Add is_lvalue attribute to plugin AttributeContext

Author: brianschubert

mypy/checkmember.py

@@ -572,7 +572,11 @@ def analyze_member_var_access(
                     if hook:
                         result = hook(
                             AttributeContext(
-                                get_proper_type(mx.original_type), result, mx.context, mx.chk
+                                get_proper_type(mx.original_type),
+                                result,
+                                mx.is_lvalue,
+                                mx.context,
+                                mx.chk,
                             )
                         )
                     return result
@@ -829,7 +833,9 @@ def analyze_var(
         result = analyze_descriptor_access(result, mx)
     if hook:
         result = hook(
-            AttributeContext(get_proper_type(mx.original_type), result, mx.context, mx.chk)
+            AttributeContext(
+                get_proper_type(mx.original_type), result, mx.is_lvalue, mx.context, mx.chk
+            )
         )
     return result
 
@@ -1148,7 +1154,9 @@ def apply_class_attr_hook(
 ) -> Type | None:
     if hook:
         result = hook(
-            AttributeContext(get_proper_type(mx.original_type), result, mx.context, mx.chk)
+            AttributeContext(
+                get_proper_type(mx.original_type), result, mx.is_lvalue, mx.context, mx.chk
+            )
         )
     return result
 

mypy/plugin.py

@@ -495,6 +495,7 @@ class MethodContext(NamedTuple):
 class AttributeContext(NamedTuple):
     type: ProperType  # Type of object with attribute
     default_attr_type: Type  # Original attribute type
+    is_lvalue: bool  # Whether the attribute is the target for an assignment
     context: Context  # Relevant location context (e.g. for error messages)
     api: CheckerPluginInterface