Should we deprecate comma?

[Marc Schütz" <schuetzm at gmx.net>]

On Monday, 24 March 2014 at 00:59:00 UTC, Andrei Alexandrescu 
wrote:
> On 3/23/14, 5:41 PM, Meta wrote:
>> On Sunday, 23 March 2014 at 20:56:45 UTC, Andrei Alexandrescu 
>> wrote:
>>> Discuss: 
>>> https://github.com/D-Programming-Language/dmd/pull/3399
>>>
>>> Andrei
>>
>> You mentioned on the Github PR that this broke some Phobos (and
>> Druntime?) code. What was the extent of the breakage? If it's 
>> small, I'd
>> say give it a year-long deprecation period and then be done 
>> with it
>> forever.
>
> The extent of the breakage is NOT among the top factors. Once a 
> piece of code goes from "compiles" to "doesn't compile" that 
> lowers the acceptance level by an order of magnitude. Only 
> after that, the extent of the breakage has any import.
>
> Top factors:
>
> 0. Any silent breakages or changes in semantics? 100000000x
>

None in this case.

> 1. How frequent is the breakage? Is most code going to still 
> work? 100x

Very infrequent, judging by other peoples' repsonses here, and 
the fact that there were only a handful of places in all of 
druntime and Phobos.

>
> 2. How much does fixing the breakage improve code? Was the 
> breaking code incorrect for the most part? 100x

As I wrote elsewhere, my main motivation for the PR was enabling 
a possible future tuple literal syntax, multiple return values, 
unpacking assignment and the like. The gains were therefore not 
so much in detecting wrong code, although apparently there is 
some from time to time:
https://d.puremagic.com/issues/show_bug.cgi?id=2659