[vtk-developers] VTK updated to CMake 3.3 and C++11

[Andrew Maclean]

This change in CMakeLists.txt will cause problems in Visual Studio:
---
if( NOT cxx_nullptr IN_LIST CMAKE_CXX11_COMPILE_FEATURES)
  option(VTK_IGNORE_CXX11_REQUIREMENT OFF)
  if(NOT VTK_IGNORE_CMAKE_CXX11_CHECKS)
    message(FATAL_ERROR "VTK now requires a compiler that supports C++11")
  endif()
endif()
---
because CMAKE_CXX11_COMPILE_FEATURES is always empty for MSVC compilers.

Anyway, if you look at
https://msdn.microsoft.com/en-us/library/hh567368.aspx
nullptr is probably a bad one to test for with microsoft compilers as it
has been supported since VS 2010.

Could I suggest using *CMAKE_CXX_COMPILER_ID* and
*CMAKE_CXX_COMPILER_VERSION* instead?

For example:
*message(STATUS "Compiler ID/Version: ${CMAKE_CXX_COMPILER_ID}
${CMAKE_CXX_COMPILER_VERSION}")*
WIll give you a line like:
*The CXX compiler identification is MSVC 19.0.24215.1*
It also works with gcc.

Regards
   Andrew





> ---------- Forwarded message ----------
> From: Robert Maynard <robert.maynard at kitware.com>
> To: vtk vtk <vtkusers at vtk.org>, VTK Developers <vtk-developers at vtk.org>
> Cc:
> Date: Wed, 18 Jan 2017 12:11:21 -0500
> Subject: [vtk-developers] VTK updated to CMake 3.3 and C++11
> I am happy to announce that over the last two weeks we have rolled out a
> series of updates to VTK that mean the minimum required CMake version
> is now 3.3 (see below), and now builds with C+11 enabled.
>
> Yes VTK now requires a C++11 capable compiler. Initial we are only asking
> for a
> minimal set of C++11 features (nullptr), but as continue forward through
> the
> year we are going require a larger set of C++11 features. The final 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+
>
> I wanted to send this announcement out to bring up a couple of points:
>
> 1. Thanks to everyone that has helped get VTK ready for C++11! The final
> CMake
> switch over to C++11 was very easy, only because of all the hard work that
> other
> developers did in anticipation of this. So thank you very much.
>
> 2. The major reason for this slow roll out of C++11 is so that we minimize
> the
> impact on current VTK merge requests, while also minimizing dashboard
> instability. Contributors please be aware of these changes if you have long
> running branches.
>
> 3. We currently have dashboard machines running GCC 4.6 & 4.7. We are
> currently
> working up a plan on how best to transition these machines to at least GCC
> 4.8
> as the roll out continues.
>
> 4. The current MinGW dashboard machine doesn't support C++11 and will be
> removed, with no plan of a replacement at Kitware. If the community is
> interested in maintaining a newer MinGW machine I can provide assistance
> on how to setup a machine.
>
>
> ============
>
> Why CMake 3.3:
>
> 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 ).
>
> - 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.
>
>
>
>

-- 
___________________________________________
Andrew J. P. Maclean

___________________________________________
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