when automoc-ing a static library results in an empty `mocs_compilation.cpp`, `ranlib` on macos warns about an empty object file: ``` /Applications/Xcode13.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: path/To/Library.a(mocs_compilation.cpp.o) has no symbols ``` possible fix: !7296