[gdal-dev] Updating requirements to C++20 for GDAL 3.13 ?

[Greg Troxel]

Even Rouault via gdal-dev <gdal-dev at lists.osgeo.org> writes:

> 1) updating our requirements to build GDAL to C++20 ?

This basically says that gcc 10 is not good enough, and 11 should be ok
and 12 is actually ok.   That seems aggressive to me, unless there's a
compelling need.

> 2) and making use of it in our exported C++ headers ? (thus requiring
> C++ consumers of our API to also be C++20)

What bad thing would happen if we don't do that?  Aggressive standards
can be hard to deal with, and I think it is better to be conservative
especially in the exported API, absent a compelling argument.

> Our current situation is C++17 required to build GDAL, and our C++
> exported headers are C++11 compatible (except some newer ones like
> gdalalgorithm_cpp.h, and some bits in )
>
> We already have 2 (optional) dependencies requiring C++20: Poppler and
> PDFium.  The next version of libarrow/libparquet will also require
> C++20. Note that C++20 is currenly only enabled in GDAL in the drivers
> whose dependencies require it.

What problems happen if we don't bump the requirement?  As I understand
your description, C++20 is required if a driver that requires it is
enabled, and not otherwise.  That doesn't seem like a problem.