From 8852aa5c19d4d2e19012d1ee43c9db2cda55c95d Mon Sep 17 00:00:00 2001
From: Daco Harkes <dacoharkes@google.com>
Date: Tue, 24 Feb 2026 05:01:40 -0800
Subject: [PATCH] [analyzer/ffi] Fix analyzer crash

TEST=tests/ffi/static_checks/regress_62716_test.dart

Fixes: https://github.com/dart-lang/sdk/issues/62716
Change-Id: I8abc006cd1e7274089ea618c970aacd0bc2267e4
Cq-Include-Trybots: luci.dart.try:analyzer-linux-release-try,analyzer-mac-release-try,analyzer-win-release-try,front-end-linux-release-x64-try,front-end-nnbd-linux-release-x64-try,front-end-nnbd-mac-release-x64-try,front-end-nnbd-win-release-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/483241
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Auto-Submit: Daco Harkes <dacoharkes@google.com>
---
 .../lib/src/generated/ffi_verifier.dart       |  9 +++-
 .../ffi/static_checks/regress_62716_test.dart | 43 +++++++++++++++++++
 2 files changed, 50 insertions(+), 2 deletions(-)
 create mode 100644 tests/ffi/static_checks/regress_62716_test.dart

diff --git a/pkg/analyzer/lib/src/generated/ffi_verifier.dart b/pkg/analyzer/lib/src/generated/ffi_verifier.dart
index a0410891e1d..d21153132f9 100644
--- a/pkg/analyzer/lib/src/generated/ffi_verifier.dart
+++ b/pkg/analyzer/lib/src/generated/ffi_verifier.dart
@@ -674,8 +674,13 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
       // Receiver can only be Pointer if the class extends
       // NativeFieldWrapperClass1.
       if (ffiSignature.normalParameterTypes[0].isPointer) {
-        var cls = declarationElement.enclosingElement as InterfaceElement;
-        if (!_extendsNativeFieldWrapperClass1(cls.thisType)) {
+        var enclosingElement = declarationElement.enclosingElement;
+        var receiverType = switch (enclosingElement) {
+          InterfaceElement() => enclosingElement.thisType,
+          ExtensionElement(extendedType: InterfaceType type) => type,
+          _ => null,
+        };
+        if (!_extendsNativeFieldWrapperClass1(receiverType)) {
           _diagnosticReporter.report(
             diag.ffiNativeOnlyClassesExtendingNativefieldwrapperclass1CanBePointer
                 .at(errorToken),
diff --git a/tests/ffi/static_checks/regress_62716_test.dart b/tests/ffi/static_checks/regress_62716_test.dart
new file mode 100644
index 00000000000..dcebc67a1dd
--- /dev/null
+++ b/tests/ffi/static_checks/regress_62716_test.dart
@@ -0,0 +1,43 @@
+// Copyright (c) 2026, 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.
+
+// Regression test for https://github.com/dart-lang/sdk/issues/62716
+
+import 'dart:ffi';
+import 'dart:nativewrappers';
+
+extension on int {
+  @Native<Void Function(Pointer<Void>)>(symbol: 'x')
+  // [error column 4]
+  // [cfe] Only classes extending NativeFieldWrapperClass1 can be passed as Pointer.
+  external void x();
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.FFI_NATIVE_ONLY_CLASSES_EXTENDING_NATIVEFIELDWRAPPERCLASS1_CAN_BE_POINTER
+}
+
+extension on dynamic {
+  @Native<Void Function(Pointer<Void>)>(symbol: 'z')
+  external void z();
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.FFI_NATIVE_ONLY_CLASSES_EXTENDING_NATIVEFIELDWRAPPERCLASS1_CAN_BE_POINTER
+  // [cfe] Expected type 'void Function(dynamic)' to be 'void Function(Pointer<Void>)', which is the Dart type corresponding to 'NativeFunction<Void Function(Pointer<Void>)>'.
+}
+
+extension on void Function() {
+  @Native<Void Function(Pointer<Void>)>(symbol: 'f')
+  external void f();
+  //            ^
+  // [analyzer] COMPILE_TIME_ERROR.FFI_NATIVE_ONLY_CLASSES_EXTENDING_NATIVEFIELDWRAPPERCLASS1_CAN_BE_POINTER
+  // [cfe] Expected type 'void Function(void Function())' to be 'void Function(Pointer<Void>)', which is the Dart type corresponding to 'NativeFunction<Void Function(Pointer<Void>)>'.
+
+  @Native<Void Function(Handle)>(symbol: 'f2')
+  external void f2();
+}
+
+extension on NativeFieldWrapperClass1 {
+  @Native<Void Function(Pointer<Void>)>(symbol: 'y')
+  external void y();
+}
+
+void main() {}