Auto merge of #83424 - cjgillot:noparam, r=lcnr

GenericParam does not need to be a HIR owner.

The special case is not required.

Universal impl traits design to regular generic parameters, and their content is owned by the enclosing item.

Existential (and opaque) impl traits generate their own enclosing item, and are collected through it.

4 files changed, 6 insertions, 54 deletions

diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 5385c4d72e4..046e7fc70fc 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -520,10 +520,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         }
                         self.visit_fn_ret_ty(&f.decl.output)
                     }
-                    TyKind::ImplTrait(def_node_id, _) => {
-                        self.lctx.allocate_hir_id_counter(def_node_id);
-                        visit::walk_ty(self, t);
-                    }
                     _ => visit::walk_ty(self, t),
                 }
             }
@@ -1431,14 +1427,10 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         // Add a definition for the in-band `Param`.
                         let def_id = self.resolver.local_def_id(def_node_id);
 
-                        self.allocate_hir_id_counter(def_node_id);
-
-                        let hir_bounds = self.with_hir_id_owner(def_node_id, |this| {
-                            this.lower_param_bounds(
-                                bounds,
-                                ImplTraitContext::Universal(in_band_ty_params, parent_def_id),
-                            )
-                        });
+                        let hir_bounds = self.lower_param_bounds(
+                            bounds,
+                            ImplTraitContext::Universal(in_band_ty_params, parent_def_id),
+                        );
                         // Set the name to `impl Bound1 + Bound2`.
                         let ident = Ident::from_str_and_span(&pprust::ty_to_string(t), span);
                         in_band_ty_params.push(hir::GenericParam {
diff --git a/compiler/rustc_middle/src/hir/map/collector.rs b/compiler/rustc_middle/src/hir/map/collector.rs
index 4602ed695fe..501e7d624d2 100644
--- a/compiler/rustc_middle/src/hir/map/collector.rs
+++ b/compiler/rustc_middle/src/hir/map/collector.rs
@@ -373,26 +373,8 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
     }
 
     fn visit_generic_param(&mut self, param: &'hir GenericParam<'hir>) {
-        if let hir::GenericParamKind::Type {
-            synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
-            ..
-        } = param.kind
-        {
-            debug_assert_eq!(
-                param.hir_id.owner,
-                self.definitions.opt_hir_id_to_local_def_id(param.hir_id).unwrap()
-            );
-            self.with_dep_node_owner(param.hir_id.owner, param, |this, hash| {
-                this.insert_with_hash(param.span, param.hir_id, Node::GenericParam(param), hash);
-
-                this.with_parent(param.hir_id, |this| {
-                    intravisit::walk_generic_param(this, param);
-                });
-            });
-        } else {
-            self.insert(param.span, param.hir_id, Node::GenericParam(param));
-            intravisit::walk_generic_param(self, param);
-        }
+        self.insert(param.span, param.hir_id, Node::GenericParam(param));
+        intravisit::walk_generic_param(self, param);
     }
 
     fn visit_const_param_default(&mut self, param: HirId, ct: &'hir AnonConst) {
diff --git a/compiler/rustc_passes/src/hir_id_validator.rs b/compiler/rustc_passes/src/hir_id_validator.rs
index 79e3b5952ac..944a3097a61 100644
--- a/compiler/rustc_passes/src/hir_id_validator.rs
+++ b/compiler/rustc_passes/src/hir_id_validator.rs
@@ -172,17 +172,4 @@ impl<'a, 'hir> intravisit::Visitor<'hir> for HirIdValidator<'a, 'hir> {
         // we are currently in. So for those it's correct that they have a
         // different owner.
     }
-
-    fn visit_generic_param(&mut self, param: &'hir hir::GenericParam<'hir>) {
-        if let hir::GenericParamKind::Type {
-            synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
-            ..
-        } = param.kind
-        {
-            // Synthetic impl trait parameters are owned by the node of the desugared type.
-            // This means it is correct for them to have a different owner.
-        } else {
-            intravisit::walk_generic_param(self, param);
-        }
-    }
 }
diff --git a/compiler/rustc_save_analysis/src/dump_visitor.rs b/compiler/rustc_save_analysis/src/dump_visitor.rs
index 15435df32be..65f16ff45a1 100644
--- a/compiler/rustc_save_analysis/src/dump_visitor.rs
+++ b/compiler/rustc_save_analysis/src/dump_visitor.rs
@@ -320,15 +320,6 @@ impl<'tcx> DumpVisitor<'tcx> {
         for param in generics.params {
             match param.kind {
                 hir::GenericParamKind::Lifetime { .. } => {}
-                hir::GenericParamKind::Type {
-                    synthetic: Some(hir::SyntheticTyParamKind::ImplTrait),
-                    ..
-                } => {
-                    return self
-                        .nest_typeck_results(self.tcx.hir().local_def_id(param.hir_id), |this| {
-                            this.visit_generics(generics)
-                        });
-                }
                 hir::GenericParamKind::Type { .. } => {
                     let param_ss = param.name.ident().span;
                     let name = escape(self.span.snippet(param_ss));