Fetch DAGMC if not found in cmakelists.txt

[jon-proximafusion]

Description

Marked as draft as this PR is mainly to check with @gonuke and @pshriwise if they would be keen on something like this?

Many other packages are included via submodule and they get smoothly installed during the compile so I was looking for ways of making the DAGMC install a bit smoother for users

I was just wondering if it is worth making the inclusion of DAGMC when compiling a little easier by automatically fetching the repo if it is requested and not found locally.

Changes like this to the cmakelists file could allow users to compile with dagmc like this

cmake .. -DOPENMC_USE_DAGMC=ON

This would provide a different route instead of cloning dagmc, compiling dagmc, cloning moab, compiling moab, passing directories to each cmake command etc.

ps this would need a small change in dagmc to fetch moab for this to work and changes in moab to make the repo more compatible with the fetch content. This issue is related

Fixes # (issue)

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[shimwell]

I've tried changing it to point to my branch where auto_moab is DDDL_INSTALL_DEPS=ON by default

Suggested change

	GIT_REPOSITORY https://github.com/svalinn/DAGMC.git
	GIT_TAG v3.2.3
	GIT_REPOSITORY https://github.com/shimwell/DAGMC.git
	GIT_TAG 8510f8efa3937480bdab9a77d3c51da17b5d0875

I've also tried pointing to @bam241 branch where DDDL_INSTALL_DEPS flag would need setting to ON

Suggested change

	GIT_REPOSITORY https://github.com/svalinn/DAGMC.git
	GIT_TAG v3.2.3
	GIT_REPOSITORY https://github.com/bam241/DAGMC.git
	GIT_TAG 99222f6d046da82710bfa8e9e9859d13fbd1f4d2

[shimwell]

Just to mention I've been trying to get this branch working locally and making use of @bam241 DAGMC branch (auto_moab) but can't quite get it to find the libraries

current error is

CMake Error at CMakeLists.txt:137 (find_package):
  Could not find a package configuration file provided by "DAGMC" with any of
  the following names:

    DAGMCConfig.cmake
    dagmc-config.cmake

[bam241]

My guess is your problem is there:
find_package(DAGMC QUIET PATH_SUFFIXES lib/cmake)
because the current build system supposes that DAGMC is installed. and relies on a FindDAGMC provided by DAGMC itself.

[shimwell]

Suggested change

	find_package(DAGMC REQUIRED PATH_SUFFIXES lib/cmake)
	set(DAGMC_DIR "${CMAKE_BINARY_DIR}/_deps/dagmc-build")
	set(DAGMC_CONFIG_DIR ${DAGMC_DIR}/lib/cmake/dagmc)
	list(APPEND CMAKE_PREFIX_PATH ${DAGMC_CONFIG_DIR})
	find_package(DAGMC REQUIRED PATH_SUFFIXES lib/cmake)

this appears to help find one of the dagmc cmake files but not the DAGMCTargets.cmake file.
Worryingly I also can't see this file using the find . -name "*.cmake" command to search for .cmake file