Changing the behavior of the comma operator

[Martin Nowak]

On Tuesday, 25 March 2014 at 17:33:20 UTC, Andrei Alexandrescu
wrote:
> 2. The semantics is the same unless warnings are enabled with 
> "-w"
>
> 3. In "-w" mode, semantics are changed in that the type of the 
> comma operator is NOT the type of its last expression, but 
> instead it's void.
>
> 4. Later on the warning will be promoted to a deprecation 
> followed by removal from the language.

Semantic changes based on warning or deprecation flags are a bad
idea, because it breaks code unless warnings are disabled.
The cycle should go warning => deprecation => semantic
change/removal, each step taking 6 month.