Load type extensions of builitin plugins

Author: alcuadrado

Diff for: v-next/hardhat/src/config.ts

@@ -1,2 +1,6 @@
+// Note: We export the builtin plugins' types here, so that any type extension
+// they may have gets loaded.
+export type * from "./internal/builtin-plugins/index.js";
+
 export type * from "@nomicfoundation/hardhat-core/config";
 export * from "@nomicfoundation/hardhat-core/config";

Diff for: v-next/hardhat/src/internal/builtin-plugins/hardhat-foo/index.ts

@@ -1,7 +1,7 @@
 import type { HardhatPlugin } from "@nomicfoundation/hardhat-core/types/plugins";
 
 import { globalFlag, task } from "@nomicfoundation/hardhat-core/config";
-import "./type-extensions.js";
+export type * from "./type-extensions.js";
 
 export default {
   id: "hardhat-foo",

Diff for: v-next/hardhat/src/internal/builtin-plugins/hardhat-foo/type-extensions.ts

@@ -1,3 +1,5 @@
+import "@nomicfoundation/hardhat-core/types/config";
+
 declare module "@nomicfoundation/hardhat-core/types/config" {
   interface FooUserConfig {
     bar?: number | number[];

Diff for: v-next/hardhat/src/internal/builtin-plugins/index.ts

@@ -1,5 +1,8 @@
 import type { HardhatPlugin } from "@nomicfoundation/hardhat-core/types/plugins";
 
+// Note: When importing a plugin, you have to export its types, so that its
+// type extensions, if any, also get loaded.
+export type * from "./hardhat-foo/index.js";
 import hardhatFoo from "./hardhat-foo/index.js";
 
 export const builtinPlugins: HardhatPlugin[] = [hardhatFoo];