Re: Do we want a hashset type?

In hashset/test/sql/order.sql, can we add the following to test
whether the optimizer
will use our index.

CREATE INDEX ON test_int4hashset_order (int4hashset_col
int4hashset_btree_ops);

-- to make sure that this work with just two rows
SET enable_seqscan TO off;

explain(costs off) SELECT * FROM test_int4hashset_order WHERE
int4hashset_col = '{1,2}'::int4hashset;
reset enable_seqscan;

Since most contrib modules, one module, only one test file, maybe we need
to consolidate all the test sql files to one sql file (int4hashset.sql)?
--------------
I didn't install the extension directly. I copied the hashset--0.0.1.sql to
another place, using gcc to compile these functions.
gcc -I/home/jian/postgres/2023_05_25_beta5421/include/server -fPIC -c
/home/jian/hashset/hashset.c
gcc -shared -o /home/jian/hashset/hashset.so /home/jian/hashset/hashset.o
then modify hashset--0.0.1.sql then in psql \i fullsqlfilename to create
these functions, types.

Because even make
PG_CONFIG=/home/jian/postgres/2023_05_25_beta5421/bin/pg_config still has
an error.
fatal error: libpq-fe.h: No such file or directory
3 | #include <libpq-fe.h>

Is there any way to put test_send_recv.c to sql test file?
Attached is a patch slightly modified README.md. feel free to change, since
i am not native english speaker...