fix(lint): resolve LIT015 shared config at class definition

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

scripts/check_type_discipline.py

@@ -122,6 +122,7 @@ import sys
 import tokenize
 from collections.abc import Iterable, Iterator, Mapping, Sequence
 from dataclasses import dataclass
+from itertools import groupby
 from multiprocessing import Pool
 from pathlib import Path
 from types import MappingProxyType
@@ -880,18 +881,35 @@ def _bool_constant(value: ast.expr) -> bool | None:
     return value.value if isinstance(value, ast.Constant) and isinstance(value.value, bool) else None
 
 
-def _module_assignment_items(tree: ast.AST) -> Iterator[tuple[str, ast.expr]]:
+def _module_assignment_items(tree: ast.AST) -> Iterator[tuple[str, tuple[int, ast.expr]]]:
     if not isinstance(tree, ast.Module):
         return
     for stmt in tree.body:
         if isinstance(stmt, ast.Assign):
-            yield from ((target.id, stmt.value) for target in stmt.targets if isinstance(target, ast.Name))
+            yield from (
+                (target.id, (stmt.lineno, stmt.value)) for target in stmt.targets if isinstance(target, ast.Name)
+            )
         elif isinstance(stmt, ast.AnnAssign) and isinstance(stmt.target, ast.Name) and stmt.value is not None:
-            yield stmt.target.id, stmt.value
+            yield stmt.target.id, (stmt.lineno, stmt.value)
 
 
-def _model_config_frozen(value: ast.expr, module_assignments: Mapping[str, ast.expr]) -> bool | None:
-    config: Final = module_assignments.get(value.id) if isinstance(value, ast.Name) else value
+def _model_config_frozen(
+    value: ast.expr,
+    module_assignments: Mapping[str, tuple[tuple[int, ast.expr], ...]],
+    class_lineno: int,
+) -> bool | None:
+    config: Final = (
+        next(
+            (
+                expression
+                for lineno, expression in reversed(module_assignments.get(value.id, ()))
+                if lineno < class_lineno
+            ),
+            None,
+        )
+        if isinstance(value, ast.Name)
+        else value
+    )
     if isinstance(config, ast.Call) and _head_name(config.func) in PYDANTIC_CONFIG_FACTORIES:
         flags: Final = tuple(_bool_constant(kw.value) for kw in config.keywords if kw.arg == "frozen")
         return flags[-1] if flags else None
@@ -921,28 +939,44 @@ def _config_class_frozen(node: ast.ClassDef) -> bool | None:
     return flags[-1] if flags else None
 
 
-def _stmt_frozen_flag(stmt: ast.stmt, module_assignments: Mapping[str, ast.expr]) -> bool | None:
+def _stmt_frozen_flag(
+    stmt: ast.stmt,
+    module_assignments: Mapping[str, tuple[tuple[int, ast.expr], ...]],
+    class_lineno: int,
+) -> bool | None:
     config_value: Final = _assigns_name(stmt, "model_config")
     if config_value is not None:
-        return _model_config_frozen(config_value, module_assignments)
+        return _model_config_frozen(config_value, module_assignments, class_lineno)
     if isinstance(stmt, ast.ClassDef) and stmt.name == "Config":
         return _config_class_frozen(stmt)
     return None
 
 
-def _class_frozen_override(cls: ast.ClassDef, module_assignments: Mapping[str, ast.expr]) -> bool | None:
+def _class_frozen_override(
+    cls: ast.ClassDef,
+    module_assignments: Mapping[str, tuple[tuple[int, ast.expr], ...]],
+    class_lineno: int,
+) -> bool | None:
     keyword_flags: Final = tuple(_bool_constant(keyword.value) for keyword in cls.keywords if keyword.arg == "frozen")
     if keyword_flags:
         return keyword_flags[-1]
-    body_flags: Final = tuple(_stmt_frozen_flag(stmt, module_assignments) for stmt in cls.body)
+    body_flags: Final = tuple(_stmt_frozen_flag(stmt, module_assignments, class_lineno) for stmt in cls.body)
     return next((flag for flag in reversed(body_flags) if flag is not None), None)
 
 
 def iter_pydantic_violations(path: Path, tree: ast.AST) -> Iterator[Violation]:
-    module_assignments: Final = MappingProxyType(dict(_module_assignment_items(tree)))
+    module_assignments: Final = MappingProxyType(
+        {
+            name: tuple(binding for _, binding in assignments)
+            for name, assignments in groupby(
+                sorted(_module_assignment_items(tree), key=lambda item: item[0]),
+                key=lambda item: item[0],
+            )
+        }
+    )
     models: Final = _pydantic_classes(tree)
     bases_of: Final = {cls: _base_names(cls) for cls in models}
-    override_of: Final = {cls: _class_frozen_override(cls, module_assignments) for cls in models}
+    override_of: Final = {cls: _class_frozen_override(cls, module_assignments, cls.lineno) for cls in models}
 
     def frozen(known: frozenset[str]) -> frozenset[str]:
         grown: Final = known | frozenset(

tests/unit/test_check_type_discipline.py

@@ -611,14 +611,37 @@ def test_shared_frozen_configdict_constant_is_clean(tmp_path):
     assert "LIT015" not in _codes(tmp_path, src)
 
 
-def test_last_shared_non_frozen_configdict_assignment_is_flagged(tmp_path):
+def test_mutable_config_before_class_is_not_hidden_by_frozen_reassignment(tmp_path):
     src: Final = (
         "from pydantic import BaseModel, ConfigDict\n"
-        "_RESPONSE_CONFIG = ConfigDict(frozen=True)\n"
         "_RESPONSE_CONFIG = ConfigDict(frozen=False)\n"
         "class Foo(BaseModel):\n"
         "    model_config = _RESPONSE_CONFIG\n"
         "    x: int\n"
+        "_RESPONSE_CONFIG = ConfigDict(frozen=True)\n"
+    )
+    assert "LIT015" in _codes(tmp_path, src)
+
+
+def test_frozen_config_before_class_survives_mutable_reassignment(tmp_path):
+    src: Final = (
+        "from pydantic import BaseModel, ConfigDict\n"
+        "_RESPONSE_CONFIG = ConfigDict(frozen=True)\n"
+        "class Foo(BaseModel):\n"
+        "    model_config = _RESPONSE_CONFIG\n"
+        "    x: int\n"
+        "_RESPONSE_CONFIG = ConfigDict(frozen=False)\n"
+    )
+    assert "LIT015" not in _codes(tmp_path, src)
+
+
+def test_config_assigned_only_after_class_is_unresolved(tmp_path):
+    src: Final = (
+        "from pydantic import BaseModel, ConfigDict\n"
+        "class Foo(BaseModel):\n"
+        "    model_config = _RESPONSE_CONFIG\n"
+        "    x: int\n"
+        "_RESPONSE_CONFIG = ConfigDict(frozen=True)\n"
     )
     assert "LIT015" in _codes(tmp_path, src)