[dart2js]: require dart2js to be invoked from an approved CLI

The dart2js snapshot is not meant to be invoked directly except from
a limited set of entry points (CLIs and internal build systems).
This change makes it an error to invoke it in unsupported ways.

Note: this change is not expected to be visible to end users.

Fixes #51695

Change-Id: I4013dd00b90bb3d54483e2f112e0ddfb8dc694e4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/289885
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Nate Biggs <natebiggs@google.com>
Commit-Queue: Sigmund Cherem <sigmund@google.com>

CHANGELOG.md

@@ -171,6 +171,13 @@
 #### Web Dev Compiler (DDC)
 - Removed deprecated command line flags `-k`, `--kernel`, and `--dart-sdk`.
 
+#### Dart2js
+
+- Cleanup related to [#46100](https://github.com/dart-lang/sdk/issues/46100):
+  the internal dart2js snapshot fails unless it is called from a supported
+  interface, such as `dart compile js`, `flutter build`, or
+  `build_web_compilers`. This is not expected to be a visible change.
+
 #### Formatter
 
 * Format `sync*` and `async*` functions with `=>` bodies.

pkg/compiler/lib/src/dart2js.dart

@@ -732,13 +732,6 @@ Future<api.CompilationResult> compile(List<String> argv,
 
   parseCommandLine(handlers, argv);
 
-  if (invoker == null) {
-    warning("The 'dart2js' entrypoint script is deprecated, "
-        "please use 'dart compile js' instead.");
-  } else if (verbose != null && !wantHelp) {
-    print("Compiler invoked from: '$invoker'");
-  }
-
   final diagnostic = diagnosticHandler = FormattingDiagnosticHandler();
   if (verbose != null) {
     diagnostic.verbose = verbose!;
@@ -778,6 +771,22 @@ Future<api.CompilationResult> compile(List<String> argv,
     helpAndExit(wantHelp, wantVersion, diagnostic.verbose);
   }
 
+  if (invoker == null) {
+    final message = "The 'dart2js' entrypoint script is deprecated, "
+        "please use 'dart compile js' instead.";
+    // Aside from asking for `-h`, dart2js fails when it is invoked from its
+    // snapshot directly and not using the supported workflows.  However, we
+    // allow invoking dart2js from Dart sources to support the dart2js team
+    // local workflows and testing.
+    if (!Platform.script.path.endsWith(".dart")) {
+      _fail(message);
+    } else {
+      warning(message);
+    }
+  } else if (verbose != null) {
+    print("Compiler invoked from: '$invoker'");
+  }
+
   if (arguments.isEmpty &&
       entryUri == null &&
       inputDillUri == null &&

pkg/compiler/tool/modular_test_suite_helper.dart

@@ -269,6 +269,7 @@ class ModularAnalysisStep extends IOModularStep {
       _dart2jsScript,
       Flags.soundNullSafety,
       if (_options.useSdk) '--libraries-spec=$_librarySpecForSnapshot',
+      if (_options.useSdk) '--invoker=modular_test',
       // If we have sources, then we aren't building the SDK, otherwise we
       // assume we are building the sdk and pass in a full dill.
       if (sources.isNotEmpty)
@@ -344,6 +345,7 @@ class ConcatenateDillsStep extends IOModularStep {
       _dart2jsScript,
       // TODO(sigmund): remove this dependency on libraries.json
       if (_options.useSdk) '--libraries-spec=$_librarySpecForSnapshot',
+      if (_options.useSdk) '--invoker=modular_test',
       Flags.soundNullSafety,
       '${Flags.entryUri}=$fakeRoot${module.mainSource}',
       '${Flags.inputDill}=${toUri(module, dillId)}',
@@ -405,6 +407,7 @@ class ComputeClosedWorldStep extends IOModularStep {
       _dart2jsScript,
       // TODO(sigmund): remove this dependency on libraries.json
       if (_options.useSdk) '--libraries-spec=$_librarySpecForSnapshot',
+      if (_options.useSdk) '--invoker=modular_test',
       Flags.soundNullSafety,
       '${Flags.entryUri}=$fakeRoot${module.mainSource}',
       '${Flags.inputDill}=${toUri(module, fullDillId)}',
@@ -455,6 +458,7 @@ class GlobalAnalysisStep extends IOModularStep {
       _dart2jsScript,
       // TODO(sigmund): remove this dependency on libraries.json
       if (_options.useSdk) '--libraries-spec=$_librarySpecForSnapshot',
+      if (_options.useSdk) '--invoker=modular_test',
       Flags.soundNullSafety,
       '${Flags.entryUri}=$fakeRoot${module.mainSource}',
       '${Flags.inputDill}=${toUri(module, globalUpdatedDillId)}',
@@ -509,6 +513,7 @@ class Dart2jsCodegenStep extends IOModularStep {
       '--packages=${sdkRoot.toFilePath()}/$packageConfigJsonPath',
       _dart2jsScript,
       if (_options.useSdk) '--libraries-spec=$_librarySpecForSnapshot',
+      if (_options.useSdk) '--invoker=modular_test',
       Flags.soundNullSafety,
       '${Flags.entryUri}=$fakeRoot${module.mainSource}',
       '${Flags.inputDill}=${toUri(module, globalUpdatedDillId)}',
@@ -563,6 +568,7 @@ class Dart2jsEmissionStep extends IOModularStep {
       '--packages=${sdkRoot.toFilePath()}/$packageConfigJsonPath',
       _dart2jsScript,
       if (_options.useSdk) '--libraries-spec=$_librarySpecForSnapshot',
+      if (_options.useSdk) '--invoker=modular_test',
       Flags.soundNullSafety,
       '${Flags.entryUri}=$fakeRoot${module.mainSource}',
       '${Flags.inputDill}=${toUri(module, globalUpdatedDillId)}',

utils/compiler/BUILD.gn

@@ -63,6 +63,7 @@ application_snapshot("dart2js") {
   vm_args = []
   main_dart = "$target_gen_dir/dart2js.dart"
   training_args = [
+    "--invoker=gn_build",
     "--packages=" +
         rebase_path("../../.dart_tool/package_config.json", root_build_dir),
     "--libraries-spec=" +

utils/dartdevc/BUILD.gn

@@ -78,6 +78,7 @@ template("dart2js_compile") {
     args = [
       "$abs_main",
       "-m",
+      "--invoker=gn_build",
       "-o$abs_output",
       "--no-source-maps",
       "--platform-binaries=" + rebase_path("$root_out_dir"),