Fix Map/List/Set equality in generated Dart structs

[nightscape]

Generated Dart structs with collection fields (Map, List, Set) were using identity comparison (==) instead of deep equality. This caused equality checks to fail even when collection contents were identical.

Fix:

• Use DeepCollectionEquality for collection fields in operator== and hashCode
• Export DeepCollectionEquality from flutter_rust_bridge_for_generated_common.dart
• Handle Optional types wrapping collections

Changes

Fixes #the-issue-number-here

Procedure and Checklist

In order to quickly iterate and avoid slowing down development pace by making CI pass, only the following simplified steps are needed, and I (fzyzcjy) will handle the rest of CI / moving the tests currently (will have more automation in the future).

• Implement the feature / fix the bug.
• Add tests in frb_example/dart_minimal.
• Make dart_minimal's CI green.

Utility commands

• Run codegen: cargo run --manifest-path /path/to/flutter_rust_bridge/frb_codegen/Cargo.toml -- generate
• Run tests: ./frb_internal test-dart-native --package frb_example/dart_minimal

[Copilot]

Pull request overview

This pull request fixes a critical bug in generated Dart struct equality checking where collection fields (Map, List, Set) were using identity comparison (==) instead of deep equality comparison. This caused equality checks to fail even when collection contents were identical.

Key Changes:

• Modified code generation logic to use DeepCollectionEquality for collection fields in operator== and hashCode
• Added recursive handling for Optional types wrapping collections
• Exported DeepCollectionEquality from the common library for generated code

Reviewed changes

Copilot reviewed 29 out of 29 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
frb_codegen/src/library/codegen/generator/api_dart/spec_generator/class/ty/structure_non_freezed.rs	Core logic change: Added needs_deep_equality() function to detect collection types and generate appropriate equality/hash code using DeepCollectionEquality
frb_dart/lib/flutter_rust_bridge_for_generated_common.dart	Exported DeepCollectionEquality from collection package for use in generated code
frb_example/pure_dart/test/api/mirror_test.dart	Added tests verifying Map and List equality works correctly for structs with identical contents
frb_example/pure_dart/lib/src/rust/api/*.dart	Generated Dart code updated to use DeepCollectionEquality for List/Map/Set fields in equality and hashCode methods
frb_example/pure_dart/lib/src/rust/api/enumeration.dart	Code formatting changes (unrelated to equality fix)

---

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[Copilot]

The needs_deep_equality function does not handle MirType::Boxed types that wrap collections (List, Map, or Set). If a field has type Box<List<T>>, Box<Map<K,V>>, or Box<Set<T>>, the function will return false and use identity comparison instead of deep equality.

Consider adding a case for MirType::Boxed that recursively checks the inner type, similar to how MirType::Optional is handled.

Suggested change

	MirType::Optional(opt) => needs_deep_equality(&opt.inner),
	MirType::Optional(opt) => needs_deep_equality(&opt.inner),
	MirType::Boxed(_) => true,

[codecov]

Codecov Report

❌ Patch coverage is 85.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.19%. Comparing base (67bfaec) to head (f2a4601).

Files with missing lines	Patch %	Lines
...t/spec_generator/class/ty/structure_non_freezed.rs	85.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #2956       +/-   ##
===========================================
- Coverage   98.57%   85.19%   -13.39%     
===========================================
  Files         464      464               
  Lines       19202    18976      -226     
===========================================
- Hits        18928    16166     -2762     
- Misses        274     2810     +2536     

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[fzyzcjy]

Great job! However, this seems to be a breaking change, maybe we should add a flag to allow users to enable/disable it. In addition, it seems that users can use freezed to generate classes with deep equality.