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# f18

## Selection of the C/C++ compiler

F18 requires a C++17 compiler. As of today, the code was only tested with g++
7.2.0, g++ 7.3.0 and clang 6.0.

For a proper installation, we assume that the PATH and LD_LIBRARY_PATH environment variables 
are properly set to use gcc, g++ and the associated libraries.   

cmake will require that the environement variables CC and CXX are properly set (else it will 
search for use the 'cc' and 'c++' program which are likely /usr/bin/cc and /usr/bin/c++) that 
can be done now or while calling cmake 

    export CC=gcc
    export CXX=g++

## Installation of LLVM & CLANG 6.0

F18 depends of the LLVM & CLANG libraries even when clang is not used as C++ compiler.  

If those libraries are not provided by your system then you may want to follow the 
build instructions at https://clang.llvm.org/get_started.html 

## Installation of F18

    ######## Choose the installation directory
   
    F18_PREFIX=...   

    ######## Get Flang sources in $ROOT/f18
    cd $ROOT
    git clone https://github.com/ThePortlandGroup/f18.git

    ######## And build it in a dedicated directory
    ######## Reminder: If LLVM & Clang where not installed in a standard 
    ########           location then you may also have to specify it via the
    ########           CMAKE_MODULE_PATH or CMAKE_PREFIX_PATH variables. 
    mkdir $ROOT/f18-build
    cd $ROOT/f18-build   
    CC=gcc CXX=g++ cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$F18_PREFIX $ROOT/f18
    make -j 4
    make install