EXIT WHEN from a nested FOR .. IN loop may produce an infinite loop

[lukaseder]

Describe the problem

EXIT WHEN from a nested FOR .. IN loop may produce an infinite loop.

To Reproduce

When playing around with potential workarounds for #148988, I stumbled upon this:

create or replace procedure "proc_ForIndexedLoopNested"()
language plpgsql
as
$$
begin
  for i in 0 .. 1 loop
    for j in 1 .. 5 loop
      raise notice '%', (("i" * 5) + "j");
      exit when j = 4;
    end loop;
  end loop;
end;
$$

call "proc_ForIndexedLoopNested"();

This just loops forever, printing weird stuff:

1
2
3
4
26
27
28
29
26
27
28
29
26
27
28
29
26
27
28

It may be the same issue as #148988, I can't tell for sure. In case it isn't, I just wanted to report this separately, because it's much worse than #148988, which doesn't produce infinite loops.

Expected behavior

It should print:

1
2
3
4
6
7
8
9

Environment:

• CockroachDB version: CockroachDB CCL v25.2.1 (x86_64-pc-linux-gnu, built 2025/06/02 23:17:23, go1.23.7 X:nocoverageredesign)
• Server OS: Linux on Docker on Windows
• Client app: JDBC

Jira issue: CRDB-51915

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