Enable tsc alwaysStrict, strictBindCallApply, noImplicitThis (#9600)

* Enable tsc alwaysStrict

* Enable tsc strictBindCallApply

* Enable tsc noImplicitThis

* Add d.ts

* Improve types

* Add ?

* Increase coverage

* Improve coverage

src/@types/common.ts

@@ -24,15 +24,16 @@ export type Writeable<T> = { -readonly [P in keyof T]: T[P] };
 export type ComponentClass = keyof JSX.IntrinsicElements | JSXElementConstructor<any>;
 export type ReactAnyComponent = React.Component | React.ExoticComponent;
 
+// Utility type for string dot notation for accessing nested object properties
 // Based on https://stackoverflow.com/a/58436959
 type Join<K, P> = K extends string | number ?
     P extends string | number ?
         `${K}${"" extends P ? "" : "."}${P}`
         : never : never;
 
-type Prev = [never, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ...0[]];
+type Prev = [never, 0, 1, 2, 3, ...0[]];
 
-export type Leaves<T, D extends number = 5> = [D] extends [never] ? never : T extends object ?
+export type Leaves<T, D extends number = 3> = [D] extends [never] ? never : T extends object ?
     { [K in keyof T]-?: Join<K, Leaves<T[K], Prev[D]>> }[keyof T] : "";
 
 export type RecursivePartial<T> = {

src/@types/commonmark.ts

@@ -0,0 +1,52 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import * as commonmark from "commonmark";
+
+declare module "commonmark" {
+    export type Attr = [key: string, value: string];
+
+    export interface HtmlRenderer {
+        // As far as @types/commonmark is concerned, these are not public, so add them
+        // https://github.com/commonmark/commonmark.js/blob/master/lib/render/html.js#L272-L296
+        text: (this: commonmark.HtmlRenderer, node: commonmark.Node) => void;
+        html_inline: (this: commonmark.HtmlRenderer, node: commonmark.Node) => void;
+        html_block: (this: commonmark.HtmlRenderer, node: commonmark.Node) => void;
+        // softbreak: () => void; // This one can't be correctly specified as it is wrongly defined in @types/commonmark
+        linebreak: (this: commonmark.HtmlRenderer) => void;
+        link: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        image: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        emph: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        strong: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        paragraph: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        heading: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        code: (this: commonmark.HtmlRenderer, node: commonmark.Node) => void;
+        code_block: (this: commonmark.HtmlRenderer, node: commonmark.Node) => void;
+        thematic_break: (this: commonmark.HtmlRenderer, node: commonmark.Node) => void;
+        block_quote: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        list: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        item: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        custom_inline: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        custom_block: (this: commonmark.HtmlRenderer, node: commonmark.Node, entering: boolean) => void;
+        esc: (s: string) => string;
+        out: (this: commonmark.HtmlRenderer, text: string) => void;
+        tag: (this: commonmark.HtmlRenderer, name: string, attrs?: Attr[], selfClosing?: boolean) => void;
+        attrs: (this: commonmark.HtmlRenderer, node: commonmark.Node) => Attr[];
+        // These are inherited from the base Renderer
+        lit: (this: commonmark.HtmlRenderer, text: string) => void;
+        cr: (this: commonmark.HtmlRenderer) => void;
+    }
+}