Work around missing promisified overloads

See gjsify/ts-for-gir#171 (comment)
and gjsify/ts-for-gir#177

src/lib/fixes.ts

@@ -18,15 +18,64 @@
 // GNU General Public License for more details.
 
 import type GLib from "gi://GLib";
+import type Gio from "gi://Gio";
+import type Soup from "gi://Soup";
 
 /**
  * This module provides workarounds and fixes for various incomplete type
  * declarations in Gnome shell types and its dependencies.
  */
 
+type Promisified<AsyncFN, FinishFN> = AsyncFN extends (
+  ...args: infer Args
+) => void
+  ? FinishFN extends (result: Gio.AsyncResult) => infer TReturn
+    ? (...args: Args) => Promise<TReturn>
+    : never
+  : never;
+
 /**
  * @see https://github.com/gjsify/ts-for-gir/issues/196
  */
 export interface GLibErrorWithStack extends GLib.Error {
   readonly stack: string;
 }
+
+/**
+ * @see https://github.com/gjsify/ts-for-gir/issues/171#issuecomment-2117301067
+ */
+export interface PromisifiedFileOutputStream extends Gio.FileOutputStream {
+  splice_async: Promisified<
+    Gio.OutputStream["splice_async"],
+    Gio.OutputStream["splice_finish"]
+  >;
+}
+
+/**
+ * @see https://github.com/gjsify/ts-for-gir/issues/171#issuecomment-2117301067
+ */
+export interface PromisifiedGioFile extends Gio.File {
+  create_async: Promisified<
+    Gio.File["create_async"],
+    Gio.File["create_finish"]
+  >;
+  delete_async: Promisified<
+    Gio.File["delete_async"],
+    Gio.File["delete_finish"]
+  >;
+}
+
+/**
+ * @see https://github.com/gjsify/ts-for-gir/issues/171#issuecomment-2117301067
+ */
+export interface PromisifiedSoupSession extends Soup.Session {
+  send_async: Promisified<
+    Soup.Session["send_async"],
+    Soup.Session["send_finish"]
+  >;
+
+  send_and_read_async: Promisified<
+    Soup.Session["send_and_read_async"],
+    Soup.Session["send_and_read_finish"]
+  >;
+}

src/lib/network/http.ts

@@ -23,6 +23,11 @@ import Soup from "gi://Soup";
 import { IOError } from "../common/gio.js";
 
 import type { ExtensionMetadata } from "resource:///org/gnome/shell/extensions/extension.js";
+import {
+  PromisifiedFileOutputStream,
+  PromisifiedGioFile,
+  PromisifiedSoupSession,
+} from "../fixes.js";
 
 export const createSession = (
   extensionMetadata: ExtensionMetadata,
@@ -83,7 +88,7 @@ export const getString = async (
   cancellable: Gio.Cancellable,
 ): Promise<string> => {
   const message = Soup.Message.new("GET", url);
-  const response = await session
+  const response = await (session as PromisifiedSoupSession)
     .send_and_read_async(message, 0, cancellable)
     .catch((cause: unknown) => {
       throw new HttpRequestError(url, `Failed to get data from ${url}`, {
@@ -146,7 +151,7 @@ const deletePartialDownloadIgnoreError = async (
   cancellable: Gio.Cancellable | null,
 ): Promise<void> => {
   try {
-    await file.delete_async(0, cancellable);
+    await (file as PromisifiedGioFile).delete_async(0, cancellable);
   } catch (error) {
     console.warn(
       `Failed to delete result of partial download at ${file.get_path() ?? ""}`,
@@ -173,7 +178,7 @@ export const downloadToFile = async (
     return;
   }
   const message = Soup.Message.new("GET", url);
-  const source = await session
+  const source = await (session as PromisifiedSoupSession)
     .send_async(message, 0, cancellable)
     .catch((cause: unknown) => {
       throw new HttpRequestError(url, `Failed to make GET request to ${url}`, {
@@ -215,15 +220,15 @@ export const downloadToFile = async (
   }
   // Now open the target file for reading, and safely delete it in case of error.
   try {
-    const sink = await target
+    const sink = await (target as PromisifiedGioFile)
       .create_async(Gio.FileCreateFlags.NONE, 0, null)
       .catch((cause: unknown) => {
         throw new IOError(
           `Failed to open target file at ${target.get_path() ?? ""} to download from ${url}`,
           { cause },
         );
       });
-    await sink
+    await (sink as PromisifiedFileOutputStream)
       .splice_async(
         source,
         Gio.OutputStreamSpliceFlags.CLOSE_SOURCE |