Address review comments

Author: aerooneqq

compiler/rustc_ast_lowering/src/delegation/generics.rs

@@ -6,7 +6,7 @@ use rustc_hir::def_id::DefId;
 use rustc_middle::ty::GenericParamDefKind;
 use rustc_middle::{bug, ty};
 use rustc_span::symbol::kw;
-use rustc_span::{Ident, Span, Symbol};
+use rustc_span::{Ident, Span, sym};
 
 use crate::{LoweringContext, ResolverAstLoweringExt};
 
@@ -115,9 +115,8 @@ impl<'hir> HirOrTyGenerics<'hir> {
         ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
         span: Span,
     ) -> &mut HirOrTyGenerics<'hir> {
-        let rename_self = matches!(self.position(), GenericsPosition::Child);
-
         if let HirOrTyGenerics::Ty(ty) = self {
+            let rename_self = matches!(ty.pos, GenericsPosition::Child);
             let params = ctx.uplift_delegation_generic_params(span, ty.generics, rename_self);
 
             *self = HirOrTyGenerics::Hir(DelegationGenerics {
@@ -147,7 +146,7 @@ impl<'hir> HirOrTyGenerics<'hir> {
                 bug!("Attempting to get generic args before uplifting to HIR")
             }
             HirOrTyGenerics::Hir(hir) => {
-                let add_lifetimes = matches!(self.position(), GenericsPosition::Parent);
+                let add_lifetimes = matches!(hir.pos, GenericsPosition::Parent);
                 ctx.create_generics_args_from_params(hir.generics.params, add_lifetimes, span)
             }
         }
@@ -159,13 +158,6 @@ impl<'hir> HirOrTyGenerics<'hir> {
             HirOrTyGenerics::Hir(hir) => hir.kind.args_propagation_details(),
         }
     }
-
-    pub(super) fn position(&self) -> GenericsPosition {
-        match self {
-            HirOrTyGenerics::Ty(ty) => ty.pos,
-            HirOrTyGenerics::Hir(hir) => hir.pos,
-        }
-    }
 }
 
 impl<'hir> GenericsGenerationResult<'hir> {
@@ -341,14 +333,12 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
             // applies to traits, `trait Trait<Self> {}` will be represented as
             // `trait Trait {}` in HIR and "unexpected keyword `Self` in generic parameters"
             // error will be emitted.
-            // Note that we do not rename `Self` to `This` after first reuse from Trait,
-            // in this case the Self should not be propagated
+            // Note that we do not rename `Self` to `This` after non-recursive reuse
+            // from Trait, in this case the `Self` should not be propagated
+            // (we rely that implicit `Self` generic param of a trait is named "Self")
             // and it is OK to have Self generic param generated during lowering.
-            let param_name = if rename_self && p.name == kw::SelfUpper {
-                Symbol::intern(&format!("This"))
-            } else {
-                p.name
-            };
+            let param_name =
+                if rename_self && p.name == kw::SelfUpper { sym::This } else { p.name };
 
             let param_ident = Ident::new(param_name, span);
             let def_name = Some(param_ident.name);