Simplify impl_of_method

Author: camsteffen

compiler/rustc_middle/src/ty/mod.rs

@@ -1992,25 +1992,15 @@ impl<'tcx> TyCtxt<'tcx> {
     /// returns the `DefId` of the trait that the trait item belongs to;
     /// otherwise, returns `None`.
     pub fn trait_of_item(self, def_id: DefId) -> Option<DefId> {
-        if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
-            let parent = self.parent(def_id);
-            if let DefKind::Trait | DefKind::TraitAlias = self.def_kind(parent) {
-                return Some(parent);
-            }
-        }
-        None
+        self.opt_parent(def_id)
+            .filter(|parent| matches!(self.def_kind(parent), DefKind::Trait | DefKind::TraitAlias))
     }
 
     /// If the given `DefId` describes a method belonging to an impl, returns the
     /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
     pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
-        if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
-            let parent = self.parent(def_id);
-            if let DefKind::Impl { .. } = self.def_kind(parent) {
-                return Some(parent);
-            }
-        }
-        None
+        self.opt_parent(def_id)
+            .filter(|parent| matches!(self.def_kind(parent), DefKind::Impl { .. }))
     }
 
     pub fn is_exportable(self, def_id: DefId) -> bool {