feat: add pragma vm:entry-point as entry point for unused files check (#461)

* feat: add pragma vm:entry-point as entry point for unused files check

* docs: add comment with the docs reference

* chore: update changelog

* chore: update changelog

* chore: replace NodeList with Iterable

Author: incendial

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+* Improve unused files check, add support for `vm:entry-point` annotation.
+
 ## 4.3.1
 
 * Update .pubignore

lib/src/analyzers/lint_analyzer/rules/rules_list/avoid_unused_parameters/visitor.dart

@@ -55,7 +55,7 @@ class _Visitor extends RecursiveAstVisitor<void> {
 
   Iterable<FormalParameter> _getUnusedParameters(
     Iterable<SyntacticEntity> children,
-    NodeList<FormalParameter> parameters,
+    Iterable<FormalParameter> parameters,
   ) {
     final result = <FormalParameter>[];
 

lib/src/analyzers/lint_analyzer/rules/rules_list/no_equal_arguments/visitor.dart

@@ -30,7 +30,7 @@ class _Visitor extends RecursiveAstVisitor<void> {
     _visitArguments(node.argumentList.arguments);
   }
 
-  void _visitArguments(NodeList<Expression> arguments) {
+  void _visitArguments(Iterable<Expression> arguments) {
     final notIgnoredArguments = arguments.where(_isNotIgnored).toList();
 
     for (final argument in notIgnoredArguments) {

lib/src/analyzers/unused_files_analyzer/unused_files_visitor.dart

@@ -35,8 +35,22 @@ class UnusedFilesVisitor extends GeneralizingAstVisitor<void> {
 
   @override
   void visitFunctionDeclaration(FunctionDeclaration node) {
-    if (node.name.name == 'main') {
+    if (node.name.name == 'main' || _hasPragmaAnnotation(node.metadata)) {
       _paths.add(_currentFilePath);
     }
   }
+
+  /// See https://github.com/dart-lang/sdk/blob/master/runtime/docs/compiler/aot/entry_point_pragma.md
+  bool _hasPragmaAnnotation(Iterable<Annotation> metadata) =>
+      metadata.where((annotation) {
+        final arguments = annotation.arguments;
+
+        return annotation.name.name == 'pragma' &&
+            arguments != null &&
+            arguments.arguments
+                .where((argument) =>
+                    argument is SimpleStringLiteral &&
+                    argument.stringValue == 'vm:entry-point')
+                .isNotEmpty;
+      }).isNotEmpty;
 }

test/resources/unused_files_analyzer/annotation_file.dart

@@ -0,0 +1,2 @@
+@pragma('vm:entry-point')
+void customEntryPoint() {}

test/resources/unused_files_analyzer/unused_file.dart

@@ -1,5 +1,6 @@
 import 'exported_file.dart';
 
+@immutable
 class SomeClass {}
 
 const instance = ExportedClass();