ENH: add settings/rules for clang-2.8

etc/settings.sh

@@ -131,6 +131,12 @@ OpenFOAM)
         gmp_version=gmp-4.2.4
         mpfr_version=mpfr-2.4.1
         ;;
+    Clang)
+        # using clang - not gcc
+        export WM_CC='clang'
+        export WM_CXX='clang++'
+        clang_version=llvm-2.8
+        ;;
     *)
         echo
         echo "Warning in $WM_PROJECT_DIR/etc/settings.sh:"
@@ -183,6 +189,25 @@ OpenFOAM)
     fi
     unset gcc_version gccDir
     unset gmp_version gmpDir  mpfr_version mpfrDir  mpc_version mpcDir
+
+    if [ -n "$clang_version" ]
+    then
+        clangDir=$WM_THIRD_PARTY_DIR/platforms/$WM_ARCH$WM_COMPILER_ARCH/$clang_version
+
+        # Check that the compiler directory can be found
+        [ -d "$clangDir" ] || {
+            echo
+            echo "Warning in $WM_PROJECT_DIR/etc/settings.sh:"
+            echo "    Cannot find $clangDir installation."
+            echo "    Please install this compiler version or if you wish to use the system compiler,"
+            echo "    change the 'compilerInstall' setting to 'system' in this file"
+            echo
+        }
+
+        _foamAddMan     $clangDir/share/man
+        _foamAddPath    $clangDir/bin
+    fi
+    unset clang_version clangDir
     ;;
 esac