Auto-merge from mysql-trunk-bugfixing.

******
This patch fixes the following bugs:
  - Bug#5889: Exit handler for a warning doesn't hide the warning in
    trigger
  - Bug#9857: Stored procedures: handler for sqlwarning ignored
  - Bug#23032: Handlers declared in a SP do not handle warnings generated
    in sub-SP
  - Bug#36185: Incorrect precedence for warning and exception handlers

The problem was in the way warnings/errors during stored routine execution
were handled. Prior to this patch the logic was as follows:

  - when a warning/an error happens: if we're executing a stored routine,
    and there is a handler for that warning/error, remember the handler,
    ignore the warning/error and continue execution.

  - after a stored routine instruction is executed: check for a remembered
    handler and activate one (if any).

This logic caused several problems:

  - if one instruction generates several warnings (errors) it's impossible
    to choose the right handler -- a handler for the first generated
    condition was chosen and remembered for activation.

  - mess with handling conditions in scopes different from the current one.

  - not putting generated warnings/errors into Warning Info (Diagnostic
    Area) is against The Standard.

The patch changes the logic as follows:

  - Diagnostic Area is cleared on the beginning of each statement that
    either is able to generate warnings, or is able to work with tables.

  - at the end of a stored routine instruction, Diagnostic Area is left
    intact.

  - Diagnostic Area is checked after each stored routine instruction. If
    an instruction generates several condition, it's now possible to take a
    look at all of them and determine an appropriate handler.

mysql-test/t/sp-code.test

@@ -649,3 +649,56 @@ END//
 DELIMITER ;//
 SHOW PROCEDURE CODE p1;
 DROP PROCEDURE p1;
+
+--echo #
+--echo # Bug#23032: Handlers declared in a SP do not handle warnings generated in sub-SP
+--echo #
+
+--echo
+--echo # - Case 4: check that "No Data trumps Warning".
+--echo
+
+CREATE TABLE t1(a INT);
+INSERT INTO t1 VALUES (1), (2), (3);
+
+delimiter |;
+
+CREATE PROCEDURE p1()
+BEGIN
+  DECLARE c CURSOR FOR SELECT a FROM t1;
+
+  OPEN c;
+  
+  BEGIN
+    DECLARE v INT;
+
+    DECLARE CONTINUE HANDLER FOR SQLWARNING
+    BEGIN
+      SELECT "Warning found!";
+      SHOW WARNINGS;
+    END;
+
+    DECLARE EXIT HANDLER FOR NOT FOUND
+    BEGIN
+      SELECT "End of Result Set found!";
+      SHOW WARNINGS;
+    END;
+
+    WHILE TRUE DO
+      FETCH c INTO v;
+    END WHILE;
+  END;
+
+  CLOSE c;
+
+  SELECT a INTO @foo FROM t1 LIMIT 1; # Clear warning stack
+END|
+
+delimiter ;|
+
+SET SESSION debug="+d,bug23032_emit_warning";
+CALL p1();
+SET SESSION debug="-d,bug23032_emit_warning";
+
+DROP PROCEDURE p1;
+DROP TABLE t1;