We may should represent Query{Func,Type,Var} as a bag of definitions and references

src/messages/cquery_base.cc

@@ -39,13 +39,13 @@ struct CqueryBaseHandler : BaseMessageHandler<Ipc_CqueryBase> {
         if (!type.def)
           continue;
         std::vector<QueryLocation> locations =
-            ToQueryLocation(db, &type.def->parents);
+            ToQueryLocation(db, type.def->parents);
         out.result = GetLsLocations(db, working_files, locations);
         break;
       } else if (ref.idx.kind == SymbolKind::Func) {
         QueryFunc& func = db->funcs[ref.idx.idx];
         std::vector<QueryLocation> locations =
-            ToQueryLocation(db, &func.def->base);
+            ToQueryLocation(db, func.def->base);
         out.result = GetLsLocations(db, working_files, locations);
         break;
       }

src/messages/cquery_derived.cc

@@ -37,13 +37,13 @@ struct CqueryDerivedHandler : BaseMessageHandler<Ipc_CqueryDerived> {
       if (ref.idx.kind == SymbolKind::Type) {
         QueryType& type = db->types[ref.idx.idx];
         std::vector<QueryLocation> locations =
-            ToQueryLocation(db, &type.derived);
+            ToQueryLocation(db, type.derived);
         out.result = GetLsLocations(db, working_files, locations);
         break;
       } else if (ref.idx.kind == SymbolKind::Func) {
         QueryFunc& func = db->funcs[ref.idx.idx];
         std::vector<QueryLocation> locations =
-            ToQueryLocation(db, &func.derived);
+            ToQueryLocation(db, func.derived);
         out.result = GetLsLocations(db, working_files, locations);
         break;
       }

src/messages/cquery_member_hierarchy.cc

@@ -66,7 +66,7 @@ ExpandNode(QueryDatabase* db, WorkingFiles* working_files, QueryTypeId root) {
     entry.name = var.def->ShortName();
     // FIXME WithGen
     entry.type_id =
-        var.def->variable_type ? var.def->variable_type->value.id : RawId(-1);
+        var.def->variable_type ? var.def->variable_type->id : RawId(-1);
     if (var.def->definition_spelling) {
       optional<lsLocation> loc =
           GetLsLocation(db, working_files, *var.def->definition_spelling);
@@ -101,7 +101,7 @@ struct CqueryMemberHierarchyInitialHandler
       if (ref.idx.kind == SymbolKind::Var) {
         QueryVar& var = db->vars[ref.idx.idx];
         if (var.def && var.def->variable_type)
-          out.result = BuildInitial(db, working_files, var.def->variable_type->value);
+          out.result = BuildInitial(db, working_files, *var.def->variable_type);
         break;
       }
     }

src/messages/cquery_type_hierarchy_tree.cc

@@ -95,7 +95,7 @@ BuildParentInheritanceHierarchyForFunc(QueryDatabase* db,
 
   // FIXME WithGen
   for (auto parent_id : root_func.def->base) {
-    QueryFunc& parent_func = db->funcs[parent_id.value.id];
+    QueryFunc& parent_func = db->funcs[parent_id.id];
     if (!parent_func.def)
       continue;
 
@@ -105,7 +105,7 @@ BuildParentInheritanceHierarchyForFunc(QueryDatabase* db,
       parent_entry.location = GetLsLocation(
           db, working_files, *parent_func.def->definition_spelling);
     parent_entry.children =
-        BuildParentInheritanceHierarchyForFunc(db, working_files, parent_id.value);
+        BuildParentInheritanceHierarchyForFunc(db, working_files, parent_id);
 
     entries.push_back(parent_entry);
   }
@@ -141,10 +141,9 @@ BuildInheritanceHierarchyForFunc(QueryDatabase* db,
     entry.children.push_back(base);
 
   // Add derived.
-  // FIXME WithGen
   for (auto derived : root_func.derived) {
     auto derived_entry =
-        BuildInheritanceHierarchyForFunc(db, working_files, derived.value);
+        BuildInheritanceHierarchyForFunc(db, working_files, derived);
     if (derived_entry)
       entry.children.push_back(*derived_entry);
   }

src/messages/cquery_vars.cc

@@ -33,13 +33,13 @@ struct CqueryVarsHandler : BaseMessageHandler<Ipc_CqueryVars> {
           QueryVar& var = db->vars[id];
           if (!var.def || !var.def->variable_type)
             continue;
-          id = var.def->variable_type->value.id;
+          id = var.def->variable_type->id;
         }
         // fallthrough
         case SymbolKind::Type: {
           QueryType& type = db->types[id];
           std::vector<QueryLocation> locations =
-              ToQueryLocation(db, &type.instances);
+              ToQueryLocation(db, type.instances);
           out.result = GetLsLocations(db, working_files, locations);
           break;
         }

src/messages/text_document_code_action.cc

@@ -159,7 +159,7 @@ optional<lsTextEdit> BuildAutoImplementForFunction(QueryDatabase* db,
     optional<std::string> type_name;
     optional<lsPosition> same_file_insert_end;
     if (func.def->declaring_type) {
-      QueryType& declaring_type = db->types[func.def->declaring_type->value.id];
+      QueryType& declaring_type = db->types[func.def->declaring_type->id];
       if (declaring_type.def) {
         type_name = std::string(declaring_type.def->ShortName());
         optional<lsRange> ls_type_def_extent = GetLsRange(

src/messages/text_document_code_lens.cc

@@ -159,10 +159,10 @@ struct TextDocumentCodeLensHandler
                       true /*force_display*/);
           AddCodeLens("derived", "derived", &common,
                       ref.loc.OffsetStartColumn(1),
-                      ToQueryLocation(db, &type.derived), nullopt,
+                      ToQueryLocation(db, type.derived), nullopt,
                       false /*force_display*/);
           AddCodeLens("var", "vars", &common, ref.loc.OffsetStartColumn(2),
-                      ToQueryLocation(db, &type.instances), nullopt,
+                      ToQueryLocation(db, type.instances), nullopt,
                       false /*force_display*/);
           break;
         }
@@ -216,14 +216,14 @@ struct TextDocumentCodeLensHandler
 
           AddCodeLens("derived", "derived", &common,
                       ref.loc.OffsetStartColumn(offset++),
-                      ToQueryLocation(db, &func.derived), nullopt,
+                      ToQueryLocation(db, func.derived), nullopt,
                       false /*force_display*/);
 
           // "Base"
           if (func.def->base.size() == 1) {
             // FIXME WithGen
             optional<QueryLocation> base_loc =
-                GetDefinitionSpellingOfSymbol(db, func.def->base[0].value);
+                GetDefinitionSpellingOfSymbol(db, func.def->base[0]);
             if (base_loc) {
               optional<lsLocation> ls_base =
                   GetLsLocation(db, working_files, *base_loc);
@@ -245,7 +245,7 @@ struct TextDocumentCodeLensHandler
             }
           } else {
             AddCodeLens("base", "base", &common, ref.loc.OffsetStartColumn(1),
-                        ToQueryLocation(db, &func.def->base), nullopt,
+                        ToQueryLocation(db, func.def->base), nullopt,
                         false /*force_display*/);
           }
 

src/messages/text_document_definition.cc

@@ -36,7 +36,7 @@ std::vector<QueryLocation> GetGotoDefinitionTargets(QueryDatabase* db,
       if (var.def && var.def->variable_type) {
         std::vector<QueryLocation> types =
             GetDeclarationsOfSymbolForGotoDefinition(
-                db, SymbolIdx(SymbolKind::Type, var.def->variable_type->value.id));
+                db, SymbolIdx(SymbolKind::Type, var.def->variable_type->id));
         ret.insert(ret.end(), types.begin(), types.end());
       }
       return ret;

src/query.cc

@@ -44,11 +44,11 @@ optional<QueryType::Def> ToQuery(const IdMap& id_map,
   result.comments = type.comments;
   result.definition_spelling = id_map.ToQuery(type.definition_spelling);
   result.definition_extent = id_map.ToQuery(type.definition_extent);
-  result.alias_of = id_map.ToQuery(type.alias_of,0);
+  result.alias_of = id_map.ToQuery(type.alias_of);
-  result.parents = id_map.ToQuery(type.parents,0);
+  result.parents = id_map.ToQuery(type.parents);
-  result.types = id_map.ToQuery(type.types,0);
+  result.types = id_map.ToQuery(type.types);
-  result.funcs = id_map.ToQuery(type.funcs,0);
+  result.funcs = id_map.ToQuery(type.funcs);
-  result.vars = id_map.ToQuery(type.vars,0);
+  result.vars = id_map.ToQuery(type.vars);
   return result;
 }
 
@@ -67,9 +67,9 @@ optional<QueryFunc::Def> ToQuery(const IdMap& id_map,
   result.comments = func.comments;
   result.definition_spelling = id_map.ToQuery(func.definition_spelling);
   result.definition_extent = id_map.ToQuery(func.definition_extent);
-  result.declaring_type = id_map.ToQuery(func.declaring_type,0);
+  result.declaring_type = id_map.ToQuery(func.declaring_type);
-  result.base = id_map.ToQuery(func.base,0);
+  result.base = id_map.ToQuery(func.base);
-  result.locals = id_map.ToQuery(func.locals,0);
+  result.locals = id_map.ToQuery(func.locals);
   result.callees = id_map.ToQuery(func.callees);
   return result;
 }
@@ -86,7 +86,7 @@ optional<QueryVar::Def> ToQuery(const IdMap& id_map, const IndexVar::Def& var) {
   result.comments = var.comments;
   result.definition_spelling = id_map.ToQuery(var.definition_spelling);
   result.definition_extent = id_map.ToQuery(var.definition_extent);
-  result.variable_type = id_map.ToQuery(var.variable_type,0);
+  result.variable_type = id_map.ToQuery(var.variable_type);
   result.parent_id = var.parent_id;
   result.parent_kind = var.parent_kind;
   result.kind = var.kind;
@@ -355,64 +355,6 @@ Maybe<QueryVarId> GetQueryVarIdFromUsr(QueryDatabase* query_db,
   return QueryVarId(idx);
 }
 
-template <typename T>
-void AddRangeWithGen(std::vector<WithGen<T>>* dest, const std::vector<T>& to_add, Generation gen) {
-  for (auto& x : to_add)
-    dest->push_back(WithGen<T>{gen, x});
-}
-
-template <typename T>
-void RemoveRangeWithGen(std::vector<WithGen<T>>* dest, const std::vector<T>& to_remove) {
-  dest->erase(std::remove_if(dest->begin(), dest->end(),
-                             [&](const WithGen<T>& t) {
-                               // TODO: make to_remove a set?
-                               return std::find(to_remove.begin(),
-                                                to_remove.end(),
-                                                t.value) != to_remove.end();
-                             }),
-              dest->end());
-}
-
-void UpdateGen(QueryDatabase* db, WithGen<QueryFuncId>& ref) {
-  ref.gen = db->funcs[ref.value.id].gen;
-}
-void UpdateGen(QueryDatabase* db, WithGen<QueryTypeId>& ref) {
-  ref.gen = db->types[ref.value.id].gen;
-}
-void UpdateGen(QueryDatabase* db, WithGen<QueryVarId>& ref) {
-  ref.gen = db->vars[ref.value.id].gen;
-}
-
-template <typename T>
-void UpdateGen(QueryDatabase* db, Maybe<T>& ref) {
-  if (ref)
-    UpdateGen(db, *ref);
-}
-
-template <typename T>
-void UpdateGen(QueryDatabase* db, std::vector<T>& ref) {
-  for (T& x : ref)
-    UpdateGen(db, x);
-}
-
-void UpdateGen(QueryDatabase* db, QueryFunc::Def& def) {
-    UpdateGen(db, def.declaring_type);
-    UpdateGen(db, def.base);
-    UpdateGen(db, def.locals);
-}
-
-void UpdateGen(QueryDatabase* db, QueryType::Def& def) {
-  UpdateGen(db, def.alias_of);
-  UpdateGen(db, def.parents);
-  UpdateGen(db, def.funcs);
-  UpdateGen(db, def.types);
-  UpdateGen(db, def.vars);
-}
-
-void UpdateGen(QueryDatabase* db, QueryVar::Def& def) {
-  UpdateGen(db, def.variable_type);
-}
-
 }  // namespace
 
 template <>
@@ -476,20 +418,6 @@ QueryVarId IdMap::ToQuery(IndexVarId id) const {
   assert(cached_var_ids_.find(id) != cached_var_ids_.end());
   return QueryVarId(cached_var_ids_.find(id)->second);
 }
-WithGen<QueryTypeId> IdMap::ToQuery(IndexTypeId id,int) const {
-  assert(cached_type_ids_.find(id) != cached_type_ids_.end());
-  return QueryTypeId(cached_type_ids_.find(id)->second);
-}
-WithGen<QueryFuncId> IdMap::ToQuery(IndexFuncId id,int) const {
-  if (id == IndexFuncId())
-    return QueryFuncId();
-  assert(cached_func_ids_.find(id) != cached_func_ids_.end());
-  return QueryFuncId(cached_func_ids_.find(id)->second);
-}
-WithGen<QueryVarId> IdMap::ToQuery(IndexVarId id,int) const {
-  assert(cached_var_ids_.find(id) != cached_var_ids_.end());
-  return QueryVarId(cached_var_ids_.find(id)->second);
-}
 QueryFuncRef IdMap::ToQuery(IndexFuncRef ref) const {
   return QueryFuncRef(ToQuery(ref.id), ToQuery(ref.loc), ref.is_implicit);
 }
@@ -857,13 +785,6 @@ void QueryDatabase::ApplyIndexUpdate(IndexUpdate* update) {
     RemoveRange(&def.def_var_name, merge_update.to_remove);           \
     VerifyUnique(def.def_var_name);                                   \
   }
-#define HANDLE_MERGEABLE_WITH_GEN(update_var_name, def_var_name, storage_name) \
-  for (auto merge_update : update->update_var_name) {                          \
-    auto& def = storage_name[merge_update.id.id];                              \
-    AddRangeWithGen(&def.def_var_name, merge_update.to_add, def.gen);          \
-    RemoveRangeWithGen(&def.def_var_name, merge_update.to_remove);             \
-    VerifyUnique(def.def_var_name);                                            \
-  }
 
   for (const std::string& filename : update->files_removed)
     files[usr_to_file[NormalizedPath(filename)].id].def = nullopt;
@@ -871,14 +792,14 @@ void QueryDatabase::ApplyIndexUpdate(IndexUpdate* update) {
 
   RemoveUsrs(SymbolKind::Type, update->types_removed);
   ImportOrUpdate(update->types_def_update);
-  HANDLE_MERGEABLE_WITH_GEN(types_derived, derived, types);
+  HANDLE_MERGEABLE(types_derived, derived, types);
-  HANDLE_MERGEABLE_WITH_GEN(types_instances, instances, types);
+  HANDLE_MERGEABLE(types_instances, instances, types);
   HANDLE_MERGEABLE(types_uses, uses, types);
 
   RemoveUsrs(SymbolKind::Func, update->funcs_removed);
   ImportOrUpdate(update->funcs_def_update);
   HANDLE_MERGEABLE(funcs_declarations, declarations, funcs);
-  HANDLE_MERGEABLE_WITH_GEN(funcs_derived, derived, funcs);
+  HANDLE_MERGEABLE(funcs_derived, derived, funcs);
   HANDLE_MERGEABLE(funcs_callers, callers, funcs);
 
   RemoveUsrs(SymbolKind::Var, update->vars_removed);
@@ -925,7 +846,6 @@ void QueryDatabase::ImportOrUpdate(
       UpdateSymbols(&existing.symbol_idx, SymbolKind::Type,
                     it->second.id);
     }
-    UpdateGen(this, *existing.def);
   }
 }
 
@@ -949,7 +869,6 @@ void QueryDatabase::ImportOrUpdate(
       UpdateSymbols(&existing.symbol_idx, SymbolKind::Func,
                     it->second.id);
     }
-    UpdateGen(this, *existing.def);
   }
 }
 
@@ -974,7 +893,6 @@ void QueryDatabase::ImportOrUpdate(
         UpdateSymbols(&existing.symbol_idx, SymbolKind::Var,
                       it->second.id);
     }
-    UpdateGen(this, *existing.def);
   }
 }
 

src/query.h

@@ -249,9 +249,9 @@ MAKE_REFLECT_STRUCT(QueryFile::Def,
                     dependencies);
 
 struct QueryType {
-  using Def = TypeDefDefinitionData<WithGen<QueryTypeId>,
+  using Def = TypeDefDefinitionData<QueryTypeId,
-                                    WithGen<QueryFuncId>,
+                                    QueryFuncId,
-                                    WithGen<QueryVarId>,
+                                    QueryVarId,
                                     QueryLocation>;
   using DefUpdate = WithUsr<Def>;
   using DerivedUpdate = MergeableUpdate<QueryTypeId, QueryTypeId>;
@@ -262,17 +262,17 @@ struct QueryType {
   Generation gen;
   Maybe<Id<void>> symbol_idx;
   optional<Def> def;
-  std::vector<WithGen<QueryTypeId>> derived;
+  std::vector<QueryTypeId> derived;
-  std::vector<WithGen<QueryVarId>> instances;
+  std::vector<QueryVarId> instances;
   std::vector<QueryLocation> uses;
 
   explicit QueryType(const Usr& usr) : usr(usr), gen(0) {}
 };
 
 struct QueryFunc {
-  using Def = FuncDefDefinitionData<WithGen<QueryTypeId>,
+  using Def = FuncDefDefinitionData<QueryTypeId,
-                                    WithGen<QueryFuncId>,
+                                    QueryFuncId,
-                                    WithGen<QueryVarId>,
+                                    QueryVarId,
                                     QueryFuncRef,
                                     QueryLocation>;
   using DefUpdate = WithUsr<Def>;
@@ -285,16 +285,16 @@ struct QueryFunc {
   Maybe<Id<void>> symbol_idx;
   optional<Def> def;
   std::vector<QueryLocation> declarations;
-  std::vector<WithGen<QueryFuncId>> derived;
+  std::vector<QueryFuncId> derived;
   std::vector<QueryFuncRef> callers;
 
   explicit QueryFunc(const Usr& usr) : usr(usr), gen(0) {}
 };
 
 struct QueryVar {
-  using Def = VarDefDefinitionData<WithGen<QueryTypeId>,
+  using Def = VarDefDefinitionData<QueryTypeId,
-                                   WithGen<QueryFuncId>,
+                                   QueryFuncId,
-                                   WithGen<QueryVarId>,
+                                   QueryVarId,
                                    QueryLocation>;
   using DefUpdate = WithUsr<Def>;
   using DeclarationsUpdate = MergeableUpdate<QueryVarId, QueryLocation>;
@@ -452,9 +452,6 @@ struct IdMap {
   QueryTypeId ToQuery(IndexTypeId id) const;
   QueryFuncId ToQuery(IndexFuncId id) const;
   QueryVarId ToQuery(IndexVarId id) const;
-  WithGen<QueryTypeId> ToQuery(IndexTypeId id, int) const;
-  WithGen<QueryFuncId> ToQuery(IndexFuncId id, int) const;
-  WithGen<QueryVarId> ToQuery(IndexVarId id, int) const;
   QueryFuncRef ToQuery(IndexFuncRef ref) const;
   QueryLocation ToQuery(IndexFunc::Declaration decl) const;
   template <typename I>

src/query_utils.cc

@@ -14,25 +14,16 @@ int ComputeRangeSize(const Range& range) {
 }
 
 template <typename Q>
-std::vector<QueryLocation> ToQueryLocation(
+std::vector<QueryLocation> ToQueryLocationHelper(
     QueryDatabase* db,
-    std::vector<Q> QueryDatabase::*collection,
+    const std::vector<Id<Q>>& ids) {
-    std::vector<WithGen<Id<Q>>>* ids_) {
-  auto& ids = *ids_;
   std::vector<QueryLocation> locs;
   locs.reserve(ids.size());
-  size_t j = 0;
+  for (auto id : ids) {
-  for (size_t i = 0; i < ids.size(); i++) {
+    optional<QueryLocation> loc = GetDefinitionSpellingOfSymbol(db, id);
-    Q& obj = (db->*collection)[ids[i].value.id];
-    if (obj.gen == ids[i].gen) {
-      optional<QueryLocation> loc =
-          GetDefinitionSpellingOfSymbol(db, ids[i].value);
     if (loc)
       locs.push_back(*loc);
-      ids[j++] = ids[i];
   }
-  }
-  ids.resize(j);
   return locs;
 }
 
@@ -171,42 +162,17 @@ std::vector<QueryLocation> ToQueryLocation(
 std::vector<QueryLocation> ToQueryLocation(
     QueryDatabase* db,
     const std::vector<QueryTypeId>& ids) {
-  std::vector<QueryLocation> locs;
+  return ToQueryLocationHelper(db, ids);
-  locs.reserve(ids.size());
-  for (const QueryTypeId& id : ids) {
-    optional<QueryLocation> loc = GetDefinitionSpellingOfSymbol(db, id);
-    if (loc)
-      locs.push_back(loc.value());
-  }
-  return locs;
 }
 std::vector<QueryLocation> ToQueryLocation(
     QueryDatabase* db,
     const std::vector<QueryFuncId>& ids) {
-  std::vector<QueryLocation> locs;
+  return ToQueryLocationHelper(db, ids);
-  locs.reserve(ids.size());
-  for (const QueryFuncId& id : ids) {
-    optional<QueryLocation> loc = GetDefinitionSpellingOfSymbol(db, id);
-    if (loc)
-      locs.push_back(loc.value());
-  }
-  return locs;
-}
-
-std::vector<QueryLocation> ToQueryLocation(
-    QueryDatabase* db,
-    std::vector<WithGen<QueryFuncId>>* ids_) {
-  return ToQueryLocation(db, &QueryDatabase::funcs, ids_);
 }
 std::vector<QueryLocation> ToQueryLocation(
     QueryDatabase* db,
-    std::vector<WithGen<QueryTypeId>>* ids_) {
+    const std::vector<QueryVarId>& ids) {
-  return ToQueryLocation(db, &QueryDatabase::types, ids_);
+  return ToQueryLocationHelper(db, ids);
-}
-std::vector<QueryLocation> ToQueryLocation(
-    QueryDatabase* db,
-    std::vector<WithGen<QueryVarId>>* ids_) {
-  return ToQueryLocation(db, &QueryDatabase::vars, ids_);
 }
 
 std::vector<QueryLocation> GetUsesOfSymbol(QueryDatabase* db,
@@ -514,8 +480,7 @@ optional<lsSymbolInformation> GetSymbolInfo(QueryDatabase* db,
       info.kind = lsSymbolKind::Function;
 
       if (func.def->declaring_type.has_value()) {
-        // FIXME WithGen
+        QueryType& container = db->types[func.def->declaring_type->id];
-        QueryType& container = db->types[func.def->declaring_type->value.id];
         if (container.def)
           info.kind = lsSymbolKind::Method;
       }

src/query_utils.h

@@ -25,12 +25,9 @@ std::vector<QueryLocation> ToQueryLocation(
 std::vector<QueryLocation> ToQueryLocation(
     QueryDatabase* db,
     const std::vector<QueryTypeId>& refs);
-std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db,
+std::vector<QueryLocation> ToQueryLocation(
-                                           std::vector<WithGen<QueryFuncId>>*);
+    QueryDatabase* db,
-std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db,
+    const std::vector<QueryVarId>& refs);
-                                           std::vector<WithGen<QueryTypeId>>*);
-std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db,
-                                           std::vector<WithGen<QueryVarId>>*);
 std::vector<QueryLocation> ToQueryLocation(QueryDatabase* db,
                                            const std::vector<QueryFuncId>& ids);
 std::vector<QueryLocation> GetUsesOfSymbol(QueryDatabase* db,
@@ -74,8 +71,8 @@ void EmitDiagnostics(WorkingFiles* working_files,
                      std::vector<lsDiagnostic> diagnostics);
 
 template <typename Q, typename Fn>
-void EachWithGen(std::vector<Q>& collection, WithGen<Id<Q>> x, Fn fn) {
+void EachWithGen(std::vector<Q>& collection, Id<Q> x, Fn fn) {
-  Q& obj = collection[x.value.id];
+  Q& obj = collection[x.id];
   // FIXME Deprecate optional<Def> def
   //  if (obj.gen == x.gen && obj.def)
   if (obj.def)
@@ -83,15 +80,10 @@ void EachWithGen(std::vector<Q>& collection, WithGen<Id<Q>> x, Fn fn) {
 }
 
 template <typename Q, typename Fn>
-void EachWithGen(std::vector<Q>& collection, std::vector<WithGen<Id<Q>>>& ids, Fn fn) {
+void EachWithGen(std::vector<Q>& collection, std::vector<Id<Q>>& ids, Fn fn) {
-  size_t j = 0;
+  for (Id<Q> x : ids) {
-  for (WithGen<Id<Q>> x : ids) {
+    Q& obj = collection[x.id];
-    Q& obj = collection[x.value.id];
-    if (1 /*obj.gen == x.gen*/) {
     if (obj.def) // FIXME Deprecate optional<Def> def
       fn(obj);
-      ids[j++] = x;
   }
 }
-  ids.resize(j);
-}