How about Go's... error on unused imports?

[Clay Smith]

Bill Baxter wrote:
> On Fri, Nov 13, 2009 at 9:51 AM, Clay Smith <clay.smith.r at gmail.com> wrote:
>> Leandro Lucarella wrote:
>>> I'm sorry to bring up another "How about Go's ..." topic, but I think this
>>> feature is very in sync with D and it should be really easy to implement.
>>>
>>> Go issues an error if you have an import that's never used, to avoid
>>> unnecessary dependencies.
>>>
>>> Do you see any reasons not to do that? I think it happens very often to
>>> stop using some import and never notice it.
>>>
>> No, this is a job to be left to the IDE, not compiler.
> 
> Well, just a small argument for the contrary, but you may be importing
> some module precisely for the purpose of getting its module
> constructors to run.  For instance the module constructor may have a
> call like RegisterComponent(thisModule) in it.  Think of a set of
> image format loaders that register themselves with the main
> ImageLoader module.  Then you call ImageLoader.load(filename).
> Nowhere in your code do you care if it is a PNG or not.  You only need
> to use the ImageLoader's API.
> 
> Also there's public imports.  And all.d type modules with nothing but
> pubilic imports.
> 
> There's no way an IDE can know about those intents.  So that argues
> that there should be a way in the language to indicate "i know it
> doesn't look like I'm using this, but I am".   And if that's in the
> language then the compiler might as well do the checking, too.
> 
> Ok, not a super strong argument... unless D changed to compile things
> the way Go does, rolling in all deps.
> 
> How about that one from Go?  Including all deps in an obj.  Could D
> use the same trick to speed up compilation further?
> 
> --bb

I'm not really understanding what you are saying, but I see no need for 
the compiler to error on unused import. If anything, the compiler can 
just ignore it, or have a flag to find unused imports. I would like my 
all.d files to not give errors :o