MDEV-11129 CREATE OR REPLACE TABLE t1 AS SELECT spfunc() crashes if spfunc() references t1

Fixed by extending unique_table() with a flag to not allow usage of
the replaced table.

I also cleaned up find_dup_table() to not use goto next.
I also added more comments to the code in find_dup_table()

1 files changed, 20 insertions, 0 deletions

diff --git a/mysql-test/r/create_or_replace.result b/mysql-test/r/create_or_replace.result
index a43dc2eaca4..0d171f9f87a 100644
--- a/mysql-test/r/create_or_replace.result
+++ b/mysql-test/r/create_or_replace.result
@@ -453,3 +453,23 @@ CREATE OR REPLACE TABLE t1 AS SELECT f1();
 UNLOCK TABLES;
 DROP FUNCTION f1;
 DROP TABLE t1;
+#
+# MDEV-11129
+# CREATE OR REPLACE TABLE t1 AS SELECT spfunc() crashes if spfunc()
+# references t1
+#
+CREATE OR REPLACE TABLE t1(a INT);
+CREATE FUNCTION f1() RETURNS VARCHAR(16383)
+BEGIN
+INSERT INTO t1 VALUES(1);
+RETURN 'test';
+END;
+$$
+CREATE OR REPLACE TABLE t1 AS SELECT f1();
+ERROR HY000: Table 't1' is specified twice, both as a target for 'CREATE' and as a separate source for data
+LOCK TABLE t1 WRITE;
+CREATE OR REPLACE TABLE t1 AS SELECT f1();
+ERROR HY000: Table 't1' was not locked with LOCK TABLES
+UNLOCK TABLES;
+DROP FUNCTION f1;
+DROP TABLE t1;