VSC internal TypeError due to if_then constraint with Enum.

[msmftc]

It appears that a recent change in PyVSC introduced a new issue. In a test that previously worked, an if_then constraint that uses IntEnum (or Enum) now causes a TypeError inside VSC. I created a small example that reproduces the error, and I verified that this example passes on earlier VSC versions. Unfortunately, I cannot determine which version, but I think the issue arose recently.

import vsc
from enum import IntEnum


class CmdTypes(IntEnum):
    TYPE_A = 0
    TYPE_B = 1


@vsc.randobj
class Cmd():
    def __init__(self):
        self.cmd_type = vsc.rand_enum_t(CmdTypes)
        self.cmd_op = vsc.rand_bit_t(1)

    @vsc.constraint
    def op_type_combination_c(self):
        with vsc.if_then(self.cmd_type == CmdTypes.TYPE_B):  # This if_then is needed to hit the bug.
           self.cmd_op == 1


cmd = Cmd()
cmd.randomize()    # This randomize() causes a TypeError in VSC.
print(f"Cmd type:  {cmd.cmd_type}, Cmd op:  {cmd.cmd_op}")

The example produces this output:

Traceback (most recent call last):
  File "/usr/lib64/python3.6/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib64/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/root/.vscode-server-insiders/extensions/ms-python.python-2021.12.1559732655/pythonFiles/lib/python/debugpy/__main__.py", line 45, in <module>
    cli.main()
  File "/root/.vscode-server-insiders/extensions/ms-python.python-2021.12.1559732655/pythonFiles/lib/python/debugpy/../debugpy/server/cli.py", line 444, in main
    run()
  File "/root/.vscode-server-insiders/extensions/ms-python.python-2021.12.1559732655/pythonFiles/lib/python/debugpy/../debugpy/server/cli.py", line 285, in run_file
    runpy.run_path(target_as_str, run_name=compat.force_str("__main__"))
  File "/usr/lib64/python3.6/runpy.py", line 263, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "/usr/lib64/python3.6/runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "/usr/lib64/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/scratch/mcgrathm/silicon-validation/lib/python/tests/experiment.py", line 23, in <module>
    cmd.randomize()
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/rand_obj.py", line 168, in randomize
    solve_fail_debug=solve_fail_debug)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/randomizer.py", line 558, in do_randomize
    fm, bounds_v.bound_m))
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/visitors/array_constraint_builder.py", line 48, in build
    m.accept(builder)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/field_composite_model.py", line 154, in accept
    v.visit_composite_field(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/model_visitor.py", line 68, in visit_composite_field
    c.accept(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/constraint_block_model.py", line 42, in accept
    v.visit_constraint_block(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/visitors/constraint_copy_builder.py", line 85, in visit_constraint_block
    super().visit_constraint_block(c)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/model_visitor.py", line 107, in visit_constraint_block
    self.visit_constraint_scope(c)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/visitors/constraint_override_visitor.py", line 25, in visit_constraint_scope
    cc.accept(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/constraint_if_else_model.py", line 63, in accept
    visitor.visit_constraint_if_else(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/visitors/array_constraint_builder.py", line 90, in visit_constraint_if_else
    is_x, val = XExprEvaluator().eval(c.cond)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/visitors/x_expr_evaluator.py", line 27, in eval
    e.accept(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/expr_bin_model.py", line 178, in accept
    visitor.visit_expr_bin(self)
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/visitors/x_expr_evaluator.py", line 118, in visit_expr_bin
    if lhs_val == rhs_val:
  File "/scratch/mcgrathm/silicon-validation/.venv/lib64/python3.6/site-packages/vsc/model/value_scalar.py", line 48, in __eq__
    v = int(rhs)
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

[mballance]

This issue is corrected in the 0.7.0 release