module: add --experimental-enable-transformation for strip-types

Author: marco-ippolito

doc/api/cli.md

@@ -933,6 +933,15 @@ files with no extension will be treated as WebAssembly if they begin with the
 WebAssembly magic number (`\0asm`); otherwise they will be treated as ES module
 JavaScript.
 
+### `--experimental-enable-transformation`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Enables the transformation of TypeScript only features.
+Imples `--experimental-strip-types`.
+
 ### `--experimental-eventsource`
 
 <!-- YAML
@@ -2911,6 +2920,7 @@ one is included in the list below.
 * `--experimental-async-context-frame`
 * `--experimental-default-type`
 * `--experimental-detect-module`
+* `--experimental-enable-transformation`
 * `--experimental-eventsource`
 * `--experimental-import-meta-resolve`
 * `--experimental-json-modules`

doc/node.1

@@ -194,6 +194,9 @@ Enable snapshot testing in the test runner.
 .It Fl -experimental-strip-types
 Enable experimental type-stripping for TypeScript files.
 .
+.It Fl -experimental-enable-transformation
+Enable transformation of TypeScript-only syntax into JavaScript code.
+.
 .It Fl -experimental-eventsource
 Enable experimental support for the EventSource Web API.
 .

lib/internal/main/eval_string.js

@@ -14,7 +14,7 @@ const {
   markBootstrapComplete,
 } = require('internal/process/pre_execution');
 const { evalModuleEntryPoint, evalScript } = require('internal/process/execution');
-const { addBuiltinLibsToObject, tsParse } = require('internal/modules/helpers');
+const { addBuiltinLibsToObject, stripTypes } = require('internal/modules/helpers');
 
 const { getOptionValue } = require('internal/options');
 
@@ -24,7 +24,7 @@ markBootstrapComplete();
 
 const code = getOptionValue('--eval');
 const source = getOptionValue('--experimental-strip-types') ?
-  tsParse(code) :
+  stripTypes(code).code :
   code;
 
 const print = getOptionValue('--print');

lib/internal/modules/cjs/loader.js

@@ -1362,8 +1362,9 @@ function loadESMFromCJS(mod, filename) {
     if (isUnderNodeModules(filename)) {
       throw new ERR_UNSUPPORTED_NODE_MODULES_TYPE_STRIPPING(filename);
     }
-    const { tsParse } = require('internal/modules/helpers');
-    source = tsParse(source);
+    const { stripTypes } = require('internal/modules/helpers');
+    const { code } = stripTypes(source, filename);
+    source = code;
   }
   const cascadedLoader = require('internal/modules/esm/loader').getOrInitializeCascadedLoader();
   const isMain = mod[kIsMainSymbol];
@@ -1576,9 +1577,9 @@ function loadCTS(module, filename) {
     throw new ERR_UNSUPPORTED_NODE_MODULES_TYPE_STRIPPING(filename);
   }
   const source = getMaybeCachedSource(module, filename);
-  const { tsParse } = require('internal/modules/helpers');
-  const content = tsParse(source);
-  module._compile(content, filename, 'commonjs');
+  const { stripTypes } = require('internal/modules/helpers');
+  const { code } = stripTypes(source, filename);
+  module._compile(code, filename, 'commonjs');
 }
 
 /**
@@ -1592,8 +1593,8 @@ function loadTS(module, filename) {
   }
   // If already analyzed the source, then it will be cached.
   const source = getMaybeCachedSource(module, filename);
-  const { tsParse } = require('internal/modules/helpers');
-  const content = tsParse(source);
+  const { stripTypes } = require('internal/modules/helpers');
+  const { code: content } = stripTypes(source, filename);
   let format;
   const pkg = packageJsonReader.getNearestParentPackageJSON(filename);
   // Function require shouldn't be used in ES modules.
@@ -1613,7 +1614,8 @@ function loadTS(module, filename) {
     if (Module._cache[parentPath]) {
       let parentSource;
       try {
-        parentSource = tsParse(fs.readFileSync(parentPath, 'utf8'));
+        const { code } = stripTypes(fs.readFileSync(parentPath, 'utf8'), parentPath);
+        parentSource = code;
       } catch {
         // Continue regardless of error.
       }

lib/internal/modules/esm/get_format.js

@@ -161,9 +161,9 @@ function getFileProtocolModuleFormat(url, context = { __proto__: null }, ignoreE
       default: { // The user did not pass `--experimental-default-type`.
         // `source` is undefined when this is called from `defaultResolve`;
         // but this gets called again from `defaultLoad`/`defaultLoadSync`.
-        const { tsParse } = require('internal/modules/helpers');
-        const parsedSource = tsParse(source);
-        const detectedFormat = detectModuleFormat(parsedSource, url);
+        const { stripTypes } = require('internal/modules/helpers');
+        const { code } = stripTypes(source, url);
+        const detectedFormat = detectModuleFormat(code, url);
         // When source is undefined, default to module-typescript.
         const format = detectedFormat ? `${detectedFormat}-typescript` : 'module-typescript';
         if (format === 'module-typescript' && foundPackageJson) {

lib/internal/modules/esm/translators.js

@@ -38,7 +38,7 @@ const { readFileSync } = require('fs');
 const { dirname, extname, isAbsolute } = require('path');
 const {
   loadBuiltinModule,
-  tsParse,
+  stripTypes,
   stripBOM,
   urlToFilename,
 } = require('internal/modules/helpers');
@@ -309,7 +309,7 @@ translators.set('require-commonjs', (url, source, isMain) => {
 translators.set('require-commonjs-typescript', (url, source, isMain) => {
   emitExperimentalWarning('Type Stripping');
   assert(cjsParse);
-  const code = tsParse(stringify(source));
+  const { code } = stripTypes(stringify(source), url);
   return createCJSModuleWrap(url, code);
 });
 
@@ -526,7 +526,7 @@ translators.set('wasm', async function(url, source) {
 translators.set('commonjs-typescript', function(url, source) {
   emitExperimentalWarning('Type Stripping');
   assertBufferSource(source, false, 'load');
-  const code = tsParse(stringify(source));
+  const { code } = stripTypes(stringify(source), url);
   debug(`Translating TypeScript ${url}`);
   return FunctionPrototypeCall(translators.get('commonjs'), this, url, code, false);
 });
@@ -535,7 +535,7 @@ translators.set('commonjs-typescript', function(url, source) {
 translators.set('module-typescript', function(url, source) {
   emitExperimentalWarning('Type Stripping');
   assertBufferSource(source, false, 'load');
-  const code = tsParse(stringify(source));
+  const { code } = stripTypes(stringify(source), url);
   debug(`Translating TypeScript ${url}`);
   return FunctionPrototypeCall(translators.get('module'), this, url, code, false);
 });

lib/internal/modules/helpers.js

@@ -300,7 +300,21 @@ function getBuiltinModule(id) {
   return normalizedId ? require(normalizedId) : undefined;
 }
 
+/**
+ * TypeScript parsing function, by default Amaro.transformSync.
+ *  @type {Function}
+ */
 let typeScriptParser;
+/**
+ * The TypeScript parsing mode, either 'strip-only' or 'transform'.
+ * @type {string}
+ */
+let typeScriptParsingMode;
+/**
+ * Whether source maps are enabled for TypeScript parsing.
+ * @type {boolean}
+ */
+let sourceMapEnabled;
 
 /**
  * Load the TypeScript parser.
@@ -318,24 +332,30 @@ function loadTypeScriptParser(parser) {
   } else {
     const amaro = require('internal/deps/amaro/dist/index');
     // Default option for Amaro is to perform Type Stripping only.
-    const defaultOptions = { __proto__: null, mode: 'strip-only' };
+    typeScriptParsingMode = getOptionValue('--experimental-enable-transformation') ? 'transform' : 'strip-only';
+    sourceMapEnabled = getOptionValue('--enable-source-maps');
     // Curry the transformSync function with the default options.
-    typeScriptParser = (source) => amaro.transformSync(source, defaultOptions);
+    typeScriptParser = amaro.transformSync;
   }
   return typeScriptParser;
 }
 
 /**
+ * @typedef {object} TransformOutput
+ * @property {string} code - The compiled code.
+ * @property {string} [map] - The source maps (optional).
+ *
  * Performs type-stripping to TypeScript source code.
  * @param {string} source TypeScript code to parse.
- * @returns {string} JavaScript code.
+ * @param {string} filename The filename of the source code.
+ * @returns {TransformOutput} The stripped TypeScript code.
  */
-function tsParse(source) {
+function stripTypes(source, filename) {
   // TODO(@marco-ippolito) Checking empty string or non string input should be handled in Amaro.
   if (!source || typeof source !== 'string') { return ''; }
   const parse = loadTypeScriptParser();
-  const { code } = parse(source);
-  return code;
+  const options = { __proto__: null, mode: typeScriptParsingMode, sourceMap: sourceMapEnabled, filename };
+  return parse(source, options);
 }
 
 function isUnderNodeModules(filename) {
@@ -354,7 +374,7 @@ module.exports = {
   loadBuiltinModule,
   makeRequireFunction,
   normalizeReferrerURL,
-  tsParse,
+  stripTypes,
   stripBOM,
   toRealPath,
   hasStartedUserCJSExecution() {

src/node_options.cc

@@ -789,6 +789,12 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "Experimental type-stripping for TypeScript files.",
             &EnvironmentOptions::experimental_strip_types,
             kAllowedInEnvvar);
+  AddOption("--experimental-enable-transformation",
+            "enable transformation of TypeScript-only"
+            "syntax in JavaScript code",
+            &EnvironmentOptions::experimental_enable_transformation,
+            kAllowedInEnvvar);
+  Implies("--experimental-enable-transformation", "--experimental-strip-types");
   AddOption("--interactive",
             "always enter the REPL even if stdin does not appear "
             "to be a terminal",

src/node_options.h

@@ -239,6 +239,7 @@ class EnvironmentOptions : public Options {
   std::vector<std::string> preload_esm_modules;
 
   bool experimental_strip_types = false;
+  bool experimental_enable_transformation = false;
 
   std::vector<std::string> user_argv;
 

test/es-module/test-typescript-transform.mjs

@@ -0,0 +1,44 @@
+import { skip, spawnPromisified } from '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import { match, strictEqual } from 'node:assert';
+import { test } from 'node:test';
+
+if (!process.config.variables.node_use_amaro) skip('Requires Amaro');
+
+test('execute a TypeScript file with transformation enabled', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    '--experimental-enable-transformation',
+    '--no-warnings',
+    fixtures.path('typescript/ts/transformation/test-enum.ts'),
+  ]);
+
+  strictEqual(result.stderr, '');
+  match(result.stdout, /Hello, TypeScript!/);
+  strictEqual(result.code, 0);
+});
+
+test('execute a TypeScript file with transformation enabled and sourcemaps', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    '--experimental-enable-transformation',
+    '--enable-source-maps',
+    '--no-warnings',
+    fixtures.path('typescript/ts/transformation/test-enum.ts'),
+  ]);
+
+  strictEqual(result.stderr, '');
+  match(result.stdout, /Hello, TypeScript!/);
+  strictEqual(result.code, 0);
+});
+
+test('reconstruct error of a TypeScript file with transformation enabled and sourcemaps', async () => {
+  const result = await spawnPromisified(process.execPath, [
+    '--experimental-enable-transformation',
+    '--enable-source-maps',
+    '--no-warnings',
+    fixtures.path('typescript/ts/transformation/test-enum-stacktrace.ts'),
+  ]);
+
+  match(result.stderr, match(result.stderr, /test-enum-stacktrace\.ts:4:7/));
+  strictEqual(result.stdout, '');
+  strictEqual(result.code, 0);
+});