Auto merge of #90675 - camelid:cleanup-impl, r=jyn514

rustdoc: Cleanup `clean::Impl` and other parts of `clean`

This PR cleans up and reduces the size of `clean::Impl`, makes some other small performance improvements, and removes some Clean impls that are either unnecessary or potentially confusing.

r? `@jyn514`

src/librustdoc/clean/auto_trait.rs

@@ -76,17 +76,17 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
             new_generics
         });
 
-        let negative_polarity;
+        let polarity;
         let new_generics = match result {
             AutoTraitResult::PositiveImpl(new_generics) => {
-                negative_polarity = false;
+                polarity = ty::ImplPolarity::Positive;
                 if discard_positive_impl {
                     return None;
                 }
                 new_generics
             }
             AutoTraitResult::NegativeImpl => {
-                negative_polarity = true;
+                polarity = ty::ImplPolarity::Negative;
 
                 // For negative impls, we use the generic params, but *not* the predicates,
                 // from the original type. Otherwise, the displayed impl appears to be a
@@ -115,15 +115,13 @@ impl<'a, 'tcx> AutoTraitFinder<'a, 'tcx> {
             visibility: Inherited,
             def_id: ItemId::Auto { trait_: trait_def_id, for_: item_def_id },
             kind: box ImplItem(Impl {
-                span: Span::dummy(),
                 unsafety: hir::Unsafety::Normal,
                 generics: new_generics,
                 trait_: Some(trait_ref.clean(self.cx)),
                 for_: ty.clean(self.cx),
                 items: Vec::new(),
-                negative_polarity,
-                synthetic: true,
-                blanket_impl: None,
+                polarity,
+                kind: ImplKind::Auto,
             }),
             cfg: None,
         })

src/librustdoc/clean/blanket_impl.rs

@@ -106,7 +106,6 @@ impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
                     visibility: Inherited,
                     def_id: ItemId::Blanket { impl_id: impl_def_id, for_: item_def_id },
                     kind: box ImplItem(Impl {
-                        span: Span::new(self.cx.tcx.def_span(impl_def_id)),
                         unsafety: hir::Unsafety::Normal,
                         generics: (
                             self.cx.tcx.generics_of(impl_def_id),
@@ -122,11 +121,10 @@ impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
                             .tcx
                             .associated_items(impl_def_id)
                             .in_definition_order()
-                            .collect::<Vec<_>>()
-                            .clean(self.cx),
-                        negative_polarity: false,
-                        synthetic: false,
-                        blanket_impl: Some(box trait_ref.self_ty().clean(self.cx)),
+                            .map(|x| x.clean(self.cx))
+                            .collect::<Vec<_>>(),
+                        polarity: ty::ImplPolarity::Positive,
+                        kind: ImplKind::Blanket(box trait_ref.self_ty().clean(self.cx)),
                     }),
                     cfg: None,
                 });

src/librustdoc/clean/inline.rs

@@ -14,7 +14,9 @@ use rustc_middle::ty::{self, TyCtxt};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::{kw, sym, Symbol};
 
-use crate::clean::{self, utils, Attributes, AttributesExt, ItemId, NestedAttributesExt, Type};
+use crate::clean::{
+    self, utils, Attributes, AttributesExt, ImplKind, ItemId, NestedAttributesExt, Type,
+};
 use crate::core::DocContext;
 use crate::formats::item_type::ItemType;
 
@@ -242,7 +244,7 @@ fn build_enum(cx: &mut DocContext<'_>, did: DefId) -> clean::Enum {
     clean::Enum {
         generics: (cx.tcx.generics_of(did), predicates).clean(cx),
         variants_stripped: false,
-        variants: cx.tcx.adt_def(did).variants.clean(cx),
+        variants: cx.tcx.adt_def(did).variants.iter().map(|v| v.clean(cx)).collect(),
     }
 }
 
@@ -253,7 +255,7 @@ fn build_struct(cx: &mut DocContext<'_>, did: DefId) -> clean::Struct {
     clean::Struct {
         struct_type: variant.ctor_kind,
         generics: (cx.tcx.generics_of(did), predicates).clean(cx),
-        fields: variant.fields.clean(cx),
+        fields: variant.fields.iter().map(|x| x.clean(cx)).collect(),
         fields_stripped: false,
     }
 }
@@ -262,11 +264,9 @@ fn build_union(cx: &mut DocContext<'_>, did: DefId) -> clean::Union {
     let predicates = cx.tcx.explicit_predicates_of(did);
     let variant = cx.tcx.adt_def(did).non_enum_variant();
 
-    clean::Union {
-        generics: (cx.tcx.generics_of(did), predicates).clean(cx),
-        fields: variant.fields.clean(cx),
-        fields_stripped: false,
-    }
+    let generics = (cx.tcx.generics_of(did), predicates).clean(cx);
+    let fields = variant.fields.iter().map(|x| x.clean(cx)).collect();
+    clean::Union { generics, fields, fields_stripped: false }
 }
 
 fn build_type_alias(cx: &mut DocContext<'_>, did: DefId) -> clean::Typedef {
@@ -446,7 +446,7 @@ crate fn build_impl(
         ),
     };
     let polarity = tcx.impl_polarity(did);
-    let trait_ = associated_trait.clean(cx);
+    let trait_ = associated_trait.map(|t| t.clean(cx));
     if trait_.as_ref().map(|t| t.def_id()) == tcx.lang_items().deref_trait() {
         super::build_deref_target_impls(cx, &trait_items, ret);
     }
@@ -490,15 +490,13 @@ crate fn build_impl(
         did,
         None,
         clean::ImplItem(clean::Impl {
-            span: clean::types::rustc_span(did, cx.tcx),
             unsafety: hir::Unsafety::Normal,
             generics,
             trait_,
             for_,
             items: trait_items,
-            negative_polarity: polarity.clean(cx),
-            synthetic: false,
-            blanket_impl: None,
+            polarity,
+            kind: ImplKind::Normal,
         }),
         box merged_attrs,
         cx,