Apply percent sign escaping to op(), custom_op()

Fixed bug where the "percent escaping" feature that occurs with dialects
that use the "format" or "pyformat" bound parameter styles was not enabled
for the :meth:`.Operations.op` and :meth:`.Operations.custom_op` methods,
for custom operators that use percent signs. The percent sign will now be
automatically doubled based on the paramstyle as necessary.

Fixes: #6016
Change-Id: I285c5fc082481c2ee989edf1b02a83a6087ea26a

1 files changed, 5 insertions, 3 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 8f046a802..0ea251fb4 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -2055,17 +2055,19 @@ class SQLCompiler(Compiled):
     def visit_custom_op_binary(self, element, operator, **kw):
         kw["eager_grouping"] = operator.eager_grouping
         return self._generate_generic_binary(
-            element, " " + operator.opstring + " ", **kw
+            element,
+            " " + self.escape_literal_column(operator.opstring) + " ",
+            **kw
         )
 
     def visit_custom_op_unary_operator(self, element, operator, **kw):
         return self._generate_generic_unary_operator(
-            element, operator.opstring + " ", **kw
+            element, self.escape_literal_column(operator.opstring) + " ", **kw
         )
 
     def visit_custom_op_unary_modifier(self, element, operator, **kw):
         return self._generate_generic_unary_modifier(
-            element, " " + operator.opstring, **kw
+            element, " " + self.escape_literal_column(operator.opstring), **kw
         )
 
     def _generate_generic_binary(