Fixed BUG#16387.

  Applied innodb-4.1-ss17 snapshot.
  Do not mistake TABLENAME_ibfk_0 for auto-generated id.

innobase/dict/dict0dict.c

@@ -2755,7 +2755,8 @@ dict_table_get_highest_foreign_id(
 		if (ut_strlen(foreign->id) > ((sizeof dict_ibfk) - 1) + len
 		    && 0 == ut_memcmp(foreign->id, table->name, len)
 		    && 0 == ut_memcmp(foreign->id + len,
-				dict_ibfk, (sizeof dict_ibfk) - 1)) {
+				dict_ibfk, (sizeof dict_ibfk) - 1)
+		    && foreign->id[len + ((sizeof dict_ibfk) - 1)] != '0') {
 			/* It is of the >= 4.0.18 format */
 
 			id = strtoul(foreign->id + len + ((sizeof dict_ibfk) - 1),

mysql-test/r/innodb.result

@@ -1794,3 +1794,16 @@ a	hex(b)
 7	D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B2
 update t1 set b = 'three' where a = 6;
 drop table t1;
+CREATE TABLE t1(a INT, PRIMARY KEY(a)) ENGINE=InnoDB;
+CREATE TABLE t2(a INT) ENGINE=InnoDB;
+ALTER TABLE t2 ADD FOREIGN KEY (a) REFERENCES t1(a);
+ALTER TABLE t2 DROP FOREIGN KEY t2_ibfk_1;
+ALTER TABLE t2 ADD CONSTRAINT t2_ibfk_0 FOREIGN KEY (a) REFERENCES t1(a);
+ALTER TABLE t2 DROP FOREIGN KEY t2_ibfk_0;
+SHOW CREATE TABLE t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `a` int(11) default NULL,
+  KEY `t2_ibfk_0` (`a`)
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t2,t1;

mysql-test/t/innodb.test

@@ -1365,4 +1365,17 @@ insert into t1 values(7,_utf8 0xD0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1D0B1
 select a,hex(b) from t1 order by b;
 update t1 set b = 'three' where a = 6;
 drop table t1;
+
+# Ensure that <tablename>_ibfk_0 is not mistreated as a
+# generated foreign key identifier.  (Bug #16387)
+
+CREATE TABLE t1(a INT, PRIMARY KEY(a)) ENGINE=InnoDB;
+CREATE TABLE t2(a INT) ENGINE=InnoDB;
+ALTER TABLE t2 ADD FOREIGN KEY (a) REFERENCES t1(a);
+ALTER TABLE t2 DROP FOREIGN KEY t2_ibfk_1;
+ALTER TABLE t2 ADD CONSTRAINT t2_ibfk_0 FOREIGN KEY (a) REFERENCES t1(a);
+ALTER TABLE t2 DROP FOREIGN KEY t2_ibfk_0;
+SHOW CREATE TABLE t2;
+DROP TABLE t2,t1;
+
 # End of 4.1 tests