- as the Concatenable mixin was changed to support calling down to

"super" instead of hardcoding to "self.type" for the default return
value, the base Comparator was returning other_comparator.type.   It's
not clear what the rationale for this was, though in theory the
base Comparator should possibly even throw an exception if the two
types aren't the same (or of the same affinity?) .
- mysql.SET was broken on this because the bitwise version adds "0"
to the value to force an integer within column_expression, we are doing type_coerces here
now in any case so that there is no type ambiguity for this
operation

3 files changed, 60 insertions, 3 deletions

diff --git a/lib/sqlalchemy/dialects/mysql/base.py b/lib/sqlalchemy/dialects/mysql/base.py
index fee05fd2d..4b3e5bcd1 100644
--- a/lib/sqlalchemy/dialects/mysql/base.py
+++ b/lib/sqlalchemy/dialects/mysql/base.py
@@ -1584,7 +1584,10 @@ class SET(_EnumeratedValues):
 
     def column_expression(self, colexpr):
         if self.retrieve_as_bitwise:
-            return colexpr + 0
+            return sql.type_coerce(
+                sql.type_coerce(colexpr, sqltypes.Integer) + 0,
+                self
+            )
         else:
             return colexpr
 
diff --git a/lib/sqlalchemy/sql/type_api.py b/lib/sqlalchemy/sql/type_api.py
index 701e2a44a..c4e830b7f 100644
--- a/lib/sqlalchemy/sql/type_api.py
+++ b/lib/sqlalchemy/sql/type_api.py
@@ -91,7 +91,7 @@ class TypeEngine(Visitable):
             boolean comparison or special SQL keywords like MATCH or BETWEEN.
 
             """
-            return op, other_comparator.type
+            return op, self.type
 
         def __reduce__(self):
             return _reconstitute_comparator, (self.expr, )
diff --git a/test/sql/test_operators.py b/test/sql/test_operators.py
index fbbdd7b62..f3dfd2daf 100644
--- a/test/sql/test_operators.py
+++ b/test/sql/test_operators.py
@@ -14,7 +14,7 @@ from sqlalchemy.sql.elements import _literal_as_text
 from sqlalchemy.schema import Column, Table, MetaData
 from sqlalchemy.sql import compiler
 from sqlalchemy.types import TypeEngine, TypeDecorator, UserDefinedType, \
-    Boolean, NullType, MatchType, Indexable
+    Boolean, NullType, MatchType, Indexable, Concatenable
 from sqlalchemy.dialects import mysql, firebird, postgresql, oracle, \
     sqlite, mssql
 from sqlalchemy import util
@@ -210,6 +210,60 @@ class DefaultColumnComparatorTest(fixtures.TestBase):
     def test_concat(self):
         self._do_operate_test(operators.concat_op)
 
+    def test_default_adapt(self):
+        class TypeOne(TypeEngine):
+            pass
+
+        class TypeTwo(TypeEngine):
+            pass
+
+        expr = column('x', TypeOne()) - column('y', TypeTwo())
+        is_(
+            expr.type._type_affinity, TypeOne
+        )
+
+    def test_concatenable_adapt(self):
+        class TypeOne(Concatenable, TypeEngine):
+            pass
+
+        class TypeTwo(Concatenable, TypeEngine):
+            pass
+
+        class TypeThree(TypeEngine):
+            pass
+
+        expr = column('x', TypeOne()) - column('y', TypeTwo())
+        is_(
+            expr.type._type_affinity, TypeOne
+        )
+        is_(
+            expr.operator, operator.sub
+        )
+
+        expr = column('x', TypeOne()) + column('y', TypeTwo())
+        is_(
+            expr.type._type_affinity, TypeOne
+        )
+        is_(
+            expr.operator, operators.concat_op
+        )
+
+        expr = column('x', TypeOne()) - column('y', TypeThree())
+        is_(
+            expr.type._type_affinity, TypeOne
+        )
+        is_(
+            expr.operator, operator.sub
+        )
+
+        expr = column('x', TypeOne()) + column('y', TypeThree())
+        is_(
+            expr.type._type_affinity, TypeOne
+        )
+        is_(
+            expr.operator, operator.add
+        )
+
 
 class CustomUnaryOperatorTest(fixtures.TestBase, testing.AssertsCompiledSQL):
     __dialect__ = 'default'