Lib change leads to larger executables

[Kristian Kilpi]

On Wed, 21 Feb 2007 11:00:44 +0200, Walter Bright  
<newshound at digitalmars.com> wrote:

>> It does, but increases the exe size of the first example from 180kb to  
>> 617kb!
>  > 180kb is when compiled using build/rebuild/jake etc (no library) and  
> the 617kb
>  > is when using dmd+lib only. Same flags in both cases: none at all
>
> Let's say you have a template instance, TI. It is declared in two  
> modules, M1 and M2:
>
> -----------M1------------
> TI
> A
> -----------M2------------
> TI
> B
> -------------------------
>
> M1 also declares A, and M2 also declares B. Now, the linker is looking  
> to resolve TI, and the first one it finds is one in M1, and so links in  
> M1. Later on, it needs to resolve B, and so links in M2. The redundant  
> TI is discarded (because it's a COMDAT).
>
> However, suppose the program never references A, and A is a chunk of  
> code that pulls in lots of other bloat. This could make the executable  
> much larger than if, in resolving TI, it had picked M2 instead.
>
> You can control which module containing TI will be pulled in by the  
> linker to resolve TI, by specifying that module first to lib.exe.
>
> You can also put TI in a third module that has neither A nor B in it.  
> When compiling M1 and M2, import that third module, so TI won't be  
> generated for M1 or M2.

Here's a quick thought. (It's probably too impractical/absurd. ;) ) Could  
template instances to be put to their own, separate modules? Then the  
linker will find a module containing the template instance only, and no  
bloat will be pulled in with it. I don't know if this would require the  
compiler to generate separate, extra .obj files for template instances or  
something.