rustdoc-json: discard non-local inherent impls

Author: its-the-shrimp

src/librustdoc/formats/cache.rs

@@ -543,19 +543,23 @@ impl<'a, 'tcx> DocFolder for CacheBuilder<'a, 'tcx> {
                 }
             }
             let impl_item = Impl { impl_item: item };
-            if impl_item.trait_did().map_or(true, |d| self.cache.traits.contains_key(&d)) {
+            let impl_def_id = impl_item.def_id();
+            let impl_trait_id = impl_item.trait_did();
+            if match impl_trait_id {
+                Some(d) => self.cache.traits.contains_key(&d),
+                None => impl_def_id.is_local(),
+            } {
                 for did in dids {
-                    if self.impl_ids.entry(did).or_default().insert(impl_item.def_id()) {
+                    if self.impl_ids.entry(did).or_default().insert(impl_def_id) {
                         self.cache
                             .impls
                             .entry(did)
                             .or_insert_with(Vec::new)
                             .push(impl_item.clone());
                     }
                 }
-            } else {
-                let trait_did = impl_item.trait_did().expect("no trait did");
-                self.cache.orphan_trait_impls.push((trait_did, dids, impl_item));
+            } else if let Some(impl_trait_id) = impl_trait_id {
+                self.cache.orphan_trait_impls.push((impl_trait_id, dids, impl_item));
             }
             None
         } else {