[gdal-dev] Suggestion for GDAL 4.0

[Andrew C Aitchison]

On Fri, 24 Oct 2025, Javier Jimenez Shaw via gdal-dev wrote:

> One breaking change for GDAL 4.0 could be to add "gdal" to the path of the
> includes for external applications or libraries.
>
> An external application should do :
> #include <gdal/cpl_string.h>
> instead of
> #include <cpl_string.h>

That does mean that if I have multiple versions installed
they would have to be in eg
   ~/gdal/4.0/include/gdal/cpl_string.h
   ~/gdal/4.1/include/gdal/cpl_string.h
   ~/gdal/git/include/gdal/cpl_string.h

instead of just
   ~/gdal/4.0/include/cpl_string.h
   ~/gdal/4.1/include/cpl_string.h
   ~/gdal/git/include/cpl_string.h

At present a single symlink will allow external applications
to use
   #include <gdal/cpl_string.h>

If we moved the header files into include/gdal
then supporting external applications that use the old scheme
could mean a symlink for each header file.

---

The people most affected by this change are probably packagers; do we
have many of those here, or would we need to ask somewhere where they
would see ?

I note that the Ubuntu (and presumably Debian) libgdal-dev package
already has its header files in /usr/include/gdal/
and the libmapserver-dev package has /usr/include/gdal in the cmake
setting: MAPSERVER_INCLUDE_DIRS
so your suggestion might be a no-op for Ubuntu developers.

[ Also true for Scientific Linux 6 (aka Red Hat 6)
   - I don't know about current Red Hat, Fedora, CentOS, ... ]

> in a similar way as many other libraries, like Eigen
> #include <Eigen/Core>
>
> It is really a big change for other libraries and applications, I know. But
> I find useful and nice to know where are "those includes coming from" in my
> application.
>
> Cheers
> Javier.
>
> PS the same would be nice in other libraries, like libgeotiff. But I do not
> expect a mayor release there.

On Ubuntu
    dpkg-query -L libgeotiff-dev | egrep include
shows that this has also been done.

-- 
Andrew C. Aitchison                      Kendal, UK
                    andrew at aitchison.me.uk