Synced folders: `includes` silently ignored + no deduplication across targets

[AlexNsbmr]

Summary

When using defaultSourceDirectoryType: syncedFolder with multi-target projects, two issues prevent proper cross-target file membership:

1. includes is silently ignored for synced folders — only excludes is implemented
2. No deduplication of synced folders across targets — same path in multiple targets creates duplicate PBXFileSystemSynchronizedRootGroup entries

Environment

• XcodeGen: 2.45.2
• Xcode: 16+
• macOS: Sequoia

Minimal reproduction

Directory structure

DummyApp/
├── project.yml
├── App/
│   └── Source/
│       ├── Feature/
│       │   └── FeatureView.swift
│       └── Shared/
│           ├── SharedModel.swift
│           └── AnotherModel.swift
├── AppTests/
│   └── AppTests.swift
└── AppExtension/
    └── ExtensionFile.swift

project.yml

name: DummyApp
options:
  defaultSourceDirectoryType: syncedFolder
  createIntermediateGroups: true
  deploymentTarget:
    iOS: 17.0

targets:
  DummyApp:
    type: application
    platform: iOS
    sources: [App]
    settings:
      PRODUCT_BUNDLE_IDENTIFIER: com.example.dummy

  DummyTests:
    type: bundle.ui-testing
    platform: iOS
    sources:
      - AppTests
      - path: App
        includes:
          - Source/Shared/SharedModel.swift
    dependencies:
      - target: DummyApp

  DummyExtension:
    type: app-extension
    platform: iOS
    sources:
      - AppExtension
      - path: App
        includes:
          - Source/Shared/AnotherModel.swift
    settings:
      PRODUCT_BUNDLE_IDENTIFIER: com.example.dummy.extension

Result

Running xcodegen generate produces:

• 2 "App" entries in the project navigator (1 PBXFileSystemSynchronizedRootGroup per target referencing App/)
• includes silently ignored — all files in App/ are included in DummyTests and DummyExtension instead of just the specified files
• No membershipExceptions generated in the pbxproj

Issue 1: includes silently ignored for synced folders

Expected: Only SharedModel.swift is included in DummyTests target.
Actual: ALL files in App/ are included (the includes is silently ignored).

Root cause

In SourceGenerator.getSourceFiles(), includePaths is computed but only used in the .group case. The .syncedFolder case ignores it entirely:

// includePaths is computed here...
let includePaths = targetSource.includes.isEmpty ? nil :
    getSourceMatches(targetSource: targetSource, patterns: targetSource.includes)

// ...but only used in .group case
case .group:
    let (groupSourceFiles, groups) = try getGroupSources(
        ...
        includePaths: includePaths.flatMap(SortedArray.init(_:)),
        ...
    )

// .syncedFolder case doesn't reference includePaths at all
case .syncedFolder:
    // creates PBXFileSystemSynchronizedRootGroup without any includes handling

Similarly, configureMembershipExceptions() in PBXProjGenerator.swift only processes excludes (via expandedExcludes) and Info.plist files, with zero references to includes.

Issue 2: No deduplication across targets

Expected: One PBXFileSystemSynchronizedRootGroup for App/ with separate PBXFileSystemSynchronizedBuildFileExceptionSet entries per target.
Actual: Two separate PBXFileSystemSynchronizedRootGroup objects → duplicate "App" folders in the project navigator.

Root cause

In SourceGenerator.getSourceFiles(), the .syncedFolder case always creates a new PBXFileSystemSynchronizedRootGroup without checking if one already exists for the same path. There is no syncedGroupsByPath cache (unlike fileReferencesByPath for file references).

Expected behavior

Ideally, XcodeGen should:

1. Support includes for synced folders — translate them to membershipExceptions in PBXFileSystemSynchronizedBuildFileExceptionSet (the included files become membership exceptions for that target, meaning "include these files in this target's build phase")
2. Deduplicate synced folders — when multiple targets reference the same directory path as a synced folder, reuse the same PBXFileSystemSynchronizedRootGroup and attach separate PBXFileSystemSynchronizedBuildFileExceptionSet entries per target

This would match how Xcode natively handles synced folders with multi-target membership (one synced folder in the navigator, with per-target membership checkboxes in File Inspector).

Workaround

Use type: group for cross-target entries:

- path: App
  type: group
  includes:
    - Source/Shared/SharedModel.swift

This works for includes but results in 2 entries in the navigator (1 synced folder + 1 group for the same directory).