Move trait bound modifiers into ast::PolyTraitRef

compiler/rustc_ast/src/ast.rs

@@ -308,7 +308,7 @@ impl TraitBoundModifiers {
 
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub enum GenericBound {
-    Trait(PolyTraitRef, TraitBoundModifiers),
+    Trait(PolyTraitRef),
     Outlives(Lifetime),
     /// Precise capturing syntax: `impl Sized + use<'a>`
     Use(ThinVec<PreciseCapturingArg>, Span),
@@ -1213,10 +1213,12 @@ impl Expr {
 
     pub fn to_bound(&self) -> Option<GenericBound> {
         match &self.kind {
-            ExprKind::Path(None, path) => Some(GenericBound::Trait(
-                PolyTraitRef::new(ThinVec::new(), path.clone(), self.span),
+            ExprKind::Path(None, path) => Some(GenericBound::Trait(PolyTraitRef::new(
+                ThinVec::new(),
+                path.clone(),
                 TraitBoundModifiers::NONE,
-            )),
+                self.span,
+            ))),
             _ => None,
         }
     }
@@ -2965,16 +2967,25 @@ pub struct PolyTraitRef {
     /// The `'a` in `for<'a> Foo<&'a T>`.
     pub bound_generic_params: ThinVec<GenericParam>,
 
+    // Optional constness, asyncness, or polarity.
+    pub modifiers: TraitBoundModifiers,
+
     /// The `Foo<&'a T>` in `<'a> Foo<&'a T>`.
     pub trait_ref: TraitRef,
 
     pub span: Span,
 }
 
 impl PolyTraitRef {
-    pub fn new(generic_params: ThinVec<GenericParam>, path: Path, span: Span) -> Self {
+    pub fn new(
+        generic_params: ThinVec<GenericParam>,
+        path: Path,
+        modifiers: TraitBoundModifiers,
+        span: Span,
+    ) -> Self {
         PolyTraitRef {
             bound_generic_params: generic_params,
+            modifiers,
             trait_ref: TraitRef { path, ref_id: DUMMY_NODE_ID },
             span,
         }

compiler/rustc_ast/src/mut_visit.rs

@@ -913,7 +913,7 @@ fn walk_fn_ret_ty<T: MutVisitor>(vis: &mut T, fn_ret_ty: &mut FnRetTy) {
 
 fn walk_param_bound<T: MutVisitor>(vis: &mut T, pb: &mut GenericBound) {
     match pb {
-        GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
+        GenericBound::Trait(trait_ref) => vis.visit_poly_trait_ref(trait_ref),
         GenericBound::Outlives(lifetime) => walk_lifetime(vis, lifetime),
         GenericBound::Use(args, span) => {
             for arg in args {
@@ -1034,7 +1034,7 @@ fn walk_trait_ref<T: MutVisitor>(vis: &mut T, TraitRef { path, ref_id }: &mut Tr
 }
 
 fn walk_poly_trait_ref<T: MutVisitor>(vis: &mut T, p: &mut PolyTraitRef) {
-    let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
+    let PolyTraitRef { bound_generic_params, modifiers: _, trait_ref, span } = p;
     bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
     vis.visit_trait_ref(trait_ref);
     vis.visit_span(span);

compiler/rustc_ast/src/util/classify.rs

@@ -263,7 +263,7 @@ fn type_trailing_braced_mac_call(mut ty: &ast::Ty) -> Option<&ast::MacCall> {
 
             ast::TyKind::TraitObject(bounds, _) | ast::TyKind::ImplTrait(_, bounds) => {
                 match bounds.last() {
-                    Some(ast::GenericBound::Trait(bound, _)) => {
+                    Some(ast::GenericBound::Trait(bound)) => {
                         match path_return_type(&bound.trait_ref.path) {
                             Some(trailing_ty) => ty = trailing_ty,
                             None => break None,

compiler/rustc_ast/src/visit.rs

@@ -329,7 +329,7 @@ pub fn walk_poly_trait_ref<'a, V>(visitor: &mut V, trait_ref: &'a PolyTraitRef)
 where
     V: Visitor<'a>,
 {
-    let PolyTraitRef { bound_generic_params, trait_ref, span: _ } = trait_ref;
+    let PolyTraitRef { bound_generic_params, modifiers: _, trait_ref, span: _ } = trait_ref;
     walk_list!(visitor, visit_generic_param, bound_generic_params);
     visitor.visit_trait_ref(trait_ref)
 }
@@ -720,7 +720,7 @@ impl WalkItemKind for ForeignItemKind {
 
 pub fn walk_param_bound<'a, V: Visitor<'a>>(visitor: &mut V, bound: &'a GenericBound) -> V::Result {
     match bound {
-        GenericBound::Trait(typ, _modifier) => visitor.visit_poly_trait_ref(typ),
+        GenericBound::Trait(trait_ref) => visitor.visit_poly_trait_ref(trait_ref),
         GenericBound::Outlives(lifetime) => visitor.visit_lifetime(lifetime, LifetimeCtxt::Bound),
         GenericBound::Use(args, _span) => {
             walk_list!(visitor, visit_precise_capturing_arg, args);

compiler/rustc_ast_lowering/src/item.rs

@@ -1504,8 +1504,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
             for bound in &bound_pred.bounds {
                 if !matches!(
                     *bound,
-                    GenericBound::Trait(_, TraitBoundModifiers {
-                        polarity: BoundPolarity::Maybe(_),
+                    GenericBound::Trait(PolyTraitRef {
+                        modifiers: TraitBoundModifiers { polarity: BoundPolarity::Maybe(_), .. },
                         ..
                     })
                 ) {

compiler/rustc_ast_lowering/src/lib.rs

@@ -1219,11 +1219,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 let bound = this.lower_poly_trait_ref(
                     &PolyTraitRef {
                         bound_generic_params: ThinVec::new(),
+                        modifiers: TraitBoundModifiers::NONE,
                         trait_ref: TraitRef { path: path.clone(), ref_id: t.id },
                         span: t.span,
                     },
                     itctx,
-                    TraitBoundModifiers::NONE,
                 );
                 let bounds = this.arena.alloc_from_iter([bound]);
                 let lifetime_bound = this.elided_dyn_bound(t.span);
@@ -1325,8 +1325,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             // We can safely ignore constness here since AST validation
                             // takes care of rejecting invalid modifier combinations and
                             // const trait bounds in trait object types.
-                            GenericBound::Trait(ty, modifiers) => {
-                                let trait_ref = this.lower_poly_trait_ref(ty, itctx, *modifiers);
+                            GenericBound::Trait(ty) => {
+                                let trait_ref = this.lower_poly_trait_ref(ty, itctx);
                                 Some(trait_ref)
                             }
                             GenericBound::Outlives(lifetime) => {
@@ -1974,9 +1974,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         itctx: ImplTraitContext,
     ) -> hir::GenericBound<'hir> {
         match tpb {
-            GenericBound::Trait(p, modifiers) => {
-                hir::GenericBound::Trait(self.lower_poly_trait_ref(p, itctx, *modifiers))
-            }
+            GenericBound::Trait(p) => hir::GenericBound::Trait(self.lower_poly_trait_ref(p, itctx)),
             GenericBound::Outlives(lifetime) => {
                 hir::GenericBound::Outlives(self.lower_lifetime(lifetime))
             }
@@ -2180,12 +2178,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         &mut self,
         p: &PolyTraitRef,
         itctx: ImplTraitContext,
-        modifiers: ast::TraitBoundModifiers,
     ) -> hir::PolyTraitRef<'hir> {
         let bound_generic_params =
             self.lower_lifetime_binder(p.trait_ref.ref_id, &p.bound_generic_params);
-        let trait_ref = self.lower_trait_ref(modifiers, &p.trait_ref, itctx);
-        let modifiers = self.lower_trait_bound_modifiers(modifiers);
+        let trait_ref = self.lower_trait_ref(p.modifiers, &p.trait_ref, itctx);
+        let modifiers = self.lower_trait_bound_modifiers(p.modifiers);
         hir::PolyTraitRef {
             bound_generic_params,
             modifiers,

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1260,7 +1260,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     if !bound_pred.bound_generic_params.is_empty() {
                         for bound in &bound_pred.bounds {
                             match bound {
-                                GenericBound::Trait(t, _) => {
+                                GenericBound::Trait(t) => {
                                     if !t.bound_generic_params.is_empty() {
                                         self.dcx()
                                             .emit_err(errors::NestedLifetimes { span: t.span });
@@ -1280,8 +1280,8 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
     fn visit_param_bound(&mut self, bound: &'a GenericBound, ctxt: BoundKind) {
         match bound {
-            GenericBound::Trait(trait_ref, modifiers) => {
-                match (ctxt, modifiers.constness, modifiers.polarity) {
+            GenericBound::Trait(trait_ref) => {
+                match (ctxt, trait_ref.modifiers.constness, trait_ref.modifiers.polarity) {
                     (BoundKind::SuperTraits, BoundConstness::Never, BoundPolarity::Maybe(_))
                         if !self.features.more_maybe_bounds =>
                     {
@@ -1321,7 +1321,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 }
 
                 // Negative trait bounds are not allowed to have associated constraints
-                if let BoundPolarity::Negative(_) = modifiers.polarity
+                if let BoundPolarity::Negative(_) = trait_ref.modifiers.polarity
                     && let Some(segment) = trait_ref.trait_ref.path.segments.last()
                 {
                     match segment.args.as_deref() {
@@ -1669,7 +1669,9 @@ fn deny_equality_constraints(
             }),
         ) {
             for bound in bounds {
-                if let GenericBound::Trait(poly, TraitBoundModifiers::NONE) = bound {
+                if let GenericBound::Trait(poly) = bound
+                    && poly.modifiers == TraitBoundModifiers::NONE
+                {
                     if full_path.segments[..full_path.segments.len() - 1]
                         .iter()
                         .map(|segment| segment.ident.name)
@@ -1697,7 +1699,9 @@ fn deny_equality_constraints(
             ) {
                 if ident == potential_param.ident {
                     for bound in bounds {
-                        if let ast::GenericBound::Trait(poly, TraitBoundModifiers::NONE) = bound {
+                        if let ast::GenericBound::Trait(poly) = bound
+                            && poly.modifiers == TraitBoundModifiers::NONE
+                        {
                             suggest(poly, potential_assoc, predicate);
                         }
                     }

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -8,7 +8,6 @@ mod item;
 
 use std::borrow::Cow;
 
-use ast::TraitBoundModifiers;
 use rustc_ast::attr::AttrIdGenerator;
 use rustc_ast::ptr::P;
 use rustc_ast::token::{
@@ -1253,6 +1252,27 @@ impl<'a> State<'a> {
 
     fn print_poly_trait_ref(&mut self, t: &ast::PolyTraitRef) {
         self.print_formal_generic_params(&t.bound_generic_params);
+
+        let ast::TraitBoundModifiers { constness, asyncness, polarity } = t.modifiers;
+        match constness {
+            ast::BoundConstness::Never => {}
+            ast::BoundConstness::Always(_) | ast::BoundConstness::Maybe(_) => {
+                self.word_space(constness.as_str());
+            }
+        }
+        match asyncness {
+            ast::BoundAsyncness::Normal => {}
+            ast::BoundAsyncness::Async(_) => {
+                self.word_space(asyncness.as_str());
+            }
+        }
+        match polarity {
+            ast::BoundPolarity::Positive => {}
+            ast::BoundPolarity::Negative(_) | ast::BoundPolarity::Maybe(_) => {
+                self.word(polarity.as_str());
+            }
+        }
+
         self.print_trait_ref(&t.trait_ref)
     }
 
@@ -1740,31 +1760,7 @@ impl<'a> State<'a> {
             }
 
             match bound {
-                GenericBound::Trait(
-                    tref,
-                    TraitBoundModifiers { constness, asyncness, polarity },
-                ) => {
-                    match constness {
-                        ast::BoundConstness::Never => {}
-                        ast::BoundConstness::Always(_) | ast::BoundConstness::Maybe(_) => {
-                            self.word_space(constness.as_str());
-                        }
-                    }
-
-                    match asyncness {
-                        ast::BoundAsyncness::Normal => {}
-                        ast::BoundAsyncness::Async(_) => {
-                            self.word_space(asyncness.as_str());
-                        }
-                    }
-
-                    match polarity {
-                        ast::BoundPolarity::Positive => {}
-                        ast::BoundPolarity::Negative(_) | ast::BoundPolarity::Maybe(_) => {
-                            self.word(polarity.as_str());
-                        }
-                    }
-
+                GenericBound::Trait(tref) => {
                     self.print_poly_trait_ref(tref);
                 }
                 GenericBound::Outlives(lt) => self.print_lifetime(*lt),

compiler/rustc_builtin_macros/src/deriving/smart_ptr.rs

@@ -333,12 +333,12 @@ fn contains_maybe_sized_bound_on_pointee(predicates: &[WherePredicate], pointee:
 }
 
 fn is_maybe_sized_bound(bound: &GenericBound) -> bool {
-    if let GenericBound::Trait(
-        trait_ref,
-        TraitBoundModifiers { polarity: ast::BoundPolarity::Maybe(_), .. },
-    ) = bound
+    if let GenericBound::Trait(trait_ref) = bound
+        && let TraitBoundModifiers { polarity: ast::BoundPolarity::Maybe(_), .. } =
+            trait_ref.modifiers
+        && is_sized_marker(&trait_ref.trait_ref.path)
     {
-        is_sized_marker(&trait_ref.trait_ref.path)
+        true
     } else {
         false
     }

compiler/rustc_expand/src/build.rs

@@ -143,24 +143,25 @@ impl<'a> ExtCtxt<'a> {
         ast::TraitRef { path, ref_id: ast::DUMMY_NODE_ID }
     }
 
-    pub fn poly_trait_ref(&self, span: Span, path: ast::Path) -> ast::PolyTraitRef {
+    pub fn poly_trait_ref(&self, span: Span, path: ast::Path, is_const: bool) -> ast::PolyTraitRef {
         ast::PolyTraitRef {
             bound_generic_params: ThinVec::new(),
+            modifiers: ast::TraitBoundModifiers {
+                polarity: ast::BoundPolarity::Positive,
+                constness: if is_const {
+                    ast::BoundConstness::Maybe(DUMMY_SP)
+                } else {
+                    ast::BoundConstness::Never
+                },
+                asyncness: ast::BoundAsyncness::Normal,
+            },
             trait_ref: self.trait_ref(path),
             span,
         }
     }
 
     pub fn trait_bound(&self, path: ast::Path, is_const: bool) -> ast::GenericBound {
-        ast::GenericBound::Trait(self.poly_trait_ref(path.span, path), ast::TraitBoundModifiers {
-            polarity: ast::BoundPolarity::Positive,
-            constness: if is_const {
-                ast::BoundConstness::Maybe(DUMMY_SP)
-            } else {
-                ast::BoundConstness::Never
-            },
-            asyncness: ast::BoundAsyncness::Normal,
-        })
+        ast::GenericBound::Trait(self.poly_trait_ref(path.span, path, is_const))
     }
 
     pub fn lifetime(&self, span: Span, ident: Ident) -> ast::Lifetime {

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -2113,7 +2113,7 @@ impl<'a> Parser<'a> {
             && let Some(poly) = bounds
                 .iter()
                 .filter_map(|bound| match bound {
-                    ast::GenericBound::Trait(poly, _) => Some(poly),
+                    ast::GenericBound::Trait(poly) => Some(poly),
                     _ => None,
                 })
                 .last()

compiler/rustc_parse/src/parser/path.rs

@@ -948,8 +948,8 @@ impl<'a> Parser<'a> {
             {
                 return Ok((false, seg.ident, seg.args.as_deref().cloned()));
             } else if let ast::TyKind::TraitObject(bounds, ast::TraitObjectSyntax::None) = &ty.kind
-                && let [ast::GenericBound::Trait(trait_ref, ast::TraitBoundModifiers::NONE)] =
-                    bounds.as_slice()
+                && let [ast::GenericBound::Trait(trait_ref)] = bounds.as_slice()
+                && trait_ref.modifiers == ast::TraitBoundModifiers::NONE
                 && let [seg] = trait_ref.trait_ref.path.segments.as_slice()
             {
                 return Ok((true, seg.ident, seg.args.as_deref().cloned()));

compiler/rustc_parse/src/parser/ty.rs

@@ -419,8 +419,13 @@ impl<'a> Parser<'a> {
         lo: Span,
         parse_plus: bool,
     ) -> PResult<'a, TyKind> {
-        let poly_trait_ref = PolyTraitRef::new(generic_params, path, lo.to(self.prev_token.span));
-        let bounds = vec![GenericBound::Trait(poly_trait_ref, TraitBoundModifiers::NONE)];
+        let poly_trait_ref = PolyTraitRef::new(
+            generic_params,
+            path,
+            TraitBoundModifiers::NONE,
+            lo.to(self.prev_token.span),
+        );
+        let bounds = vec![GenericBound::Trait(poly_trait_ref)];
         self.parse_remaining_bounds(bounds, parse_plus)
     }
 
@@ -1085,8 +1090,9 @@ impl<'a> Parser<'a> {
             }
         }
 
-        let poly_trait = PolyTraitRef::new(lifetime_defs, path, lo.to(self.prev_token.span));
-        Ok(GenericBound::Trait(poly_trait, modifiers))
+        let poly_trait =
+            PolyTraitRef::new(lifetime_defs, path, modifiers, lo.to(self.prev_token.span));
+        Ok(GenericBound::Trait(poly_trait))
     }
 
     // recovers a `Fn(..)` parenthesized-style path from `fn(..)`