Problem when using fused type with class inheritance in Cython

metric.pyx

ctypedef float[:,:] float2d
ctypedef double[:,:] double2d

ctypedef fused Line:
    float2d
    double2d

cdef class Metric:
    cdef float dist(Metric self, Line line) nogil:
        pass

cdef class SubMetric(Metric):
    pass

setup.py

# -- setup.py --
import numpy as np

from setuptools import setup
from Cython.Distutils import build_ext
from numpy.distutils.extension import Extension

setup(
    cmdclass={'build_ext': build_ext},
    ext_modules=[Extension("metric",
                           ["metric.pyx"],
                           language='c++',
                           include_dirs=[np.get_include()])
                 ]
)

I've been able to compile this reproducer with Cython 0.29.23.

Great news! Now I need to remember why I needed that for exactly ^_^.

You posted this snippet in this Cython-users group thread. :)