xcode is not even *trying* to compile some of my .mm files, then fails while linking

I'm copying some objective c++ files over from another (working) project.

I get no errors when compiling, but get a linker error:

Undefined symbols:

"_OBJC_CLASS_$_Buzzy2", referenced from: objc-cla开发者_StackOverflow中文版ss-ref-to-Buzzy2 in AudioModeFactory.o ld: symbol(s) not found collect2: ld returned 1 exit status

Looking over the compiler output, I see that xcode never even tried to compile this class. The .h and .mm for the class are there in the source. Its header is imported in to another class, and there are no compiler complaints about that, but the compiler never touches it. I've tried cleaning all targets, touching the files, with no luck. Any idea what's going on here?

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Check the target settings of the .mm files to make sure you have the right targets checked.