konstantin-mapbox
## Summary `destinationFilters` on a `TargetSource` work for regular (`group`) sources: each file gets `platformFilters` on its `PBXBuildFile`. For `type: syncedFolder` the same key is silently ignored, so every file in the folder compiles for all destinations of the target. Xcode itself supports per-file platform filters inside synced folders via `platformFiltersByRelativePath` on `PBXFileSystemSynchronizedBuildFileExceptionSet`, and the bundled XcodeProj already models that field (tuist/XcodeProj#1065, in XcodeProj 9.8.0+). ## Reproduction ```yaml name: Demo targets: App: type: application supportedDestinations: [iOS, visionOS] sources: - path: Sources type: syncedFolder excludes: - VisionOSMain.swift destinationFilters: [iOS] - path: Sources type: syncedFolder includes: - VisionOSMain.swift destinationFilters: [visionOS] ``` `Sources/AppDelegate.swift` uses `UIScreen`, `Sources/VisionOSMain.swift` is a visionOS `@main`. ## Expected The generated exception set carries the filters, the way Xcode writes them when you uncheck "Any Supported Platform" in the file inspector: ``` platformFiltersByRelativePath = { AppDelegate.swift = (ios, ); VisionOSMain.swift = (xros, ); }; ``` and the visionOS build does not compile `AppDelegate.swift`. ## Actual `membershipExceptions` are emitted from `excludes`/`includes`, but there is no `platformFiltersByRelativePath` at all. Building for visionOS compiles `AppDelegate.swift` and fails with `'UIScreen' is unavailable in visionOS`. No warning that the key is ignored. I verified that Xcode honors a hand-written `platformFiltersByRelativePath` in the generated project (Xcode 26.5): the filtered files are skipped on the other platform for both iOS and visionOS builds. Folder keys are not honored by Xcode, only file paths, so the generator would need to enumerate matching files the same way `syncedFolderExceptions` already does for excludes. ## Environment - XcodeGen 2.45.4 (same on 2.46.0 / master) - Xcode 26.5 - macOS 26 Related, but different: #1589 / #1587 (excludes), #1602 / #1604 (includes), #1607 (directory-level exceptions).