Rollup merge of #131652 - compiler-errors:modifiers, r=Nadrieril,jieyouxu

Move polarity into `PolyTraitRef` rather than storing it on the side

Arguably we could move these modifiers into `TraitRef` instead of `PolyTraitRef`, but I see `TraitRef` as simply the *path* part of the trait ref. It doesn't really matter -- refactoring this further is much easier now.

Author: matthiaskrgr

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

@@ -1219,13 +1219,12 @@ 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 bound = (bound, hir::TraitBoundModifier::None);
                 let bounds = this.arena.alloc_from_iter([bound]);
                 let lifetime_bound = this.elided_dyn_bound(t.span);
                 (bounds, lifetime_bound)
@@ -1326,10 +1325,9 @@ 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);
-                                let polarity = this.lower_trait_bound_modifiers(*modifiers);
-                                Some((trait_ref, polarity))
+                            GenericBound::Trait(ty) => {
+                                let trait_ref = this.lower_poly_trait_ref(ty, itctx);
+                                Some(trait_ref)
                             }
                             GenericBound::Outlives(lifetime) => {
                                 if lifetime_bound.is_none() {
@@ -1958,21 +1956,15 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             span_ext: DUMMY_SP,
         });
 
-        hir::GenericBound::Trait(
-            hir::PolyTraitRef {
-                bound_generic_params: &[],
-                trait_ref: hir::TraitRef {
-                    path: self.make_lang_item_path(
-                        trait_lang_item,
-                        opaque_ty_span,
-                        Some(bound_args),
-                    ),
-                    hir_ref_id: self.next_id(),
-                },
-                span: opaque_ty_span,
+        hir::GenericBound::Trait(hir::PolyTraitRef {
+            bound_generic_params: &[],
+            modifiers: hir::TraitBoundModifier::None,
+            trait_ref: hir::TraitRef {
+                path: self.make_lang_item_path(trait_lang_item, opaque_ty_span, Some(bound_args)),
+                hir_ref_id: self.next_id(),
             },
-            hir::TraitBoundModifier::None,
-        )
+            span: opaque_ty_span,
+        })
     }
 
     #[instrument(level = "trace", skip(self))]
@@ -1982,10 +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),
-                self.lower_trait_bound_modifiers(*modifiers),
-            ),
+            GenericBound::Trait(p) => hir::GenericBound::Trait(self.lower_poly_trait_ref(p, itctx)),
             GenericBound::Outlives(lifetime) => {
                 hir::GenericBound::Outlives(self.lower_lifetime(lifetime))
             }
@@ -2189,12 +2178,17 @@ 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);
-        hir::PolyTraitRef { bound_generic_params, trait_ref, span: self.lower_span(p.span) }
+        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,
+            trait_ref,
+            span: self.lower_span(p.span),
+        }
     }
 
     fn lower_mt(&mut self, mt: &MutTy, itctx: ImplTraitContext) -> hir::MutTy<'hir> {
@@ -2634,10 +2628,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     Res::Def(DefKind::Trait | DefKind::TraitAlias, _) => {
                         let principal = hir::PolyTraitRef {
                             bound_generic_params: &[],
+                            modifiers: hir::TraitBoundModifier::None,
                             trait_ref: hir::TraitRef { path, hir_ref_id: hir_id },
                             span: self.lower_span(span),
                         };
-                        let principal = (principal, hir::TraitBoundModifier::None);
 
                         // The original ID is taken by the `PolyTraitRef`,
                         // so the `Ty` itself needs a different one.

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1263,7 +1263,7 @@ 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 });
@@ -1283,8 +1283,8 @@ 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 =>
                     {
@@ -1324,7 +1324,7 @@ 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() {
@@ -1672,7 +1672,9 @@ 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)
@@ -1700,7 +1702,9 @@ 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_borrowck/src/diagnostics/region_errors.rs

@@ -254,7 +254,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
         debug!(?hrtb_bounds);
 
         hrtb_bounds.iter().for_each(|bound| {
-            let Trait(PolyTraitRef { trait_ref, span: trait_span, .. }, _) = bound else {
+            let Trait(PolyTraitRef { trait_ref, span: trait_span, .. }) = bound else {
                 return;
             };
             diag.span_note(*trait_span, fluent::borrowck_limitations_implies_static);
@@ -277,7 +277,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                     return;
                 };
                 bounds.iter().for_each(|bd| {
-                    if let Trait(PolyTraitRef { trait_ref: tr_ref, .. }, _) = bd
+                    if let Trait(PolyTraitRef { trait_ref: tr_ref, .. }) = bd
                         && let Def(_, res_defid) = tr_ref.path.res
                         && res_defid == trait_res_defid // trait id matches
                         && let TyKind::Path(Resolved(_, path)) = bounded_ty.kind

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -837,7 +837,7 @@ impl<'tcx> MirBorrowckCtxt<'_, '_, 'tcx> {
                 hir_ty
             );
         };
-        if let hir::OpaqueTy { bounds: [hir::GenericBound::Trait(trait_ref, _)], .. } = opaque_ty
+        if let hir::OpaqueTy { bounds: [hir::GenericBound::Trait(trait_ref)], .. } = opaque_ty
             && let Some(segment) = trait_ref.trait_ref.path.segments.last()
             && let Some(args) = segment.args
             && let [constraint] = args.constraints