Re: help wanted (fmgr.c)

At 2006-09-11 10:25:22 +0200, pgdev(at)xs4all(dot)nl wrote:
>
> What are we testing to be NULL here?
> Do we expect str to changed at line 1715

No. (Read the comment just above the function.)

The code is like this, starting from line 1703:

if (str == NULL && flinfo->fn_strict)
return (Datum) 0;

That is, if the function is declared strict, and the argument (str) is
0, just return NULL straightaway. Then it sets up the fcinfo and calls
the function, and then:

...

/* Should get null result if and only if str is NULL */
if (str == NULL)
{
if (!fcinfo.isnull)
elog(ERROR, "input function %u returned non-NULL",
fcinfo.flinfo->fn_oid);
}
else
{
if (fcinfo.isnull)
elog(ERROR, "input function %u returned NULL",
fcinfo.flinfo->fn_oid);
}

This says: If the argument is NULL and the input function didn't return
a NULL, log an error; but if the argument is non-NULL and the function
returned NULL, log this other error. (Note that a function would set
fcinfo->isnull to indicate that it wants to return an SQL NULL, as
explained in $DOC/plhandler.html)

-- ams