[Dune-devel] Required CMake version

[Dominic Kempf]

Hey everybody,

I was a bit silent about this during the last days, as I do not care as
much about the CMake requirements
(in one direction or the other actually). But I would like to give some
input as to why we proposed a higher
CMake requirement a while ago:

The dune enable all packages feature only works partially with cmake lesser
than 3.1.
In fact it currently errors out under some circumstances:
https://gitlab.dune-project.org/core/dune-common/blob/master/cmake/modules/DuneEnableAllPackages.cmake#L275
Although only Dune modules that build libraries and link executables
against these are affected,
we considered it cleaner to just raise the CMake bar.

After all, I think that the enable all packages feature has brought quite a
bit of convenience for our users -
I havn't seen a bug report/mailing list question that could be solved by
call dune_add_mpi_flags ever since its introduction.
Before those happened several times a year.

I hope that helps a fact-based discussion of the topic,
Best,
Dominic

On Thu, Jan 4, 2018 at 11:12 AM, Christian Engwer <
christian.engwer at uni-muenster.de> wrote:

> Dear Christoph,
>
> Thanks for partially answering my questions :-)
>
> I start with one further important question:
>
> > What is dangerous, if dune-common requests 3.1 but downstream modules
> > use 2.8.12. Then CMake is in the wrong mode and will interpret things
> > differently. That is what we called "subtle bugs".
>
> what happens if downstream modules impose higher requirement? Is this
> also dangerous?
>
> This is what happened before and this was one of the arguments to jump
> to the newer version. Following this argument, dune-core would loose
> control over which version to require.
>
> and then to your answers
>
> > 2) Steffen and Dominic found some bugs in older CMake version, and they
> > wished to switch to CMake 3.1 already in 2015. Having the switch with
> > Dune 2.6 seems reasonable.
>
> again this is extremely vague. If we had specific cmake code, which is
> necessary to work around bugs in cmake < 3.1 and is hard to maintain I
> would have guessed, that someone updates this code, but this has not
> happened.
>
> As such changes didn't happen for 2.6, I think Markus question,
> whether 3.1 is necessary, is totally reasonable. This does not imply
> that we need to switch back to 2.8, but asking this question should
> not be problem. And "we decided this" is not a proper answer.
>
> Best
> Christian
>
>
> _______________________________________________
> Dune-devel mailing list
> Dune-devel at lists.dune-project.org
> http://lists.dune-project.org/mailman/listinfo/dune-devel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.dune-project.org/pipermail/dune-devel/attachments/20180104/caad4ca5/attachment.htm>