python / python/mypy

Plugin's get_type_analyze_hook is not used for Annotated type in type alias or generic specialization

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描述

Bug Report

Mypy doesn't use plugin's get_type_analyze_hook for Annotated type used in type alias or generic specialization. However, the hook is used for custom types (not Annotated) used in these contexts, and it's also called for Annotated used in other contexts.

To Reproduce

plugin.py

from typing import Callable

from mypy.plugin import AnalyzeTypeContext, Plugin
from mypy.types import NoneType, Type

def plugin(version: str):
    return MyPlugin

class MyPlugin(Plugin):
    def get_type_analyze_hook(self, fullname: str) -> Callable[[AnalyzeTypeContext], Type] | None:
        if fullname in {'typing.Annotated', 'typing_extensions.Annotated'}:
            return _type_analyze
        return None

def _type_analyze(ctx: AnalyzeTypeContext) -> Type:
    ctx.api.note('Analyzing type of Annotated[...]', ctx.context)
    return NoneType()  # for the sake of example

module.py

from typing import Annotated, Generic, TypeAlias, TypeVar, reveal_type

AnnotatedTA: TypeAlias = Annotated[dict, None]
typed_with_alias: AnnotatedTA
reveal_type(typed_with_alias)  # Revealed type is "builtins.dict[Any, Any]"

typed_directly: Annotated[dict, None]  # Analyzing type of Annotated[...]
reveal_type(typed_directly)  # Revealed type is "None", as expected


T = TypeVar('T')

class GenericType(Generic[T]):
    dummy: T

class Specialization(GenericType[Annotated[dict, None]]):
    ...

reveal_type(Specialization().dummy)  # Revealed type is "builtins.dict[Any, Any]"

Expected Behavior

All revealed types are None as requested by _type_analyze hook

Actual Behavior

Only directly typed variable typed_directly has the type requested by plugin

Your Environment

  • Mypy version used: 1.10.1
  • Mypy command-line flags: none
  • Mypy configuration options from mypy.ini (and other config files): plugins = plugin.py
  • Python version used: 3.8, 3.12

Background

I'm writing a plugin which generates TypedDictType for Annotated[dict, ...] annotations based on some external configuration files. The arguments to Annotated are string literals, so I can't really use generics. In runtime these are just normal dicts.

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  1. 先读完整个 Issue,再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库,在一个分支上完成修改。
  4. 提交 Pull Request,并在描述里引用这个 Issue 编号。

调研方向

首先使用报告中的 Python 和 mypy 版本运行 plugin.py 和 module.py reproducer,然后跟踪 Annotated 在直接使用、TypeAlias 和泛型特化情况下的类型分析。完成标准是 hook 在这三种情况下都被调用,并且每个 reveal_type 都按 _type_analyze 的要求报告 None。

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评估

技术栈
python
领域
devtools
Issue 类型
缺陷
难度
3/5
预计耗时
1-2 天
活跃度
停滞
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描述清楚
新手友好度
48/100

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