AssertionError with strange Switch

[nmigen-issue-migration]

Issue by ZirconiumX
Monday Jan 13, 2020 at 20:31 GMT
Originally opened as m-labs/nmigen#305

---

from enum import Enum

from nmigen import *
from nmigen.back import verilog


class Piece(Enum):
    BISHOP = 2 # Has to be specifically > 1 to crash


class Square(Elaboratable):
    def __init__(self):
        self.i_piece = Signal(1)

    def elaborate(self, platform):
        m = Module()

        with m.Switch(self.i_piece):
            with m.Case(Piece.BISHOP): # Has to be this enum; inlining the value of 2 works fine
                pass

        return m


sq = Square()

print(verilog.convert(sq, ports=[sq.i_piece]))

This produces:

Traceback (most recent call last):
  File "testcase.py", line 27, in <module>
    print(verilog.convert(sq, ports=[sq.i_piece]))
  File "/usr/local/lib/python3.7/dist-packages/nmigen-0.2.dev17+ge18385b-py3.7.egg/nmigen/back/verilog.py", line 76, in convert
    rtlil_text = rtlil.convert(*args, **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/nmigen-0.2.dev17+ge18385b-py3.7.egg/nmigen/back/rtlil.py", line 1010, in convert
    fragment = ir.Fragment.get(elaboratable, platform).prepare(**kwargs)
  File "/usr/local/lib/python3.7/dist-packages/nmigen-0.2.dev17+ge18385b-py3.7.egg/nmigen/hdl/ir.py", line 67, in get       obj = obj.elaborate(platform)
  File "testcase.py", line 20, in elaborate
    pass
  File "/usr/lib/python3.7/contextlib.py", line 119, in __exit__
    next(self.gen)
  File "/usr/local/lib/python3.7/dist-packages/nmigen-0.2.dev17+ge18385b-py3.7.egg/nmigen/hdl/dsl.py", line 264, in Switch
    self._pop_ctrl()
  File "/usr/local/lib/python3.7/dist-packages/nmigen-0.2.dev17+ge18385b-py3.7.egg/nmigen/hdl/dsl.py", line 405, in _pop_ctrl
    src_loc=src_loc, case_src_locs=switch_case_src_locs))
  File "/usr/local/lib/python3.7/dist-packages/nmigen-0.2.dev17+ge18385b-py3.7.egg/nmigen/hdl/ast.py", line 1296, in __init__
    assert len(key) == len(self.test)
AssertionError

It minimised very oddly, but this is the smallest I could get it.