Should inherit compile information from NGSolve project?

[stefanozampini]

Just tried a build, with an NGSolve successfully built and compiled using -DCMAKE_C_COMPILER=mpicc -DCMAKE_CXX_COMPILER=mpicxx

Then, when configuring and building the interface,

kl-18448:build szampini$ cmake .. -DPETSC_EXECUTABLE_RUNS=YES 
-- The C compiler identification is AppleClang 10.0.1.10010046
-- The CXX compiler identification is AppleClang 10.0.1.10010046
-- Check for working C compiler: /usr/local/opt/ccache/libexec/cc
-- Check for working C compiler: /usr/local/opt/ccache/libexec/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/local/opt/ccache/libexec/c++
-- Check for working CXX compiler: /usr/local/opt/ccache/libexec/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Netgen: /Users/szampini/Devel/ngsolve/install/Contents/Resources/CMake
-- petsc_lib_dir /Users/szampini/Devel/petsc/arch-debug/lib
-- Recognized PETSc install with single library for all packages
-- Performing Test MULTIPASS_TEST_1_petsc_works_minimal
-- Performing Test MULTIPASS_TEST_1_petsc_works_minimal - Failed
-- Performing Test MULTIPASS_TEST_2_petsc_works_allincludes
-- Performing Test MULTIPASS_TEST_2_petsc_works_allincludes - Success
-- PETSc requires extra include paths, but links correctly with only interface libraries.  This is an unexpected configuration (but it seems to work fine).
 XXXXXXXXXXX inc needed /Users/szampini/Devel/petsc/include;/Users/szampini/Devel/petsc/arch-debug/include;/Users/szampini/Devel/petsc-pkgs/include;/opt/X11/include;/usr/local/include;/usr/local/opt/zlib/include;/Users/szampini/local/include;/usr/X11/include
 INCLUDES:  /Users/szampini/Devel/petsc/include;/Users/szampini/Devel/petsc/arch-debug/include;/Users/szampini/Devel/petsc-pkgs/include;/opt/X11/include;/usr/local/include;/usr/local/opt/zlib/include;/Users/szampini/local/include;/usr/X11/include
-- Found PETSc: /Users/szampini/Devel/petsc/include;/Users/szampini/Devel/petsc/arch-debug/include;/Users/szampini/Devel/petsc-pkgs/include;/opt/X11/include;/usr/local/include;/usr/local/opt/zlib/include;/Users/szampini/local/include;/usr/X11/include (found version "3.13.4.99") 
-- Compiling the Real PETSc interface!
-- Setting build type to NGSolve build type: RelWithDebInfo
-- Found PythonInterp: /usr/local/bin/python3 (found suitable version "3.8.5", minimum required is "3") 
-- Found PythonLibs: /usr/local/Frameworks/Python.framework/Versions/3.8/lib/libpython3.8.dylib (found suitable version "3.8.5", minimum required is "3") 
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/szampini/Devel/ngs-petsc/build
kl-18448:build szampini$ make -j6
Scanning dependencies of target libpetscinterface
[ 28%] Building CXX object src/CMakeFiles/libpetscinterface.dir/python_ngspetsc.cpp.o
[ 28%] Building CXX object src/CMakeFiles/libpetscinterface.dir/petsc_linalg.cpp.o
[ 42%] Building CXX object src/CMakeFiles/libpetscinterface.dir/utils.cpp.o
[ 71%] Building CXX object src/CMakeFiles/libpetscinterface.dir/petsc_pc.cpp.o
[ 71%] Building CXX object src/CMakeFiles/libpetscinterface.dir/petsc_snes.cpp.o
[ 85%] Building CXX object src/CMakeFiles/libpetscinterface.dir/petsc_ksp.cpp.o
[100%] Linking CXX shared library libpetscinterface.so
Undefined symbols for architecture x86_64:
  "_MPI_Allreduce", referenced from:
      ngs_petsc_interface::NGs2PETScVecMap::NGs2PETScVecMap(unsigned long, int, std::__1::shared_ptr<ngla::ParallelDofs>, std::__1::shared_ptr<ngcore::BitArray>) in petsc_linalg.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [src/libpetscinterface.so] Error 1
make[1]: *** [src/CMakeFiles/libpetscinterface.dir/all] Error 2
make: *** [all] Error 2

I get it working by specifying again the MPI compiler wrappers to the interface configure. However, since the interface depends on NGSolve, I think it should get compiler information from NGSolve itself