[swift-dev] This little program currently compiles fine, but should it?

[Chris Lattner]

> On Dec 15, 2015, at 3:42 PM, Jens Persson via swift-dev <swift-dev at swift.org> wrote:
> 
> Ok thanks, and what about the initial topic of this thread, ie stuff like this:
> 
> func f() {
>     1; "two"; 3.0
>     [4, 5]; 6 * 7
>     print("No warnings or errors!")
> }
> f() // No warnings or errors!
> 
> Should I file a bug for that too or is this by design / has this been discussed somewhere already?

There is a discussion on the swift-evolution mailing list about making “@warn_unused_results” semantics the default for all non-void functions.  To me, that seems like the cleanest path to address these issues.

-Chris

> 
> 
> 
> On Tue, Dec 15, 2015 at 11:54 PM, Dave Abrahams <dabrahams at apple.com <mailto:dabrahams at apple.com>> wrote:
> 
>> On Dec 14, 2015, at 11:04 AM, Jens Persson via swift-dev <swift-dev at swift.org <mailto:swift-dev at swift.org>> wrote:
>> 
>> Yes, and I don't know if there is any particular reason why the == operator for Int doesn't have @warn_unused_result while the one for Doubles has:
>> 
>> func f() { 1 == 2 } // OK
>> func g() { 1.0 == 2.0 } // Warning: Result of call '==' is unused
> 
> That’s an oversight; please file a radar!
> 
>> 
>> On Mon, Dec 14, 2015 at 7:40 PM, Johan Jensen <jj at johanjensen.dk <mailto:jj at johanjensen.dk>> wrote:
>> Because currently only unused variable/constant declarations have warnings/fix-its attached to them.
>> There have been some discussion on making non-void functions warn of unused results <https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001580.html> and it’s possible that this would be in style with that.
>> Perhaps (basically) empty statements should also give a warning?
>> 
>> —Johan
>> 
>> On Mon, Dec 14, 2015 at 7:08 PM, Jens Persson via swift-dev <swift-dev at swift.org <mailto:swift-dev at swift.org>> wrote:
>> func ok() {
>>     let s = "see"; "Why are there exactly "
>>     0 == 0 * 42
>>     "warnings and errors in this code"
>>     let t = s + "?"
>>     print(t)
>> }
>> ok() // see?
>> 
>>  
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>> 
>> 
>> 
>> 
>> -- 
>> bitCycle AB | Smedjegatan 12 | 742 32 Östhammar | Sweden
>> http://www.bitcycle.com/ <http://www.bitcycle.com/>
>> Phone: +46-73-753 24 62
>> E-mail: jens at bitcycle.com <mailto:jens at bitcycle.com>
>> 
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> -Dave
> 
> 
> 
> 
> 
> 
> -- 
> bitCycle AB | Smedjegatan 12 | 742 32 Östhammar | Sweden
> http://www.bitcycle.com/ <http://www.bitcycle.com/>
> Phone: +46-73-753 24 62
> E-mail: jens at bitcycle.com <mailto:jens at bitcycle.com>
> 
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