Factor out GenericBound::LangItemTrait

Author: camsteffen

compiler/rustc_ast_lowering/src/lib.rs

@@ -800,8 +800,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn lower_ident(&self, ident: Ident) -> Ident {
         Ident::new(ident.name, self.lower_span(ident.span))
     }
-
-    fn lang_item_qpath(&mut self, lang_item: hir::LangItem, span: Span) -> hir::QPath<'hir> {
+    fn lang_item_path(
+        &mut self,
+        lang_item: hir::LangItem,
+        args: Option<&'hir hir::GenericArgs<'hir>>,
+        span: Span,
+    ) -> &'hir hir::Path<'hir> {
         let def_id = self.tcx.require_lang_item(lang_item, Some(span));
         let res = Res::Def(lang_item.target().to_def_kind(), def_id);
         let name = self.tcx.item_name(def_id);
@@ -812,10 +816,20 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     // associated items require a self segment - this works well enough
                     hir::PathSegment::new(Ident::empty(), self.next_id(), Res::Err)
                 });
-        let segment = hir::PathSegment::new(Ident::new(name, span), self.next_id(), res);
+        let segment = hir::PathSegment {
+            ident: Ident::new(name, span),
+            hir_id: self.next_id(),
+            res,
+            infer_args: args.is_none(),
+            args,
+        };
         let segments =
             self.arena.alloc_from_iter(self_segment.into_iter().chain(iter::once(segment)));
-        let path = self.arena.alloc(hir::Path { span, res, segments });
+        self.arena.alloc(hir::Path { span, res, segments })
+    }
+
+    fn lang_item_qpath(&mut self, lang_item: hir::LangItem, span: Span) -> hir::QPath<'hir> {
+        let path = self.lang_item_path(lang_item, None, span);
         hir::QPath::Resolved(None, path)
     }
 
@@ -2088,21 +2102,22 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             }
             FnRetTy::Default(ret_ty_span) => self.arena.alloc(self.ty_tup(*ret_ty_span, &[])),
         };
-
+        let span = self.lower_span(span);
         // "<Output = T>"
         let future_args = self.arena.alloc(hir::GenericArgs {
             args: &[],
             bindings: arena_vec![self; self.output_ty_binding(span, output_ty)],
             parenthesized: false,
             span_ext: DUMMY_SP,
         });
-
-        hir::GenericBound::LangItemTrait(
-            // ::std::future::Future<future_params>
-            hir::LangItem::Future,
-            self.lower_span(span),
-            self.next_id(),
-            future_args,
+        let path = self.lang_item_path(hir::LangItem::Future, Some(future_args), span);
+        hir::GenericBound::Trait(
+            hir::PolyTraitRef {
+                bound_generic_params: &[],
+                trait_ref: hir::TraitRef { path, hir_ref_id: self.next_id() },
+                span,
+            },
+            hir::TraitBoundModifier::None,
         )
     }
 

compiler/rustc_borrowck/src/diagnostics/region_name.rs

@@ -781,22 +781,34 @@ impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
         if let hir::ItemKind::OpaqueTy(hir::OpaqueTy {
             bounds:
                 [
-                    hir::GenericBound::LangItemTrait(
-                        hir::LangItem::Future,
-                        _,
-                        _,
-                        hir::GenericArgs {
-                            bindings:
-                                [
-                                    hir::TypeBinding {
-                                        ident: Ident { name: sym::Output, .. },
-                                        kind:
-                                            hir::TypeBindingKind::Equality { term: hir::Term::Ty(ty) },
-                                        ..
-                                    },
-                                ],
+                    hir::GenericBound::Trait(
+                        hir::PolyTraitRef {
+                            trait_ref: hir::TraitRef {
+                                path: hir::Path {
+                                    segments: [
+                                        ..,
+                                        hir::PathSegment {
+                                            args: Some(hir::GenericArgs {
+                                                args: [],
+                                                bindings: [hir::TypeBinding {
+                                                    ident: Ident { name: sym::Output, .. },
+                                                    kind: hir::TypeBindingKind::Equality {
+                                                        term: hir::Term::Ty(ty)
+                                                    },
+                                                    ..
+                                                }],
+                                                ..
+                                           }),
+                                            ..
+                                        }
+                                    ],
+                                    ..
+                                },
+                                ..
+                            },
                             ..
                         },
+                        _,
                     ),
                 ],
             ..

compiler/rustc_hir/src/hir.rs

@@ -2,7 +2,6 @@ use crate::def::{CtorKind, DefKind, Res};
 use crate::def_id::DefId;
 pub(crate) use crate::hir_id::{HirId, ItemLocalId, OwnerId};
 use crate::intravisit::FnKind;
-use crate::LangItem;
 
 use rustc_ast as ast;
 use rustc_ast::util::parser::ExprPrecedence;
@@ -427,8 +426,6 @@ pub enum TraitBoundModifier {
 #[derive(Clone, Debug, HashStable_Generic)]
 pub enum GenericBound<'hir> {
     Trait(PolyTraitRef<'hir>, TraitBoundModifier),
-    // FIXME(davidtwco): Introduce `PolyTraitRef::LangItem`
-    LangItemTrait(LangItem, Span, HirId, &'hir GenericArgs<'hir>),
     Outlives(&'hir Lifetime),
 }
 
@@ -443,7 +440,6 @@ impl GenericBound<'_> {
     pub fn span(&self) -> Span {
         match self {
             GenericBound::Trait(t, ..) => t.span,
-            GenericBound::LangItemTrait(_, span, ..) => *span,
             GenericBound::Outlives(l) => l.span,
         }
     }

compiler/rustc_hir/src/intravisit.rs

@@ -809,10 +809,6 @@ pub fn walk_param_bound<'v, V: Visitor<'v>>(visitor: &mut V, bound: &'v GenericB
         GenericBound::Trait(ref typ, _modifier) => {
             visitor.visit_poly_trait_ref(typ);
         }
-        GenericBound::LangItemTrait(_, _span, hir_id, args) => {
-            visitor.visit_id(hir_id);
-            visitor.visit_generic_args(args);
-        }
         GenericBound::Outlives(ref lifetime) => visitor.visit_lifetime(lifetime),
     }
 }

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -642,37 +642,57 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         )
     }
 
-    fn instantiate_poly_trait_ref_inner(
+    /// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct
+    /// a full trait reference. The resulting trait reference is returned. This may also generate
+    /// auxiliary bounds, which are added to `bounds`.
+    ///
+    /// Example:
+    ///
+    /// ```ignore (illustrative)
+    /// poly_trait_ref = Iterator<Item = u32>
+    /// self_ty = Foo
+    /// ```
+    ///
+    /// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`.
+    ///
+    /// **A note on binders:** against our usual convention, there is an implied bounder around
+    /// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions.
+    /// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>`
+    /// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be
+    /// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly,
+    /// however.
+    #[instrument(level = "debug", skip(self, span, constness, bounds, speculative))]
+    pub(crate) fn instantiate_poly_trait_ref(
         &self,
-        hir_id: hir::HirId,
+        trait_ref: &hir::TraitRef<'_>,
         span: Span,
-        binding_span: Option<Span>,
         constness: ty::BoundConstness,
+        self_ty: Ty<'tcx>,
         bounds: &mut Bounds<'tcx>,
         speculative: bool,
-        trait_ref_span: Span,
-        trait_def_id: DefId,
-        trait_segment: &hir::PathSegment<'_>,
-        args: &GenericArgs<'_>,
-        infer_args: bool,
-        self_ty: Ty<'tcx>,
     ) -> GenericArgCountResult {
+        let trait_def_id = trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise());
+        let trait_segment = trait_ref.path.segments.last().unwrap();
+
+        self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {});
+        self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, false);
+
         let (substs, arg_count) = self.create_substs_for_ast_path(
-            trait_ref_span,
+            trait_ref.path.span,
             trait_def_id,
             &[],
             trait_segment,
-            args,
-            infer_args,
+            trait_segment.args(),
+            trait_segment.infer_args,
             Some(self_ty),
             Some(constness),
         );
 
         let tcx = self.tcx();
-        let bound_vars = tcx.late_bound_vars(hir_id);
+        let bound_vars = tcx.late_bound_vars(trait_ref.hir_ref_id);
         debug!(?bound_vars);
 
-        let assoc_bindings = self.create_assoc_bindings_for_generic_args(args);
+        let assoc_bindings = self.create_assoc_bindings_for_generic_args(trait_segment.args());
 
         let poly_trait_ref =
             ty::Binder::bind_with_vars(ty::TraitRef::new(trait_def_id, substs), bound_vars);
@@ -684,13 +704,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         for binding in &assoc_bindings {
             // Specify type to assert that error was already reported in `Err` case.
             let _: Result<_, ErrorGuaranteed> = self.add_predicates_for_ast_type_binding(
-                hir_id,
+                trait_ref.hir_ref_id,
                 poly_trait_ref,
                 binding,
                 bounds,
                 speculative,
                 &mut dup_bindings,
-                binding_span.unwrap_or(binding.span),
+                binding.span,
                 constness,
             );
             // Okay to ignore `Err` because of `ErrorGuaranteed` (see above).
@@ -699,95 +719,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         arg_count
     }
 
-    /// Given a trait bound like `Debug`, applies that trait bound the given self-type to construct
-    /// a full trait reference. The resulting trait reference is returned. This may also generate
-    /// auxiliary bounds, which are added to `bounds`.
-    ///
-    /// Example:
-    ///
-    /// ```ignore (illustrative)
-    /// poly_trait_ref = Iterator<Item = u32>
-    /// self_ty = Foo
-    /// ```
-    ///
-    /// this would return `Foo: Iterator` and add `<Foo as Iterator>::Item = u32` into `bounds`.
-    ///
-    /// **A note on binders:** against our usual convention, there is an implied bounder around
-    /// the `self_ty` and `poly_trait_ref` parameters here. So they may reference bound regions.
-    /// If for example you had `for<'a> Foo<'a>: Bar<'a>`, then the `self_ty` would be `Foo<'a>`
-    /// where `'a` is a bound region at depth 0. Similarly, the `poly_trait_ref` would be
-    /// `Bar<'a>`. The returned poly-trait-ref will have this binder instantiated explicitly,
-    /// however.
-    #[instrument(level = "debug", skip(self, span, constness, bounds, speculative))]
-    pub(crate) fn instantiate_poly_trait_ref(
-        &self,
-        trait_ref: &hir::TraitRef<'_>,
-        span: Span,
-        constness: ty::BoundConstness,
-        self_ty: Ty<'tcx>,
-        bounds: &mut Bounds<'tcx>,
-        speculative: bool,
-    ) -> GenericArgCountResult {
-        let hir_id = trait_ref.hir_ref_id;
-        let binding_span = None;
-        let trait_ref_span = trait_ref.path.span;
-        let trait_def_id = trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise());
-        let trait_segment = trait_ref.path.segments.last().unwrap();
-        let args = trait_segment.args();
-        let infer_args = trait_segment.infer_args;
-
-        self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {});
-        self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, false);
-
-        self.instantiate_poly_trait_ref_inner(
-            hir_id,
-            span,
-            binding_span,
-            constness,
-            bounds,
-            speculative,
-            trait_ref_span,
-            trait_def_id,
-            trait_segment,
-            args,
-            infer_args,
-            self_ty,
-        )
-    }
-
-    pub(crate) fn instantiate_lang_item_trait_ref(
-        &self,
-        lang_item: hir::LangItem,
-        span: Span,
-        hir_id: hir::HirId,
-        args: &GenericArgs<'_>,
-        self_ty: Ty<'tcx>,
-        bounds: &mut Bounds<'tcx>,
-    ) {
-        let binding_span = Some(span);
-        let constness = ty::BoundConstness::NotConst;
-        let speculative = false;
-        let trait_ref_span = span;
-        let trait_def_id = self.tcx().require_lang_item(lang_item, Some(span));
-        let trait_segment = &hir::PathSegment::invalid();
-        let infer_args = false;
-
-        self.instantiate_poly_trait_ref_inner(
-            hir_id,
-            span,
-            binding_span,
-            constness,
-            bounds,
-            speculative,
-            trait_ref_span,
-            trait_def_id,
-            trait_segment,
-            args,
-            infer_args,
-            self_ty,
-        );
-    }
-
     fn ast_path_to_mono_trait_ref(
         &self,
         span: Span,
@@ -953,11 +884,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         false,
                     );
                 }
-                &hir::GenericBound::LangItemTrait(lang_item, span, hir_id, args) => {
-                    self.instantiate_lang_item_trait_ref(
-                        lang_item, span, hir_id, args, param_ty, bounds,
-                    );
-                }
                 hir::GenericBound::Outlives(lifetime) => {
                     let region = self.ast_region_to_region(lifetime, None);
                     bounds

compiler/rustc_hir_analysis/src/collect/lifetimes.rs

@@ -1074,32 +1074,6 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
         })
     }
 
-    fn visit_param_bound(&mut self, bound: &'tcx hir::GenericBound<'tcx>) {
-        match bound {
-            hir::GenericBound::LangItemTrait(_, _, hir_id, _) => {
-                // FIXME(jackh726): This is pretty weird. `LangItemTrait` doesn't go
-                // through the regular poly trait ref code, so we don't get another
-                // chance to introduce a binder. For now, I'm keeping the existing logic
-                // of "if there isn't a Binder scope above us, add one", but I
-                // imagine there's a better way to go about this.
-                let (binders, scope_type) = self.poly_trait_ref_binder_info();
-
-                self.record_late_bound_vars(*hir_id, binders);
-                let scope = Scope::Binder {
-                    hir_id: *hir_id,
-                    lifetimes: FxIndexMap::default(),
-                    s: self.scope,
-                    scope_type,
-                    where_bound_origin: None,
-                };
-                self.with(scope, |this| {
-                    intravisit::walk_param_bound(this, bound);
-                });
-            }
-            _ => intravisit::walk_param_bound(self, bound),
-        }
-    }
-
     fn visit_poly_trait_ref(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) {
         debug!("visit_poly_trait_ref(trait_ref={:?})", trait_ref);
 

compiler/rustc_hir_pretty/src/lib.rs

@@ -2102,11 +2102,6 @@ impl<'a> State<'a> {
                     }
                     self.print_poly_trait_ref(tref);
                 }
-                GenericBound::LangItemTrait(lang_item, span, ..) => {
-                    self.word("#[lang = \"");
-                    self.print_ident(Ident::new(lang_item.name(), *span));
-                    self.word("\"]");
-                }
                 GenericBound::Outlives(lt) => {
                     self.print_lifetime(lt);
                 }