parse_plus) @@ -826,7 +843,7 @@ impl<'a> Parser<'a> { Ok(TyKind::MacCall(P(MacCall { path, args: self.parse_delim_args()? }))) } else if allow_plus == AllowPlus::Yes && self.check_plus() { // `Trait1 + Trait2 + 'a` - self.parse_remaining_bounds_path(ThinVec::new(), path, lo, true) + self.parse_remaining_bounds_path(ThinVec::new(), path, lo, true, ast::Parens::No) } else { // Just a type path. Ok(TyKind::Path(None, path)) @@ -892,10 +909,10 @@ impl<'a> Parser<'a> { fn parse_generic_bound(&mut self) -> PResult<'a, GenericBound> { let lo = self.token.span; let leading_token = self.prev_token; - let has_parens = self.eat(exp!(OpenParen)); + 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, has_parens)? + self.parse_generic_lt_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 @@ -904,7 +921,7 @@ impl<'a> Parser<'a> { let (args, args_span) = self.parse_precise_capturing_args()?; GenericBound::Use(args, use_span.to(args_span)) } else { - self.parse_generic_ty_bound(lo, has_parens, &leading_token)? + self.parse_generic_ty_bound(lo, parens, &leading_token)? }; Ok(bound) @@ -914,10 +931,14 @@ impl<'a> Parser<'a> { /// ```ebnf /// LT_BOUND = LIFETIME /// ``` - fn parse_generic_lt_bound(&mut self, lo: Span, has_parens: bool) -> PResult<'a, GenericBound> { + fn parse_generic_lt_bound( + &mut self, + lo: Span, + parens: ast::Parens, + ) -> PResult<'a, GenericBound> { let lt = self.expect_lifetime(); let bound = GenericBound::Outlives(lt); - if has_parens { + if let ast::Parens::Yes = parens { // FIXME(Centril): Consider not erroring here and accepting `('lt)` instead, // possibly introducing `GenericBound::Paren(P<GenericBound>)`? self.recover_paren_lifetime(lo)?; @@ -1090,7 +1111,7 @@ impl<'a> Parser<'a> { fn parse_generic_ty_bound( &mut self, lo: Span, - has_parens: bool, + parens: ast::Parens, leading_token: &Token, ) -> PResult<'a, GenericBound> { let (mut lifetime_defs, binder_span) = self.parse_late_bound_lifetime_defs()?; @@ -1116,7 +1137,7 @@ 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, has_parens); + return self.parse_generic_lt_bound(lo, parens); } if let (more_lifetime_defs, Some(binder_span)) = self.parse_late_bound_lifetime_defs()? { @@ -1183,7 +1204,7 @@ impl<'a> Parser<'a> { self.recover_fn_trait_with_lifetime_params(&mut path, &mut lifetime_defs)?; } - if has_parens { + if let ast::Parens::Yes = parens { // Someone has written something like `&dyn (Trait + Other)`. The correct code // would be `&(dyn Trait + Other)` if self.token.is_like_plus() && leading_token.is_keyword(kw::Dyn) { @@ -1203,7 +1224,7 @@ impl<'a> Parser<'a> { } let poly_trait = - PolyTraitRef::new(lifetime_defs, path, modifiers, lo.to(self.prev_token.span)); + PolyTraitRef::new(lifetime_defs, path, modifiers, lo.to(self.prev_token.span), parens); Ok(GenericBound::Trait(poly_trait)) } diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs index e7b8c988cd4..6230b8cfbec 100644 --- a/compiler/rustc_resolve/src/late/diagnostics.rs +++ b/compiler/rustc_resolve/src/late/diagnostics.rs @@ -3832,6 +3832,7 @@ fn mk_where_bound_predicate( ref_id: DUMMY_NODE_ID, }, span: DUMMY_SP, + parens: ast::Parens::No, })], }; |