Bug#25373: Stored functions wasn't compared correctly which leads to a wrong

result.

For built-in functions like sqrt() function names are hard-coded and can be
compared by pointer. But this isn't the case for a used-defined stored
functions - names there are dynamical and should be compared as strings.

Now the Item_func::eq() function employs my_strcasecmp() function to compare
used-defined stored functions names.

mysql-test/r/sp.result

@@ -5741,4 +5741,17 @@ END|
 CALL bug24117()|
 DROP PROCEDURE bug24117|
 DROP TABLE t3|
+DROP FUNCTION IF EXISTS bug25373|
+CREATE FUNCTION bug25373(p1 INTEGER) RETURNS INTEGER
+LANGUAGE SQL DETERMINISTIC
+RETURN p1;|
+CREATE TABLE t3 (f1 INT, f2 FLOAT)|
+INSERT INTO t3 VALUES (1, 3.4), (1, 2), (1, 0.9), (2, 8), (2, 7)|
+SELECT SUM(f2), bug25373(f1) FROM t3 GROUP BY bug25373(f1) WITH ROLLUP|
+SUM(f2)	bug25373(f1)
+6.3000000715256	1
+15	2
+21.300000071526	NULL
+DROP FUNCTION bug25373|
+DROP TABLE t3|
 drop table t1,t2;

mysql-test/t/sp.test

@@ -6714,6 +6714,21 @@ CALL bug24117()|
 DROP PROCEDURE bug24117|
 DROP TABLE t3|
 
+#
+# Bug#25373: Stored functions wasn't compared correctly which leads to a wrong
+#            result.
+#
+--disable_warnings
+DROP FUNCTION IF EXISTS bug25373|
+--disable_warnings
+CREATE FUNCTION bug25373(p1 INTEGER) RETURNS INTEGER
+LANGUAGE SQL DETERMINISTIC
+RETURN p1;|
+CREATE TABLE t3 (f1 INT, f2 FLOAT)|
+INSERT INTO t3 VALUES (1, 3.4), (1, 2), (1, 0.9), (2, 8), (2, 7)|
+SELECT SUM(f2), bug25373(f1) FROM t3 GROUP BY bug25373(f1) WITH ROLLUP|
+DROP FUNCTION bug25373|
+DROP TABLE t3|
 #
 # NOTE: The delimiter is `|`, and not `;`. It is changed to `;`
 #       at the end of the file!

sql/item_func.cc

@@ -409,8 +409,13 @@ bool Item_func::eq(const Item *item, bool binary_cmp) const
   if (item->type() != FUNC_ITEM)
     return 0;
   Item_func *item_func=(Item_func*) item;
-  if (arg_count != item_func->arg_count ||
-      func_name() != item_func->func_name())
+  Item_func::Functype func_type;
+  if ((func_type= functype()) != item_func->functype() ||
+      arg_count != item_func->arg_count ||
+      (func_type != Item_func::FUNC_SP &&
+       func_name() != item_func->func_name()) ||
+      (func_type == Item_func::FUNC_SP &&
+       my_strcasecmp(system_charset_info, func_name(), item_func->func_name())))
     return 0;
   for (uint i=0; i < arg_count ; i++)
     if (!args[i]->eq(item_func->args[i], binary_cmp))