From d1a014542a1907bc77ccecedc672111dec944d50 Mon Sep 17 00:00:00 2001
From: Hiroshi Ogawa <hi.ogawa.zz@gmail.com>
Date: Thu, 9 Dec 2021 07:33:43 +0900
Subject: [PATCH] fix: collect only valid fields in mypy plugin (#3247)

* fix: collect only valid fields in mypy plugin

* Fix flake8 C901 in `PydanticModelTransformer.collect_fields`
---
 changes/3146-hi-ogawa.md                     |  1 +
 pydantic/mypy.py                             |  4 +++-
 tests/mypy/modules/plugin_success.py         | 14 +++++++++++++-
 tests/mypy/outputs/plugin-success-strict.txt |  3 +--
 4 files changed, 18 insertions(+), 4 deletions(-)
 create mode 100644 changes/3146-hi-ogawa.md

diff --git a/changes/3146-hi-ogawa.md b/changes/3146-hi-ogawa.md
new file mode 100644
index 0000000..d0f3cb4
--- /dev/null
+++ b/changes/3146-hi-ogawa.md
@@ -0,0 +1 @@
+Fix mypy plugin to collect fields based on `pydantic.utils.is_valid_field` so that it ignores untyped private variables
diff --git a/pydantic/mypy.py b/pydantic/mypy.py
index 1dfd49e..9aa0878 100644
--- a/pydantic/mypy.py
+++ b/pydantic/mypy.py
@@ -1,6 +1,8 @@
 from configparser import ConfigParser
 from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Type as TypingType, Union
 
+from pydantic.utils import is_valid_field
+
 try:
     import toml
 except ImportError:  # pragma: no cover
@@ -247,7 +249,7 @@ class PydanticModelTransformer:
                 continue
 
             lhs = stmt.lvalues[0]
-            if not isinstance(lhs, NameExpr):
+            if not isinstance(lhs, NameExpr) or not is_valid_field(lhs.name):
                 continue
 
             if not stmt.new_syntax and self.plugin_config.warn_untyped_fields:
diff --git a/tests/mypy/modules/plugin_success.py b/tests/mypy/modules/plugin_success.py
index 6fb6d63..217eebc 100644
--- a/tests/mypy/modules/plugin_success.py
+++ b/tests/mypy/modules/plugin_success.py
@@ -1,6 +1,6 @@
 from typing import ClassVar, Optional, Union
 
-from pydantic import BaseModel, BaseSettings, Field, create_model
+from pydantic import BaseModel, BaseSettings, Field, create_model, validator
 from pydantic.dataclasses import dataclass
 
 
@@ -169,3 +169,15 @@ class SettingsModel(BaseSettings):
 
 
 settings = SettingsModel.construct()
+
+
+def f(name: str) -> str:
+    return name
+
+
+class ModelWithAllowReuseValidator(BaseModel):
+    name: str
+    _normalize_name = validator('name', allow_reuse=True)(f)
+
+
+model_with_allow_reuse_validator = ModelWithAllowReuseValidator(name='xyz')
diff --git a/tests/mypy/outputs/plugin-success-strict.txt b/tests/mypy/outputs/plugin-success-strict.txt
index 8e61a4a..80365a9 100644
--- a/tests/mypy/outputs/plugin-success-strict.txt
+++ b/tests/mypy/outputs/plugin-success-strict.txt
@@ -1,4 +1,3 @@
 29: error: Unexpected keyword argument "z" for "Model"  [call-arg]
 64: error: Untyped fields disallowed  [pydantic-field]
-79: error: Argument "x" to "OverrideModel" has incompatible type "float"; expected "int"  [arg-type]
-125: error: Untyped fields disallowed  [pydantic-field]
\ No newline at end of file
+79: error: Argument "x" to "OverrideModel" has incompatible type "float"; expected "int"  [arg-type]
\ No newline at end of file