Merge "Enable F821"

4 files changed, 25 insertions, 10 deletions

diff --git a/lib/sqlalchemy/sql/base.py b/lib/sqlalchemy/sql/base.py
index 60456223f..a7324c45f 100644
--- a/lib/sqlalchemy/sql/base.py
+++ b/lib/sqlalchemy/sql/base.py
@@ -19,9 +19,12 @@ from .visitors import ClauseVisitor
 from .. import exc
 from .. import util
 
-coercions = None  # type: types.ModuleType
-elements = None  # type: types.ModuleType
-type_api = None  # type: types.ModuleType
+if util.TYPE_CHECKING:
+    from types import ModuleType
+
+coercions = None  # type: ModuleType
+elements = None  # type: ModuleType
+type_api = None  # type: ModuleType
 
 PARSE_AUTOCOMMIT = util.symbol("PARSE_AUTOCOMMIT")
 NO_ARG = util.symbol("NO_ARG")
diff --git a/lib/sqlalchemy/sql/coercions.py b/lib/sqlalchemy/sql/coercions.py
index 12ec7c750..b3bf4e93b 100644
--- a/lib/sqlalchemy/sql/coercions.py
+++ b/lib/sqlalchemy/sql/coercions.py
@@ -17,10 +17,13 @@ from .. import inspection
 from .. import util
 from ..util import collections_abc
 
-elements = None  # type: types.ModuleType
-schema = None  # type: types.ModuleType
-selectable = None  # type: types.ModuleType
-sqltypes = None  # type: types.ModuleType
+if util.TYPE_CHECKING:
+    from types import ModuleType
+
+elements = None  # type: ModuleType
+schema = None  # type: ModuleType
+selectable = None  # type: ModuleType
+sqltypes = None  # type: ModuleType
 
 
 def _is_literal(element):
diff --git a/lib/sqlalchemy/sql/elements.py b/lib/sqlalchemy/sql/elements.py
index d94d91b16..422eb6220 100644
--- a/lib/sqlalchemy/sql/elements.py
+++ b/lib/sqlalchemy/sql/elements.py
@@ -43,6 +43,11 @@ from .. import exc
 from .. import inspection
 from .. import util
 
+if util.TYPE_CHECKING:
+    from typing import Any
+    from typing import Optional
+    from typing import Union
+
 
 def collate(expression, collation):
     """Return the clause ``expression COLLATE collation``.
@@ -709,7 +714,7 @@ class ColumnElement(
     _alt_names = ()
 
     def self_group(self, against=None):
-        # type: (Module, Module, Optional[Any]) -> ClauseEleent
+        # type: (Optional[Any]) -> ClauseElement
         if (
             against in (operators.and_, operators.or_, operators._asbool)
             and self.type._type_affinity is type_api.BOOLEANTYPE._type_affinity
diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index 8f5503db0..136c9f868 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -50,6 +50,10 @@ from .visitors import InternalTraversal
 from .. import exc
 from .. import util
 
+if util.TYPE_CHECKING:
+    from typing import Any
+    from typing import Optional
+
 
 class _OffsetLimitParam(BindParameter):
     @property
@@ -2096,7 +2100,7 @@ class SelectBase(
     _memoized_property = util.group_expirable_memoized_property()
 
     def _generate_fromclause_column_proxies(self, fromclause):
-        # type: (FromClause)
+        # type: (FromClause) -> None
         raise NotImplementedError()
 
     def _refresh_for_new_column(self, column):
@@ -2344,7 +2348,7 @@ class SelectStatementGrouping(GroupedElement, SelectBase):
     _is_select_container = True
 
     def __init__(self, element):
-        # type: (SelectBase)
+        # type: (SelectBase) -> None
         self.element = coercions.expect(roles.SelectStatementRole, element)
 
     @property