Checking for size of "long double" : 16 (cached)

../numpy-1.25.0/numpy/core/meson.build:379:4: ERROR: Problem encountered: No idea what this is ....

# long double representation detection (see setup_common.py)
# TODO: this is still incomplete, and different from how it's done in the
# numpy.distutils based build, see https://github.com/mesonbuild/meson/issues/11068
longdouble_size = cc.sizeof('long double')
if longdouble_size == 8
  if host_machine.endian() == 'little'
    longdouble_format = 'IEEE_DOUBLE_LE'
  else
    longdouble_format = 'IEEE_DOUBLE_BE'
  endif
elif longdouble_size == 12
  error('This should not be possible, 12 bits of "content" should still result in sizeof() being 16. Please report this error!'
  )
elif longdouble_size == 16
  if host_machine.endian() == 'little'
    # FIXME: this varies, there's multiple formats here! Not yet implemented.
    #        TBD how we deal with the mess of old long double formats.
    longdouble_format = 'INTEL_EXTENDED_16_BYTES_LE'
  else
    error('No idea what this is ....')
  endif
else
  error('Unknown long double size: ' + londouble_size)
endif
cdata.set10('HAVE_LDOUBLE_' + longdouble_format, true)