[swift2objc] Support Swift ARC features

[nikeokoronkwo]

Fixes #2053

This pull request adds support for Swift ARC features including lazy, weak and unowned variables.

• Parsing the features from the symbol graph
• Adding minor transformation logic (just an @objc suffices)
• Updating generation logic to incorporate these features
  • lazy variables
  • weak variables
  • unowned variables
• Writing tests for the given feature

[liamappelbe]

I need to figure out why the workflows aren't running. I'm pretty sure you can't apply any of these annotations to a property with a custom getter. So I think the generated code in classes_and_properties_output.swift won't compile (and the test should fail).

The weak and unowned annotations determine how reference counting works for a stored property. Our wrapper doesn't actually hold any direct references to the underlying property, so these annotations probably aren't relevant to us.

Similarly for the lazy annotation, the laziness is all handled by the underlying property, so I'm not sure it's actually relevant at the wrapper level.

I like the refactor in parse_variable_declaration.dart, with the ParsedPropertyInfo, so
if the rest of this PR isn't needed, maybe it still makes sense to land that by itself?

[nikeokoronkwo]

The weak and unowned annotations determine how reference counting works for a stored property. Our wrapper doesn't actually hold any direct references to the underlying property, so these annotations probably aren't relevant to us.

Similarly for the lazy annotation, the laziness is all handled by the underlying property, so I'm not sure it's actually relevant at the wrapper level.

I was thinking we would want to model Swift relationships and functionality as closely as possible, as end users might expect a class to work in a certain way, which is why I aimed at preserved such functionality in the wrappers

[liamappelbe]

I was thinking we would want to model Swift relationships and functionality as closely as possible, as end users might expect a class to work in a certain way, which is why I aimed at preserved such functionality in the wrappers

I don't think you're allowed to put these annotations on computed properties. I think they're only for stored properties. Their functionality wouldn't really make sense for computed properties.

[github-actions]

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// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
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pkgs/jni/lib/src/third_party/generated_bindings.dart
pkgs/native_doc_dartifier/example/native_doc_dartifier_example.dart
pkgs/native_doc_dartifier/lib/native_doc_dartifier.dart
pkgs/native_doc_dartifier/lib/src/native_doc_dartifier_base.dart
pkgs/objective_c/lib/src/ns_input_stream.dart

[coveralls]

coverage: 82.829% (+0.06%) from 82.772%
when pulling 9176d1e on nikeokoronkwo:swift2objc-arc-features
into 9ef9699 on dart-lang:main.

[nikeokoronkwo]

I don't think you're allowed to put these annotations on computed properties. I think they're only for stored properties.

I tried using them, and it compiled to give me Objective-C header code successfully.
I believe as long as the computed properties have the necessary getters and setters, they should work.

I like the refactor in parse_variable_declaration.dart, with the ParsedPropertyInfo, so if the rest of this PR isn't needed, maybe it still makes sense to land that by itself?

Much of that refactor should be merged into main already thanks to #2056.