After a short search I found a post which says, that currently 
and in future no warning is shown if unused variables exist. Is 
that correct?

On Thursday, May 10, 2012 22:30:14 Namespace wrote:
> After a short search I found a post which says, that currently
> and in future no warning is shown if unused variables exist. Is
> that correct?

There is not currently any such warning, and I wouldn't expect there to ever 
be one. As I understand it, Walter Bright finds them to be annoying, so they're 
unlikely to be added, just because of that. But it would also cause issues for 
some generic/generated code to have to worry about unused variables, so there 
are also technical issues why warning about them would be a problem.

The online documentation _does_ incorrectly state that unused local variables 
is an error, which caused some debate when that was brought up. There's also a 
related bug report ( http://d.puremagic.com/issues/show_bug.cgi?id=3960 ).

So, it's not 100% certain that there will never be a warning for unused 
variables, but I'd be surprised if such a warning was ever added.

- Jonathan M Davis

Ah, I see.
I wrote a short code that detects "normal" unused variables. 
"Normal" means those variables, which has built-in types.  This 
means, that no types created by the user/programmer will detect. 
Furthermore, it doesn't detect arrays yet, but maybe there are 
some people here, who would help me to complete it.

unused_vars.d: http://codepad.org/K5OCjlF3
unused_test.d: http://codepad.org/Bk9cXqD2
vertex.d: http://codepad.org/G1HH31Kx

Compile and run with: unused_vars <file>, e.g. unused_vars 
unused_test.d

At this point I would also like to ask if there is something that 
identifies unused imports?

No interest, I see.
I improved the code again. Now, even user-defined types, and 
(associative) arrays detected.
I'm sure there are a lot of situations where my code will fail, 
but I will continue working on it.
Therefore criticisms and suggestions were really helpful.

The new code: http://codepad.org/lvAFx4oP

And two new test files:
http://codepad.org/SgezNiYm
http://codepad.org/y2NYrEgt