Re: Question about duplicate JSONTYPE_JSON check

On 2025-Mar-12, Amit Langote wrote:

> I was able to construct a test case that crashes due to this bug:
>
> CREATE TYPE mood AS ENUM ('happy', 'sad', 'neutral');
> CREATE FUNCTION mood_to_json(mood) RETURNS json AS $$
> SELECT to_json($1::text);
> $$ LANGUAGE sql IMMUTABLE;
> CREATE CAST (mood AS json) WITH FUNCTION mood_to_json(mood) AS IMPLICIT;
>
> SELECT JSON_OBJECT('happy'::mood: '123'::jsonb);
> server closed the connection unexpectedly

Good reaction time :-) I see that that line shows as not even uncovered
in the report, but as non-existant (no background color as opposed to
red):

https://coverage.postgresql.org/src/backend/utils/adt/jsonb.c.gcov.html#660

Evidently the compiler must be optimizing it out as dead code.

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"Update: super-fast reaction on the Postgres bugs mailing list. The report
was acknowledged [...], and a fix is under discussion.
The wonders of open-source !"
https://twitter.com/gunnarmorling/status/1596080409259003906