Use jiti for sync loading from TS Plugin (#803)

packages/typescript-plugin/package.json

@@ -21,6 +21,7 @@
     "prepack": "yarn build"
   },
   "dependencies": {
+    "jiti": "~2.4.2",
     "@glint/core": "^1.4.0",
     "@volar/typescript": "2.4.11"
   },

packages/typescript-plugin/src/typescript-server-plugin.ts

@@ -1,57 +1,37 @@
-import type ts from 'typescript';
+const { createJiti } = require('jiti');
+const jiti = createJiti(__filename);
 
-// Top level "imports" need to be CJS `require`s because TS Plugins must be CJS;
-// we dynamically import() the ESM modules we need below within the async fn
-// to cross the gap between CJS and ESM.
 const {
-  createAsyncLanguageServicePlugin,
-} = require('@volar/typescript/lib/quickstart/createAsyncLanguageServicePlugin.js');
+  createLanguageServicePlugin,
+} = require('@volar/typescript/lib/quickstart/createLanguageServicePlugin.js');
 
-/**
- * Volar provides two variants of functions for initializing a TS Plugin:
- * - createLanguageServicePlugin
- * - createAsyncLanguageServicePlugin
- *
- * The only difference is whether their setup callback is an async function or not.
- * The reason we use the async variant is because of our use of `await import`, which
- * we need in order to import the ESM glint package into our CJS VSCode extension.
- *
- * Unfortunately this singular tick of async appears to be causing a few race conditions,
- * in particular that when freshly booting VSCode on a .gts file, there might not be
- * any diagnostic messages until something "kicks" the TS Plugin to run, e.g.
- * by editing the file.
- */
-const plugin = createAsyncLanguageServicePlugin(
-  ['.gts', '.gjs', '.hbs'],
-  (fileName: string) => {
-    if (fileName.endsWith('.gts')) {
-      return 3 satisfies ts.ScriptKind.TS;
-    } else if (fileName.endsWith('.gjs')) {
-      return 1 satisfies ts.ScriptKind.JS;
-    }
-    return 3 satisfies ts.ScriptKind.TS;
-  },
-  async (_ts: any, info: any) => {
-    // The diagnostics race condition mentioned above appears to happen or at least
-    // be exacerbated by the fact that we use `await import` here.
-    const glintCore = await import('@glint/core');
+const plugin = createLanguageServicePlugin((_ts: typeof import('typescript'), info: any) => {
+  /**
+   * we use the jiti (https://github.com/unjs/jiti) runtime to make it possible to
+   * synchronously load the ESM glint libaries from the current CommonJS context. It is a requirement
+   * that TypeScript plugins are written in CommonJS, which poses issues with
+   * having Glint be authored in ESM due to the requirement that typically `await import`
+   * is required to load ESM modules from CJS. But with jiti we can synchronously load the ESM
+   * modules from CJS which lets us avoid a ton of hacks and complexity we (or Volar)
+   * would otherwise have to write to bridge the sync/async APIs.
+   */
+  const glintCore = jiti('@glint/core');
 
-    const { findConfig, createEmberLanguagePlugin } = glintCore;
+  const { findConfig, createEmberLanguagePlugin } = glintCore;
 
-    const cwd = info.languageServiceHost.getCurrentDirectory();
-    const glintConfig = findConfig(cwd);
+  const cwd = info.languageServiceHost.getCurrentDirectory();
+  const glintConfig = findConfig(cwd);
 
-    if (glintConfig && glintConfig.enableTsPlugin) {
-      const gtsLanguagePlugin = createEmberLanguagePlugin(glintConfig);
-      return {
-        languagePlugins: [gtsLanguagePlugin],
-      };
-    } else {
-      return {
-        languagePlugins: [],
-      };
-    }
-  },
-);
+  if (glintConfig && glintConfig.enableTsPlugin) {
+    const gtsLanguagePlugin = createEmberLanguagePlugin(glintConfig);
+    return {
+      languagePlugins: [gtsLanguagePlugin],
+    };
+  } else {
+    return {
+      languagePlugins: [],
+    };
+  }
+});
 
 export = plugin;

yarn.lock

@@ -9686,6 +9686,11 @@ jest-worker@^27.4.5:
     merge-stream "^2.0.0"
     supports-color "^8.0.0"
 
+jiti@~2.4.2:
+  version "2.4.2"
+  resolved "https://registry.yarnpkg.com/jiti/-/jiti-2.4.2.tgz#d19b7732ebb6116b06e2038da74a55366faef560"
+  integrity sha512-rg9zJN+G4n2nfJl5MW3BMygZX56zKPNVEYYqq7adpmMh4Jn2QNEwhvQlFy6jPVdcod7txZtKHWnyZiA3a0zP7A==
+
 js-string-escape@^1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/js-string-escape/-/js-string-escape-1.0.1.tgz#e2625badbc0d67c7533e9edc1068c587ae4137ef"