Auto merge of rust-lang#93938 - BoxyUwU:fix_res_self_ty, r=lcnr

Make `Res::SelfTy` a struct variant and update docs

I found pattern matching on a `(Option<DefId>, Option<(DefId, bool)>)` to not be super readable, additionally the doc comments on the types in a tuple variant aren't visible anywhere at use sites as far as I can tell (using rust analyzer + vscode)

The docs incorrectly assumed that the `DefId` in `Option<(DefId, bool)>` would only ever be for an impl item and I also found the code examples to be somewhat unclear about which `DefId` was being talked about.

r? `@lcnr` since you reviewed the last PR changing these docs

clippy_lints/src/trait_bounds.rs

@@ -98,7 +98,7 @@ impl<'tcx> LateLintPass<'tcx> for TraitBounds {
                 if let WherePredicate::BoundPredicate(ref bound_predicate) = predicate;
                 if !bound_predicate.span.from_expansion();
                 if let TyKind::Path(QPath::Resolved(_, Path { segments, .. })) = bound_predicate.bounded_ty.kind;
-                if let Some(PathSegment { res: Some(Res::SelfTy(Some(def_id), _)), .. }) = segments.first();
+                if let Some(PathSegment { res: Some(Res::SelfTy{ trait_: Some(def_id), alias_to: _ }), .. }) = segments.first();
 
                 if let Some(
                     Node::Item(

clippy_lints/src/use_self.rs

@@ -204,7 +204,7 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
                 ref types_to_skip,
             }) = self.stack.last();
             if let TyKind::Path(QPath::Resolved(_, path)) = hir_ty.kind;
-            if !matches!(path.res, Res::SelfTy(..) | Res::Def(DefKind::TyParam, _));
+            if !matches!(path.res, Res::SelfTy { .. } | Res::Def(DefKind::TyParam, _));
             if !types_to_skip.contains(&hir_ty.hir_id);
             let ty = if in_body > 0 {
                 cx.typeck_results().node_type(hir_ty.hir_id)
@@ -231,7 +231,7 @@ impl<'tcx> LateLintPass<'tcx> for UseSelf {
         }
         match expr.kind {
             ExprKind::Struct(QPath::Resolved(_, path), ..) => match path.res {
-                Res::SelfTy(..) => (),
+                Res::SelfTy { .. } => (),
                 Res::Def(DefKind::Variant, _) => lint_path_to_variant(cx, path),
                 _ => span_lint(cx, path.span),
             },

clippy_utils/src/lib.rs

@@ -1460,7 +1460,7 @@ pub fn is_self(slf: &Param<'_>) -> bool {
 
 pub fn is_self_ty(slf: &hir::Ty<'_>) -> bool {
     if let TyKind::Path(QPath::Resolved(None, path)) = slf.kind {
-        if let Res::SelfTy(..) = path.res {
+        if let Res::SelfTy { .. } = path.res {
             return true;
         }
     }