Bug #121675 Prepared bitwise aggregates accept 512-byte binary parameters

Description:
Prepared grouped BIT_AND(), BIT_OR(), and BIT_XOR(), as well as windowed BIT_XOR(), accept a 512-byte binary parameter and return a 512-byte result. The equivalent expressions with a statically known 512-byte operand are rejected with error 3514.

Decisive observation:
For each affected prepared statement, bindings of 511, 512, and 1 bytes returned these result lengths in order:

511
512
1

The corresponding static 512-byte expression failed with:

ERROR 3514 (HY000): Aggregate bitwise functions cannot accept arguments longer than 511 bytes; consider using the SUBSTRING() function

Semantic mismatch:
Binary operands to BIT_AND(), BIT_OR(), and BIT_XOR() may not exceed 511 bytes. That limit should apply regardless of whether the operand length is known when the statement is prepared or supplied when it is executed. The 511-byte and rebound 1-byte values should succeed, while the 512-byte execution should raise error 3514.

Impact:
Affected prepared statements bypass the documented operand-size limit and produce a result that the equivalent static expression rejects. No persistent database state is involved; deallocating the statement and clearing the bound variable is sufficient cleanup.

Tested versions:
MySQL 9.7.2, source revision 561753af986c3c006c4b6c7caa8359748fb55b22.

Environment and configuration:
Linux on amd64. No relevant non-default configuration was recorded.

Additional information:
This occurs when a grouped BIT_AND, BIT_OR, or BIT_XOR aggregate, or a windowed BIT_XOR aggregate, is prepared and executed with a 512-byte binary parameter.

How to repeat:
Save the following as reproducer.sql and run:

mysql --force < reproducer.sql

-- Grouped BIT_AND
PREPARE s FROM 'SELECT OCTET_LENGTH(BIT_AND(?)) AS result_length';
SET @arg = REPEAT(_binary 'x', 511);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 512);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 1);
EXECUTE s USING @arg;
DEALLOCATE PREPARE s;

SELECT OCTET_LENGTH(BIT_AND(REPEAT(_binary 'x', 512)));

-- Grouped BIT_OR
PREPARE s FROM 'SELECT OCTET_LENGTH(BIT_OR(?)) AS result_length';
SET @arg = REPEAT(_binary 'x', 511);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 512);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 1);
EXECUTE s USING @arg;
DEALLOCATE PREPARE s;

SELECT OCTET_LENGTH(BIT_OR(REPEAT(_binary 'x', 512)));

-- Grouped BIT_XOR
PREPARE s FROM 'SELECT OCTET_LENGTH(BIT_XOR(?)) AS result_length';
SET @arg = REPEAT(_binary 'x', 511);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 512);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 1);
EXECUTE s USING @arg;
DEALLOCATE PREPARE s;

SELECT OCTET_LENGTH(BIT_XOR(REPEAT(_binary 'x', 512)));

-- Windowed BIT_XOR
PREPARE s FROM 'SELECT OCTET_LENGTH(BIT_XOR(?) OVER ()) AS result_length';
SET @arg = REPEAT(_binary 'x', 511);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 512);
EXECUTE s USING @arg;
SET @arg = REPEAT(_binary 'x', 1);
EXECUTE s USING @arg;
DEALLOCATE PREPARE s;
SET @arg = NULL;

SELECT OCTET_LENGTH(BIT_XOR(REPEAT(_binary 'x', 512)) OVER ());

Each prepared block returns result_length values 511, 512, and 1. Each static 512-byte control raises error 3514 instead. The --force option allows the client to proceed to the next block after each expected static-control error.

Suggested fix:
Apply the execution-time 511-byte operand-size validation consistently to grouped BIT_AND(), BIT_OR(), and BIT_XOR(), and to windowed BIT_XOR(), when the operand length is supplied through a parameter marker.