lseg_horizontal(PG_FUNCTION_ARGS)
{
	LSEG	   *lseg = PG_GETARG_LSEG_P(0);

	PG_RETURN_BOOL(FPeq(lseg->p[0].y, lseg->p[1].y));
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.