Compile Imported Modules

[Jonathan Marler via Digitalmars-d]

On Thursday, 24 August 2017 at 18:12:03 UTC, H. S. Teoh wrote:
> On Thu, Aug 24, 2017 at 06:00:15PM +0000, Jonathan Marler via 
> Digitalmars-d wrote:
>> On Thursday, 24 August 2017 at 17:49:27 UTC, H. S. Teoh wrote:
>> > Uh, no.  This will definitely break separate compilation, 
>> > and some people will be very unhappy about that.
>> 
>> I couldn't think of a case that it would break.  Can you share 
>> the cases you thought of?
>
> Suppose you have main.d and module.d, and you want to compile 
> them separately:
>
> 	dmd -c main.d
> 	dmd -c module.d
> 	dmd -ofmyprogram main.o module.o
>
> If dmd defaulted to auto-importing, then `dmd -c main.d` would 
> also compile module.d (assuming main.d imports `module`), 
> contrary to what was intended in a separate compilation 
> scenario, and the last command will produce a linker error from 
> duplicated symbols.
>
> This is just a simple case, of course. But in general, changing 
> the meaning of `dmd -c source.d` will break existing build 
> scripts.  Sure, you could ask people to update their build 
> scripts to include `-no-auto-imports`, but that requires effort 
> from users, who will be unhappy that upgrading dmd broke their 
> build scripts.  For large projects, such a change may not be 
> trivial as in the above example.
>
>
> T

Actually this feature is mutually exclusive with the "-c" case.  
It doesn't make sense to compile imported modules unless you are 
also linking an executable.  So your example would work as 
expected.

Do you have any other cases you thought of that would not work? 
Like I said I couldn't think of any.  I'm not saying that that's 
enough reason to make it an "opt-out" feature, it's just 
something to think about.  The feature could also be an "opt-in" 
feature at first and eventually made "opt-out" if it makes sense. 
  But I'd still like to know people's thoughts/concerns either way.