Missing semicolumn in anonymous plpgsql block does not raise syntax error

Hi,

I would like to report a potential bug in postgres 15.4, also reproduced on
15.6.

*The exact sequence of steps:*
Connect to a postgres 15.4 database and run the following statements:

CREATE TABLE foo3(id serial PRIMARY key, txt text);

INSERT INTO foo3 (txt) VALUES ('aaa'),('bbb');

DO $$

DECLARE

l_cnt int;

BEGIN

l_cnt := 1

DELETE FROM foo3 WHERE id=1;

END; $$;

*The output you got:*

1. The script passes (no error message) even though there's a missing
semicolon (;) after "l_cnt := 1"
2. The script doesn't actually delete the record from foo3

This caused us a production issue where we thought changes were applied
(script passed successfully) but changes weren't actually applied.

If I move the line "l_cnt := 1" to after the DELETE statement like so:

DO $$

DECLARE

l_cnt int;

BEGIN

DELETE FROM foo3 WHERE id=1;

l_cnt := 1

END; $$;

I get the error - as expected:

SQL Error [42601]: ERROR: syntax error at end of input
Position: 89

Furthermore, replacing the DELETE statement with an UPDATE statement in the
original code does raise an error:

DO $$

DECLARE

l_cnt int;

BEGIN

l_cnt := 1

UPDATE foo3 SET txt='ccc' WHERE id=1;

END; $$;

SQL Error [42601]: ERROR: syntax error at or near "foo3"
Position: 62

But adding the semicolon - it works correctly with either UPDATE or DELETE.

I ran the original code using the following clients to make sure it's not a
client problem:

1. psql

2. DBeaver using standard JDBC drivers

3. Flyway using JDBC drivers

*Versions:*

PostgreSQL 15.6 (Homebrew) on x86_64-apple-darwin23.2.0, compiled by Apple
clang version 15.0.0 (clang-1500.1.0.2.5), 64-bit l - running locally on my
MacBook

PostgreSQL 15.4 on aarch64-unknown-linux-gnu, compiled by
aarch64-unknown-linux-gnu-gcc (GCC) 9.5.0, 64-bit - running on AWS RDS
Aurora

*Installed Extensions (On AWS RDS):*

oid |extname
|extowner|extnamespace|extrelocatable|extversion|extconfig |extcondition|
----------+-------------------------+--------+------------+--------------+----------+------------+------------+
16463|btree_gist | 10| 2200|true
|1.7 |NULL |NULL |
1463651797|deel_password_check_rules| 16399| 2200|false
|1.0 |NULL |NULL |
16464|fuzzystrmatch | 10| 2200|true
|1.1 |NULL |NULL |
958297705|pg_repack | 10| 2200|false
|1.4.8 |NULL |NULL |
16465|pg_stat_statements | 10| 2200|true
|1.9 |NULL |NULL |
1463506085|pg_tle | 10| 1463506084|false
|1.1.1 |{1463506117}|{""} |
16467|pg_trgm | 10| 2200|true
|1.6 |NULL |NULL |
16468|pgcrypto | 10| 2200|true
|1.3 |NULL |NULL |
14498|plpgsql | 10| 11|false
|1.0 |NULL |NULL |
16469|postgres_fdw | 10| 2200|true
|1.1 |NULL |NULL |
16470|tablefunc | 10| 2200|true
|1.0 |NULL |NULL |
16471|unaccent | 10| 2200|true
|1.1 |NULL |NULL |
16472|uuid-ossp | 10| 2200|true
|1.1 |NULL |NULL |

Please let me know what other information I can provide.

Thanks,

Mor