Don't permit transition tables with TRUNCATE triggers.

Prior to this prohibition, such a trigger caused a crash.

Thomas Munro, per a report from Neha Sharma.  I added a
regression test.

Discussion: http://postgr.es/m/CAEepm=0VR5W-N38eTkO_FqJbGqQ_ykbBRmzmvHyxDhy1p=0Csw@mail.gmail.com

src/backend/commands/trigger.c

@@ -366,6 +366,11 @@ CreateTrigger(CreateTrigStmt *stmt, const char *queryString,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 						 errmsg("transition table name can only be specified for an AFTER trigger")));
 
+			if (TRIGGER_FOR_TRUNCATE(tgtype))
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("TRUNCATE triggers with transition tables are not supported")));
+
 			if (tt->isNew)
 			{
 				if (!(TRIGGER_FOR_INSERT(tgtype) ||

src/test/regress/expected/plpgsql.out

@@ -5943,6 +5943,14 @@ BEGIN
   RETURN NULL;
 END;
 $$;
+-- should fail, TRUNCATE is not compatible with transition tables
+CREATE TRIGGER alter_table_under_transition_tables_upd_trigger
+  AFTER TRUNCATE OR UPDATE ON alter_table_under_transition_tables
+  REFERENCING OLD TABLE AS d NEW TABLE AS i
+  FOR EACH STATEMENT EXECUTE PROCEDURE
+    alter_table_under_transition_tables_upd_func();
+ERROR:  TRUNCATE triggers with transition tables are not supported
+-- should work
 CREATE TRIGGER alter_table_under_transition_tables_upd_trigger
   AFTER UPDATE ON alter_table_under_transition_tables
   REFERENCING OLD TABLE AS d NEW TABLE AS i

src/test/regress/sql/plpgsql.sql

@@ -4736,6 +4736,14 @@ BEGIN
 END;
 $$;
 
+-- should fail, TRUNCATE is not compatible with transition tables
+CREATE TRIGGER alter_table_under_transition_tables_upd_trigger
+  AFTER TRUNCATE OR UPDATE ON alter_table_under_transition_tables
+  REFERENCING OLD TABLE AS d NEW TABLE AS i
+  FOR EACH STATEMENT EXECUTE PROCEDURE
+    alter_table_under_transition_tables_upd_func();
+
+-- should work
 CREATE TRIGGER alter_table_under_transition_tables_upd_trigger
   AFTER UPDATE ON alter_table_under_transition_tables
   REFERENCING OLD TABLE AS d NEW TABLE AS i