[vm/ffi] Fix DynamicLibrary extension name

And add changelog entry.

Follow up of: https://dart-review.googlesource.com/c/sdk/+/135463

Closes: https://github.com/dart-lang/sdk/issues/35903
Closes: https://github.com/dart-lang/sdk/issues/40636

Change-Id: I877f735c54e466031715c775d37544617402f9ff
Cq-Include-Trybots: luci.dart.try:vm-ffi-android-debug-arm-try,vm-kernel-nnbd-linux-release-x64-try,analyzer-linux-release-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/136124
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

CHANGELOG.md

@@ -50,6 +50,15 @@ case of `name` instead of converting them to lowercase.
   * `Dart_IsNonNullableType`
   * `Dart_IsNullableType`
 
+### Foreign Function Interface (`dart:ffi`)
+
+* **Breaking Change**: `Pointer.asFunction` and `DynamicLibrary.lookupFunction`
+  changed to extension methods. Invoking them dynamically previously already
+  threw an Exception, so runtime behavior stays the same. However, the
+  extension methods are only visible if `dart:ffi` is imported directly. So
+  this breaks code where `dart:ffi` is not directly imported. Fix: add an
+  import of `dart:ffi`.
+
 ### Tools
 
 #### Dart Dev Compiler (DDC)

pkg/analyzer/lib/src/generated/ffi_verifier.dart

@@ -158,9 +158,10 @@ class FfiVerifier extends RecursiveAstVisitor<void> {
   }
 
   /// Return `true` if the given [element] represents the extension
-  /// `LibraryExtension`.
+  /// `DynamicLibraryExtension`.
   bool _isDynamicLibraryExtension(Element element) =>
-      element.name == 'LibraryExtension' && element.library.name == 'dart.ffi';
+      element.name == 'DynamicLibraryExtension' &&
+      element.library.name == 'dart.ffi';
 
   /// Returns `true` iff [nativeType] is a `ffi.NativeFunction<???>` type.
   bool _isNativeFunctionInterfaceType(DartType nativeType) {

pkg/analyzer/lib/src/test_utilities/mock_sdk.dart

@@ -544,7 +544,7 @@ extension NativeFunctionPointer<NF extends Function>
 class Struct extends NativeType {}
 
 abstract class DynamicLibrary {}
-extension LibraryExtension on DynamicLibrary {
+extension DynamicLibraryExtension on DynamicLibrary {
   external F lookupFunction<T extends Function, F extends Function>(
       String symbolName);
 }

pkg/vm/lib/transformations/ffi.dart

@@ -238,8 +238,8 @@ class FfiTransformer extends Transformer {
             index.getMember('dart:ffi', 'NativeFunctionPointer', 'asFunction'),
         asFunctionInternal =
             index.getTopLevelMember('dart:ffi', '_asFunctionInternal'),
-        lookupFunctionMethod =
-            index.getMember('dart:ffi', 'LibraryExtension', 'lookupFunction'),
+        lookupFunctionMethod = index.getMember(
+            'dart:ffi', 'DynamicLibraryExtension', 'lookupFunction'),
         fromFunctionMethod =
             index.getMember('dart:ffi', 'Pointer', 'fromFunction'),
         libraryLookupMethod =

sdk/lib/_internal/vm/lib/ffi_dynamic_library_patch.dart

@@ -51,7 +51,7 @@ class DynamicLibrary {
   Pointer<Void> get handle => Pointer.fromAddress(getHandle());
 }
 
-extension LibraryExtension on DynamicLibrary {
+extension DynamicLibraryExtension on DynamicLibrary {
   @patch
   DS lookupFunction<NS extends Function, DS extends Function>(
           String symbolName) =>

sdk/lib/ffi/dynamic_library.dart

@@ -41,7 +41,7 @@ class DynamicLibrary {
 }
 
 /// Methods which cannot be invoked dynamically.
-extension LibraryExtension on DynamicLibrary {
+extension DynamicLibraryExtension on DynamicLibrary {
   /// Helper that combines lookup and cast to a Dart function.
   external F lookupFunction<T extends Function, F extends Function>(
       String symbolName);

sdk_nnbd/lib/_internal/vm/lib/ffi_dynamic_library_patch.dart

@@ -50,7 +50,7 @@ class DynamicLibrary {
   Pointer<Void> get handle => Pointer.fromAddress(getHandle());
 }
 
-extension LibraryExtension on DynamicLibrary {
+extension DynamicLibraryExtension on DynamicLibrary {
   @patch
   DS lookupFunction<NS extends Function, DS extends Function>(
           String symbolName) =>

sdk_nnbd/lib/ffi/dynamic_library.dart

@@ -39,7 +39,7 @@ class DynamicLibrary {
 }
 
 /// Methods which cannot be invoked dynamically.
-extension LibraryExtension on DynamicLibrary {
+extension DynamicLibraryExtension on DynamicLibrary {
   /// Helper that combines lookup and cast to a Dart function.
   external F lookupFunction<T extends Function, F extends Function>(
       String symbolName);