anchor.diff:  
     nativeBuildInputs = [ gfortran ];
   
  -  buildInputs = lib.optionals stdenv.cc.isClang [
  +  buildInputs = optionals stdenv.cc.isClang [
       # TODO: This may mismatch the LLVM version sin the stdenv, see #79818.
       llvmPackages.openmp
  -  ];
  +  ] ++ optional enableMpi mpi;
   
     configureFlags =
       [ "--enable-shared"
  
positive.code: , enableAvx2 ? stdenv.hostPlatform.avx2Support
  , enableAvx512 ? stdenv.hostPlatform.avx512Support
  , enableFma ? stdenv.hostPlatform.fmaSupport
  }:
  
  with lib;
  
negative.code:     ++ optional enableAvx512 "--enable-avx512"
      ++ optional enableFma "--enable-fma"
      ++ [ "--enable-openmp" ]
      ++ optional enableMpi "--enable-mpi"
      # doc generation causes Fortran wrapper generation which hard-codes gcc
      ++ optional (!withDoc) "--disable-doc";
  
  