MDEV-25295 Aborted FTS_DOC_ID_INDEX considered as existing FTS_DOC_ID_INDEX during DDL

InnoDB should skip the dropped aborted FTS_DOC_ID_INDEX while
checking the existing FTS_DOC_ID_INDEX in the table. InnoDB
should able to create new FTS_DOC_ID_INDEX if the fulltext
index is being added for the first time.

mysql-test/suite/innodb_fts/r/fulltext.result

@@ -691,3 +691,16 @@ FTS_DOC_ID	t
 2	foo bar
 3	foo
 DROP TABLE t;
+#
+# MDEV-25295 Aborted FTS_DOC_ID_INDEX considered as
+# 	existing FTS_DOC_ID_INDEX during DDL
+#
+SET sql_mode='';
+CREATE TABLE t1 (FTS_DOC_ID BIGINT UNSIGNED NOT NULL,title CHAR(1),body TEXT)engine=innodb;
+INSERT INTO t1 (FTS_DOC_ID,title,body)VALUES(1,0,0), (1,0,0);
+CREATE FULLTEXT INDEX idx1 ON t1 (title,body);
+ERROR 23000: Duplicate entry '' for key '*UNKNOWN*'
+CREATE FULLTEXT INDEX idx1 ON t1 (title,body);
+ERROR 23000: Duplicate entry '' for key '*UNKNOWN*'
+DROP TABLE t1;
+SET sql_mode = DEFAULT;

mysql-test/suite/innodb_fts/t/fulltext.test

@@ -717,3 +717,17 @@ while ($N)
 }
 
 DROP TABLE t;
+
+--echo #
+--echo # MDEV-25295 Aborted FTS_DOC_ID_INDEX considered as
+--echo # 	existing FTS_DOC_ID_INDEX during DDL
+--echo #
+SET sql_mode='';
+CREATE TABLE t1 (FTS_DOC_ID BIGINT UNSIGNED NOT NULL,title CHAR(1),body TEXT)engine=innodb;
+INSERT INTO t1 (FTS_DOC_ID,title,body)VALUES(1,0,0), (1,0,0);
+--error ER_DUP_ENTRY
+CREATE FULLTEXT INDEX idx1 ON t1 (title,body);
+--error ER_DUP_ENTRY
+CREATE FULLTEXT INDEX idx1 ON t1 (title,body);
+DROP TABLE t1;
+SET sql_mode = DEFAULT;

storage/innobase/handler/handler0alter.cc

@@ -2404,9 +2404,11 @@ innobase_fts_check_doc_id_index(
 	for (index = dict_table_get_first_index(table);
 	     index; index = dict_table_get_next_index(index)) {
 
+
 		/* Check if there exists a unique index with the name of
-		FTS_DOC_ID_INDEX_NAME */
-		if (innobase_strcasecmp(index->name, FTS_DOC_ID_INDEX_NAME)) {
+		FTS_DOC_ID_INDEX_NAME and ignore the corrupted index */
+		if (index->type & DICT_CORRUPT
+		    || innobase_strcasecmp(index->name, FTS_DOC_ID_INDEX_NAME)) {
 			continue;
 		}