Enable @typescript-eslint/explicit-function-return-type in /src (#9788)

* Enable `@typescript-eslint/explicit-member-accessibility` on /src

* Prettier

* Enable `@typescript-eslint/explicit-function-return-type` in /src

* Fix types

* tsc strict fixes

* Delint

* Fix test

* Fix bad merge

src/contexts/MatrixClientContext.tsx

@@ -14,7 +14,15 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import React, { ComponentClass, createContext, forwardRef, useContext } from "react";
+import React, {
+    ComponentClass,
+    createContext,
+    forwardRef,
+    PropsWithoutRef,
+    ForwardRefExoticComponent,
+    useContext,
+    RefAttributes,
+} from "react";
 import { MatrixClient } from "matrix-js-sdk/src/client";
 
 const MatrixClientContext = createContext<MatrixClient>(undefined);
@@ -25,11 +33,16 @@ export interface MatrixClientProps {
     mxClient: MatrixClient;
 }
 
-export function useMatrixClientContext() {
+export function useMatrixClientContext(): MatrixClient {
     return useContext(MatrixClientContext);
 }
 
-const matrixHOC = <ComposedComponentProps extends {}>(ComposedComponent: ComponentClass<ComposedComponentProps>) => {
+const matrixHOC = <ComposedComponentProps extends {}>(
+    ComposedComponent: ComponentClass<ComposedComponentProps>,
+): ForwardRefExoticComponent<
+    PropsWithoutRef<Omit<ComposedComponentProps, "mxClient">> &
+        RefAttributes<InstanceType<ComponentClass<ComposedComponentProps>>>
+> => {
     type ComposedComponentInstance = InstanceType<typeof ComposedComponent>;
 
     // eslint-disable-next-line react-hooks/rules-of-hooks

src/contexts/RoomContext.ts

@@ -68,6 +68,6 @@ const RoomContext = createContext<IRoomState>({
 });
 RoomContext.displayName = "RoomContext";
 export default RoomContext;
-export function useRoomContext() {
+export function useRoomContext(): IRoomState {
     return useContext(RoomContext);
 }

src/contexts/SDKContext.ts

@@ -78,7 +78,7 @@ export class SdkContextClass {
      * Automatically construct stores which need to be created eagerly so they can register with
      * the dispatcher.
      */
-    public constructEagerStores() {
+    public constructEagerStores(): void {
         this._RoomViewStore = this.roomViewStore;
     }