use fully qualified, locatable names for all use of api.named_type()

Fixed mypy regression where the release of mypy 0.930 added additional
internal checks to the format of "named types", requiring that they be
fully qualified and locatable. This broke the mypy plugin for SQLAlchemy,
raising an assertion error, as there was use of symbols such as
``__builtins__`` and other un-locatable or unqualified names that
previously had not raised any assertions.

Fixes: #7496
Change-Id: I037680606a1d51158ef6503508ec76c5d5adc946

doc/build/changelog/unreleased_14/7496.rst

@@ -0,0 +1,11 @@
+.. change::
+    :tags: bug, mypy
+    :tickets: 7496
+
+    Fixed mypy regression where the release of mypy 0.930 added additional
+    internal checks to the format of "named types", requiring that they be
+    fully qualified and locatable. This broke the mypy plugin for SQLAlchemy,
+    raising an assertion error, as there was use of symbols such as
+    ``__builtins__`` and other un-locatable or unqualified names that
+    previously had not raised any assertions.
+

lib/sqlalchemy/ext/mypy/apply.py

@@ -36,6 +36,7 @@
 
 from . import infer
 from . import util
+from .names import NAMED_TYPE_SQLA_MAPPED
 
 
 def apply_mypy_mapped_attr(
@@ -134,7 +135,7 @@ def re_apply_declarative_assignments(
                     and isinstance(stmt.rvalue.callee.expr, NameExpr)
                     and stmt.rvalue.callee.expr.node is not None
                     and stmt.rvalue.callee.expr.node.fullname
-                    == "sqlalchemy.orm.attributes.Mapped"
+                    == NAMED_TYPE_SQLA_MAPPED
                     and stmt.rvalue.callee.name == "_empty_constructor"
                     and isinstance(stmt.rvalue.args[0], CallExpr)
                     and isinstance(stmt.rvalue.args[0].callee, RefExpr)
@@ -165,7 +166,7 @@ def re_apply_declarative_assignments(
 
             if python_type_for_type is not None:
                 left_node.type = api.named_type(
-                    "__sa_Mapped", [python_type_for_type]
+                    NAMED_TYPE_SQLA_MAPPED, [python_type_for_type]
                 )
 
     if update_cls_metadata:
@@ -202,12 +203,12 @@ class User(Base):
 
     if left_hand_explicit_type is not None:
         left_node.type = api.named_type(
-            "__sa_Mapped", [left_hand_explicit_type]
+            NAMED_TYPE_SQLA_MAPPED, [left_hand_explicit_type]
         )
     else:
         lvalue.is_inferred_def = False
         left_node.type = api.named_type(
-            "__sa_Mapped",
+            NAMED_TYPE_SQLA_MAPPED,
             [] if python_type_for_type is None else [python_type_for_type],
         )
 

lib/sqlalchemy/ext/mypy/decl_class.py

@@ -327,7 +327,7 @@ class MyClass:
         )
 
     left_node.node.type = api.named_type(
-        "__sa_Mapped", [left_hand_explicit_type]
+        names.NAMED_TYPE_SQLA_MAPPED, [left_hand_explicit_type]
     )
 
     # this will ignore the rvalue entirely

lib/sqlalchemy/ext/mypy/infer.py

@@ -147,7 +147,7 @@ class MyClass:
         type_is_a_collection = True
         if python_type_for_type is not None:
             python_type_for_type = api.named_type(
-                "__builtins__.list", [python_type_for_type]
+                names.NAMED_TYPE_BUILTINS_LIST, [python_type_for_type]
             )
     elif (
         uselist_arg is None or api.parse_bool(uselist_arg) is True
@@ -438,7 +438,7 @@ def _infer_type_from_left_and_inferred_right(
 
     if not is_subtype(left_hand_explicit_type, python_type_for_type):
         effective_type = api.named_type(
-            "__sa_Mapped", [orig_python_type_for_type]
+            names.NAMED_TYPE_SQLA_MAPPED, [orig_python_type_for_type]
         )
 
         msg = (
@@ -507,7 +507,9 @@ def infer_type_from_left_hand_type_only(
         )
         util.fail(api, msg.format(node.name), node)
 
-        return api.named_type("__sa_Mapped", [AnyType(TypeOfAny.special_form)])
+        return api.named_type(
+            names.NAMED_TYPE_SQLA_MAPPED, [AnyType(TypeOfAny.special_form)]
+        )
 
     else:
         # use type from the left hand side
@@ -529,7 +531,7 @@ def extract_python_type_from_typeengine(
                     return Instance(first_arg.node, [])
             # TODO: support other pep-435 types here
         else:
-            return api.named_type("__builtins__.str", [])
+            return api.named_type(names.NAMED_TYPE_BUILTINS_STR, [])
 
     assert node.has_base("sqlalchemy.sql.type_api.TypeEngine"), (
         "could not extract Python type from node: %s" % node

lib/sqlalchemy/ext/mypy/names.py

@@ -47,6 +47,12 @@
 DECLARATIVE_MIXIN: int = util.symbol("DECLARATIVE_MIXIN")  # type: ignore
 QUERY_EXPRESSION: int = util.symbol("QUERY_EXPRESSION")  # type: ignore
 
+# names that must succeed with mypy.api.named_type
+NAMED_TYPE_BUILTINS_OBJECT = "builtins.object"
+NAMED_TYPE_BUILTINS_STR = "builtins.str"
+NAMED_TYPE_BUILTINS_LIST = "builtins.list"
+NAMED_TYPE_SQLA_MAPPED = "sqlalchemy.orm.attributes.Mapped"
+
 _lookup: Dict[str, Tuple[int, Set[str]]] = {
     "Column": (
         COLUMN,

lib/sqlalchemy/ext/mypy/plugin.py

@@ -142,7 +142,7 @@ def _dynamic_class_hook(ctx: DynamicClassDefContext) -> None:
         )
         info.bases = [Instance(cls_arg.node, [])]
     else:
-        obj = ctx.api.named_type("__builtins__.object")
+        obj = ctx.api.named_type(names.NAMED_TYPE_BUILTINS_OBJECT)
 
         info.bases = [obj]
 
@@ -152,7 +152,7 @@ def _dynamic_class_hook(ctx: DynamicClassDefContext) -> None:
         util.fail(
             ctx.api, "Not able to calculate MRO for declarative base", ctx.call
         )
-        obj = ctx.api.named_type("__builtins__.object")
+        obj = ctx.api.named_type(names.NAMED_TYPE_BUILTINS_OBJECT)
         info.bases = [obj]
         info.fallback_to_any = True