Intel compiler complains about FALLTHROUGH

[byrnHDF]

\src\H5checksum.c(419,9): : warning : unannotated fall-through between switch labels [-Wimplicit-fallthrough]

because of define in H5private.h:

#   if defined(__clang__) || defined(__GNUC__) && __GNUC__ >= 7 && !defined(__INTEL_COMPILER)
#       define H5_ATTR_FALLTHROUGH __attribute__((fallthrough));
#   else
#       define H5_ATTR_FALLTHROUGH /* FALLTHROUGH */
#   endif

why is the "&& !defined(__INTEL_COMPILER)" as the compiler suggests adding the attribute?

[byrnHDF]

The C compiler identification is IntelLLVM 2023.1.0 with MSVC-like command-line

[derobins]

Is this on Windows?