Regression on master: mypy unconditionally crashes when used with --enable-error-code for multiple error codes

[AlexWaygood]

Crash Report

On the master branch, mypy unconditionally crashes if used with the command-line options --enable-error-code ignore-without-code. I've bisected the regression to:

• Allow per-module error codes #13502

Traceback

Traceback (most recent call last):
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\alexw\coding\mypy\venv\Scripts\mypy.exe\__main__.py", line 7, in <module>
  File "C:\Users\alexw\coding\mypy\mypy\__main__.py", line 15, in console_entry
    main()
  File "C:\Users\alexw\coding\mypy\mypy\main.py", line 95, in main
    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
  File "C:\Users\alexw\coding\mypy\mypy\main.py", line 174, in run_build
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 186, in build
    result = _build(
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 269, in _build
    graph = dispatch(sources, manager, stdout)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 2873, in dispatch
    process_graph(graph, manager)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 3257, in process_graph
    process_stale_scc(graph, scc, manager)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 3378, in process_stale_scc
    graph[id].write_cache()
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 2447, in write_cache
    new_interface_hash, self.meta = write_cache(
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 1639, in write_cache
    meta_str = json_dumps(meta, manager.options.debug_cache)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 1510, in json_dumps
    return json.dumps(obj, sort_keys=True)
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\json\__init__.py", line 238, in dumps
    **kw).encode(obj)
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\json\encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\json\encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\json\encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type ErrorCode is not JSON serializable

To Reproduce

• cd into a local clone of mypy, activate a local environment with an editable install of mypy.
• Checkout the master branch.
• Run mypy --enable-error-code ignore-without-code on any repository. I've reproduced it using the selfcheck (python -m mypy --config-file mypy_self_check.ini -p mypy --enable-error-code ignore-without-code) and also on my local clone of flake8-pyi, which has the ignore-without-code error code enabled as part of its default mypy configuration.

[AlexWaygood]

--enable-error-code also crashes with other error codes (but with different tracebacks). E.g. for --enable-error-code no-untyped-call, I get:

mypy pyi.py --enable-error-code no-untyped-call
Traceback (most recent call last):
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\alexw\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "C:\Users\alexw\coding\mypy\venv\Scripts\mypy.exe\__main__.py", line 7, in <module>
  File "C:\Users\alexw\coding\mypy\mypy\__main__.py", line 15, in console_entry
    main()
  File "C:\Users\alexw\coding\mypy\mypy\main.py", line 95, in main
    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
  File "C:\Users\alexw\coding\mypy\mypy\main.py", line 174, in run_build
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 186, in build
    result = _build(
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 269, in _build
    graph = dispatch(sources, manager, stdout)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 2875, in dispatch
    process_graph(graph, manager)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 3259, in process_graph
    process_stale_scc(graph, scc, manager)
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 3380, in process_stale_scc
    graph[id].write_cache()
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 2449, in write_cache
    new_interface_hash, self.meta = write_cache(
  File "C:\Users\alexw\coding\mypy\mypy\build.py", line 1631, in write_cache
    "options": options.select_options_affecting_cache(),
  File "C:\Users\alexw\coding\mypy\mypy\options.py", line 460, in select_options_affecting_cache
    val = sorted(val)
TypeError: '<' not supported between instances of 'ErrorCode' and 'ErrorCode'

[ilevkivskyi]

Yeah, I was too lazy to add an incremental test. Need to convert those codes to strings when serializing