assimp: ccache from system might be picked up

[Thyre]

On my personal system, where a lot of programs like pkgconf, ccache and so on are installed outside of EasyBuild, some packages fail to build with the existing EasyConfigs. With assimp, we run into the following issue:

By default assimp builds with ccache enabled, see: https://github.com/assimp/assimp/blob/46c26eda5a3e212e086fc96b453ecb68f4b3ae75/CMakeLists.txt#L49

This is probably not needed for EasyBuild, and can also introduce issues when ccache is found on the system, but is not built by EasyBuild:

259 cd /data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/easybuild_obj/code && /usr/bin/ccache /data/EasyBuild-develop/software/GCCcore/13.3.0/bin/g++ -DASSIMP_BUILD_DLL_EXPORT -DASSIMP_BUILD_NO_C4D_IMPORTER -DASSIMP_BUILD_NO_M3D_EXPORTER -DASSIMP_BUILD_NO_M3D_IMPORTER -DASSIMP_BUILD_NO_OWN_ZLIB -DASSIMP_BU    ILD_NO_USD_IMPORTER -DASSIMP_IMPORTER_GLTF_USE_OPEN3DGC=1 -DMINIZ_USE_UNALIGNED_LOADS_AND_STORES=0 -DOPENDDLPARSER_BUILD -DRAPIDJSON_HAS_STDSTRING=1 -DRAPIDJSON_NOMEMBERITERATORCLASS -Dassimp_EXPORTS -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/easybuild_obj/include -I/data/EasyBuild-develop/buil    d/assimp/5.4.3/GCCcore-13.3.0/easybuild_obj -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/include -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/. -I/data/EasyBuild-develop/software    /zlib/1.3.1-GCCcore-13.3.0/include -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/../contrib/pugixml/src -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/../contrib/utf8cpp/source -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3    /code/../contrib/rapidjson/include -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/../contrib -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/../contrib/unzip -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/../contrib/open    ddlparser/include -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/../include -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/easybuild_obj/code/../include -I/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/.. -fvisibility=hidden -fno-strict-al    iasing -Wall -O2 -ftree-vectorize -march=native -fno-math-errno -O3 -DNDEBUG -std=gnu++17 -fPIC -Wno-dangling-reference -MD -MT code/CMakeFiles/assimp.dir/Common/SceneCombiner.cpp.o -MF CMakeFiles/assimp.dir/Common/SceneCombiner.cpp.o.d -o CMakeFiles/assimp.dir/Common/SceneCombiner.cpp.o -c /data/EasyBuild-deve    lop/build/assimp/5.4.3/GCCcore-13.3.0/assimp-5.4.3/code/Common/SceneCombiner.cpp
260 /usr/bin/ccache: /data/EasyBuild-develop/software/GCCcore/13.3.0/lib64/libstdc++.so.6: version `CXXABI_1.3.15' not found (required by /usr/bin/ccache)
261 make[2]: *** [code/CMakeFiles/assimp.dir/build.make:275: code/CMakeFiles/assimp.dir/Common/SpatialSort.cpp.o] Error 1
262 /usr/bin/ccache: /data/EasyBuild-develop/software/GCCcore/13.3.0/lib64/libstdc++.so.6: version `CXXABI_1.3.15' not found (required by /usr/bin/ccache)
263 make[2]: *** [code/CMakeFiles/assimp.dir/build.make:289: code/CMakeFiles/assimp.dir/Common/SceneCombiner.cpp.o] Error 1
264 make[2]: Leaving directory '/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/easybuild_obj'
265 make[1]: *** [CMakeFiles/Makefile2:163: code/CMakeFiles/assimp.dir/all] Error 2
266 make[1]: Leaving directory '/data/EasyBuild-develop/build/assimp/5.4.3/GCCcore-13.3.0/easybuild_obj'
267 make: *** [Makefile:139: all] Error 2

We should probably disable this via ASSIMP_BUILD_USE_CCACHE=OFF, or add a build dependency to ccache.

[Micket]

I wonder if we have some global flag to disable ccache, like CCACHE_BASEDIR set to builddir. Hunting down every build tool that might use this stuff feels more tedious

[Thyre]

There is CCACHE_DISABLE, but that still requires ccache to be present and working. CMake itself is not aware of ccache and projects might make us of it in different ways as far as I know.