DMD Refuses to Compile Multiple Source Files

[Mike Parker via Digitalmars-d-learn]

On Wednesday, 18 January 2017 at 04:06:23 UTC, Samwise wrote:
> On Wednesday, 18 January 2017 at 03:51:50 UTC, ketmar wrote:
>> On Wednesday, 18 January 2017 at 03:37:46 UTC, Samwise wrote:
>>> extern int getReturnCode() {
>>> 	return 4;
>>> }
>>>
>>> still does not compile using the command from above. I may 
>>> very well be misunderstanding you though.
>>
>> yep. *both* prototype and real declaration should b
>> `extern(C)`. `(C)` part is important too!
>
> I have both the header in hello.d and the actual function in 
> getReturnCode.d as extern, and it still fails with the same 
> error.

extern(C), not simply extern. It turns off the name mangling. But 
really, the proper thing to do is to drop the prototype and 
import the module with the implementation. It's tge way modules 
are intended to be used. Unless you're doing something specidic 
like writing a library that calls an arbitrary user function.