mypy守护进程持续崩溃求助：附报错回溯信息

问题描述 #

使用mypy及VS Code的mypy扩展时，遭遇守护进程崩溃，报错回溯如下：

Traceback (most recent call last):
  File "mypy\dmypy_server.py", line 230, in serve
  File "mypy\dmypy_server.py", line 273, in run_command
  File "mypy\dmypy_server.py", line 332, in cmd_run
  File "mypy\dmypy_server.py", line 389, in check
  File "mypy\dmypy_server.py", line 424, in initialize_fine_grained
  File "mypy\build.py", line 180, in build
  File "mypy\build.py", line 256, in _build
  File "mypy\build.py", line 2680, in dispatch
  File "mypy\build.py", line 2838, in load_graph
  File "mypy\build.py", line 1909, in __init__
  File "mypy\build.py", line 2070, in parse_file
  File "mypy\build.py", line 798, in parse_file
  File "mypy\parse.py", line 25, in parse
  File "mypy\fastparse.py", line 196, in parse
  File "mypy\fastparse.py", line 370, in visit
  File "mypy\fastparse.py", line 731, in visit_Module
  File "mypy\fastparse.py", line 409, in translate_stmt_list
  File "mypy\fastparse.py", line 370, in visit
  File "mypy\fastparse.py", line 744, in visit_FunctionDef
  File "mypy\fastparse.py", line 842, in do_func_def
  File "mypy\fastparse.py", line 481, in as_required_block
  File "mypy\fastparse.py", line 409, in translate_stmt_list
  File "mypy\fastparse.py", line 370, in visit
  File "mypy\fastparse.py", line 1020, in visit_AnnAssign
  File "mypy\fastparse.py", line 1645, in visit
  File "mypy\fastparse.py", line 1882, in visit_Subscript
AttributeError: 'NoneType' object has no attribute 'col_offset'

已尝试mypy 0.960至0.971版本、VS Code mypy扩展0.2.0至0.2.1版本的多种组合，问题未解决。

排查与解决方法 #

• 定位出错代码

  1. 关闭VS Code的mypy守护进程，用命令行执行mypy --no-incremental <你的项目路径>，禁用增量检查模式，通常会输出具体的错误文件和行号。
  2. 在VS Code设置中，将mypy.fineGrained设为false，禁用细粒度检查，重新运行类型检查，获取更明确的报错位置。

• 检查类型标注语法
  重点排查函数内的变量标注（AnnAssign语句），尤其是带下标表达式的类型（如List[int]、Dict[str, Any]）：

  • 检查是否有语法错误，比如漏写括号、未闭合的下标
  • 确认类型别名是否已正确定义
  • 排查嵌套下标表达式的合法性，比如Tuple[str]需改为Tuple[str, ...]表示变长元组

• 临时规避方案
  在项目的mypy.ini或pyproject.toml中添加配置，禁用mypy的快速解析器：

  [mypy]
  fastparse = false
  

  改用传统解析器可绕过该崩溃问题。

• 升级版本
  升级mypy至最新稳定版（如1.5+），同时更新VS Code的mypy扩展到最新版本，新版本可能已修复该解析器bug。

• 提交bug报告
  若定位到稳定复现的代码片段，可整理为最小示例，提交至mypy官方仓库的issues中，附带版本信息和报错回溯。

内容的提问来源于stack exchange，提问作者vianmixt