TypeDecorator passes "outer" flag to itself for set_parent accounting

Fixed bug first introduced in as some combination of :ticket:`2892`,
:ticket:`2919` nnd :ticket:`3832` where the attachment events for a
:class:`_types.TypeDecorator` would be doubled up against the "impl" class,
if the "impl" were also a :class:`_types.SchemaType`. The real-world case
is any :class:`_types.TypeDecorator` against :class:`_types.Enum` or
:class:`_types.Boolean` would get a doubled
:class:`_schema.CheckConstraint` when the ``create_constraint=True`` flag
is set.

Fixes: #6152
Change-Id: I3218b7081297270c132421f6765b5c3673d10a5c

2 files changed, 12 insertions, 10 deletions

diff --git a/lib/sqlalchemy/sql/sqltypes.py b/lib/sqlalchemy/sql/sqltypes.py
index a73c61147..367b2e203 100644
--- a/lib/sqlalchemy/sql/sqltypes.py
+++ b/lib/sqlalchemy/sql/sqltypes.py
@@ -1092,7 +1092,7 @@ class SchemaType(SchemaEventTarget):
                 util.portable_instancemethod(self._on_metadata_drop),
             )
 
-    def _set_parent(self, column):
+    def _set_parent(self, column, **kw):
         column._on_table_attach(util.portable_instancemethod(self._set_table))
 
     def _variant_mapping_for_set_table(self, column):
@@ -2857,11 +2857,11 @@ class ARRAY(SchemaEventTarget, Indexable, Concatenable, TypeEngine):
     def compare_values(self, x, y):
         return x == y
 
-    def _set_parent(self, column):
+    def _set_parent(self, column, **kw):
         """Support SchemaEventTarget"""
 
         if isinstance(self.item_type, SchemaEventTarget):
-            self.item_type._set_parent(column)
+            self.item_type._set_parent(column, **kw)
 
     def _set_parent_with_dispatch(self, parent):
         """Support SchemaEventTarget"""
diff --git a/lib/sqlalchemy/sql/type_api.py b/lib/sqlalchemy/sql/type_api.py
index 9752750c5..bfce00cb5 100644
--- a/lib/sqlalchemy/sql/type_api.py
+++ b/lib/sqlalchemy/sql/type_api.py
@@ -1063,18 +1063,20 @@ class TypeDecorator(SchemaEventTarget, TypeEngine):
         """
         return self.impl._type_affinity
 
-    def _set_parent(self, column):
+    def _set_parent(self, column, outer=False, **kw):
         """Support SchemaEventTarget"""
 
         super(TypeDecorator, self)._set_parent(column)
 
-        if isinstance(self.impl, SchemaEventTarget):
-            self.impl._set_parent(column)
+        if not outer and isinstance(self.impl, SchemaEventTarget):
+            self.impl._set_parent(column, outer=False, **kw)
 
     def _set_parent_with_dispatch(self, parent):
         """Support SchemaEventTarget"""
 
-        super(TypeDecorator, self)._set_parent_with_dispatch(parent)
+        super(TypeDecorator, self)._set_parent_with_dispatch(
+            parent, outer=True
+        )
 
         if isinstance(self.impl, SchemaEventTarget):
             self.impl._set_parent_with_dispatch(parent)
@@ -1495,14 +1497,14 @@ class Variant(TypeDecorator):
         else:
             return self.impl
 
-    def _set_parent(self, column):
+    def _set_parent(self, column, **kw):
         """Support SchemaEventTarget"""
 
         if isinstance(self.impl, SchemaEventTarget):
-            self.impl._set_parent(column)
+            self.impl._set_parent(column, **kw)
         for impl in self.mapping.values():
             if isinstance(impl, SchemaEventTarget):
-                impl._set_parent(column)
+                impl._set_parent(column, **kw)
 
     def _set_parent_with_dispatch(self, parent):
         """Support SchemaEventTarget"""