Fix for Bug#12652873 - 61392: CONTINUE HANDLER FOR NOT FOUND BEING

TRIGGERED FROM INTERNAL STORED FUNCTION.

The problem was that RETURN statement in stored programs did not
clear the Diagnostics Area, as it should have done according to
the SQL Standard.

The user-visible problem was that in some cases an SQL-condition,
raised in the nested function call, would be visible in the outer
scope, which in turn would lead to incorrect handler activation.

The fix is to clear the Diagnostics Area before executing RETURN
statement.

Note, that after the patch, there is no way to throw an SQL-warning
out of a stored function. From the user's view point, he/she will not
get any warning, even if there were warnings, raised during
the function execution.

This change is backward incompatible, but it makes the behaviour of
stored programs more in line with The Standard.

Author: Alexander Nozdrin

mysql-test/r/func_rollback.result

@@ -190,8 +190,6 @@ END;
 SELECT f1_insert_select(2);
 f1_insert_select(2)
 1
-Warnings:
-Warning	1048	Column 'f2' cannot be null
 SELECT * FROM t1_not_null ORDER BY f1,f2;
 f1	f2
 2	0
@@ -267,8 +265,6 @@ END;
 SELECT f1_insert_with_two_rows();
 f1_insert_with_two_rows()
 1
-Warnings:
-Warning	1048	Column 'f2' cannot be null
 SELECT * FROM t1_not_null ORDER BY f1,f2;
 f1	f2
 10	0

mysql-test/r/signal.result

@@ -1313,19 +1313,25 @@ drop procedure test_signal $$
 #
 # Test where SIGNAL can be used
 #
+
+# RETURN statement clears Diagnostics Area, thus
+# the warnings raised in a stored function are not
+# visible outsidef the stored function. So, we're using
+# @@warning_count variable to check that SIGNAL succeeded.
+
 create function test_signal_func() returns integer
 begin
+DECLARE v INT;
 DECLARE warn CONDITION FOR SQLSTATE "01XXX";
 SIGNAL warn SET
 MESSAGE_TEXT = "This function SIGNAL a warning",
 MYSQL_ERRNO = 1012;
-return 5;
+SELECT @@warning_count INTO v;
+return v;
 end $$
 select test_signal_func() $$
 test_signal_func()
-5
-Warnings:
-Warning	1012	This function SIGNAL a warning
+1
 drop function test_signal_func $$
 create function test_signal_func() returns integer
 begin

mysql-test/r/sp-error.result

@@ -2846,3 +2846,50 @@ CALL p2();
 SET SESSION max_error_count= @old_max_error_count;
 DROP PROCEDURE p1;
 DROP PROCEDURE p2;
+
+# Bug#12652873: 61392: Continue handler for NOT FOUND being triggered
+# from internal stored function.
+
+DROP FUNCTION IF EXISTS f1;
+DROP FUNCTION IF EXISTS f2;
+DROP TABLE IF EXISTS t1;
+
+CREATE TABLE t1 (a INT, b INT);
+INSERT INTO t1 VALUES (1, 2);
+
+# f1() raises NOT_FOUND condition.
+# Raising NOT_FOUND can not be simulated by SIGNAL,
+# because SIGNAL would raise SQL-error in that case.
+
+CREATE FUNCTION f1() RETURNS INTEGER
+BEGIN
+DECLARE v VARCHAR(5) DEFAULT -1;
+SELECT b FROM t1 WHERE a = 2 INTO v;
+RETURN v;
+END|
+
+# Here we check that the NOT_FOUND condition raised in f1()
+# is not visible in the outer function (f2), i.e. the continue
+# handler in f2() will not be called.
+
+CREATE FUNCTION f2() RETURNS INTEGER
+BEGIN
+DECLARE v INTEGER;
+DECLARE CONTINUE HANDLER FOR NOT FOUND
+SET @msg = 'Handler activated.';
+SELECT f1() INTO v;
+RETURN v;
+END|
+SET @msg = '';
+
+SELECT f2();
+f2()
+-1
+
+SELECT @msg;
+@msg
+
+
+DROP FUNCTION f1;
+DROP FUNCTION f2;
+DROP TABLE t1;

mysql-test/r/sp.result

@@ -5425,13 +5425,9 @@ end|
 select func_20028_a()|
 func_20028_a()
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select func_20028_b()|
 func_20028_b()
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select func_20028_c()|
 ERROR 22012: Division by 0
 call proc_20028_a()|
@@ -5484,13 +5480,9 @@ end|
 select func_20028_a()|
 func_20028_a()
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select func_20028_b()|
 func_20028_b()
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select func_20028_c()|
 func_20028_c()
 NULL
@@ -6110,8 +6102,6 @@ END|
 SELECT bug5274_f2()|
 bug5274_f2()
 x
-Warnings:
-Warning	1265	Data truncated for column 'bug5274_f1' at row 1
 DROP FUNCTION bug5274_f1|
 DROP FUNCTION bug5274_f2|
 drop procedure if exists proc_21513|
@@ -6204,19 +6194,13 @@ c1
 SELECT f1(2);
 f1(2)
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 PREPARE s1 FROM 'SELECT f1(2)';
 EXECUTE s1;
 f1(2)
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 EXECUTE s1;
 f1(2)
 0
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 DROP PROCEDURE p1;
 DROP PROCEDURE p2;
 DROP FUNCTION f1;

mysql-test/r/view_grant.result

@@ -341,13 +341,9 @@ use mysqltest;
 select * from v1;
 f2()
 NULL
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select * from v2;
 f2()
 NULL
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select * from v3;
 ERROR HY000: View 'mysqltest.v3' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
 select * from v4;
@@ -387,13 +383,9 @@ ERROR HY000: View 'mysqltest.v2' references invalid table(s) or column(s) or fun
 select * from v3;
 f2()
 NULL
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select * from v4;
 f2()
 NULL
-Warnings:
-Warning	1329	No data - zero rows fetched, selected, or processed
 select * from v5;
 ERROR HY000: View 'mysqltest.v5' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
 drop view v1, v2, v3, v4, v5;