[cfe] Disallow script tag in part file

In response to #52575

Change-Id: I452575517c378dda3000b8fcbf4f66274b1583a6
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/315420
Reviewed-by: Chloe Stefantsova <cstefantsova@google.com>
Commit-Queue: Johnni Winther <johnniwinther@google.com>

pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart

@@ -11845,6 +11845,16 @@ const MessageCode messageReturnWithoutExpressionSync = const MessageCode(
     problemMessage:
         r"""A value must be explicitly returned from a non-void function.""");
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeScriptTagInPartFile = messageScriptTagInPartFile;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageScriptTagInPartFile = const MessageCode(
+    "ScriptTagInPartFile",
+    problemMessage: r"""A part file cannot have script tag.""",
+    correctionMessage:
+        r"""Try removing the script tag or the 'part of' directive.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(Uri uri_)> templateSdkRootNotFound =
     const Template<Message Function(Uri uri_)>(

pkg/front_end/lib/src/fasta/source/outline_builder.dart

@@ -2376,6 +2376,7 @@ class OutlineBuilder extends StackListenerImpl {
   @override
   void handleScript(Token token) {
     debugEvent("Script");
+    libraryBuilder.addScriptToken(token.charOffset);
   }
 
   @override

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

@@ -169,6 +169,9 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
 
   Uri? partOfUri;
 
+  /// Offset of the first script tag (`#!...`) in this library or part.
+  int? _scriptTokenOffset;
+
   List<MetadataBuilder>? metadata;
 
   /// The current declaration that is being built. When we start parsing a
@@ -855,6 +858,14 @@ class SourceLibraryBuilder extends LibraryBuilderImpl {
       Uri newFileUri = resolve(fileUri, uri, uriOffset);
       loader.read(partOfUri!, uriOffset, fileUri: newFileUri, accessor: this);
     }
+    if (_scriptTokenOffset != null) {
+      addProblem(
+          messageScriptTagInPartFile, _scriptTokenOffset!, noLength, fileUri);
+    }
+  }
+
+  void addScriptToken(int charOffset) {
+    _scriptTokenOffset ??= charOffset;
   }
 
   void addFields(List<MetadataBuilder>? metadata, int modifiers,

pkg/front_end/messages.status

@@ -903,6 +903,8 @@ ReturnTypeFunctionExpression/example: Fail
 ReturnWithoutExpressionAsync/analyzerCode: Fail
 ReturnWithoutExpressionSync/analyzerCode: Fail
 ReturnWithoutExpressionSync/part_wrapped_script: Fail
+ScriptTagInPartFile/analyzerCode: Fail
+ScriptTagInPartFile/example: Fail
 SdkRootNotFound/analyzerCode: Fail
 SdkRootNotFound/example: Fail
 SdkSpecificationNotFound/analyzerCode: Fail

pkg/front_end/messages.yaml

@@ -7028,4 +7028,8 @@ JointPatternVariableWithLabelDefault:
     test(x) { switch(x) { case var a: default: return a; } }
 
 UnsupportedMacroApplication:
-  problemMessage: "This macro application didn't apply correctly."
+  problemMessage: "This macro application didn't apply correctly."
+
+ScriptTagInPartFile:
+  problemMessage: "A part file cannot have script tag."
+  correctionMessage: "Try removing the script tag or the 'part of' directive."

pkg/front_end/testcases/general/script_tag_in_part_file.dart

@@ -0,0 +1,7 @@
+#!/usr/bin/env dart
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of 'script_tag_in_part_file_lib.dart';
+void run() => print("Running!");

pkg/front_end/testcases/general/script_tag_in_part_file.dart.strong.expect

@@ -0,0 +1,17 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/script_tag_in_part_file.dart:1:1: Error: A part file cannot have script tag.
+// Try removing the script tag or the 'part of' directive.
+// #!/usr/bin/env dart
+// ^
+//
+import self as self;
+import "dart:core" as core;
+
+part script_tag_in_part_file.dart;
+static method /* from org-dartlang-testcase:///script_tag_in_part_file.dart */ run() → void
+  return core::print("Running!");
+static method main() → void
+  return self::run();

pkg/front_end/testcases/general/script_tag_in_part_file.dart.strong.transformed.expect

@@ -0,0 +1,17 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/script_tag_in_part_file.dart:1:1: Error: A part file cannot have script tag.
+// Try removing the script tag or the 'part of' directive.
+// #!/usr/bin/env dart
+// ^
+//
+import self as self;
+import "dart:core" as core;
+
+part script_tag_in_part_file.dart;
+static method /* from org-dartlang-testcase:///script_tag_in_part_file.dart */ run() → void
+  return core::print("Running!");
+static method main() → void
+  return self::run();

pkg/front_end/testcases/general/script_tag_in_part_file.dart.textual_outline.expect

@@ -0,0 +1,3 @@
+#!/usr/bin/env dart
+part of 'script_tag_in_part_file_lib.dart';
+void run() => print("Running!");

pkg/front_end/testcases/general/script_tag_in_part_file.dart.weak.expect

@@ -0,0 +1,17 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/script_tag_in_part_file.dart:1:1: Error: A part file cannot have script tag.
+// Try removing the script tag or the 'part of' directive.
+// #!/usr/bin/env dart
+// ^
+//
+import self as self;
+import "dart:core" as core;
+
+part script_tag_in_part_file.dart;
+static method /* from org-dartlang-testcase:///script_tag_in_part_file.dart */ run() → void
+  return core::print("Running!");
+static method main() → void
+  return self::run();

pkg/front_end/testcases/general/script_tag_in_part_file.dart.weak.modular.expect

@@ -0,0 +1,17 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/script_tag_in_part_file.dart:1:1: Error: A part file cannot have script tag.
+// Try removing the script tag or the 'part of' directive.
+// #!/usr/bin/env dart
+// ^
+//
+import self as self;
+import "dart:core" as core;
+
+part script_tag_in_part_file.dart;
+static method /* from org-dartlang-testcase:///script_tag_in_part_file.dart */ run() → void
+  return core::print("Running!");
+static method main() → void
+  return self::run();

pkg/front_end/testcases/general/script_tag_in_part_file.dart.weak.outline.expect

@@ -0,0 +1,16 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/script_tag_in_part_file.dart:1:1: Error: A part file cannot have script tag.
+// Try removing the script tag or the 'part of' directive.
+// #!/usr/bin/env dart
+// ^
+//
+import self as self;
+
+part script_tag_in_part_file.dart;
+static method /* from org-dartlang-testcase:///script_tag_in_part_file.dart */ run() → void
+  ;
+static method main() → void
+  ;

pkg/front_end/testcases/general/script_tag_in_part_file.dart.weak.transformed.expect

@@ -0,0 +1,17 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/general/script_tag_in_part_file.dart:1:1: Error: A part file cannot have script tag.
+// Try removing the script tag or the 'part of' directive.
+// #!/usr/bin/env dart
+// ^
+//
+import self as self;
+import "dart:core" as core;
+
+part script_tag_in_part_file.dart;
+static method /* from org-dartlang-testcase:///script_tag_in_part_file.dart */ run() → void
+  return core::print("Running!");
+static method main() → void
+  return self::run();

pkg/front_end/testcases/general/script_tag_in_part_file_lib.dart

@@ -0,0 +1,8 @@
+#!/usr/bin/env dart
+// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part 'script_tag_in_part_file.dart';
+
+void main() => run();

pkg/front_end/testcases/textual_outline.status

@@ -117,6 +117,7 @@ general/null_safety_invalid_experiment: FormatterCrash
 general/null_safety_invalid_experiment_and_language_version: FormatterCrash
 general/records_opt_out: FormatterCrash
 general/sealed_class_declaration: FormatterCrash
+general/script_tag_in_part_file: FormatterCrash
 general/type_parameters_on_void: FormatterCrash
 general/type_variable_in_static_context: FormatterCrash
 general/var_as_type_name: FormatterCrash