dmypy deameon crash after switching branches

[aljazerzen]

Crash Report

• run dmypy on a codebase
• git switch (i.e. major changes to the codebase)
• dmypy run

Traceback

Daemon crashed!
Traceback (most recent call last):
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/dmypy_server.py", line 229, in serve
    resp = self.run_command(command, data)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/dmypy_server.py", line 272, in run_command
    return method(self, **data)
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/dmypy_server.py", line 331, in cmd_run
    return self.check(sources, is_tty, terminal_width)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/dmypy_server.py", line 393, in check
    messages = self.fine_grained_increment_follow_imports(sources)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/dmypy_server.py", line 568, in fine_grained_increment_follow_imports
    messages = fine_grained_manager.update(changed, [])
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/server/update.py", line 245, in update
    result = self.update_one(changed_modules, initial_set, removed_set, blocking_error)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/server/update.py", line 328, in update_one
    result = self.update_module(next_id, next_path, next_id in removed_set)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/server/update.py", line 393, in update_module
    result = update_module_isolated(module, path, manager, previous_modules, graph,
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/server/update.py", line 615, in update_module_isolated
    state.type_check_first_pass()
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/build.py", line 2186, in type_check_first_pass
    self.type_checker().check_first_pass()
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 318, in check_first_pass
    self.accept(d)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 426, in accept
    report_internal_error(err, self.errors.file, stmt.line, self.errors, self.options)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/errors.py", line 902, in report_internal_error
    raise err
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 424, in accept
    stmt.accept(self)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/nodes.py", line 739, in accept
    return visitor.visit_func_def(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 774, in visit_func_def
    self._visit_func_def(defn)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 778, in _visit_func_def
    self.check_func_item(defn, name=defn.name)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 840, in check_func_item
    self.check_func_def(defn, typ, name)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 1025, in check_func_def
    self.accept(item.body)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 426, in accept
    report_internal_error(err, self.errors.file, stmt.line, self.errors, self.options)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/errors.py", line 902, in report_internal_error
    raise err
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 424, in accept
    stmt.accept(self)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/nodes.py", line 1086, in accept
    return visitor.visit_block(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 2151, in visit_block
    self.accept(s)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 426, in accept
    report_internal_error(err, self.errors.file, stmt.line, self.errors, self.options)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/errors.py", line 902, in report_internal_error
    raise err
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 424, in accept
    stmt.accept(self)
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/nodes.py", line 1402, in accept
    return visitor.visit_match_stmt(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 4097, in visit_match_stmt
    pattern_types = [self.pattern_checker.accept(p, subject_type) for p in s.patterns]
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checker.py", line 4097, in <listcomp>
    pattern_types = [self.pattern_checker.accept(p, subject_type) for p in s.patterns]
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checkpattern.py", line 107, in accept
    result = o.accept(self)
             ^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/patterns.py", line 137, in accept
    return visitor.visit_class_pattern(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/aljaz/EdgeDB/venv/lib/python3.11/site-packages/mypy/checkpattern.py", line 466, in visit_class_pattern
    assert type_info is not None
AssertionError

To Reproduce

It doesn't happen always, but I'd say 40% of the time. I don't know if it is related to our codebase.

Your Environment

• Mypy version used: 0.941
• Mypy command-line flags: see below
• Mypy configuration options from mypy.ini (and other config files): see below
• Python version used: 3.11.0
• Operating system and version: Linux, Ubuntu 20.04

[tool.mypy]
python_version = "3.10"
plugins = "edb/tools/mypy/plugin.py"
follow_imports = "normal"
ignore_missing_imports = true
warn_redundant_casts = true
warn_unused_configs = true
show_column_numbers = true
show_error_codes = true

... omitted dir specific options ...

(see full mypy config here: https://github.com/edgedb/edgedb/blob/d985f5086769461463c037de7dbd32e219ad8573/pyproject.toml#L103-L174)

[AlexWaygood]

Mypy 0.941 is a very old version of mypy — can you confirm that this still crashes on mypy 0.991? (Ideally if you could try the master branch as well, that would be great — there have been a few daemon-related fixes recently that haven't been released yet. E.g. #12744 has reportedly fixed quite a few daemon-related crashes.)

[aljazerzen]

Woah, you are fast!

I'll switch to 0.991 and report back if this is still happening.

[AlexWaygood]

@aljazerzen, were you able to reproduce this on 0.991 or master? If not we should probably close the issue :)

[aljazerzen]

No, it hasn't happened since, this can be closed.

Thanks for help!

[AlexWaygood]

No worries, thanks for filing the issue and following up!