Fix metadata-generator on Xcode 13

[adrian-branescu]

I've enabled TNS_DEBUG_METADATA_PATH and tested using the following environment

{ N } runtime: 8.1
OS: macOS Big Sur 11.6.1
Xcode: 13.2.1 (AppleClang 13.0.0.13000029)
Target: iOS 15.0.1 (physical device)

metadata-generation-stderr-arm64.txt contains hundreds of fatal error: could not build module

While building module 'VisionKit' imported from /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/VisionKit.framework/Headers/VisionKit.h:9:
While building module 'UIKit' imported from /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/VisionKit.framework/Headers/VNDocumentCameraViewController.h:9:
While building module 'Foundation' imported from /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/UIKit.framework/Headers/UIKit.h:8:
In file included from <module-includes>:1:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/Foundation.framework/Headers/Foundation.h:130:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSURLSession.h:500:168: error: expected ')'
- (void)readDataOfMinLength:(NSUInteger)minBytes maxLength:(NSUInteger)maxBytes timeout:(NSTimeInterval)timeout completionHandler:(void (^) (NSData * _Nullable_result data, BOOL atEOF, NSError * _Nullable error))completionHandler;
                                                                                                                                                                       ^
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSURLSession.h:500:141: note: to match this '('
- (void)readDataOfMinLength:(NSUInteger)minBytes maxLength:(NSUInteger)maxBytes timeout:(NSTimeInterval)timeout completionHandler:(void (^) (NSData * _Nullable_result data, BOOL atEOF, NSError * _Nullable error))completionHandler;
                                                                                                                                            ^
While building module 'VisionKit' imported from /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/VisionKit.framework/Headers/VisionKit.h:9:
While building module 'UIKit' imported from /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/VisionKit.framework/Headers/VNDocumentCameraViewController.h:9:
In file included from <module-includes>:1:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/UIKit.framework/Headers/UIKit.h:8:9: fatal error: could not build module 'Foundation'
#import <Foundation/Foundation.h>
 ~~~~~~~^

The build succeeds though, but looking at the YAML dumped for the native plugins a lot of methods and data types are missing. This explains the crashes reported on iOS 15+ devices if Xcode 13 was used to build the native app.

If I repeat the same experiment with Xcode 12.5.1 (AppleClang 12.0.5.12050022) instead, then metadata-generation-stderr-arm64.txt log no longer contains any fatal error and the YAMLs and .d.ts typings look fine.

I suspect that metadata-generator Clang plugin needs to be updated to take into account AppleClang 13 breaking changes.

This issue will become more pressing for the NativeScript community as times goes by because Apple states the following

Starting April 2022, iOS and iPadOS apps submitted to the App Store must be built with Xcode 13 and the iOS 15 SDK. 

[adrian-branescu]

It seems the _Nullable_result attribute that was causing trouble to metadata-generator in the above example was introduced in Clang 12. Since you are linking with clang 8 it explains why it can't parse that method of NSURLSession.

Xcode 12.5.1 -> SDK 14.5

Xcode 13.2.1 -> SDK 15.2

[adrian-branescu]

@NathanWalker the above issue replicates only when you have CLANG_ENABLE_MODULES=YES set in the native app.
This env variable propagates to metadata generator and causes the fatal errors mentioned above.

I've investigated further and the errors reported using TNS_DEBUG_METADATA_PATH are still there even with CLANG_ENABLE_MODULES=NO, just they are no longer fatal.

Without updating the clang version used by the metadata-generator it will eventually no longer be able to correctly parse the headers of the native SDKs, causing missing data types and methods at runtime.

[rigor789]

@adrian-branescu give @nativescript/ios@8.2.4-alpha.2 a go it uses clang13.0.1 and should work as expected now!