Apply lint rule @typescript-eslint/no-empty-object-type (#4679)

.eslintrc.cjs

@@ -112,8 +112,13 @@ module.exports = {
                 "@typescript-eslint/ban-ts-comment": "off",
                 // We're okay with assertion errors when we ask for them
                 "@typescript-eslint/no-non-null-assertion": "off",
+                "@typescript-eslint/no-empty-object-type": [
+                    "error",
+                    {
                         // We do this sometimes to brand interfaces
-                "@typescript-eslint/no-empty-object-type": "off",
+                        allowInterfaces: "with-single-extends",
+                    },
+                ],
 
                 "quotes": "off",
                 // We use a `logger` intermediary module
@@ -147,6 +152,7 @@ module.exports = {
                 // We don't need super strict typing in test utilities
                 "@typescript-eslint/explicit-function-return-type": "off",
                 "@typescript-eslint/explicit-member-accessibility": "off",
+                "@typescript-eslint/no-empty-object-type": "off",
             },
         },
     ],

spec/test-utils/webrtc.ts

@@ -17,6 +17,7 @@ limitations under the License.
 import {
     ClientEvent,
     ClientEventHandlerMap,
+    EmptyObject,
     EventType,
     GroupCall,
     GroupCallIntent,
@@ -466,7 +467,7 @@ export class MockCallMatrixClient extends TypedEventEmitter<EmittedEvents, Emitt
         [roomId: string, eventType: EventType, content: any, statekey: string]
     >();
     public sendToDevice = jest.fn<
-        Promise<{}>,
+        Promise<EmptyObject>,
         [eventType: string, contentMap: SendToDeviceContentMap, txnId?: string]
     >();
 

spec/unit/rust-crypto/rust-crypto.spec.ts

@@ -33,6 +33,7 @@ import {
     AccountDataEvents,
     Device,
     DeviceVerification,
+    EmptyObject,
     encodeBase64,
     HttpApiEvent,
     HttpApiEventHandlerMap,
@@ -2348,7 +2349,7 @@ class DummyAccountDataClient
         }
     }
 
-    public async setAccountData(eventType: string, content: any): Promise<{}> {
+    public async setAccountData(eventType: string, content: any): Promise<EmptyObject> {
         this.storage.set(eventType, content);
         this.emit(
             ClientEvent.AccountData,

src/@types/common.ts

@@ -20,3 +20,5 @@ export type NonEmptyArray<T> = [T, ...T[]];
 export type Without<T, U> = { [P in Exclude<keyof T, keyof U>]?: never };
 export type XOR<T, U> = T | U extends object ? (Without<T, U> & U) | (Without<U, T> & T) : T | U;
 export type Writeable<T> = { -readonly [P in keyof T]: T[P] };
+
+export type EmptyObject = Record<PropertyKey, never>;

src/@types/event.ts

@@ -38,7 +38,7 @@ import {
 import { IGroupCallRoomMemberState, IGroupCallRoomState } from "../webrtc/groupCall.ts";
 import { MSC3089EventContent } from "../models/MSC3089Branch.ts";
 import { M_BEACON, M_BEACON_INFO, MBeaconEventContent, MBeaconInfoEventContent } from "./beacon.ts";
-import { XOR } from "./common.ts";
+import { EmptyObject } from "./common.ts";
 import { ReactionEventContent, RoomMessageEventContent, StickerEventContent } from "./events.ts";
 import {
     MCallAnswer,
@@ -337,7 +337,7 @@ export interface StateEvents {
     [EventType.RoomJoinRules]: RoomJoinRulesEventContent;
     [EventType.RoomMember]: RoomMemberEventContent;
     // XXX: Spec says this event has 3 required fields but kicking such an invitation requires sending `{}`
-    [EventType.RoomThirdPartyInvite]: XOR<RoomThirdPartyInviteEventContent, {}>;
+    [EventType.RoomThirdPartyInvite]: RoomThirdPartyInviteEventContent | EmptyObject;
     [EventType.RoomPowerLevels]: RoomPowerLevelsEventContent;
     [EventType.RoomName]: RoomNameEventContent;
     [EventType.RoomTopic]: RoomTopicEventContent;
@@ -351,13 +351,13 @@ export interface StateEvents {
     [EventType.SpaceChild]: SpaceChildEventContent;
     [EventType.SpaceParent]: SpaceParentEventContent;
 
-    [EventType.PolicyRuleUser]: XOR<PolicyRuleEventContent, {}>;
+    [EventType.PolicyRuleUser]: PolicyRuleEventContent | EmptyObject;
-    [EventType.PolicyRuleRoom]: XOR<PolicyRuleEventContent, {}>;
+    [EventType.PolicyRuleRoom]: PolicyRuleEventContent | EmptyObject;
-    [EventType.PolicyRuleServer]: XOR<PolicyRuleEventContent, {}>;
+    [EventType.PolicyRuleServer]: PolicyRuleEventContent | EmptyObject;
 
     // MSC3401
     [EventType.GroupCallPrefix]: IGroupCallRoomState;
-    [EventType.GroupCallMemberPrefix]: XOR<IGroupCallRoomMemberState, XOR<SessionMembershipData, {}>>;
+    [EventType.GroupCallMemberPrefix]: IGroupCallRoomMemberState | SessionMembershipData | EmptyObject;
 
     // MSC3089
     [UNSTABLE_MSC3089_BRANCH.name]: MSC3089EventContent;
@@ -372,7 +372,7 @@ export interface StateEvents {
 export interface AccountDataEvents extends SecretStorageAccountDataEvents {
     [EventType.PushRules]: IPushRules;
     [EventType.Direct]: { [userId: string]: string[] };
-    [EventType.IgnoredUserList]: { [userId: string]: {} };
+    [EventType.IgnoredUserList]: { ignored_users: { [userId: string]: EmptyObject } };
     "m.secret_storage.default_key": { key: string };
     // Flag set by the rust SDK (Element X) and also used by us to mark that the user opted out of backup
     // (I don't know why it's m.org.matrix...)

src/@types/extensible_events.ts

@@ -97,12 +97,12 @@ export type AnyRelation = TSNamespace<typeof REFERENCE_RELATION> | string;
 /**
  * An m.relates_to relationship
  */
-export type RelatesToRelationship<R = never, C = never> = {
+export type RelatesToRelationship<R = never> = {
     "m.relates_to": {
         // See https://github.com/microsoft/TypeScript/issues/23182#issuecomment-379091887 for array syntax
         rel_type: [R] extends [never] ? AnyRelation : TSNamespace<R>;
         event_id: string;
-    } & DefaultNever<C, {}>;
+    };
 };
 
 /**

src/@types/global.d.ts

@@ -60,6 +60,7 @@ declare global {
               };
     }
 
+    // eslint-disable-next-line @typescript-eslint/no-empty-object-type
     interface DummyInterfaceWeShouldntBeUsingThis {}
 
     interface Navigator {

src/@types/polls.ts

@@ -22,6 +22,7 @@ import {
     RelatesToRelationship,
     TSNamespace,
 } from "./extensible_events.ts";
+import { EmptyObject } from "./common.ts";
 
 /**
  * Identifier for a disclosed poll.
@@ -109,7 +110,7 @@ export const M_POLL_END = new UnstableValue("m.poll.end", "org.matrix.msc3381.po
 /**
  * The event definition for an m.poll.end event (in content)
  */
-export type PollEndEvent = EitherAnd<{ [M_POLL_END.name]: {} }, { [M_POLL_END.altName]: {} }>;
+export type PollEndEvent = EitherAnd<{ [M_POLL_END.name]: EmptyObject }, { [M_POLL_END.altName]: EmptyObject }>;
 
 /**
  * The content for an m.poll.end event

src/client.ts

@@ -249,6 +249,7 @@ import { Capabilities, ServerCapabilities } from "./serverCapabilities.ts";
 import { sha256 } from "./digest.ts";
 import { keyFromAuthData } from "./common-crypto/key-passphrase.ts";
 import { discoverAndValidateOIDCIssuerWellKnown, OidcClientConfig, validateAuthMetadataAndKeys } from "./oidc/index.ts";
+import { EmptyObject } from "./@types/common.ts";
 
 export type Store = IStore;
 
@@ -4251,7 +4252,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
     public setAccountData<K extends keyof AccountDataEvents>(
         eventType: K,
         content: AccountDataEvents[K] | Record<string, never>,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const path = utils.encodeUri("/user/$userId/account_data/$type", {
             $userId: this.credentials.userId!,
             $type: eventType,
@@ -4338,8 +4339,8 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: an empty object
      * @returns Rejects: with an error response.
      */
-    public setIgnoredUsers(userIds: string[]): Promise<{}> {
+    public setIgnoredUsers(userIds: string[]): Promise<EmptyObject> {
-        const content = { ignored_users: {} as Record<string, object> };
+        const content = { ignored_users: {} as Record<string, EmptyObject> };
         userIds.forEach((u) => {
             content.ignored_users[u] = {};
         });
@@ -4520,7 +4521,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object
      * @returns Rejects: with an error response.
      */
-    public setRoomTag(roomId: string, tagName: string, metadata: ITagMetadata = {}): Promise<{}> {
+    public setRoomTag(roomId: string, tagName: string, metadata: ITagMetadata = {}): Promise<EmptyObject> {
         const path = utils.encodeUri("/user/$userId/rooms/$roomId/tags/$tag", {
             $userId: this.credentials.userId!,
             $roomId: roomId,
@@ -4534,7 +4535,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object
      * @returns Rejects: with an error response.
      */
-    public deleteRoomTag(roomId: string, tagName: string): Promise<{}> {
+    public deleteRoomTag(roomId: string, tagName: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/user/$userId/rooms/$roomId/tags/$tag", {
             $userId: this.credentials.userId!,
             $roomId: roomId,
@@ -4549,7 +4550,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public setRoomAccountData(roomId: string, eventType: string, content: Record<string, any>): Promise<{}> {
+    public setRoomAccountData(roomId: string, eventType: string, content: Record<string, any>): Promise<EmptyObject> {
         const path = utils.encodeUri("/user/$userId/rooms/$roomId/account_data/$type", {
             $userId: this.credentials.userId!,
             $roomId: roomId,
@@ -5449,7 +5450,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      *   Check progress on [MSC4140](https://github.com/matrix-org/matrix-spec-proposals/pull/4140) for more details.
      */
     // eslint-disable-next-line
-    public async _unstable_updateDelayedEvent(delayId: string, action: UpdateDelayedEventAction): Promise<{}> {
+    public async _unstable_updateDelayedEvent(delayId: string, action: UpdateDelayedEventAction): Promise<EmptyObject> {
         if (!(await this.doesServerSupportUnstableFeature(UNSTABLE_MSC4140_DELAYED_EVENTS))) {
             throw Error("Server does not support the delayed events API");
         }
@@ -5480,7 +5481,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         receiptType: ReceiptType,
         body?: Record<string, any>,
         unthreaded = false,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         if (this.isGuest()) {
             return Promise.resolve({}); // guests cannot send receipts so don't bother.
         }
@@ -5496,7 +5497,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         const shouldAddThreadId = !unthreaded && this.supportsThreads();
         const fullBody = shouldAddThreadId ? { ...body, thread_id: threadIdForReceipt(event) } : body;
 
-        const promise = this.http.authedRequest<{}>(Method.Post, path, undefined, fullBody || {});
+        const promise = this.http.authedRequest<EmptyObject>(Method.Post, path, undefined, fullBody || {});
 
         const room = this.getRoom(event.getRoomId());
         if (room && this.credentials.userId) {
@@ -5516,7 +5517,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         event: MatrixEvent | null,
         receiptType = ReceiptType.Read,
         unthreaded = false,
-    ): Promise<{} | undefined> {
+    ): Promise<EmptyObject | undefined> {
         if (!event) return;
         const eventId = event.getId()!;
         const room = this.getRoom(event.getRoomId());
@@ -5546,7 +5547,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         rmEventId: string,
         rrEvent?: MatrixEvent,
         rpEvent?: MatrixEvent,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const room = this.getRoom(roomId);
         if (room?.hasPendingEvent(rmEventId)) {
             throw new Error(`Cannot set read marker to a pending event (${rmEventId})`);
@@ -5627,7 +5628,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public sendTyping(roomId: string, isTyping: boolean, timeoutMs: number): Promise<{}> {
+    public sendTyping(roomId: string, isTyping: boolean, timeoutMs: number): Promise<EmptyObject> {
         if (this.isGuest()) {
             return Promise.resolve({}); // guests cannot send typing notifications so don't bother.
         }
@@ -5745,7 +5746,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public invite(roomId: string, userId: string, reason?: string): Promise<{}> {
+    public invite(roomId: string, userId: string, reason?: string): Promise<EmptyObject> {
         return this.membershipChange(roomId, userId, KnownMembership.Invite, reason);
     }
 
@@ -5756,7 +5757,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public inviteByEmail(roomId: string, email: string): Promise<{}> {
+    public inviteByEmail(roomId: string, email: string): Promise<EmptyObject> {
         return this.inviteByThreePid(roomId, "email", email);
     }
 
@@ -5768,7 +5769,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public async inviteByThreePid(roomId: string, medium: string, address: string): Promise<{}> {
+    public async inviteByThreePid(roomId: string, medium: string, address: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/rooms/$roomId/invite", { $roomId: roomId });
 
         const identityServerUrl = this.getIdentityServerUrl(true);
@@ -5800,7 +5801,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public leave(roomId: string): Promise<{}> {
+    public leave(roomId: string): Promise<EmptyObject> {
         return this.membershipChange(roomId, undefined, KnownMembership.Leave);
     }
 
@@ -5858,7 +5859,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: TODO
      * @returns Rejects: with an error response.
      */
-    public ban(roomId: string, userId: string, reason?: string): Promise<{}> {
+    public ban(roomId: string, userId: string, reason?: string): Promise<EmptyObject> {
         return this.membershipChange(roomId, userId, KnownMembership.Ban, reason);
     }
 
@@ -5868,12 +5869,12 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public async forget(roomId: string, deleteRoom = true): Promise<{}> {
+    public async forget(roomId: string, deleteRoom = true): Promise<EmptyObject> {
         // API returns an empty object
         const path = utils.encodeUri("/rooms/$room_id/forget", {
             $room_id: roomId,
         });
-        const response = await this.http.authedRequest<{}>(Method.Post, path);
+        const response = await this.http.authedRequest<EmptyObject>(Method.Post, path);
         if (deleteRoom) {
             this.store.removeRoom(roomId);
             this.emit(ClientEvent.DeleteRoom, roomId);
@@ -5885,7 +5886,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: Object (currently empty)
      * @returns Rejects: with an error response.
      */
-    public unban(roomId: string, userId: string): Promise<{}> {
+    public unban(roomId: string, userId: string): Promise<EmptyObject> {
         // unbanning != set their state to leave: this used to be
         // the case, but was then changed so that leaving was always
         // a revoking of privilege, otherwise two people racing to
@@ -5905,7 +5906,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public kick(roomId: string, userId: string, reason?: string): Promise<{}> {
+    public kick(roomId: string, userId: string, reason?: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/rooms/$roomId/kick", {
             $roomId: roomId,
         });
@@ -5921,7 +5922,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         userId: string | undefined,
         membership: Membership,
         reason?: string,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         // API returns an empty object
         const path = utils.encodeUri("/rooms/$room_id/$membership", {
             $room_id: roomId,
@@ -5972,9 +5973,9 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Rejects: with an error response.
      */
     // eslint-disable-next-line camelcase
-    public setProfileInfo(info: "avatar_url", data: { avatar_url: string }): Promise<{}>;
+    public setProfileInfo(info: "avatar_url", data: { avatar_url: string }): Promise<EmptyObject>;
-    public setProfileInfo(info: "displayname", data: { displayname: string }): Promise<{}>;
+    public setProfileInfo(info: "displayname", data: { displayname: string }): Promise<EmptyObject>;
-    public setProfileInfo(info: "avatar_url" | "displayname", data: object): Promise<{}> {
+    public setProfileInfo(info: "avatar_url" | "displayname", data: object): Promise<EmptyObject> {
         const path = utils.encodeUri("/profile/$userId/$info", {
             $userId: this.credentials.userId!,
             $info: info,
@@ -5986,7 +5987,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public async setDisplayName(name: string): Promise<{}> {
+    public async setDisplayName(name: string): Promise<EmptyObject> {
         const prom = await this.setProfileInfo("displayname", { displayname: name });
         // XXX: synthesise a profile update for ourselves because Synapse is broken and won't
         const user = this.getUser(this.getUserId()!);
@@ -6001,7 +6002,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: `{}` an empty object.
      * @returns Rejects: with an error response.
      */
-    public async setAvatarUrl(url: string): Promise<{}> {
+    public async setAvatarUrl(url: string): Promise<EmptyObject> {
         const prom = await this.setProfileInfo("avatar_url", { avatar_url: url });
         // XXX: synthesise a profile update for ourselves because Synapse is broken and won't
         const user = this.getUser(this.getUserId()!);
@@ -8363,7 +8364,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @param stopClient - whether to stop the client before calling /logout to prevent invalid token errors.
      * @returns Promise which resolves: On success, the empty object `{}`
      */
-    public async logout(stopClient = false): Promise<{}> {
+    public async logout(stopClient = false): Promise<EmptyObject> {
         if (this.crypto?.backupManager?.getKeyBackupEnabled()) {
             try {
                 while ((await this.crypto.backupManager.backupPendingKeys(200)) > 0);
@@ -8421,7 +8422,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * or UIA auth data.
      */
     public async requestLoginToken(auth?: AuthDict): Promise<UIAResponse<LoginTokenPostResponse>> {
-        const body: UIARequest<{}> = { auth };
+        const body: UIARequest<unknown> = { auth };
         return this.http.authedRequest<UIAResponse<LoginTokenPostResponse>>(
             Method.Post,
             "/login/get_token",
@@ -8662,7 +8663,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         rmEventId: string,
         rrEventId?: string,
         rpEventId?: string,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const path = utils.encodeUri("/rooms/$roomId/read_markers", {
             $roomId: roomId,
         });
@@ -8737,7 +8738,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public createAlias(alias: string, roomId: string): Promise<{}> {
+    public createAlias(alias: string, roomId: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/directory/room/$alias", {
             $alias: alias,
         });
@@ -8754,7 +8755,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: an empty object `{}`.
      * @returns Rejects: with an error response.
      */
-    public deleteAlias(alias: string): Promise<{}> {
+    public deleteAlias(alias: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/directory/room/$alias", {
             $alias: alias,
         });
@@ -8808,7 +8809,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public setRoomDirectoryVisibility(roomId: string, visibility: Visibility): Promise<{}> {
+    public setRoomDirectoryVisibility(roomId: string, visibility: Visibility): Promise<EmptyObject> {
         const path = utils.encodeUri("/directory/list/room/$roomId", {
             $roomId: roomId,
         });
@@ -9083,7 +9084,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public async addThreePidOnly(data: IAddThreePidOnlyBody): Promise<{}> {
+    public async addThreePidOnly(data: IAddThreePidOnlyBody): Promise<EmptyObject> {
         const path = "/account/3pid/add";
         return this.http.authedRequest(Method.Post, path, undefined, data);
     }
@@ -9099,7 +9100,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public async bindThreePid(data: IBindThreePidBody): Promise<{}> {
+    public async bindThreePid(data: IBindThreePidBody): Promise<EmptyObject> {
         const path = "/account/3pid/bind";
         return this.http.authedRequest(Method.Post, path, undefined, data);
     }
@@ -9153,7 +9154,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: to an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public setPassword(authDict: AuthDict, newPassword: string, logoutDevices?: boolean): Promise<{}> {
+    public setPassword(authDict: AuthDict, newPassword: string, logoutDevices?: boolean): Promise<EmptyObject> {
         const path = "/account/password";
         const data = {
             auth: authDict,
@@ -9161,7 +9162,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
             logout_devices: logoutDevices,
         };
 
-        return this.http.authedRequest<{}>(Method.Post, path, undefined, data);
+        return this.http.authedRequest<EmptyObject>(Method.Post, path, undefined, data);
     }
 
     /**
@@ -9195,7 +9196,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Rejects: with an error response.
      */
     // eslint-disable-next-line camelcase
-    public setDeviceDetails(deviceId: string, body: { display_name: string }): Promise<{}> {
+    public setDeviceDetails(deviceId: string, body: { display_name: string }): Promise<EmptyObject> {
         const path = utils.encodeUri("/devices/$device_id", {
             $device_id: deviceId,
         });
@@ -9211,7 +9212,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: result object
      * @returns Rejects: with an error response.
      */
-    public deleteDevice(deviceId: string, auth?: AuthDict): Promise<{}> {
+    public deleteDevice(deviceId: string, auth?: AuthDict): Promise<EmptyObject> {
         const path = utils.encodeUri("/devices/$device_id", {
             $device_id: deviceId,
         });
@@ -9233,7 +9234,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: result object
      * @returns Rejects: with an error response.
      */
-    public deleteMultipleDevices(devices: string[], auth?: AuthDict): Promise<{}> {
+    public deleteMultipleDevices(devices: string[], auth?: AuthDict): Promise<EmptyObject> {
         const body: Body = { devices };
 
         if (auth) {
@@ -9274,7 +9275,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: Empty json object on success
      * @returns Rejects: with an error response.
      */
-    public setPusher(pusher: IPusherRequest): Promise<{}> {
+    public setPusher(pusher: IPusherRequest): Promise<EmptyObject> {
         const path = "/pushers/set";
         return this.http.authedRequest(Method.Post, path, undefined, pusher);
     }
@@ -9286,7 +9287,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: Empty json object on success
      * @returns Rejects: with an error response.
      */
-    public removePusher(pushKey: string, appId: string): Promise<{}> {
+    public removePusher(pushKey: string, appId: string): Promise<EmptyObject> {
         const path = "/pushers/set";
         const body = {
             pushkey: pushKey,
@@ -9304,7 +9305,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
     public setLocalNotificationSettings(
         deviceId: string,
         notificationSettings: LocalNotificationSettings,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const key = `${LOCAL_NOTIFICATION_SETTINGS_PREFIX.name}.${deviceId}` as const;
         return this.setAccountData(key, notificationSettings);
     }
@@ -9341,7 +9342,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         kind: PushRuleKind,
         ruleId: Exclude<string, RuleId>,
         body: Pick<IPushRule, "actions" | "conditions" | "pattern">,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         // NB. Scope not uri encoded because devices need the '/'
         const path = utils.encodeUri("/pushrules/" + scope + "/$kind/$ruleId", {
             $kind: kind,
@@ -9354,7 +9355,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @returns Promise which resolves: an empty object `{}`
      * @returns Rejects: with an error response.
      */
-    public deletePushRule(scope: string, kind: PushRuleKind, ruleId: Exclude<string, RuleId>): Promise<{}> {
+    public deletePushRule(scope: string, kind: PushRuleKind, ruleId: Exclude<string, RuleId>): Promise<EmptyObject> {
         // NB. Scope not uri encoded because devices need the '/'
         const path = utils.encodeUri("/pushrules/" + scope + "/$kind/$ruleId", {
             $kind: kind,
@@ -9373,7 +9374,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         kind: PushRuleKind,
         ruleId: RuleId | string,
         enabled: boolean,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const path = utils.encodeUri("/pushrules/" + scope + "/$kind/$ruleId/enabled", {
             $kind: kind,
             $ruleId: ruleId,
@@ -9391,7 +9392,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         kind: PushRuleKind,
         ruleId: RuleId | string,
         actions: PushRuleAction[],
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const path = utils.encodeUri("/pushrules/" + scope + "/$kind/$ruleId/actions", {
             $kind: kind,
             $ruleId: ruleId,
@@ -9517,7 +9518,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         return this.http.authedRequest(Method.Get, "/keys/changes", qps);
     }
 
-    public uploadDeviceSigningKeys(auth?: AuthDict, keys?: CrossSigningKeys): Promise<{}> {
+    public uploadDeviceSigningKeys(auth?: AuthDict, keys?: CrossSigningKeys): Promise<EmptyObject> {
         // API returns empty object
         const data = Object.assign({}, keys);
         if (auth) Object.assign(data, { auth });
@@ -9857,7 +9858,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
               medium: string;
               mxid: string;
           }
-        | {}
+        | EmptyObject
     > {
         // Note: we're using the V2 API by calling this function, but our
         // function contract requires a V1 response. We therefore have to
@@ -9953,7 +9954,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      *    supplied.
      * @returns Promise which resolves: to an empty object `{}`
      */
-    public sendToDevice(eventType: string, contentMap: SendToDeviceContentMap, txnId?: string): Promise<{}> {
+    public sendToDevice(eventType: string, contentMap: SendToDeviceContentMap, txnId?: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/sendToDevice/$eventType/$txnId", {
             $eventType: eventType,
             $txnId: txnId ? txnId : this.makeTxnId(),
@@ -10047,7 +10048,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         baseUrl: string,
         accessToken: string,
         termsUrls: string[],
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const url = this.termsUrlForService(serviceType, baseUrl);
         const headers = {
             Authorization: "Bearer " + accessToken,
@@ -10070,7 +10071,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @param reason - The reason the content is being reported. May be blank.
      * @returns Promise which resolves to an empty object if successful
      */
-    public reportEvent(roomId: string, eventId: string, score: number, reason: string): Promise<{}> {
+    public reportEvent(roomId: string, eventId: string, score: number, reason: string): Promise<EmptyObject> {
         const path = utils.encodeUri("/rooms/$roomId/report/$eventId", {
             $roomId: roomId,
             $eventId: eventId,

src/crypto-api/CryptoEventHandlerMap.ts

@@ -18,6 +18,7 @@ import { CryptoEvent } from "./CryptoEvent.ts";
 import { VerificationRequest } from "./verification.ts";
 import { UserVerificationStatus } from "./index.ts";
 import { RustBackupCryptoEventMap } from "../rust-crypto/backup.ts";
+import { EmptyObject } from "../@types/common.ts";
 
 /**
  * A map of the {@link CryptoEvent} fired by the {@link CryptoApi} and their payloads.
@@ -26,7 +27,7 @@ export type CryptoEventHandlerMap = {
     [CryptoEvent.VerificationRequestReceived]: (request: VerificationRequest) => void;
     [CryptoEvent.UserTrustStatusChanged]: (userId: string, userTrustLevel: UserVerificationStatus) => void;
     [CryptoEvent.KeyBackupDecryptionKeyCached]: (version: string) => void;
-    [CryptoEvent.KeysChanged]: (data: {}) => void;
+    [CryptoEvent.KeysChanged]: (data: EmptyObject) => void;
     [CryptoEvent.WillUpdateDevices]: (users: string[], initialFetch: boolean) => void;
     [CryptoEvent.DevicesUpdated]: (users: string[], initialFetch: boolean) => void;
     [CryptoEvent.LegacyCryptoStoreMigrationProgress]: (progress: number, total: number) => void;

src/crypto/EncryptionSetup.ts

@@ -26,6 +26,7 @@ import { TypedEventEmitter } from "../models/typed-event-emitter.ts";
 import { AccountDataClient, SecretStorageKeyDescription } from "../secret-storage.ts";
 import { BootstrapCrossSigningOpts, CrossSigningKeyInfo } from "../crypto-api/index.ts";
 import { AccountDataEvents } from "../@types/event.ts";
+import { EmptyObject } from "../@types/common.ts";
 
 interface ICrossSigningKeys {
     authUpload: BootstrapCrossSigningOpts["authUploadDeviceSigningKeys"];
@@ -267,7 +268,7 @@ class AccountDataClientAdapter
     public setAccountData<K extends keyof AccountDataEvents>(
         type: K,
         content: AccountDataEvents[K] | Record<string, never>,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const event = new MatrixEvent({ type, content });
         const lastEvent = this.values.get(type);
         this.values.set(type, event);

src/crypto/OutgoingRoomKeyRequestManager.ts

@@ -22,6 +22,7 @@ import { IRoomKeyRequestBody, IRoomKeyRequestRecipient } from "./index.ts";
 import { CryptoStore, OutgoingRoomKeyRequest } from "./store/base.ts";
 import { EventType, ToDeviceMessageId } from "../@types/event.ts";
 import { MapWithDefault } from "../utils.ts";
+import { EmptyObject } from "../@types/common.ts";
 
 /**
  * Internal module. Management of outgoing room key requests.
@@ -460,7 +461,7 @@ export class OutgoingRoomKeyRequestManager {
         message: RequestMessage,
         recipients: IRoomKeyRequestRecipient[],
         txnId?: string,
-    ): Promise<{}> {
+    ): Promise<EmptyObject> {
         const contentMap = new MapWithDefault<string, Map<string, Record<string, any>>>(() => new Map());
         for (const recip of recipients) {
             const userDeviceMap = contentMap.getOrCreate(recip.userId);

src/embedded.ts

@@ -57,7 +57,7 @@ import { ToDeviceBatch, ToDevicePayload } from "./models/ToDeviceMessage.ts";
 import { DeviceInfo } from "./crypto/deviceinfo.ts";
 import { IOlmDevice } from "./crypto/algorithms/megolm.ts";
 import { MapWithDefault, recursiveMapToObject } from "./utils.ts";
-import { TypedEventEmitter } from "./matrix.ts";
+import { EmptyObject, TypedEventEmitter } from "./matrix.ts";
 
 interface IStateEventRequest {
     eventType: string;
@@ -431,15 +431,16 @@ export class RoomWidgetClient extends MatrixClient {
      * @experimental This currently relies on an unstable MSC (MSC4140).
      */
     // eslint-disable-next-line
-    public async _unstable_updateDelayedEvent(delayId: string, action: UpdateDelayedEventAction): Promise<{}> {
+    public async _unstable_updateDelayedEvent(delayId: string, action: UpdateDelayedEventAction): Promise<EmptyObject> {
         if (!(await this.doesServerSupportUnstableFeature(UNSTABLE_MSC4140_DELAYED_EVENTS))) {
             throw Error("Server does not support the delayed events API");
         }
 
-        return await this.widgetApi.updateDelayedEvent(delayId, action);
+        await this.widgetApi.updateDelayedEvent(delayId, action);
+        return {};
     }
 
-    public async sendToDevice(eventType: string, contentMap: SendToDeviceContentMap): Promise<{}> {
+    public async sendToDevice(eventType: string, contentMap: SendToDeviceContentMap): Promise<EmptyObject> {
         await this.widgetApi.sendToDevice(eventType, false, recursiveMapToObject(contentMap));
         return {};
     }

src/http-api/fetch.ts

@@ -68,7 +68,7 @@ export class FetchHttpApi<O extends IHttpOpts> {
         this.opts.idBaseUrl = url;
     }
 
-    public idServerRequest<T extends {} = Record<string, unknown>>(
+    public idServerRequest<T extends object = Record<string, unknown>>(
         method: Method,
         path: string,
         params: Record<string, string | string[]> | undefined,

src/interactive-auth.ts

@@ -134,6 +134,7 @@ export type AuthDict =
     | RecaptchaDict
     | EmailIdentityDict
     | { type: Exclude<string, AuthType>; [key: string]: any }
+    // eslint-disable-next-line @typescript-eslint/no-empty-object-type
     | {};
 
 export class NoAuthFlowFoundError extends Error {
@@ -421,10 +422,12 @@ export class InteractiveAuth<T> {
         // use the sessionid from the last request, if one is present.
         let auth: AuthDict;
         if ((this.data as IAuthData)?.session) {
-            auth = {
+            auth = Object.assign(
+                {
                     session: (this.data as IAuthData).session,
-            };
+                },
-            Object.assign(auth, authData);
+                authData,
+            );
         } else {
             auth = authData;
         }

src/matrixrtc/MembershipManager.ts

@@ -10,6 +10,7 @@ import { CallMembership, DEFAULT_EXPIRE_DURATION, SessionMembershipData } from "
 import { Focus } from "./focus.ts";
 import { isLivekitFocusActive } from "./LivekitFocus.ts";
 import { MembershipConfig } from "./MatrixRTCSession.ts";
+import { EmptyObject } from "../@types/common.ts";
 /**
  * This interface defines what a MembershipManager uses and exposes.
  * This interface is what we use to write tests and allows to change the actual implementation
@@ -203,7 +204,7 @@ export class LegacyMembershipManager implements IMembershipManager {
             this.updateCallMembershipRunning = false;
         }
     };
-    private makeNewMembership(deviceId: string): SessionMembershipData | {} {
+    private makeNewMembership(deviceId: string): SessionMembershipData | EmptyObject {
         // If we're joined, add our own
         if (this.isJoined()) {
             return this.makeMyMembership(deviceId);
@@ -239,7 +240,7 @@ export class LegacyMembershipManager implements IMembershipManager {
         const localDeviceId = this.client.getDeviceId();
         if (!localUserId || !localDeviceId) throw new Error("User ID or device ID was null!");
 
-        let newContent: {} | SessionMembershipData = {};
+        let newContent: EmptyObject | SessionMembershipData = {};
         // TODO: add back expiary logic to non-legacy events
         // previously we checked here if the event is timed out and scheduled a check if not.
         // maybe there is a better way.

src/models/MSC3089TreeSpace.ts

@@ -35,6 +35,7 @@ import { FileType } from "../http-api/index.ts";
 import { KnownMembership } from "../@types/membership.ts";
 import { RoomPowerLevelsEventContent, SpaceChildEventContent } from "../@types/state_events.ts";
 import type { EncryptedFile, FileContent } from "../@types/media.ts";
+import { EmptyObject } from "../@types/common.ts";
 
 /**
  * The recommended defaults for a tree space's power levels. Note that this
@@ -81,7 +82,7 @@ export enum TreePermissions {
 
 declare module "../@types/media" {
     interface FileContent {
-        [UNSTABLE_MSC3089_LEAF.name]?: {};
+        [UNSTABLE_MSC3089_LEAF.name]?: EmptyObject;
     }
 }
 

src/models/event.ts

@@ -49,6 +49,7 @@ import { EventTimeline } from "./event-timeline.ts";
 import { Membership } from "../@types/membership.ts";
 import { DecryptionFailureCode } from "../crypto-api/index.ts";
 import { RoomState } from "./room-state.ts";
+import { EmptyObject } from "../@types/common.ts";
 
 export { EventStatus } from "./event-status.ts";
 
@@ -1376,7 +1377,7 @@ export class MatrixEvent extends TypedEventEmitter<MatrixEventEmittedEvents, Mat
      *
      * @returns The redaction event JSON, or an empty object
      */
-    public getRedactionEvent(): IEvent | {} | null {
+    public getRedactionEvent(): IEvent | EmptyObject | null {
         if (!this.isRedacted()) return null;
 
         if (this.clearEvent?.unsigned) {

src/secret-storage.ts

@@ -29,6 +29,7 @@ import encryptAESSecretStorageItem from "./utils/encryptAESSecretStorageItem.ts"
 import decryptAESSecretStorageItem from "./utils/decryptAESSecretStorageItem.ts";
 import { AESEncryptedSecretStoragePayload } from "./@types/AESEncryptedSecretStoragePayload.ts";
 import { AccountDataEvents, SecretStorageAccountDataEvents } from "./@types/event.ts";
+import { EmptyObject } from "./@types/common.ts";
 
 export const SECRET_STORAGE_ALGORITHM_V1_AES = "m.secret_storage.v1.aes-hmac-sha2";
 
@@ -151,7 +152,7 @@ export interface AccountDataClient extends TypedEventEmitter<ClientEvent.Account
     setAccountData: <K extends keyof AccountDataEvents>(
         eventType: K,
         content: AccountDataEvents[K] | Record<string, never>,
-    ) => Promise<{}>;
+    ) => Promise<EmptyObject>;
 }
 
 /**

src/sliding-sync.ts

@@ -265,7 +265,7 @@ export enum ExtensionState {
 /**
  * An interface that must be satisfied to register extensions
  */
-export interface Extension<Req extends {}, Res extends {}> {
+export interface Extension<Req extends object, Res extends object> {
     /**
      * The extension name to go under 'extensions' in the request body.
      * @returns The JSON key.