[swift-evolution] ? suffix for <, >, <=, >= comparisons with optionals to prevent subtle bugs

[Jacob Bandes-Storch]

Agreed — or, I think, these operators could/should simply be removed.

I filed <rdar://22833869> about this a while ago, which was marked as
Duplicate/<rdar://16966712>.

Summary:
> This returns true:
>     (nil as Int?) < 0
> This also returns true, which makes even less sense:
>     (nil as Int?) < Int.min



Expected Results:
> nil < 0, nil > 0, and nil == 0, should all be false. nil != 0 should be true.
> Alternatively, just *don't* provide < and > operators that accept optional arguments.



Actual Results:
> nil < 0 is true. Others are as expected.


See also: https://twitter.com/jtbandes/status/646914031433871364


Jacob

On Thu, Dec 3, 2015 at 3:42 PM, Amir Michail <a.michail at me.com> wrote:

> Such comparisons with optionals can result in hard to find bugs.
>
> For example consider:
>
> let f = x < 5  // x is of type Int? and may be nil
>
> The proposed ? suffix would be used as follows and makes the possibility
> of nil very clear:
>
> let f = x? < 5
>
>
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