Re: [HACKERS] merging some features from plpgsql2 project

Jim Nasby <Jim.Nasby@BlueTreble.com> writes:
> On 1/7/17 5:39 AM, Pavel Stehule wrote:
>> I checked current implementation of FOUND variable. If we introduce new
>> auto variable ROW_COUNT - exactly like FOUND, then it doesn't introduce
>> any compatibility break.

> Except it would break every piece of code that had a row_count variable,
> though I guess you could see which scoping level the variable had been
> defined in.

If FOUND were declared at an outer scoping level such that any
user-created declaration overrode the name, then we could do likewise
for other auto variables and not fear compatibility breaks.

Currently, though, we don't seem to be quite there: it looks like
FOUND is an outer variable with respect to DECLARE blocks, but it's
more closely nested than parameter names.  Compare:

regression=# create function foo1(bool) returns bool as
'declare found bool := $1; begin return found; end' language plpgsql;
CREATE FUNCTION
regression=# select foo1(true);
 foo1
------
 t
(1 row)

regression=# create function foo2(found bool) returns bool as
regression-# 'begin return found; end' language plpgsql;
CREATE FUNCTION
regression=# select foo2(true);
 foo2
------
 f
(1 row)

Not sure if changing this would be a good thing or not --- was
there reasoning behind this behavior, or was it just accidental?

                        regards, tom lane