esm: phase two of new esm implementation

This PR updates the current `--experimental-modules` implementation
based on the work of the modules team  and reflects Phase 2 of our
new modules plan.

The largest differences from the current implementation include

* `packge.type` which can be either `module` or `commonjs`
  - `type: "commonjs"`:
    - `.js` is parsed as commonjs
    - default for entry point without an extension is commonjs
  - `type: "module"`:
    - `.js` is parsed as esm
    - does not support loading JSON or Native Module by default
    - default for entry point without an extension is esm
* `--entry-type=[mode]`
  - allows you set the type on entry point.
* A new file extension `.cjs`.
  - this is specifically to support importing commonjs in the
    `module` mode.
  - this is only in the esm loader, the commonjs loader remains
    untouched, but the extension will work in the old loader if you use
    the full file path.
* `--es-module-specifier-resolution=[type]`
  - options are `explicit` (default) and `node`
  - by default our loader will not allow for optional extensions in
    the import, the path for a module must include the extension if
    there is one
  - by default our loader will not allow for importing directories that
    have an index file
  - developers can use `--es-module-specifier-resolution=node` to
    enable the commonjs specifier resolution algorithm
  - This is not a “feature” but rather an implementation for
    experimentation. It is expected to change before the flag is
    removed
* `--experimental-json-loader`
  - the only way to import json when `"type": "module"`
  - when enable all `import 'thing.json'` will go through the
    experimental loader independent of mode
  - based on https://github.com/whatwg/html/issues/4315
* You can use `package.main` to set an entry point for a module
  - the file extensions used in main will be resolved based on the
    `type` of the module

Refs: https://github.com/nodejs/modules/blob/master/doc/plan-for-new-modules-implementation.md
Refs: https://github.com/GeoffreyBooth/node-import-file-specifier-resolution-proposal
Refs: https://github.com/nodejs/modules/pull/180
Refs: https://github.com/nodejs/ecmascript-modules/pull/6
Refs: https://github.com/nodejs/ecmascript-modules/pull/12
Refs: https://github.com/nodejs/ecmascript-modules/pull/28
Refs: https://github.com/nodejs/modules/issues/255
Refs: https://github.com/whatwg/html/issues/4315
Refs: https://github.com/w3c/webcomponents/issues/770
Co-authored-by: Myles Borins <MylesBorins@google.com>
Co-authored-by: John-David Dalton <john.david.dalton@gmail.com>
Co-authored-by: Evan Plaice <evanplaice@gmail.com>
Co-authored-by: Geoffrey Booth <webmaster@geoffreybooth.com>
Co-authored-by: Michaël Zasso <targos@protonmail.com>

PR-URL: https://github.com/nodejs/node/pull/26745
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Ben Coe <bencoe@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>

1 files changed, 43 insertions, 2 deletions

diff --git a/src/node_options.cc b/src/node_options.cc
index 5687fb327b..bd20b6385d 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -107,6 +107,32 @@ void EnvironmentOptions::CheckOptions(std::vector<std::string>* errors) {
     errors->push_back("--loader requires --experimental-modules be enabled");
   }
 
+  if (!module_type.empty()) {
+    if (!experimental_modules) {
+      errors->push_back("--entry-type requires "
+                        "--experimental-modules to be enabled");
+    }
+    if (module_type != "commonjs" && module_type != "module") {
+      errors->push_back("--entry-type must \"module\" or \"commonjs\"");
+    }
+  }
+
+  if (experimental_json_modules && !experimental_modules) {
+    errors->push_back("--experimental-json-modules requires "
+                      "--experimental-modules be enabled");
+  }
+
+  if (!es_module_specifier_resolution.empty()) {
+    if (!experimental_modules) {
+      errors->push_back("--es-module-specifier-resolution requires "
+                        "--experimental-modules be enabled");
+    }
+    if (es_module_specifier_resolution != "node" &&
+        es_module_specifier_resolution != "explicit") {
+      errors->push_back("invalid value for --es-module-specifier-resolution");
+    }
+  }
+
   if (syntax_check_only && has_eval_string) {
     errors->push_back("either --check or --eval can be used, not both");
   }
@@ -214,6 +240,10 @@ DebugOptionsParser::DebugOptionsParser() {
 }
 
 EnvironmentOptionsParser::EnvironmentOptionsParser() {
+  AddOption("--experimental-json-modules",
+            "experimental JSON interop support for the ES Module loader",
+            &EnvironmentOptions::experimental_json_modules,
+            kAllowedInEnvironment);
   AddOption("--experimental-modules",
             "experimental ES Module support and caching modules",
             &EnvironmentOptions::experimental_modules,
@@ -253,6 +283,11 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "custom loader",
             &EnvironmentOptions::userland_loader,
             kAllowedInEnvironment);
+  AddOption("--es-module-specifier-resolution",
+            "Select extension resolution algorithm for es modules; "
+            "either 'explicit' (default) or 'node'",
+            &EnvironmentOptions::es_module_specifier_resolution,
+            kAllowedInEnvironment);
   AddOption("--no-deprecation",
             "silence deprecation warnings",
             &EnvironmentOptions::no_deprecation,
@@ -271,10 +306,12 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             kAllowedInEnvironment);
   AddOption("--preserve-symlinks",
             "preserve symbolic links when resolving",
-            &EnvironmentOptions::preserve_symlinks);
+            &EnvironmentOptions::preserve_symlinks,
+            kAllowedInEnvironment);
   AddOption("--preserve-symlinks-main",
             "preserve symbolic links when resolving the main module",
-            &EnvironmentOptions::preserve_symlinks_main);
+            &EnvironmentOptions::preserve_symlinks_main,
+            kAllowedInEnvironment);
   AddOption("--prof-process",
             "process V8 profiler output generated using --prof",
             &EnvironmentOptions::prof_process);
@@ -301,6 +338,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "show stack traces on process warnings",
             &EnvironmentOptions::trace_warnings,
             kAllowedInEnvironment);
+  AddOption("--entry-type",
+            "set module type name of the entry point",
+            &EnvironmentOptions::module_type,
+            kAllowedInEnvironment);
 
   AddOption("--check",
             "syntax check script without executing",