Assert in test_bms_membership();

Postgresql 19 added a new module, src/test/modules/test_bitmapset.
It contains the function test_bms_membership(), which is a wrapper
around bms_membership. Passing some string that are not valid Bitmapset
representation to this function will result to assert. For example

SELECT test_bms_membership('b 1 2)');
or
SELECT test_bms_membership('true');

[backtrace.txt]

|The assertion appears to occur becaus| in
#define TEXT_TO_BITMAPSET(str) (test_bitmapset.c:91) casts to Bitmapset*
without type checking, using stringToNode, which obviously can return
types other than T_Bitmapset (read.c:247). This pointer, with the wrong
type, is then passed to bms_membership, where it fails the assert
with type checking (bitmapset.c:905).

The fix simply adds a check whether the type is valid or not,
as done in the bms_is_valid_set()(bitmapset.c:87) function.

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Best regards,
Ilya Cherdakov
Postgres Professional: https://postgrespro.com