[DAS] Fixes import library for extension members in pattern matching

Bug: #61883
Change-Id: Ib661e1278d6aae30f554373e3aefc79020f81684
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/473860
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Auto-Submit: Felipe Morschel <git@fmorschel.dev>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

Author: FMorschel

pkg/analysis_server/lib/src/services/correction/dart/import_library.dart

@@ -102,6 +102,18 @@ class ImportLibrary extends MultiCorrectionProducer {
     };
   }
 
+  DartType? _getTypeForPattern(AstNode node) {
+    var parent = node.parent;
+    while (parent is DartPattern || parent?.parent is DartPattern) {
+      if (parent is ObjectPattern) {
+        return parent.type.type;
+      }
+      parent = parent?.parent;
+    }
+    // We don't know how to answer this.
+    return null;
+  }
+
   Future<(_ImportLibraryCombinator?, _ImportLibraryCombinatorMultiple?)>
   _importEditCombinators(
     LibraryImport import,
@@ -442,6 +454,15 @@ class ImportLibrary extends MultiCorrectionProducer {
           node.operator.type == TokenType.TILDE) {
         targetType = node.operand.staticType;
       }
+    } else if (node is PatternFieldName) {
+      memberName = node.name?.lexeme ?? '';
+      if (memberName.isEmpty) {
+        return const [];
+      }
+      targetType = _getTypeForPattern(node);
+    } else if (node is DeclaredVariablePattern) {
+      memberName = node.name.lexeme;
+      targetType = _getTypeForPattern(node);
     } else {
       return const [];
     }

pkg/analysis_server/test/src/services/correction/fix/import_library_project_test.dart

@@ -848,6 +848,54 @@ void f() {
     await assertNoFix();
   }
 
+  Future<void> test_pattern() async {
+    newFile('$testPackageLibPath/a.dart', '''
+extension IntExt on int {
+  int get foo => 0;
+}
+''');
+
+    await resolveTestCode('''
+void f(Object o) {
+  if (o case int(foo: int())) {}
+}
+''');
+
+    await assertHasFix('''
+import 'package:test/a.dart';
+
+void f(Object o) {
+  if (o case int(foo: int())) {}
+}
+''');
+  }
+
+  Future<void> test_pattern_simplified() async {
+    newFile('$testPackageLibPath/a.dart', '''
+extension IntExt on int {
+  int get foo => 0;
+}
+''');
+
+    await resolveTestCode('''
+void f(Object o) {
+  if (o case int(:var foo)) {
+    print(foo);
+  }
+}
+''');
+
+    await assertHasFix('''
+import 'package:test/a.dart';
+
+void f(Object o) {
+  if (o case int(:var foo)) {
+    print(foo);
+  }
+}
+''');
+  }
+
   Future<void> test_relativeDirective() async {
     newFile('$testPackageLibPath/a.dart', '''
 class Foo {}