IOS-1269 feat: add AddComponentModifier Macro

[ElonPark]

Background (Required)

• IOS-1269
• Introduced Swift Macros support to reduce boilerplate code when creating component modifiers in KarrotListKit framework
• Component developers frequently write repetitive setter methods that follow the same pattern, which leads to maintenance overhead and potential inconsistencies
• Goal is to automate the generation of these methods using compile-time code generation with Swift Macros

Changes (Required)

Swift Macros Infrastructure Setup

• Updated Swift tools version from 5.5 to 5.9 in Package.swift
• Added swift-syntax dependency (509.0.0..<602.0.0) for macro compilation support
• Created new KarrotListKitMacros target with compiler plugin support
• Added KarrotListKitMacrosTests target for macro testing

@AddComponentModifier Macro Implementation

• Implemented @AddComponentModifier peer-attached macro in AddComponentModifier.swift
• Created AddComponentModifierMacro.swift with logic to:
  • Analyze closure property types
  • Generate method signatures by removing "Handler" suffix
  • Inherit access level from parent struct
• Added support utilities:
  • AccessLevelModifier.swift for handling access levels (public, internal, private)
  • KarrotListKitMacroError.swift for error handling
  • KarrotListKitPlugin.swift for compiler plugin registration

Sample App Updates

• Updated VerticalLayoutItemComponent.swift with macro usage examples:
  • Simple handler without parameters
  • Handler with single value parameter
  • Handler with multiple parameters
  • Handler with named parameters
• Updated Package.resolved to version 3 format

CI/CD Pipeline Modernization

• Upgraded GitHub Actions workflow environment:
  • macOS: 14 → 15
  • Xcode: 15.2/16.1 → 16.4
  • iOS Simulator: iPhone 15 (iOS 17.2) → iPhone 16 (iOS 18.1)
• Added strategy matrix to test both Debug and Release configurations
• Added check-macro-compatibility job for Swift macro compatibility verification

Test Methods (Required)

Unit Tests Added

• AddComponentModifierMacroTests.swift (167 lines) covering:
  • Macro behavior with different access levels (public, internal, private)
  • Error handling for invalid property types
  • Method generation from various closure signatures
  • Proper "Handler" suffix removal from property names

CI/CD Testing Strategy

• Automated testing in both Debug and Release configurations
• Cross-platform compatibility testing with latest Xcode 16.4
• Swift macro compatibility verification in separate job
• Sample app build validation with macro-generated code

Review Notes

Key Review Points

• The @AddComponentModifier macro eliminates boilerplate code by automatically generating setter methods for closure properties
• Access level inheritance ensures generated methods match the visibility of their parent struct
• Swift tools version upgrade to 5.9 is required for macro support

Design Decisions

• Chose peer-attached macro approach to preserve original property while adding convenience methods
• "Handler" suffix removal convention aligns with Swift naming patterns (e.g., onTapButtonHandler → onTapButton() method)
• Comprehensive error handling for compile-time feedback when macro is misused

Future Considerations

• Could extend macro to support additional modifier patterns beyond closures
• Consider adding customization options via macro parameters
• Monitor Swift Macros evolution for potential improvements

Technical Dependencies

• Requires Xcode 15.0+ for Swift Macros support
• swift-syntax package version must be compatible with Swift compiler version

[jaxtynSong]

LGTM 👍 👍