[geos-devel] NEWS comments

[Greg Troxel]

Sebastiaan Couwenberg <sebastic at xs4all.nl> writes:

> On 8/21/18 3:04 PM, Regina Obe wrote:
>> gdt said

>>>   The C++11 description is not entirely clear to me, and I think it
>>>   should be extra loud up front.  It's a big deal as many systems have
>>>   default compilers that are too old for C++11 (but this is a widespread
>>>   issue with the combination of C++ and gcc).
>> [Regina Obe] 
>> Agreed will bring to the top of the news
>
> C++11 is being adopted by other major components in the geospatial
> ecosystem, GDAL most notably. This just means that people stuck with
> compilers that don't support C++11 cannot build those new releases of
> the projects in question. That's not much different than requiring
> features of recent Qt5 releases for example, if you systems cannot
> provide that, you're stuck with older releases.

True, and note that I did not complain that C++11 was being required,
just that the explanation of what that meant was not clear enough.

Specifically, i wondered whether I needed to put a "force c++11" line in
the pkgsrc control file that's used when other packages link against
geos.

>>>   Presumably there is no requirement to use C++11 anything to link
>>>   against geos_c.   Perhaps that should be stated, even though it would
>>>   be bizarre otherwise, given the amount of trouble that the C++/gcc
>>>   siutation has caused.
>> [Regina Obe] 
>> I would think not.  Can someone else confirm this question?
>
> Projects shouldn't use the GEOS C++ API, if they do, they get to deal
> with the consequences (I'm looking at you OSSIM).

I have a note that gdal uses the GEOS C++ API as well, and my gdal 2.2.4
installation broke after updating geos (and not rebuilding gdal yet):

$ldd /usr/pkg/lib/libgdal.so|grep geos
        -lgeos_c.1 => /usr/pkg/lib/libgeos_c.so.1
        -lgeos-3.7.0 => /usr/pkg/lib/libgeos-3.7.0.so
        -lgeos-3.6.2 => not found

(which I think is depending on the c lib, and then the c++)


> All projects, except ossim, in Debian that build on GEOS use the stable
> C API which is not affected by the C++11 compiler requirements.

That is as I epxected, but I just find this situation often more tricky
than expected.

> From what I've seen of C++11, you probably want to adopt it for your C++
> project anyhow, so if GEOS requiring it pushes that issue to the
> forefront that's a good thing.

That's a separate issue.  I'm coming at this from the point of view of
packaging many things each of which has their own requirements,
sometimes conflicting.  While I get your point about C++ needing to move
to C++11, pkgsrc is also enabling people to build the non-C++11 subset
of the world on systems with older compilers.  So I'm just trying to
encode what's required, and I really did not mean to complain about how
things are, just to ask that it be really clear in NEWS.
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