Detector for unused variables

[Jonathan M Davis]

On Monday, July 30, 2012 21:02:14 Namespace wrote:
> That's right. But the majority of programming languages has this
> feature, but D does not. This feature is undeniable effective, so
> IMO there is no reason which stands against a warning for unused
> variables. Or can you tell me some personal reasons, without
> quoting Walter?

Aside from the fact that it can be really annoying when the compiler complains 
about unused parameters? I believe that the bug report that you posted to 
includes some discussion on some of the technical issues caused by making 
unused variables a warning. In particular, it causes problems for generic code 
as well as template constraints. A _lot_ of templates used for template 
constraints would generate warnings if usused variables were a warning. So, 
if you were compiling with -w, it would become _very_ easy to have your 
program not compile. And there are plenty of cases where generated code ends 
up with unused variables, and it's fine.

I grant you that it's undesirable to have unused variables sitting around in 
most functions, but there _are_ cases where disallowing that (as making it a 
warning effectively does) causes problems. This is the sort of thing that's 
better left to a lint-like tool IMHO.

- Jonathan M Davis