Re: Aren't lseg_eq and lseg_ne broken?

By chance I just noticed that lseg equality is coded as

Datum
lseg_eq(PG_FUNCTION_ARGS)
{
LSEG *l1 = PG_GETARG_LSEG_P(0);
LSEG *l2 = PG_GETARG_LSEG_P(1);

PG_RETURN_BOOL(FPeq(l1->p[0].x, l2->p[0].x) &&
FPeq(l1->p[1].y, l2->p[1].y) &&
FPeq(l1->p[0].x, l2->p[0].x) &&
FPeq(l1->p[1].y, l2->p[1].y));
}

Surely this should be

PG_RETURN_BOOL(FPeq(l1->p[0].x, l2->p[0].x) &&
FPeq(l1->p[0].y, l2->p[0].y) &&
FPeq(l1->p[1].x, l2->p[1].x) &&
FPeq(l1->p[1].y, l2->p[1].y));

since I don't think I like this result:

regression=# select '[(0, 0), (1, 1)]'::lseg = '[(0, 42), (2, 1)]'::lseg;
?column?
----------
t
(1 row)

lseg_ne has the identical bug.

Checking the CVS archives, I see that this error dates back to the
original Berkeley code, so I'm a bit hesitant to just change it.
Is there any possibility that it really should work this way?

regards, tom lane

Tom Lane wrote:
> By chance I just noticed that lseg equality is coded as
>
> Datum
> lseg_eq(PG_FUNCTION_ARGS)
> {
> LSEG *l1 = PG_GETARG_LSEG_P(0);
> LSEG *l2 = PG_GETARG_LSEG_P(1);
>
> PG_RETURN_BOOL(FPeq(l1->p[0].x, l2->p[0].x) &&
> FPeq(l1->p[1].y, l2->p[1].y) &&
> FPeq(l1->p[0].x, l2->p[0].x) &&
> FPeq(l1->p[1].y, l2->p[1].y));
> }
>
> Surely this should be
>
> PG_RETURN_BOOL(FPeq(l1->p[0].x, l2->p[0].x) &&
> FPeq(l1->p[0].y, l2->p[0].y) &&
> FPeq(l1->p[1].x, l2->p[1].x) &&
> FPeq(l1->p[1].y, l2->p[1].y));

Yep, there could be no possible reason to double-test something like the
original code does. It must be wrong.

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