fix: correctly support conditional imports for check-unused-code (#1097)

* fix: correctly support conditional imports for check-unused-code

* chore: ignore deprecation message

Author: incendial

CHANGELOG.md

@@ -7,6 +7,7 @@
 * feat: add static code diagnostic [`prefer-using-list-view`](https://dartcodemetrics.dev/docs/rules/flutter/prefer-using-list-view).
 * feat: add static code diagnostic [`avoid-unnecessary-conditionals`](https://dartcodemetrics.dev/docs/rules/common/avoid-unnecessary-conditionals).
 * feat: support boolean literals removal for [`prefer-conditional-expressions`](https://dartcodemetrics.dev/docs/rules/common/prefer-conditional-expressions) auto-fix.
+* fix: correctly support conditional imports for [`check-unused-code`](https://dartcodemetrics.dev/docs/cli/check-unused-code).
 
 ## 5.1.0
 

lib/src/analyzers/unused_code_analyzer/models/file_elements_usage.dart

@@ -16,10 +16,13 @@ class FileElementsUsage {
 
   final Set<String> exports = {};
 
+  final Map<Set<String>, Set<Element>> conditionalElements = {};
+
   void merge(FileElementsUsage other) {
     prefixMap.addAll(other.prefixMap);
     elements.addAll(other.elements);
     usedExtensions.addAll(other.usedExtensions);
     exports.addAll(other.exports);
+    conditionalElements.addAll(other.conditionalElements);
   }
 }

lib/src/analyzers/unused_code_analyzer/unused_code_analyzer.dart

@@ -210,25 +210,25 @@ class UnusedCodeAnalyzer {
             .contains(declaredSource.fullName);
   }
 
-  bool _isUnused(
-    FileElementsUsage codeUsages,
-    String path,
-    Element element,
-  ) =>
-      !codeUsages.elements.any(
-        (usedElement) => _isUsed(usedElement, element),
-      ) &&
-      !codeUsages.usedExtensions.any(
-        (usedElement) => _isUsed(usedElement, element),
-      ) &&
-      !codeUsages.prefixMap.values.any(
-        (usage) =>
-            usage.paths.contains(path) &&
-            usage.elements.any((usedElement) =>
+  bool _isUnused(FileElementsUsage codeUsages, String path, Element element) =>
+      !codeUsages.conditionalElements.entries.any((entry) =>
+          entry.key.contains(path) &&
+          entry.value.any((usedElement) =>
+              _isUsed(usedElement, element) ||
+              (usedElement.name == element.name &&
+                  usedElement.kind == element.kind))) &&
+      !codeUsages.elements
+          .any((usedElement) => _isUsed(usedElement, element)) &&
+      !codeUsages.usedExtensions
+          .any((usedElement) => _isUsed(usedElement, element)) &&
+      !codeUsages.prefixMap.values.any((usage) =>
+          usage.paths.contains(path) &&
+          usage.elements.any(
+            (usedElement) =>
                 _isUsed(usedElement, element) ||
                 (usedElement.name == element.name &&
-                    usedElement.kind == element.kind)),
-      );
+                    usedElement.kind == element.kind),
+          ));
 
   UnusedCodeIssue _createUnusedCodeIssue(
     ElementImpl element,

lib/src/analyzers/unused_code_analyzer/used_code_visitor.dart

@@ -3,6 +3,7 @@
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
+import 'package:collection/collection.dart';
 
 import '../../utils/flutter_types_utils.dart';
 import 'models/file_elements_usage.dart';
@@ -13,6 +14,31 @@ import 'models/prefix_element_usage.dart';
 class UsedCodeVisitor extends RecursiveAstVisitor<void> {
   final fileElementsUsage = FileElementsUsage();
 
+  UsedCodeVisitor();
+
+  @override
+  void visitImportDirective(ImportDirective node) {
+    if (node.configurations.isNotEmpty) {
+      final paths = node.configurations.map((config) {
+        final uri = config.resolvedUri;
+
+        return (uri is DirectiveUriWithSource) ? uri.source.fullName : null;
+      }).whereNotNull();
+      // ignore: deprecated_member_use
+      final mainImport = node.element2?.importedLibrary?.source.fullName;
+
+      final allPaths = {if (mainImport != null) mainImport, ...paths};
+
+      fileElementsUsage.conditionalElements.update(
+        allPaths,
+        (conditionalElements) => conditionalElements,
+        ifAbsent: () => {},
+      );
+    }
+
+    super.visitImportDirective(node);
+  }
+
   @override
   void visitExportDirective(ExportDirective node) {
     super.visitExportDirective(node);
@@ -130,6 +156,24 @@ class UsedCodeVisitor extends RecursiveAstVisitor<void> {
     return false;
   }
 
+  bool _recordConditionalElement(Element element) {
+    final elementPath = element.source?.fullName;
+    if (elementPath == null) {
+      return false;
+    }
+
+    final entries = fileElementsUsage.conditionalElements.entries;
+    for (final conditionalElement in entries) {
+      if (conditionalElement.key.contains(elementPath)) {
+        conditionalElement.value.add(element);
+
+        return true;
+      }
+    }
+
+    return false;
+  }
+
   /// Records use of a not prefixed [element].
   void _recordUsedElement(Element element) {
     // Ignore if an unknown library.
@@ -157,11 +201,16 @@ class UsedCodeVisitor extends RecursiveAstVisitor<void> {
       return;
     }
 
-    // Usage in State<WidgetClassName> is not a sing of usage.
+    // Usage in State<WidgetClassName> is not a sign of usage.
     if (_isUsedAsNamedTypeForWidgetState(identifier)) {
       return;
     }
 
+    // Record elements that are imported with conditional imports
+    if (_recordConditionalElement(element)) {
+      return;
+    }
+
     // Record `importPrefix.identifier` into 'prefixMap'.
     if (_recordPrefixMap(identifier, element)) {
       return;

test/resources/unused_code_analyzer/conditional_prefixed_file.dart

@@ -0,0 +1,3 @@
+int calculate() => 1;
+
+bool helloWorld() => false; // LINT

test/resources/unused_code_analyzer/unconditional_prefixed_file.dart

@@ -0,0 +1 @@
+int calculate() => 2;

test/resources/unused_code_analyzer/unused_code_example.dart

@@ -3,7 +3,10 @@
 import 'public_members.dart';
 import 'unconditional_file.dart'
     if (dart.library.html) 'conditional_file.dart'
-    if (dart.library.io) 'conditional_file.dart' as config;
+    if (dart.library.io) 'conditional_file.dart';
+import 'unconditional_prefixed_file.dart'
+    if (dart.library.html) 'conditional_prefixed_file.dart'
+    if (dart.library.io) 'conditional_prefixed_file.dart' as config;
 
 void main() {
   final widget = MyWidget('hello');
@@ -23,7 +26,9 @@ void main() {
 
   SomeEnum.hello;
 
-  config.calculateResults();
+  calculateResults();
+
+  config.calculate();
 
   setPadding();
 }

test/src/analyzers/unused_code_analyzer/unused_code_analyzer_test.dart

@@ -35,8 +35,8 @@ void main() {
           );
         });
 
-        test('should report 4 files and not report excluded file', () {
-          expect(result, hasLength(4));
+        test('should report 5 files and not report excluded file', () {
+          expect(result, hasLength(5));
         });
 
         test('should analyze not used files', () async {
@@ -84,6 +84,27 @@ void main() {
           expect(firstIssue.location.column, 1);
         });
 
+        test('should analyze conditional prefixed import files', () async {
+          final unconditionalReport = result.firstWhereOrNull(
+            (report) =>
+                report.path.endsWith('unconditional_prefixed_file.dart'),
+          );
+
+          expect(unconditionalReport, null);
+
+          final report = result.firstWhere(
+            (report) => report.path.endsWith('conditional_prefixed_file.dart'),
+          );
+
+          expect(report.issues, hasLength(1));
+
+          final firstIssue = report.issues.first;
+          expect(firstIssue.declarationName, 'helloWorld');
+          expect(firstIssue.declarationType, 'function');
+          expect(firstIssue.location.line, 3);
+          expect(firstIssue.location.column, 1);
+        });
+
         test('should analyze files', () async {
           final report = result.firstWhere(
             (report) => report.path.endsWith('public_members.dart'),