[vtk-developers] Plan to make CMake 3.3 and C++11 required

[Robert Maynard]

We have merged in the branch to require CMake 3.3 today. So I will be
keeping an eye on the dashboard machines and updating machines over
the next couple of days.

I also expect to have a MR open end of this week that will explicitly
enable C++11 with a goal to have that merged in on Monday Jan 16.

On Wed, Jan 4, 2017 at 2:06 PM, Robert Maynard
<robert.maynard at kitware.com> wrote:
> As we start a new year, it is time to announce that we are planning on
> rolling out a series of updates to VTK that are starting with the update
> of the minimum required CMake version.
>
> We have chosen CMake 3.3 as the minimum required version for numerous reasons,
> the most important of those reasons being:
>
> - It is the first CMake release that offers C++11 support for all four major
>   compilers ( GCC / MSVC / Clang / XCode ). [1]
>
> - The CMake version is sufficiently new enough that it allows for a cleaning
>   of the existing CMake infrastructure. The current CMake minimum version
>   requires VTK to maintain forks of numerous FindPackages and Modules that are
>   part of newer CMake versions.
>
> - Supports HTTPS downloads, with all the official binaries come with support.
>   Allowing for migration of external data to a HTTPS only server. Something we
>   are going to require in the near future. [2]
>
> As mentioned above this year we have a series of upgrades planned to VTK which
> require moving the minimum CMake version to 3.3. The most significant
> of these changes to all developers is the requirement of a C++11 capable
> compiler.
>
> Yes you heard that correct, VTK is going to soon require a C++11 capable
> compiler. To be more exact we are going to require a compiler that understands
> the significant majority of the C++11 language and runtime additions. The exact
> versions for each compiler have not been set in stone, but a rough estimation
> would be:
>   - GCC 4.8+
>   - Clang 3.3+
>   - XCode 5.0+
>   - MSVC 2013+
> As we progress through the year, I expect a more concrete list of supported
> compilers will be determined and documented.
>
> Now the roll out for C++11 support is going to happen in multiple stages
> with an initial plan being:
>
> Stage 1: We require CMake 3.3, upgrade all dashboards, work through developer
>          reported issues with the version bump
>
> Stage 2: Explicitly enable C++11 compiler flags during CMake
> configuration. Again
>          we will have to upgrade/retire dashboards, work through developer
>          reported issues.
>
> Stage 3: Update the VTK Coding Standards for C++11.
>
> Stage 4: Allow C++11 to be used in VTK ( outside currently permitted usage ).
>
> Notes:
>
> 1 - If you are using a different compiler vendor than one of those listed above
>     please see if it is currently supported
>     ( https://cmake.org/cmake/help/v3.7/manual/cmake-compile-features.7.html ).
>     If the vendor is not explicitly listed please contact me, so we can discuss
>     what options are available.
>
> 2 - https://data.kitware.com is transitioning to be the location for all
>     external data, and requires a SSL connection.