String right truncation error when preparing a query with a LIKE predicate without wildcards with UTF8 encoding and connection charset WIN1251.

[sim1984]

WI-V5.0.2.1582 Firebird 5.0 4a67617

Create database

chcp 1251

SET NAMES WIN1251;

CREATE DATABASE 'inet4://localhost:3055/test'
USER "SYSDBA" PASSWORD 'masterkey'
PAGE_SIZE 8192
DEFAULT CHARACTER SET UTF8;

RECREATE TABLE T (
  ID BIGINT NOT NULL,
  NAME_UTF8 VARCHAR(50),
  NAME_WIN1251 VARCHAR(50) CHARACTER SET WIN1251,
  PRIMARY KEY (ID)
);


INSERT INTO T(ID, NAME_UTF8, NAME_WIN1251) VALUES (1, 'abc', 'abc');
INSERT INTO T(ID, NAME_UTF8, NAME_WIN1251) VALUES (2, 'Ават', 'Ават');

COMMIT;

Query:

SET NAMES WIN1251;
CONNECT 'inet4://localhost:3055/test'
USER "SYSDBA" PASSWORD 'masterkey';

SELECT COUNT(*)
FROM T
WHERE NAME_WIN1251 LIKE 'Ават';

                COUNT
=====================
                    1

SELECT COUNT(*)
FROM T
WHERE NAME_UTF8 LIKE 'Ават';

Statement failed, SQLSTATE = 22001
arithmetic exception, numeric overflow, or string truncation
-string right truncation
-expected length 0, actual 1

-- Why??? But

SELECT COUNT(*)
FROM T
WHERE NAME_UTF8 LIKE 'Ава_';

                COUNT
=====================
                    1

[sim1984]

This is also reproduced in Firebird 4.0.2.

If the connection encoding is changed to UTF8 and the console encoding to 65001, then the error will not be raised for NAME_UTF8 LIKE 'Ават'.