#!/usr/bin/env python3
from nmigen import *
from nmigen.compat import *
from nmigen.vendor.board.icestick import *

class Compat(Module):
    def __init__(self):
        self.tx = Signal()

if __name__ == "__main__":
    plat = ICEStickPlatform()
    m = Compat()
    plat.build(m)

./testcase.py 
Traceback (most recent call last):
  File "./testcase.py", line 13, in <module>
    plat.build(m)
  File "/home/thomas/.local/lib/python3.7/site-packages/nmigen-9f643ce-py3.7.egg/nmigen/build/plat.py", line 48, in build
    plan = self.prepare(fragment, name, **kwargs)
  File "/home/thomas/.local/lib/python3.7/site-packages/nmigen-9f643ce-py3.7.egg/nmigen/build/plat.py", line 62, in prepare
    fragment = Fragment.get(fragment, self)
  File "/home/thomas/.local/lib/python3.7/site-packages/nmigen-9f643ce-py3.7.egg/nmigen/hdl/ir.py", line 66, in get
    raise AttributeError("Object '{!r}' cannot be elaborated".format(obj))
AttributeError: Object '<__main__.Compat object at 0x7fb954c57390>' cannot be elaborated