CMake build for fluidity

[jrper]

In a previous issue ( #113 ) @ggorman suggested migrating fluidity to use CMake as its build system would make some of our support issues (particularly VTK) easier. Over the long weekend I've been experimenting with getting a working build together (see the branch https://github.com/FluidityProject/fluidity/tree/cmake_build). It's not finished yet, and brought up some other issues I'll be questioning shortly, but to summarise my findings so far:

1. VTK is indeed really easy, and PETSc isn't too nasty either
2. The language syntax makes a bit little bit more sense as a new user than autoconf, and feels a bit more like a programming exercise
3. The cross-compiler and cross-platform support is good,

however, as @stephankramer said, debugging is annoying and it's unclear which of multiple routes is the best way to pass a given flag to a given compiler.

I'm assuming this will be a won't fix, but I thought I'd open this to further discussion, particularly in the case that there's interest in having an experimental or unsupported CMake build scheme available for people on weird systems.

[stephankramer]

Had a quick look at that branch, and it looks great! Would be very interested to have a more detailed, offline discussion about how far you got.

[tmbgreaves]

Thanks from me also - currently completely tied up with learning the intricacies of Jenkins plus docker but very interested to discuss / look at this more when time permits.

[Patol75]

I am terribly late to the party here, but is there any chance for this Fluidity CMake build to get finalised? The reason why I am asking is that CMake has deprecated the command-line argument --find-package (e.g. here and here) which is used in Fluidity's configure to retrieve some information about VTK. In particular, configure fails with the newer VTK 9:

configure: Checking for VTK automagic.
CMake Error at /apps/cmake/3.18.2/share/cmake-3.18/Modules/FindThreads.cmake:62 (message):
  FindThreads only works if either C or CXX language is enabled
Call Stack (most recent call first):
  /g/data/xd2/modules/vtk/9.1.0/lib64/cmake/vtk-9.1/VTK-vtk-module-find-packages.cmake:115 (find_package)
  /g/data/xd2/modules/vtk/9.1.0/lib64/cmake/vtk-9.1/vtk-config.cmake:150 (include)
  /apps/cmake/3.18.2/share/cmake-3.18/Modules/CMakeFindPackageMode.cmake:183 (find_package)

There are probably workarounds to replace the erroring commands (associated source code called by --find-package here)

VTK_FLAGS=`cmake --find-package -DNAME=VTK -DCOMPILER_ID=gcc -DLANGUAGE=Fortran -DMODE=COMPILE`
VTK_LIBS=`cmake --find-package -DNAME=VTK -DCOMPILER_ID=gcc -DLANGUAGE=Fortran -DMODE=LINK`

using, for example, the approaches detailed here, here and here, but I have not had success with them. Potentially something along the lines of

cmake_minimum_required(VERSION 3.16)
project(VTK_Info)

find_package(VTK
  REQUIRED)

  message("${VTK_VERSION}")
  message("${VTK_MAJOR_VERSION}")
  message("${VTK_MINOR_VERSION}")
  message("${VTK_BUILD_VERSION}")
  message("${VTK_AVAILABLE_COMPONENTS}")
  message("${VTK_PREFIX_PATH}")
  message("${VTK_LEGACY_REMOVE}")
  message("${VTK_HAS_VTKm}")
  message("${VTK_PYTHON_VERSION}")
  message("${VTK_WRAP_PYTHON}")
  message("${VTK_PYTHONPATH}")
  message("${VTK_LIBRARIES}")
  message("${VTK_AUTOINIT_INCLUDE}")
  message("${VTK_QT_VERSION}")
  message("${VTK_QML_DIR}")
  message("${VTK_ENABLE_VR_COLLABORATION}")
  message("${VTK_SMP_BACKENDS}")

foreach(lib_name ${VTK_LIBRARIES})
  get_target_property(lib_file ${lib_name} LOCATION)
  get_target_property(include_dir ${lib_name} INTERFACE_INCLUDE_DIRECTORIES)
  message("${lib_file}")
  message("${include_dir}")
endforeach()

could contain valuable information for Fluidity's configure, but my knowledge here is limited. Any input greatly appreciated.

[tmbgreaves]

Impressive thread necromancy there, @Patol75 :-)

I'd also be very keen to revive this one as the VTK/CMake thing has been biting me frequently over the past couple of years. I've generally given up on anything automated and just hacked configure / Makefiles to get the info in.

Unfortunately at the moment IC ESE has reassigned my job to cover for missing staff in the department and I have no time to do any Fluidity work until things settle down :-(