OpenCV fails to compile in a mixed source project with resources due to conflicting NO macro definition

[jeffremer]

What happened?

As of tuist@4.11.0 the opencv-spm dependency (source) fails to compile with an Expected identifier error in the headers.

This is is warned against in their headers…

#if defined(NO)
#  warning Detected Apple 'NO' macro definition, it can cause build conflicts. Please, include this header before any Apple headers.
#endif

The Apple NO macro definition is being pulled in because tuist is setting the GCC_PREFIX_HEADER setting as of this change causing a build conflict.

Please, include this header before any Apple headers.

Open CV headers need to be included before any Apple header and the tuist set prefix header is causing Apple headers to come in automatically first.

If I stop the prefix header from being set (for instance no resources or Objective-C) then things work fine.

How do we reproduce it?

1. Use the attached project and run tuist install && tuist generate
2. Build the OpenCVTuistExample app

OpenCVTuistExample.zip

Error log

Build OpenCVTuistExample_2024-05-13T12-43-14.txt

macOS version

13.5.2

Tuist version

4.11.0

Xcode version

15.2

[jeffremer]

Interestingly if I remove the top level openCV import in the OpenCVWrapper.mm file attached in the project then it compiles just fine.

So, we have a workaround right now…but this still does feel like a bug, or at least something that would be nice to have more control over.

[fortmarek]

Hey 👋

Yeah, the SPM integration doesn't use GCC_PREFIX_HEADER and we know using it is not ideal as commented here when we initially added this setting (the PR you linked doesn't actually add that flag, it has been there longer).

The fix should be to use -include flags which is what SPM is doing. As mentioned in the linked comment, I wasn't able to get it working in that PR, but we might need to try another time.

We'll put it into our backlog but if you would like to dive deeper into this one, I'm more than happy to provide guidance and pointers to fix this 👀