This is, probably, not very important, but still ...
I checked compilation on Linux via "umk CLANG -bsu".
Problems:

benchmarks/stdlist - 'gtk/gtk.h' file not found (weird)
benchmarks/Sort - call to 'Sort__' is ambiguous
benchmarks/CoLoop - copying variable of type 'std::atomic<int>' invokes deleted constructor
benchmarks/BenchmarkTess - crashes Clang ...
benchmarks/AllocMT - use of undeclared identifier 'Parse'; did you mean 'Parser'?
examples/SDLSoundDemo - 'begin_code.h' file not found
reference/SDL2Uword - 'begin_code.h' file not found
reference/UWord_FB - use of undeclared identifier 'K_PLUS'