Optimizer trace and context escape a double quote twice in the first range of a long range list

CREATE TABLE t1 (c VARCHAR(10), KEY (c));

INSERT INTO t1 VALUES ('a"1'),('b"2'),('x'),('y');

SET optimizer_trace='enabled=on';

SELECT c FROM t1 WHERE c IN ('a"1', 'b"2');

SELECT INSTR(trace, CONCAT(CHAR(92), CHAR(92))) INTO @n FROM information_schema.OPTIMIZER_TRACE;

--let $n= query_get_value(SELECT @n AS n, n, 1)

if ($n != 0)

{

  --die The optimizer trace escapes the double quote in the first range twice, in a list of ranges longer than one line

}

SET optimizer_trace=DEFAULT;

DROP TABLE t1;

mysqltest: At line 9: The optimizer trace escapes the double quote in the first range twice, in a list of ranges longer than one line

                        "ranges": [

                          "(a\\\"1) <= (c) <= (a\\\"1)",

                          "(b\"2) <= (c) <= (b\"2)"

                        ],

+--------+---------------------+---------------------+

| MySQL  | First range         | Second range        |

+--------+---------------------+---------------------+

| 5.5.62 | no optimizer trace  | no optimizer trace  |

| 5.6.51 | "a\"1 <= c <= a\"1" | "b\"2 <= c <= b\"2" |

| 5.7.44 | "a\"1 <= c <= a\"1" | "b\"2 <= c <= b\"2" |

| 8.0.36 | "c = 'a\\\"1'"      | "c = 'b\\\"2'"      |

| 9.1.0  | "c = 'a\\\"1'"      | "c = 'b\\\"2'"      |

+--------+---------------------+---------------------+

CREATE TABLE t1 (c VARCHAR(20), KEY (c));

INSERT INTO t1 VALUES ('aaaaaaaa"1'),('bbbbbbbb"2'),('cccccccc"3'),('x'),('y');

SET optimizer_record_context=ON;

SELECT c FROM t1 WHERE c IN ('aaaaaaaa"1', 'bbbbbbbb"2', 'cccccccc"3');

SET optimizer_record_context=OFF;

SELECT context INTO DUMPFILE '../../tmp/ctx.sql' FROM information_schema.OPTIMIZER_CONTEXT;

--source $MYSQLTEST_VARDIR/tmp/ctx.sql

--remove_file $MYSQLTEST_VARDIR/tmp/ctx.sql

SET optimizer_replay_context='opt_context';

SELECT c FROM t1 WHERE c IN ('aaaaaaaa"1', 'bbbbbbbb"2', 'cccccccc"3');

--let $w= query_get_value(SHOW WARNINGS, Code, 1)

SET optimizer_replay_context='';

if ($w == 4270)

{

  --die The replay of the recorded optimizer context gives warning 4270, as the first range in the context is escaped twice

}

DROP TABLE t1;

mysqltest: At line 15: The replay of the recorded optimizer context gives warning 4270, as the first range in the context is escaped twice

Warning	4270	Failed to match the stats from replay context with the optimizer stats: the given list of ranges i.e. [(aaaaaaaa"1) <= (c) <= (aaaaaaaa"1), (bbbbbbbb"2) <= (c) <= (bbbbbbbb"2), (cccccccc"3) <= (c) <= (cccccccc"3), ] doesn't exist in the list of ranges for table_name test.t1 and index_name c