[ffigen] Experiment to remove synth blocks

[liamappelbe]

Missing features:

• Constructing blocks from function pointers instead of closures
• Unregistering block closures when the block is destroyed
• One of the blocking block tests is deadlocking

[github-actions]

PR Health

Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
objective_c	Breaking	4.0.0	4.1.0-wip	5.0.0 Got "4.1.0-wip" expected >= "5.0.0" (breaking changes)	⚠️

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Changelog Entry ❗

Package	Changed Files
package:objective_c	pkgs/objective_c/lib/src/c_bindings_generated.dart pkgs/objective_c/lib/src/internal.dart pkgs/objective_c/lib/src/objective_c_bindings_generated.dart

Changes to files need to be accounted for in their respective changelogs.

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API leaks ⚠️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols
objective_c	ObjCBlockBase c._ObjCBlockImpl _ObjCBlockRef _ObjCObject _Dart_FinalizableHandle _ObjCProtocol _ObjCSelector _ObjCMethodDesc _ObjCObjectRef _NSZone

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License Headers ✔️

// Copyright (c) 2025, 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.

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no missing headers

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Unrelated files missing license headers

Files
pkgs/jni/lib/src/third_party/generated_bindings.dart
pkgs/native_assets_builder/test_data/native_dynamic_linking/bin/native_dynamic_linking.dart
pkgs/objective_c/lib/src/ns_input_stream.dart

[brianquinlan]

Unfortunately, I need to be able to call blocks e.g.

      ncb.NSURLSessionDataDelegate
          .URLSession_dataTask_didReceiveResponse_completionHandler_
          .implementAsListener(protoBuilder,
              (nsSession, nsDataTask, nsResponse, nsCompletionHandler) {
        final exactResponse = URLResponse._exactURLResponseType(nsResponse);
        final disposition = onResponse(
            URLSession._(nsSession,
                isBackground: isBackground, hasDelegate: true),
            URLSessionTask._(nsDataTask),
            exactResponse);
        nsCompletionHandler.call(disposition);
      });

[brianquinlan]

The generated code also seems to have some issues:

[brianquinlan]

There are some other code gen issues like:

Try importing the library that defines 'registerBlockClosure', correcting the name to the name of an existing function, or defining a function named 'registerBlockClosure'.dart[undefined_function](https://dart.dev/diagnostics/undefined_function)```

[liamappelbe]

@brianquinlan Those errors look like you're not using the version of package:objective_c from this branch. Might need a dependency override with a path dep.

I'll work on supporting the call operator today.

[liamappelbe]

Added support for the call operator