Bug#28318 (CREATE FUNCTION (UDF) requires a schema) -- part II

The root cause of the issue was that the CREATE FUNCTION grammar,
for User Defined Functions, was using the sp_name rule.
The sp_name rule is intended for fully qualified stored procedure names,
like either ident.ident, or just ident but with a default database
implicitly selected.

A UDF does not have a fully qualified name, only a name (ident), and should
not use the sp_name grammar fragment during parsing.

The fix is to re-organize the CREATE FUNCTION grammar, to better separate:
- creating UDF (no definer, can have AGGREGATE, simple ident)
- creating Stored Functions (definer, no AGGREGATE, fully qualified name)

With the test case provided, another issue was exposed which is also fixed:
the DROP FUNCTION statement was using sp_name and also failing when no database
is implicitly selected, when droping UDF functions.
The fix is also to change the grammar so that DROP FUNCTION works with
both the ident.ident syntax (to drop a stored function), or just the ident
syntax (to drop either a UDF or a Stored Function, in the current database)

mysql-test/r/sp-error.result

@@ -1211,7 +1211,7 @@ ERROR 42S02: Unknown table 'c' in field list
 drop procedure bug15091;
 drop function if exists bug16896;
 create aggregate function bug16896() returns int return 1;
-ERROR 42000: AGGREGATE is not supported for stored functions
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '() returns int return 1' at line 1
 DROP PROCEDURE IF EXISTS bug14702;
 CREATE IF NOT EXISTS PROCEDURE bug14702()
 BEGIN
@@ -1457,7 +1457,7 @@ CREATE DATABASE mysqltest;
 USE mysqltest;
 DROP DATABASE mysqltest;
 SELECT inexistent(), 1 + ,;
-ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1
+ERROR 42000: FUNCTION inexistent does not exist
 SELECT inexistent();
 ERROR 42000: FUNCTION inexistent does not exist
 SELECT .inexistent();

mysql-test/r/udf.result

@@ -95,10 +95,10 @@ FR
 DROP TABLE bug19904;
 CREATE DEFINER=CURRENT_USER() FUNCTION should_not_parse
 RETURNS STRING SONAME "should_not_parse.so";
-ERROR HY000: Incorrect usage of SONAME and DEFINER
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'RETURNS STRING SONAME "should_not_parse.so"' at line 2
 CREATE DEFINER=someone@somewhere FUNCTION should_not_parse
 RETURNS STRING SONAME "should_not_parse.so";
-ERROR HY000: Incorrect usage of SONAME and DEFINER
+ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'RETURNS STRING SONAME "should_not_parse.so"' at line 2
 create table t1(f1 int);
 insert into t1 values(1),(2);
 explain select myfunc_int(f1) from t1 order by 1;

mysql-test/t/sp-error.test

@@ -1744,7 +1744,7 @@ drop procedure bug15091;
 drop function if exists bug16896;
 --enable_warnings
 
---error ER_SP_NO_AGGREGATE
+--error ER_PARSE_ERROR
 create aggregate function bug16896() returns int return 1;
 
 
@@ -2099,7 +2099,10 @@ DROP DATABASE IF EXISTS mysqltest;
 CREATE DATABASE mysqltest;
 USE mysqltest;
 DROP DATABASE mysqltest;
---error ER_PARSE_ERROR
+# Both ER_SP_DOES_NOT_EXIST and ER_PARSE_ERROR are valid here,
+# the result is implementation dependent:
+# See Bug#29816 for details
+--error ER_SP_DOES_NOT_EXIST
 SELECT inexistent(), 1 + ,;
 --error ER_SP_DOES_NOT_EXIST
 SELECT inexistent();

mysql-test/t/udf.test

@@ -113,11 +113,11 @@ DROP TABLE bug19904;
 # Bug#21269: DEFINER-clause is allowed for UDF-functions
 #
 
---error ER_WRONG_USAGE
+--error ER_PARSE_ERROR
 CREATE DEFINER=CURRENT_USER() FUNCTION should_not_parse
 RETURNS STRING SONAME "should_not_parse.so";
 
---error ER_WRONG_USAGE
+--error ER_PARSE_ERROR
 CREATE DEFINER=someone@somewhere FUNCTION should_not_parse
 RETURNS STRING SONAME "should_not_parse.so";
 #

sql/sql_parse.cc

@@ -4016,12 +4016,6 @@ end_with_restore_list:
     if (check_access(thd,INSERT_ACL,"mysql",0,1,0,0))
       break;
 #ifdef HAVE_DLOPEN
-    if (sp_find_routine(thd, TYPE_ENUM_FUNCTION, lex->spname,
-                        &thd->sp_func_cache, FALSE))
-    {
-      my_error(ER_UDF_EXISTS, MYF(0), lex->spname->m_name.str);
-      goto error;
-    }
     if (!(res = mysql_create_function(thd, &lex->udf)))
       send_ok(thd);
 #else