[cmake-developers] Should CMAKE_LINK_DEPENDS_NO_SHARED be on by default?

[Matthew Woehlke]

On 2013-02-25 14:00, Brad King wrote:
> On 02/25/2013 01:29 PM, Matthew Woehlke wrote:
>> On 2013-02-24 10:29, Stephen Kelly wrote:
>>> CMAKE_LINK_DEPENDS_NO_SHARED was introduced in this cycle, but off by
>>> default. It seems useful enough to be on by default. Is there any reason not
>>> to enable it by default?
>>
>> What is the use case for this?
>>
>> I'm having a hard time imagining a case where it buys you anything. What
>> would cause a .so to change often that you would *not* want to re-link?
>
> The case here is that when a .so re-links its *dependents* do not
> need to be re-linked too.  Since the .so is not statically linked
> into the dependents they should not need to be linked again.  The
> dynamic loader will simply see the updated .so at runtime.  Refer
> back to the thread I linked earlier:
>
>   http://thread.gmane.org/gmane.comp.programming.tools.cmake.user/43246/focus=44469

I guess I'm still not seeing it without rereading the entire thread. 
Anyway, thanks for the quick explanation.

I guess my personal opinion is that I can think of enough theoretical 
ways where a relink might be needed, and haven't encountered a project 
where the relink cost is sufficiently high, to feel that I would 
personally want to not relink.

If CMake could somehow compare the public API that was previously 
linked, versus the new flavor thereof, I would probably be more willing 
to trust such an optimization. (One could also argue that this would be 
a better job for the build tool.)

-- 
Matthew