Bug #31928: Search fails on '1000-00-00' date after sql_mode change

When constructing a key image stricter date checking (from sql_mode)
should not be enabled, because it will reject invalid dates that the
server would otherwise accept for searching when there's no index.
 
Fixed by disabling strict date checking when constructing a key image.

mysql-test/r/type_date.result

@@ -202,7 +202,6 @@ a
 Warnings:
 Warning	1292	Incorrect date value: '0000-00-00' for column 'a' at row 1
 Warning	1292	Incorrect date value: '0000-00-00' for column 'a' at row 1
-Warning	1292	Incorrect date value: '0000-00-00' for column 'a' at row 1
 SELECT * FROM t2 WHERE a = '0000-00-00';
 a
 0000-00-00
@@ -214,4 +213,42 @@ INSERT INTO t1 VALUES ('0000-00-00');
 ERROR 22007: Incorrect date value: '0000-00-00' for column 'a' at row 1
 SET SQL_MODE=DEFAULT;
 DROP TABLE t1,t2;
+CREATE TABLE t1 (a DATE);
+CREATE TABLE t2 (a DATE);
+CREATE INDEX i ON t1 (a);
+INSERT INTO t1 VALUES ('1000-00-00'),('1000-00-00');
+INSERT INTO t2 VALUES ('1000-00-00'),('1000-00-00');
+SELECT * FROM t1 WHERE a = '1000-00-00';
+a
+1000-00-00
+1000-00-00
+SELECT * FROM t2 WHERE a = '1000-00-00';
+a
+1000-00-00
+1000-00-00
+SET SQL_MODE=TRADITIONAL;
+EXPLAIN SELECT * FROM t1 WHERE a = '1000-00-00';
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ref	i	i	4	const	1	Using where; Using index
+Warnings:
+Warning	1292	Incorrect date value: '1000-00-00' for column 'a' at row 1
+Warning	1292	Incorrect date value: '1000-00-00' for column 'a' at row 1
+SELECT * FROM t1 WHERE a = '1000-00-00';
+a
+1000-00-00
+1000-00-00
+Warnings:
+Warning	1292	Incorrect date value: '1000-00-00' for column 'a' at row 1
+Warning	1292	Incorrect date value: '1000-00-00' for column 'a' at row 1
+SELECT * FROM t2 WHERE a = '1000-00-00';
+a
+1000-00-00
+1000-00-00
+Warnings:
+Warning	1292	Incorrect date value: '1000-00-00' for column 'a' at row 1
+Warning	1292	Incorrect date value: '1000-00-00' for column 'a' at row 1
+INSERT INTO t1 VALUES ('1000-00-00');
+ERROR 22007: Incorrect date value: '1000-00-00' for column 'a' at row 1
+SET SQL_MODE=DEFAULT;
+DROP TABLE t1,t2;
 End of 5.0 tests

mysql-test/t/type_date.test

@@ -190,4 +190,24 @@ INSERT INTO t1 VALUES ('0000-00-00');
 SET SQL_MODE=DEFAULT;
 DROP TABLE t1,t2;
 
+#
+# Bug #31928: Search fails on '1000-00-00' date after sql_mode change
+#
+
+CREATE TABLE t1 (a DATE);
+CREATE TABLE t2 (a DATE);
+CREATE INDEX i ON t1 (a);
+INSERT INTO t1 VALUES ('1000-00-00'),('1000-00-00');
+INSERT INTO t2 VALUES ('1000-00-00'),('1000-00-00');
+SELECT * FROM t1 WHERE a = '1000-00-00';
+SELECT * FROM t2 WHERE a = '1000-00-00';
+SET SQL_MODE=TRADITIONAL;
+EXPLAIN SELECT * FROM t1 WHERE a = '1000-00-00';
+SELECT * FROM t1 WHERE a = '1000-00-00';
+SELECT * FROM t2 WHERE a = '1000-00-00';
+--error ER_TRUNCATED_WRONG_VALUE
+INSERT INTO t1 VALUES ('1000-00-00');
+SET SQL_MODE=DEFAULT;
+DROP TABLE t1,t2;
+
 --echo End of 5.0 tests

sql/sql_select.h

@@ -548,14 +548,17 @@ public:
   enum store_key_result copy()
   {
     enum store_key_result result;
-    enum_check_fields saved_count_cuted_fields= 
-      to_field->table->in_use->count_cuted_fields;
+    THD *thd= to_field->table->in_use;
+    enum_check_fields saved_count_cuted_fields= thd->count_cuted_fields;
+    ulong sql_mode= thd->variables.sql_mode;
+    thd->variables.sql_mode&= ~(MODE_NO_ZERO_IN_DATE | MODE_NO_ZERO_DATE);
 
-    to_field->table->in_use->count_cuted_fields= CHECK_FIELD_IGNORE;
+    thd->count_cuted_fields= CHECK_FIELD_IGNORE;
 
     result= copy_inner();
 
-    to_field->table->in_use->count_cuted_fields= saved_count_cuted_fields;
+    thd->count_cuted_fields= saved_count_cuted_fields;
+    thd->variables.sql_mode= sql_mode;
 
     return result;
   }