“Use of '@import' when modules are disabled” Error for FirebaseUiAuth

[audkar]

Step 1: Are you in the right place?

80% chance 🤔

Step 2: Describe your environment

• Objective C or Swift: Swift5
• iOS version: 13.5
• Firebase SDK version: 6.6
• FirebaseUI version: 8.4.0
• CocoaPods Version: 1.9.1

Step 3: Describe the problem:

Using FirebasUI dependencies in kotlin-native with cocoapods support throws error during compilation.
Not sure if valid fix, but if I replace module imports in FirebaseUI code then our project compiles successfully.

• @import UIKit; => #import <UIKit/UIKit.h>
• @import Foundation => #import <Foundation/Foundation.h>

edit:

• setting Enable modules (C and Object-c) is true for project.
• cacaopods Podfile contains use_frameworks! :linkage => :static

Steps to reproduce:

1. Add 'FirebaseUI/Google dependency to to kotlin-native project
2. Execute gradle podspec cmd
3. Execute pod install
4. Build iOS project
5. Observe error

Observed Results:

Use of '@import' when modules are disabled

error is thrown in 3 places:

• FirebaseAuthUI.h
• FUIAuthErrors.h
• FirebaseGoogleAuthUI.h

Expected Results:

Successful compilation

[schramm]

Hi. I am having the same issue building FirebaseUI for iOS, mixing C++ and ObjectiveC. No idea how to fix this. Any help?
Edit: I managed to fix it following @audkar suggestion. I am not sure about further implications of replacing @import by #import. Anyways, It would be handy if the FirebaseUI team replaces the source with these modifications to make the framework compatible with Objective-C++ code.

[audkar]

@morganchen12 would you accept PR which replaces these imports?

[morganchen12]

Yes, PRs are very welcome.

[jinyuyoulong]

https://answers.unity.com/questions/1679641/use-of.html

need c++ flag setup

[top-master]

Using -fmodules and -fcxx-modules flags fixes this as long as the file extension is .m
(but not supported by .mm or rather Objective-C++ yet, year 2021).

Note that I tested with both g++ and clang++ compilers (as I really wanted to make this work).