I’m building a Cocos2d-x game for Android on a Mac, using Android NDK, and I get many warnings like this when compiling the C++ part:
/usr/include/module.map:1662:22: warning: unknown attribute 'extern_c' [-Wignored-attributes]
Is it dangerous? How can I fix it?
I'm guessing that extern_c is a compiler directive for the module map saying it is referencing functions from C++ that were written in the C language (different call frame structure).
The LLVM portion of the CLANG compiler is probably having a version mismatch. http://clang.llvm.org/docs/Modules.html#module-maps
Try a command line $ clang -v
You may have to verify the compiler library version xcode->preferences->locations->command line tools.
Ultimately you will want to clear this up so your stack frames match the arguments and your not referencing a C language function.