Re: [HACKERS] Lost a function overloading capability in v6.3

From: jwieck(at)debis(dot)com (Jan Wieck)
To: lockhart(at)alumni(dot)caltech(dot)edu (Thomas G(dot) Lockhart)
Cc: jwieck(at)debis(dot)com, meskes(at)topsystem(dot)de, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] Lost a function overloading capability in v6.3
Date: 1998-03-04 15:10:19
Message-ID: m0yAFoK-000BFRC@orion.SAPserv.Hamburg.dsh.de
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Tom wrote:
>
> > > > > When I run this same thing on v6.3, I get a date sometime in 1974 which
> > > > > I think might actually be derived from a pointer interpreted as an
> > > > > integer :(
> >
> > The bug is that when the language is internal but the
> > function isn't in the builtin table, fmgr_info() (in fmgr.c)
> > doesn't set fn_nargs. So fmgr_c() calls abstime_datetime()
> > without arguments.
> >
> > Add
> >
> > finfo->fn_nargs = procedureStruct->pronargs;
> >
> > in the INTERNALlanguageId arm of the switch in fmgr.c (line
> > 198).
>
> THANKS JAN! I was just getting started doing a binary search of the source trees
> trying to find when the problem was introduced. This saved me a _lot_ of time...
>
> I just tried it and it works! I added the line just below the elog(ERROR) check
> in that same block of code.
>
> Now, should this be done conditionally or is it OK to set this all the time? I
> looked back at the v6.2.1 code and this field was not explicitly set in this
> area, so has the behavior of something else changed? What would you suggest??

I think it's O.K. to set it all the time. As far as I can
see, the declarations for the builtin functions have the
correct nargs settings (varcharin 3 args). And this is what
they have in the pg_proc's pronargs attribute. Adding the
above line only touches overloading builtin functions. Since
the call of such an overload goes through fmgr_c(), it MUST
be done (fmgr_c must know how many arguments to pass).

Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#======================================== jwieck(at)debis(dot)com (Jan Wieck) #

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