Re: Precedence of standard comparison operators

On 2/19/15 10:48 AM, Tom Lane wrote:
> I've not really experimented with this at all; it would be useful for
> example to see how many regression tests break as a gauge for how
> troublesome such changes would be.  I thought I'd ask whether there's
> any chance at all of such a change getting accepted before doing any
> serious work on it.

I think we should try to do it, but we need a way for users to see what
is going on.  If we just put into the release notes, "the precedences of
>= and <= have been changed, but we don't expect this to cause many
problems", there might be wide-spread panic.

One way would be to have a knob that warns/logs/debugs when it sees an
<= or >= call in a place that would change meaning.  Perhaps in
transformAExprOp().  This might be an expensive check, but it wouldn't
have to be on all the time.  We could also add a flag to the A_Expr node
that remember whether the expression was parenthesized, so that users
could update their code with parentheses to shut the warning up.

I think this would be a standard_conforming_strings-like transition.