Suppose I have a file with a simple templated function. I compile that to a static library. I then compile another file that uses the library into an executable. When compiled to the static library, you don't know in advance what types it will call on the templated function, so that must be resolved when compiling the executable. So what information is in the static library that allows this to take place? Is the library just a simple collection of object files?

On Monday, 11 March 2019 at 19:53:53 UTC, jmh530 wrote:
> So what information is in the static library that allows this to take place?

None. The information is in in the source or interface file (.d/.di). Templates can't be compiled before they're instantiated.

On Mon, Mar 11, 2019 at 07:53:53PM +0000, jmh530 via Digitalmars-d-learn wrote:
> Suppose I have a file with a simple templated function. I compile that to a static library. I then compile another file that uses the library into an executable. When compiled to the static library, you don't know in advance what types it will call on the templated function, so that must be resolved when compiling the executable. So what information is in the static library that allows this to take place? Is the library just a simple collection of object files?

Templates are never compiled into any object code.  Only template instantiations are.

This is why you cannot elide the template body from a .di file -- because in order to instantiate the template, the compiler must know the full definition of the template.  Unlike functions, where you can just declare the function signature, and the body can be an opaque binary blob that's only supplied in a precompiled object/library file.


T

-- 
Famous last words: I wonder what will happen if I do *this*...

On Monday, 11 March 2019 at 20:11:37 UTC, ag0aep6g wrote:
> On Monday, 11 March 2019 at 19:53:53 UTC, jmh530 wrote:
>> So what information is in the static library that allows this to take place?
>
> None. The information is in in the source or interface file (.d/.di). Templates can't be compiled before they're instantiated.

Ah, so you need the .lib files and the .di files to get it work.

On 2019-03-11 21:59, jmh530 wrote:

> Ah, so you need the .lib files and the .di files to get it work.

You need the .di or .d files regardless if it's a template or not. Because you need to know which declarations are available. In addition to that, for templates the source (and not just the declaration) need to be present as well in the .di/.d files.

-- 
/Jacob Carlborg