macOS clang compilation failed when linking.

[LittleFall]

I deleted all cmake cache and reproduced again.

[100%] Linking CXX executable tiflash
Undefined symbols for architecture x86_64:
  "_inside_main", referenced from:
      DateLUTImpl::DateLUTImpl(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in libcommond.a(DateLUTImpl.cpp.o)
ld: symbol(s) not found for architecture x86_64

$ clang -v
Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin20.3.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

maybe related to #2143

[solotzg]

Same error in Apple clang version 11.0.0 (clang-1100.0.33.17).