What is peculiar about our math.h implementation?

[elekktretterr@xxxxxxxxxxxxxx]

I'm trying to compile LDC (D compiler for LLVM), I fixed most errors, but
this one puzzles me:

/home/petr/sources/ldc/dmd2/root/port.c: In static member function 'static
int Port::isNan(double)':
/home/petr/sources/ldc/dmd2/root/port.c:382: error: '::isnan' has not been
declared
/home/petr/sources/ldc/dmd2/root/port.c: In static member function 'static
int Port::isNan(long double)':
/home/petr/sources/ldc/dmd2/root/port.c:393: error: '::isnan' has not been
declared
/home/petr/sources/ldc/dmd2/root/port.c: In static member function 'static
int Port::isInfinity(double)':
/home/petr/sources/ldc/dmd2/root/port.c:427: error: '::isinf' has not been
declared


The math.h header is definitely included

Any ideas?
Petr