Re: CAST(... ON DEFAULT) - WIP build on top of Error-Safe User Functions

On Mon, Mar 30, 2026 at 4:57 PM Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>
> From the v25 I have committed everything except 0001 and 0009. I will
> continue reviewing the rest.
>

I’ve had a glance over the remaining patches; here are a few comments:

V25-0001:

- if (relation->schemaname)
+ if (escontext == NULL)
ereport(elevel,
- (errcode(ERRCODE_UNDEFINED_TABLE),
- errmsg("relation \"%s.%s\" does not exist",
- relation->schemaname, relation->relname)));
+ errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+ relation->schemaname ?
+ errmsg("relation \"%s.%s\" does not exist",
+ relation->schemaname, relation->relname) :
+ errmsg("relation \"%s\" does not exist",
+ relation->relname));
else
- ereport(elevel,
- (errcode(ERRCODE_UNDEFINED_TABLE),
- errmsg("relation \"%s\" does not exist",
- relation->relname)));
+ ereturn(escontext, InvalidOid,
+ errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+ relation->schemaname ?
+ errmsg("relation \"%s.%s\" does not exist",
+ relation->schemaname, relation->relname) :
+ errmsg("relation \"%s\" does not exist",
+ relation->relname));
}

The error code changed here -- was this intentional?
--

v25-0009 :

+SELECT CAST('abc'::bpchar AS citext DEFAULT NULL ON CONVERSION ERROR); -- error
+ERROR: cannot cast type character to citext when DEFAULT expression
is specified in CAST ... ON CONVERSION ERROR
+LINE 1: SELECT CAST('abc'::bpchar AS citext DEFAULT NULL ON CONVERSI...
+ ^
+HINT: Safe type cast for user-defined types are not yet supported.

"Should the HINT be this DETAIL? I believe a hint should provide
guidance for the user to handle the error, but here the user cannot do
anything with the given information.
--

/* Generic macro for applying evaluate_expr */
-#define ece_evaluate_expr(node) \
+#define ece_evaluate_expr(node, escontext) \
((Node *) evaluate_expr((Expr *) (node), \
exprType((Node *) (node)), \
exprTypmod((Node *) (node)), \
- exprCollation((Node *) (node))))
+ exprCollation((Node *) (node)), \
+ escontext))

I think we can simply cast escontext to Node * here, instead of
having the caller do it.

Regards,
Amul