feat: parse parameter decorators for transforms

cli/index.d.ts

@@ -276,7 +276,10 @@ export abstract class Transform {
   /** Called when parsing is complete, before a program is instantiated from the AST. */
   afterParse?(parser: Parser): void | Promise<void>;
 
-  /** Called after the program is instantiated. */
+  /**
+   * Called after the program is instantiated and before compilation-time validation runs.
+   * This is the last hook where transforms can rewrite preserved AST-only syntax before it is rejected.
+   */
   afterInitialize?(program: Program): void | Promise<void>;
 
   /** Called when compilation is complete, before the module is being validated. */

cli/index.js

@@ -718,7 +718,7 @@ export async function main(argv, options) {
     stats.initializeTime += stats.end(begin);
   }
 
-  // Call afterInitialize transform hook
+  // Call afterInitialize transform hook, the last AST rewrite point before compilation-time validation.
   {
     let error = await applyTransform("afterInitialize", program);
     if (error) return prepareResult(error);

eslint.config.js

@@ -25,6 +25,10 @@ export default defineConfig([
 
     // FIXME: Tagged template literal tests with invalid escapes
     "tests/compiler/templateliteral.ts",
+
+    // Decorators on `this` are not allowed typically in TypeScript, but this
+    // fixture exercises that AS-only syntax and is validated by transform tests.
+    "tests/transform/parameter-decorators.ts",
   ]),
 
   js.configs.recommended,

package.json

@@ -85,8 +85,8 @@
     "test:browser": "node --enable-source-maps tests/browser",
     "test:asconfig": "cd tests/asconfig && npm run test",
     "test:transform": "npm run test:transform:esm && npm run test:transform:cjs",
-    "test:transform:esm": "node bin/asc tests/compiler/empty --transform ./tests/transform/index.js --noEmit && node bin/asc tests/compiler/empty --transform ./tests/transform/simple.js --noEmit",
-    "test:transform:cjs": "node bin/asc tests/compiler/empty --transform ./tests/transform/cjs/index.js --noEmit && node bin/asc tests/compiler/empty --transform ./tests/transform/cjs/simple.js --noEmit",
+    "test:transform:esm": "node bin/asc tests/compiler/empty --transform ./tests/transform/index.js --noEmit && node bin/asc tests/compiler/empty --transform ./tests/transform/simple.js --noEmit && node bin/asc tests/transform/parameter-decorators.ts --transform ./tests/transform/remove-parameter-decorators.js --noEmit",
+    "test:transform:cjs": "node bin/asc tests/compiler/empty --transform ./tests/transform/cjs/index.js --noEmit && node bin/asc tests/compiler/empty --transform ./tests/transform/cjs/simple.js --noEmit && node bin/asc tests/transform/parameter-decorators.ts --transform ./tests/transform/cjs/remove-parameter-decorators.js --noEmit",
     "test:cli": "node tests/cli/options.js",
     "asbuild": "npm run asbuild:debug && npm run asbuild:release",
     "asbuild:debug": "node bin/asc --config src/asconfig.json --target debug",