Re: [sqlsmith] Failed to generate plan on lateral subqueries

I wrote:
> Ah-hah --- the new check I added in join_is_legal understood about
> chains of LATERAL references, but it forgot that we could also have chains
> of outer-join ordering constraints. When we're looking to see if joining
> on the basis of a LATERAL reference would break some later outer join, we
> have to look at outer joins to the outer joins' inner relations, too.

> Fixed in the attached. I also stuck all of join_is_legal's
> lateral-related checks inside an "if (root->hasLateralRTEs)" block,
> which will save some time in typical queries with no LATERAL. That
> makes that section of the patch a bit bigger than before, but it's
> mostly just reindentation.

As threatened, here's a patch on top of that that gets rid of
LateralJoinInfo. I'm pretty happy with this, although I have an
itchy feeling that we could dispense with the lateral_vars lists too.

regards, tom lane