Comparison between Sage and mpmath numbers is broken

[fredrik-johansson]

Comparison between Sage and mpmath numbers works with mpmath numbers on the left, but not on the right:

sage: mpmath.mpf(1) < 3
True
sage: 1 < mpmath.mpf(3)
False
sage: 4 == mpmath.mpf(4)
False

Found by Harald Schilly (see #8791).

This appears to be a bug in Sage (or Cython). Sage's numbers do the pure-Python equivalent of not returning NotImplemented when compared to unrecognized types. For a minimal example:

sage: class X(object):
....:         def __init__(self, v): self.v = v
....:     def __lt__(self, other): return self.v < int(other)
....:     def __gt__(self, other): return self.v > int(other)
....:
sage: X(1) < 3
True
sage: 1 < X(3)
False
sage: X(1) < int(3)
True
sage: int(1) < X(3)
True

Component: basic arithmetic

Reviewer: Jeroen Demeyer

Issue created by migration from https://trac.sagemath.org/ticket/8924

[mkoeppe]

comment:1

The tests from the description work as of 7.4.beta0.

[jdemeyer]

Reviewer: Jeroen Demeyer

[jdemeyer]

comment:2

I think this is fixed by #21163.

[embray]

comment:3

Determined to be invalid/duplicate/wontfix (closing as "wontfix" as a catch-all resolution).