Re: Mark unconditionally-safe implicit coercions as leakproof

On Fri, Jul 24, 2020 at 12:17 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I went through the system's built-in implicit coercions to see
> which ones are unconditionally successful. These could all be
> marked leakproof, as per attached patch. This came up in the
> context of the nearby discussion about CASE, but it seems like
> an independent improvement. If you have a function f(int8)
> that is leakproof, you don't want it to effectively become
> non-leakproof when you apply it to an int4 or int2 column.
>
> One that I didn't mark leakproof is rtrim1(), which is the
> infrastructure for char(n) to text coercion. It looks like it
> actually does qualify right now, but the code is long enough and
> complex enough that I think such a marking would be a bit unsafe.
>
> Any objections?

IMHO, this is a nice improvement.

--
Robert Haas
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