Re: [EXTERNAL] Re: Q: library dependencies

[Nick Bowler]

On 2020-09-25, John Calcote <john.calcote@gmail.com> wrote:
> On Fri, Sep 25, 2020 at 10:45 AM Bob Friesenhahn 
> <bfriesen@simple.dallas.tx.us> wrote:
>> Exactly!  It might as well be a tar file except that the 'ar' archiver
>> knows how to add/update/remove files from it and that is not possible
>> with a tar file.  The ability to do incremental updates of the archive
>> file is important as objects are built/rebuilt.  The 'make' program
>> itself already understands archive files.
>>
>
> I did not know this about libtool and convenience libraries. Do you have
> any historical notion of why this was done? I ask because this sort of
> behaviour total defeats the linker's ability to discard unused objects,
> does it not?

As I mentioned elsethread, at least with current versions, this only
appears to actually happen when convenience libraries are linked into
libraries (which OP is doing).  This _has_ to happen for the use case
that convenience libraries are described to be, well, convenient for:
linking a set of common object files into multiple shared libraries.

Obviously "unused object" is a nontrivial concept when linking libraries.

Cheers,
  Nick