Re: New CORRESPONDING clause design

Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> 2017-03-18 17:50 GMT+01:00 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
>> I'm not impressed by using A_Const for the members of the CORRESPONDING
>> name list. That's not a clever solution, that's a confusing kluge,
>> because it's a complete violation of the meaning of A_Const. Elsewhere
>> we just use lists of String for name lists, and that seems sufficient
>> here. Personally I'd just use the existing columnList production rather
>> than rolling your own.

> The reason was attach a location to name for more descriptive error
> message.

[ shrug... ] The patch fails to actually use the location anywhere.
If it had, you might have noticed that it's attaching the wrong location
to all elements except the first :-(. So I'm not very excited about that.
I definitely don't see a reason for CORRESPONDING to track locations of
name list elements when no other name list productions do. It might be
worth proposing a followon patch to change all of them (perhaps by adding
a location field to struct "Value") and then make use of the locations in
error messages more widely.

regards, tom lane