C++ division operator overloading unwanted cast

[10se1ucgo]

When wrapping a class like so

# vec3.pxd
cdef extern from "math3d_c.h":
    cdef cppclass Vector3[T]:
        T x, y, z
        Vector3() except +
        Vector3(T x, T y, T z) except +

        Vector3[T] operator*(T &b)
        Vector3[T] operator/(T &b)

# math3d.pyx
from . cimport vec3

cdef class Vector3:
    cdef vec3.Vector3[double] c_vec

    def __init__(self, double x=0, double y=0, double z=0):
        self.c_vec.x = x
        self.c_vec.y = y
        self.c_vec.z = z

    def __mul__(Vector3 a, double scalar):
        return new_vector3_from(a.c_vec * scalar)

    def __truediv__(Vector3 a, double scalar):
        if scalar == 0:
            raise ZeroDivisionError("Vector3 division by zero")
        return new_vector3_from(a.c_vec / scalar)

# new_vector3_from just constructs a Python Vector3 object from a C++ Vector3 object, unrelated

The code generated by Cython for __mul__ is correct, however for __truediv__, Cython unnecessarily casts scalar to a Vector3.

// mul
 __pyx_t_1 = ((PyObject *)__pyx_f_6extlib_6math3d_new_vector3_from((__pyx_v_a->c_vec * __pyx_v_scalar))); if (unlikely(!__pyx_t_1)) __PYX_ERR(0, 30, __pyx_L1_error)

// truediv
__pyx_t_2 = ((PyObject *)__pyx_f_6extlib_6math3d_new_vector3_from((__pyx_v_a->c_vec / ((Vector3<double> )__pyx_v_scalar)))); if (unlikely(!__pyx_t_2)) __PYX_ERR(0, 43, __pyx_L1_error)

Which, of course, causes an error if the wrapped class doesn't provide an overload for that method.

[scoder]

That looks wrong. Might be a problem with the code that tries to find a common floatish type for true division.

Please also see
http://docs.cython.org/en/latest/src/userguide/special_methods.html#arithmetic-operators

[tcdude]

I encountered the same behavior. All other arithmetic operators I used in my code work as expected, only overloading __truediv__() somehow leads to this unwanted cast.

I'm happy to provide more detailed information if necessary to help track the problem down, but the original text pretty much sums up the unwanted behavior.