Re: Odd behavior with PG_TRY

On Mon, Jan 2, 2017 at 11:14 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> wrote:
> In the attached patch (snippet below), I'm seeing something strange with
> args->in.r.atts[]. Prior to entering the PG_TRY block, I can inspect things
> in lldb just fine:
>
> (lldb) call args->in.r.atts[0].func
> (PLyDatumToObFunc) $49 = 0x000000010fc4dc70
> (plpython3.so`PLyString_FromDatum at plpy_typeio.c:621)
> (lldb) call &args->in.r.atts[0]
> (PLyDatumToOb *) $50 = 0x00007fd2b302f6d0
> (lldb) call args->in.r.atts[0]
> (PLyDatumToOb) $51 = {
> func = 0x000000010fc4dc70 (plpython3.so`PLyString_FromDatum at
> plpy_typeio.c:621)
> typfunc = {
> fn_addr = 0x000000010f478b50 (postgres`textout at varlena.c:521)
> fn_oid = 47
> ...
>
> But I'm getting a EXC_BAD_ACCESS (code=1, address=0xb302f6d0) on the last if
> in the snippet below. Looking at the variables again, I see:
>
> (lldb) call args->in.r.atts[i].func
> error: Couldn't apply expression side effects : Couldn't dematerialize a
> result variable: couldn't read its memory
> (lldb) call args->in.r.atts[i]
> error: Couldn't apply expression side effects : Couldn't dematerialize a
> result variable: couldn't read its memory
>

Looks strange, what is the value of 'i'? Did you get the same result
if you try to print args->in.r.atts[0] inside PG_TRY?

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com