[flake8-pyi] Ignore 'unused' private type dicts in class scopes (#9952)

## Summary

If these are defined within class scopes, they're actually attributes of
the class, and can be accessed through the class itself.

(We preserve our existing behavior for `.pyi` files.)

Closes https://github.com/astral-sh/ruff/issues/9948.

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI049.py

@@ -17,7 +17,19 @@ class _UsedTypedDict(TypedDict):
 class _CustomClass(_UsedTypedDict):
     bar: list[int]
 
+
 _UnusedTypedDict3 = TypedDict("_UnusedTypedDict3", {"foo": int})
 _UsedTypedDict3 = TypedDict("_UsedTypedDict3", {"bar": bytes})
 
+
 def uses_UsedTypedDict3(arg: _UsedTypedDict3) -> None: ...
+
+
+# In `.py` files, we don't flag unused definitions in class scopes (unlike in `.pyi`
+# files).
+class _CustomClass3:
+    class _UnusedTypeDict4(TypedDict):
+        pass
+
+    def method(self) -> None:
+        _CustomClass3._UnusedTypeDict4()

crates/ruff_linter/resources/test/fixtures/flake8_pyi/PYI049.pyi

@@ -35,3 +35,13 @@ _UnusedTypedDict3 = TypedDict("_UnusedTypedDict3", {"foo": int})
 _UsedTypedDict3 = TypedDict("_UsedTypedDict3", {"bar": bytes})
 
 def uses_UsedTypedDict3(arg: _UsedTypedDict3) -> None: ...
+
+
+# In `.pyi` files, we flag unused definitions in class scopes as well as in the global
+# scope (unlike in `.py` files).
+class _CustomClass3:
+    class _UnusedTypeDict4(TypedDict):
+        pass
+
+    def method(self) -> None:
+        _CustomClass3._UnusedTypeDict4()

crates/ruff_linter/src/checkers/ast/analyze/deferred_scopes.rs

@@ -281,6 +281,9 @@ pub(crate) fn deferred_scopes(checker: &mut Checker) {
             }
         }
 
+        if checker.source_type.is_stub()
+            || matches!(scope.kind, ScopeKind::Module | ScopeKind::Function(_))
+        {
             if checker.enabled(Rule::UnusedPrivateTypeVar) {
                 flake8_pyi::rules::unused_private_type_var(checker, scope, &mut diagnostics);
             }
@@ -293,6 +296,7 @@ pub(crate) fn deferred_scopes(checker: &mut Checker) {
             if checker.enabled(Rule::UnusedPrivateTypedDict) {
                 flake8_pyi::rules::unused_private_typed_dict(checker, scope, &mut diagnostics);
             }
+        }
 
         if checker.enabled(Rule::AsyncioDanglingTask) {
             ruff::rules::asyncio_dangling_binding(scope, &checker.semantic, &mut diagnostics);

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI049_PYI049.py.snap

@@ -15,13 +15,11 @@ PYI049.py:9:7: PYI049 Private TypedDict `_UnusedTypedDict2` is never used
 10 |     bar: int
    |
 
-PYI049.py:20:1: PYI049 Private TypedDict `_UnusedTypedDict3` is never used
+PYI049.py:21:1: PYI049 Private TypedDict `_UnusedTypedDict3` is never used
    |
-18 |     bar: list[int]
+21 | _UnusedTypedDict3 = TypedDict("_UnusedTypedDict3", {"foo": int})
-19 | 
-20 | _UnusedTypedDict3 = TypedDict("_UnusedTypedDict3", {"foo": int})
    | ^^^^^^^^^^^^^^^^^ PYI049
-21 | _UsedTypedDict3 = TypedDict("_UsedTypedDict3", {"bar": bytes})
+22 | _UsedTypedDict3 = TypedDict("_UsedTypedDict3", {"bar": bytes})
    |
 
 

crates/ruff_linter/src/rules/flake8_pyi/snapshots/ruff_linter__rules__flake8_pyi__tests__PYI049_PYI049.pyi.snap

@@ -24,4 +24,13 @@ PYI049.pyi:34:1: PYI049 Private TypedDict `_UnusedTypedDict3` is never used
 35 | _UsedTypedDict3 = TypedDict("_UsedTypedDict3", {"bar": bytes})
    |
 
+PYI049.pyi:43:11: PYI049 Private TypedDict `_UnusedTypeDict4` is never used
+   |
+41 | # scope (unlike in `.py` files).
+42 | class _CustomClass3:
+43 |     class _UnusedTypeDict4(TypedDict):
+   |           ^^^^^^^^^^^^^^^^ PYI049
+44 |         pass
+   |
+