0002-require_unused_neg_com-v1.patch

diff --git a/src/backend/catalog/pg_operator.c b/src/backend/catalog/pg_operator.c
index b0570c33b6..15128235d4 100644
--- a/src/backend/catalog/pg_operator.c
+++ b/src/backend/catalog/pg_operator.c
@@ -557,11 +557,6 @@ OperatorCreate(const char *operatorName,
 	/* Add dependencies for the entry */
 	address = makeOperatorDependencies(tup, true, isUpdate);
 
-	/* Post creation hook for new operator */
-	InvokeObjectPostCreateHook(OperatorRelationId, operatorObjectId, 0);
-
-	table_close(pg_operator_desc, RowExclusiveLock);
-
 	/*
 	 * If a commutator and/or negator link is provided, update the other
 	 * operator(s) to point at this one, if they don't already have a link.
@@ -579,6 +574,11 @@ OperatorCreate(const char *operatorName,
 	if (OidIsValid(commutatorId) || OidIsValid(negatorId))
 		OperatorUpd(operatorObjectId, commutatorId, negatorId, false);
 
+	/* Post creation hook for new operator */
+	InvokeObjectPostCreateHook(OperatorRelationId, operatorObjectId, 0);
+
+	table_close(pg_operator_desc, RowExclusiveLock);
+
 	return address;
 }
 
@@ -692,8 +692,28 @@ OperatorUpd(Oid baseId, Oid commId, Oid negId, bool isDelete)
 			t->oprcom = InvalidOid;
 			update_commutator = true;
 		}
-		else if (!isDelete && !OidIsValid(t->oprcom))
+		else if (!isDelete && baseId != t->oprcom)
 		{
+			/*
+			 * When filling in a shell operator the commutator's oprcom field
+			 * will already be set to the baseId so we don't need to make an
+			 * update in that case.
+			 */
+
+			if (OidIsValid(t->oprcom))
+			{
+				/*
+				 * When commutator's oprcom is already filled in that means
+				 * that it's part of a pair of commutators and by definition
+				 * the existing oprcom must be equivalent to the baseId
+				 * operator. It doesn't make sense to allow the baseId alter
+				 * or create to succeed in this case so raise an error.
+				 */
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("commutator commutates another operator")));
+			}
+
 			t->oprcom = baseId;
 			update_commutator = true;
 		}
@@ -737,8 +757,28 @@ OperatorUpd(Oid baseId, Oid commId, Oid negId, bool isDelete)
 			t->oprnegate = InvalidOid;
 			update_negator = true;
 		}
-		else if (!isDelete && !OidIsValid(t->oprnegate))
+		else if (!isDelete && baseId != t->oprnegate)
 		{
+			/*
+			 * When filling in a shell operator the negator's oprnegate field
+			 * will already be set to the baseId so we don't need to make an
+			 * update in that case.
+			 */
+
+			if (OidIsValid(t->oprnegate))
+			{
+				/*
+				 * When negator's oprnegate is already filled in that means
+				 * that it's part of a pair of negators and by definition the
+				 * existing oprnegate must be equivalent to the baseId
+				 * operator. It doesn't make sense to allow the baseId alter
+				 * or create to succeed in this case so raise an error.
+				 */
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
+						 errmsg("negator negates another operator")));
+			}
+
 			t->oprnegate = baseId;
 			update_negator = true;
 		}
diff --git a/src/test/regress/expected/create_operator.out b/src/test/regress/expected/create_operator.out
index 49070ce90f..600699f407 100644
--- a/src/test/regress/expected/create_operator.out
+++ b/src/test/regress/expected/create_operator.out
@@ -296,6 +296,52 @@ CREATE OPERATOR ===!!! (
 );
 ERROR:  operator cannot be its own negator
 ROLLBACK;
+-- test that we can't use part of an existing commutator or negator pair as a
+-- commutator or negator
+CREATE FUNCTION create_op_test_fn(boolean, boolean)
+RETURNS boolean AS $$
+    SELECT NULL::BOOLEAN;
+$$ LANGUAGE sql IMMUTABLE;
+CREATE OPERATOR === (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    commutator = ===@@@,
+    negator = ===!!!
+);
+CREATE OPERATOR ===!!! (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    negator = ===
+);
+CREATE OPERATOR ===@@@ (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    commutator = ===
+);
+-- test trying to use === as a commutator fails
+CREATE OPERATOR ===@ (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    commutator = ===
+);
+ERROR:  commutator commutates another operator
+-- test trying to use === as a negator fails
+CREATE OPERATOR ===@ (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    negator = ===
+);
+ERROR:  negator negates another operator
+-- cleanup
+DROP OPERATOR ===@@@(bool, bool);
+DROP OPERATOR ===!!!(bool, bool);
+DROP OPERATOR ===(bool, bool);
+DROP FUNCTION create_op_test_fn;
 -- invalid: non-lowercase quoted identifiers
 CREATE OPERATOR ===
 (
diff --git a/src/test/regress/sql/create_operator.sql b/src/test/regress/sql/create_operator.sql
index 168cad3814..03e2157a57 100644
--- a/src/test/regress/sql/create_operator.sql
+++ b/src/test/regress/sql/create_operator.sql
@@ -246,6 +246,51 @@ CREATE OPERATOR ===!!! (
 );
 ROLLBACK;
 
+-- test that we can't use part of an existing commutator or negator pair as a
+-- commutator or negator
+CREATE FUNCTION create_op_test_fn(boolean, boolean)
+RETURNS boolean AS $$
+    SELECT NULL::BOOLEAN;
+$$ LANGUAGE sql IMMUTABLE;
+CREATE OPERATOR === (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    commutator = ===@@@,
+    negator = ===!!!
+);
+CREATE OPERATOR ===!!! (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    negator = ===
+);
+CREATE OPERATOR ===@@@ (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    commutator = ===
+);
+-- test trying to use === as a commutator fails
+CREATE OPERATOR ===@ (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    commutator = ===
+);
+-- test trying to use === as a negator fails
+CREATE OPERATOR ===@ (
+    leftarg = boolean,
+    rightarg = boolean,
+    procedure = create_op_test_fn,
+    negator = ===
+);
+-- cleanup
+DROP OPERATOR ===@@@(bool, bool);
+DROP OPERATOR ===!!!(bool, bool);
+DROP OPERATOR ===(bool, bool);
+DROP FUNCTION create_op_test_fn;
+
 -- invalid: non-lowercase quoted identifiers
 CREATE OPERATOR ===
 (