A patch for Bug#11763166 (55847: SHOW WARNINGS returns empty

result set when SQLEXCEPTION is active.

The problem was in a hackish THD::no_warnings_for_error attribute.
When it was set, an error was not written to Warning_info -- only
Diagnostics_area state was changed. That means, Diagnostics_area
might contain error state, which is not present in Warning_info.

The user-visible problem was that in some cases SHOW WARNINGS
returned empty result set (i.e. there were no warnings) while
the previous SQL statement failed. According to the MySQL
protocol errors must be presented in warning list.

The main idea of this patch is to remove THD::no_warnings_for_error.
There were few places where it was used:
  - sql_admin.cc, handling of REPAIR TABLE USE_FRM.
  - sql_show.cc, when calling fill_schema_table_from_frm().
  - sql_show.cc, when calling fill_table().
The fix is to either use internal-error-handlers, or to use
temporary Warning_info storing warnings, which might be ignored.

This patch is needed to fix Bug 11763162 (55843).

1 files changed, 40 insertions, 0 deletions

diff --git a/mysql-test/t/warnings.test b/mysql-test/t/warnings.test
index 98e1db62d84..5569776904f 100644
--- a/mysql-test/t/warnings.test
+++ b/mysql-test/t/warnings.test
@@ -228,3 +228,43 @@ DROP TABLE t1;
 SHOW ERRORS;
 
 --echo End of 5.0 tests
+
+#
+# Bug#55847: SHOW WARNINGS returns empty result set when SQLEXCEPTION is active
+#
+
+--echo
+--echo -- Bug#55847
+--echo
+
+--disable_warnings
+DROP TABLE IF EXISTS t1;
+DROP FUNCTION IF EXISTS f1;
+--enable_warnings
+
+CREATE TABLE t1(a INT UNIQUE);
+
+delimiter |;
+
+CREATE FUNCTION f1(x INT) RETURNS INT
+BEGIN
+  INSERT INTO t1 VALUES(x);
+  INSERT INTO t1 VALUES(x);
+  RETURN x;
+END|
+
+delimiter ;|
+
+--echo
+
+--error ER_DUP_ENTRY
+SHOW TABLES WHERE f1(11) = 11;
+
+--echo
+
+SHOW WARNINGS;
+
+--echo
+
+DROP TABLE t1;
+DROP FUNCTION f1;