Re: Recent failures on buildfarm member hornet

Noah Misch <noah(at)leadboat(dot)com> writes:
> On Tue, Oct 06, 2020 at 09:56:49PM -0400, Tom Lane wrote:
>> Now that *is* surprising. Could you poke a little further to determine
>> which module is getting miscompiled? (gram.o seems like the next most
>> likely bet.)

> gram.o was it. (The way I rebuilt gram.o also rebuilt parser.o and scan.o,
> but those seem far less likely.)

This suggests that the problem is misoptimization of gram.y's
makeOrderedSetArgs:

/* don't merge into the next line, as list_concat changes directargs */
ndirectargs = list_length(directargs);

return list_make2(list_concat(directargs, orderedargs),
makeInteger(ndirectargs));

I think that if the compiler did what the comment says not to, it'd match
this symptom. However, I'm baffled as to why our recent pg_list.h changes
would've affected that.

regards, tom lane