Bug #33813: Schema names are case-sensitive in DROP FUNCTION

      
Additional fix:
 1. Revert the unification of DROP FUNCTION
and DROP PROCEDURE, because DROP FUNCTION can be used to
drop UDFs (that have a non-qualified name and don't require
database name to be present and valid).
 2. Fixed the case sensitivity problem by adding a call to 
check_db_name() (similar to the sp_name production).

sql/sql_yacc.yy

@@ -7507,9 +7507,16 @@ drop:
 	    lex->drop_if_exists=$3;
 	    lex->name=$4.str;
 	 }
-	| DROP FUNCTION_SYM if_exists sp_name
+	| DROP FUNCTION_SYM if_exists ident '.' ident
 	  {
-            LEX *lex= Lex;
+            THD *thd= YYTHD;
+            LEX *lex= thd->lex;
+            sp_name *spname;
+            if ($4.str && check_db_name($4.str))
+            {
+	      my_error(ER_WRONG_DB_NAME, MYF(0), $4.str);
+	      MYSQL_YYABORT;
+	    }
 	    if (lex->sphead)
 	    {
 	      my_error(ER_SP_NO_DROP_SP, MYF(0), "FUNCTION");
@@ -7517,7 +7524,32 @@ drop:
 	    }
 	    lex->sql_command = SQLCOM_DROP_FUNCTION;
 	    lex->drop_if_exists= $3;
-	    lex->spname= $4;
+	    spname= new sp_name($4, $6, true);
+            if (spname == NULL)
+              MYSQL_YYABORT;
+	    spname->init_qname(thd);
+	    lex->spname= spname;
+	  }
+	| DROP FUNCTION_SYM if_exists ident
+	  {
+            THD *thd= YYTHD;
+            LEX *lex= thd->lex;
+            LEX_STRING db= {0, 0};
+            sp_name *spname;
+	    if (lex->sphead)
+	    {
+	      my_error(ER_SP_NO_DROP_SP, MYF(0), "FUNCTION");
+	      MYSQL_YYABORT;
+	    }
+            if (thd->db && lex->copy_db_to(&db.str, &db.length))
+              MYSQL_YYABORT;
+	    lex->sql_command = SQLCOM_DROP_FUNCTION;
+	    lex->drop_if_exists= $3;
+	    spname= new sp_name(db, $4, false);
+            if (spname == NULL)
+              MYSQL_YYABORT;
+	    spname->init_qname(thd);
+	    lex->spname= spname;
 	  }
 	| DROP PROCEDURE if_exists sp_name
 	  {