MDEV-14376 Explicit CAST(CHAR(N)) erroneously escalates warnings to errors in STRICT_ALL_TABLES

mysql-test/t/cast.test

@@ -587,3 +587,140 @@ SHOW CREATE TABLE t1;
 SELECT * FROM t1;
 DROP TABLE t1;
 SET sql_mode=DEFAULT;
+
+
+--echo #
+--echo # MDEV-14376 Explicit CAST(CHAR(N)) erroneously escalates warnings to errors in STRICT_ALL_TABLES
+--echo #
+
+SET sql_mode=STRICT_ALL_TABLES;
+SELECT CAST('xxx' AS CHAR(1));
+
+CREATE OR REPLACE TABLE t1 (a VARCHAR(1));
+INSERT INTO t1 VALUES (CAST('xxx' AS CHAR(1)));
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 (a VARCHAR(3));
+INSERT INTO t1 VALUES ('xxx');
+UPDATE t1 SET a=CAST(a AS CHAR(1));
+DROP TABLE t1;
+
+DELIMITER $$;
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET latin1;
+  SET a=CAST('xxx' AS CHAR(1));
+END;
+$$
+DELIMITER ;$$
+
+DELIMITER $$;
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET latin1;
+  SET a=CAST(_latin1'xxx' AS CHAR(1) CHARACTER SET latin1);
+END;
+$$
+DELIMITER ;$$
+
+DELIMITER $$;
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET latin1;
+  SET a=CAST(_latin1'xxx' AS CHAR(1) CHARACTER SET utf8);
+END;
+$$
+DELIMITER ;$$
+
+DELIMITER $$;
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET utf8;
+  SET a=CAST('xxx' AS CHAR(1));
+END;
+$$
+DELIMITER ;$$
+
+DELIMITER $$;
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET utf8;
+  SET a=CAST(_latin1'xxx' AS CHAR(1) CHARACTER SET latin1);
+END;
+$$
+DELIMITER ;$$
+
+DELIMITER $$;
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET utf8;
+  SET a=CAST(_latin1'xxx' AS CHAR(1) CHARACTER SET utf8);
+END;
+$$
+DELIMITER ;$$
+
+
+--echo # Conversion problems still escalate warnings to errors (without right truncation)
+
+DELIMITER $$;
+--error ER_CANNOT_CONVERT_CHARACTER
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET utf8;
+  SET a=CAST(_utf8 0xD18F AS CHAR(1) CHARACTER SET latin1);
+END;
+$$
+DELIMITER ;$$
+
+
+--echo # Conversion problems still escalate warnings to errors (with right truncation)
+
+DELIMITER $$;
+--error ER_CANNOT_CONVERT_CHARACTER
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(30) CHARACTER SET utf8;
+  SET a=CAST(_utf8 0xD18FD18F AS CHAR(1) CHARACTER SET latin1);
+END;
+$$
+DELIMITER ;$$
+
+
+--echo # CAST(number AS CHAR) escalates warnings to errors on truncation
+
+CREATE OR REPLACE TABLE t1 (a VARCHAR(10));
+--error ER_TRUNCATED_WRONG_VALUE
+INSERT INTO t1 VALUES (CAST(123 AS CHAR(1)));
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 (a VARCHAR(10));
+INSERT INTO t1 VALUES ('1');
+--error ER_TRUNCATED_WRONG_VALUE
+UPDATE t1 SET a=CAST(123 AS CHAR(1));
+DROP TABLE t1;
+
+DELIMITER $$;
+--error ER_TRUNCATED_WRONG_VALUE
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(10);
+  SET a=CAST(123 AS CHAR(1));
+END;
+$$
+DELIMITER ;$$
+
+
+--echo # CAST(temporal AS CHAR) escalates warnings to errors on truncation
+
+CREATE OR REPLACE TABLE t1 (a VARCHAR(10));
+--error ER_TRUNCATED_WRONG_VALUE
+INSERT INTO t1 VALUES (CAST(TIME'10:20:30' AS CHAR(1)));
+DROP TABLE t1;
+
+CREATE OR REPLACE TABLE t1 (a VARCHAR(10));
+INSERT INTO t1 VALUES ('1');
+--error ER_TRUNCATED_WRONG_VALUE
+UPDATE t1 SET a=CAST(TIME'10:20:30' AS CHAR(1));
+DROP TABLE t1;
+
+DELIMITER $$;
+--error ER_TRUNCATED_WRONG_VALUE
+BEGIN NOT ATOMIC
+  DECLARE a VARCHAR(10);
+  SET a=CAST(TIME'10:20:30' AS CHAR(1));
+END;
+$$
+DELIMITER ;$$
+
+SET sql_mode=DEFAULT;

sql/item_timefunc.cc

@@ -2434,6 +2434,8 @@ void Item_char_typecast::check_truncation_with_warn(String *src, uint dstlen)
     THD *thd= current_thd;
     char char_type[40];
     ErrConvString err(src);
+    bool save_abort_on_warning= thd->abort_on_warning;
+    thd->abort_on_warning&= !m_suppress_warning_to_error_escalation;
     my_snprintf(char_type, sizeof(char_type), "%s(%lu)",
                 cast_cs == &my_charset_bin ? "BINARY" : "CHAR",
                 (ulong) cast_length);
@@ -2441,6 +2443,7 @@ void Item_char_typecast::check_truncation_with_warn(String *src, uint dstlen)
                         ER_TRUNCATED_WRONG_VALUE,
                         ER_THD(thd, ER_TRUNCATED_WRONG_VALUE), char_type,
                         err.ptr());
+    thd->abort_on_warning= save_abort_on_warning;
   }
 }
 
@@ -2551,7 +2554,7 @@ void Item_char_typecast::fix_length_and_dec_numeric()
 }
 
 
-void Item_char_typecast::fix_length_and_dec_str()
+void Item_char_typecast::fix_length_and_dec_generic()
 {
   fix_length_and_dec_internal(from_cs= args[0]->dynamic_result() ?
                                        0 :

sql/item_timefunc.h

@@ -1089,6 +1089,7 @@ class Item_char_typecast :public Item_str_func
   CHARSET_INFO *cast_cs, *from_cs;
   bool charset_conversion;
   String tmp_value;
+  bool m_suppress_warning_to_error_escalation;
   bool has_explicit_length() const { return cast_length != ~0U; }
   String *reuse(String *src, uint32 length);
   String *copy(String *src, CHARSET_INFO *cs);
@@ -1097,14 +1098,20 @@ class Item_char_typecast :public Item_str_func
   void fix_length_and_dec_internal(CHARSET_INFO *fromcs);
 public:
   Item_char_typecast(THD *thd, Item *a, uint length_arg, CHARSET_INFO *cs_arg):
-    Item_str_func(thd, a), cast_length(length_arg), cast_cs(cs_arg) {}
+    Item_str_func(thd, a), cast_length(length_arg), cast_cs(cs_arg),
+    m_suppress_warning_to_error_escalation(false) {}
   enum Functype functype() const { return CHAR_TYPECAST_FUNC; }
   bool eq(const Item *item, bool binary_cmp) const;
   const char *func_name() const { return "cast_as_char"; }
   CHARSET_INFO *cast_charset() const { return cast_cs; }
   String *val_str(String *a);
+  void fix_length_and_dec_generic();
   void fix_length_and_dec_numeric();
-  void fix_length_and_dec_str();
+  void fix_length_and_dec_str()
+  {
+    fix_length_and_dec_generic();
+    m_suppress_warning_to_error_escalation= true;
+  }
   void fix_length_and_dec()
   {
     args[0]->type_handler()->Item_char_typecast_fix_length_and_dec(this);

sql/sql_type.cc

@@ -4339,7 +4339,7 @@ bool Type_handler::
 bool Type_handler::
        Item_char_typecast_fix_length_and_dec(Item_char_typecast *item) const
 {
-  item->fix_length_and_dec_str();
+  item->fix_length_and_dec_generic();
   return false;
 }
 
@@ -4352,6 +4352,14 @@ bool Type_handler_numeric::
 }
 
 
+bool Type_handler_string_result::
+       Item_char_typecast_fix_length_and_dec(Item_char_typecast *item) const
+{
+  item->fix_length_and_dec_str();
+  return false;
+}
+
+
 bool Type_handler::
        Item_time_typecast_fix_length_and_dec(Item_time_typecast *item) const
 {

sql/sql_type.h

@@ -1717,6 +1717,7 @@ class Type_handler_string_result: public Type_handler
                                   MYSQL_TIME *, ulonglong fuzzydate) const;
   bool Item_func_between_fix_length_and_dec(Item_func_between *func) const;
   longlong Item_func_between_val_int(Item_func_between *func) const;
+  bool Item_char_typecast_fix_length_and_dec(Item_char_typecast *) const;
   cmp_item *make_cmp_item(THD *thd, CHARSET_INFO *cs) const;
   in_vector *make_in_vector(THD *, const Item_func_in *, uint nargs) const;
   bool Item_func_in_fix_comparator_compatible_types(THD *thd,