Don't worry about it then. I know we already use it in csympy:
https://github.com/sympy/csympy/blob/8d40df996db2340f300a893560a013d5be51cc60/src/functions.cpp#L860

and if csympy compiles with clang for you, it must work. But if the change you did doesn't work yet, then we can't use it, as we need to be able to compile csympy with most compilers.