Disallow dynamic require/import in extensions

Follow up on https://github.com/microsoft/vscode/pull/296220

Let's make sure more code doesn't introduce this pattern without some thought

eslint.config.js

@@ -2112,6 +2112,30 @@ export default tseslint.config(
 			'comma-dangle': ['warn', 'only-multiline']
 		}
 	},
+	// Extension main sources (excluding tests)
+	{
+		files: [
+			'extensions/**/*.ts',
+
+		],
+		ignores: [
+			'extensions/**/*.test.ts',
+		],
+		rules: {
+			// Ban dynamic require() and import() calls in extensions to ensure tree-shaking works
+			'no-restricted-syntax': [
+				'warn',
+				{
+					'selector': `CallExpression[callee.name='require'][arguments.0.type!='Literal']`,
+					'message': 'Use static imports instead of dynamic require() calls to enable tree-shaking.'
+				},
+				{
+					'selector': `ImportExpression[source.type!='Literal']`,
+					'message': 'Use static imports instead of dynamic import() calls to enable tree-shaking.'
+				},
+			],
+		}
+	},
 	// markdown-language-features
 	{
 		files: [

extensions/typescript-language-features/web/src/serverHost.ts

@@ -104,6 +104,8 @@ function createServerHost(
 
 			const scriptPath = combinePaths(packageRoot, browser);
 			try {
+				// This file isn't bundled so we really do want a dynamic import here
+				// eslint-disable-next-line no-restricted-syntax
 				const { default: module } = await import(/* webpackIgnore: true */ scriptPath);
 				return { module, error: undefined };
 			} catch (e) {