Fix install.sh --without-cxx

.github/workflows/build.yml

@@ -94,6 +94,7 @@ jobs:
           - os: macos-15
             compiler: flang
             brew_via_install: 1
+            CONFIGURE_ARGS: --without-cxx # just for argument coverage
           - os: macos-26
             compiler: flang
             brew_via_install: 1
@@ -144,6 +145,7 @@ jobs:
             compiler: flang
             version: 21
             container: phhargrove/llvm-flang:21.1.0-latest
+            CONFIGURE_ARGS: --without-cxx # just for argument coverage
           - os: ubuntu-24.04
             compiler: flang
             version: 20
@@ -196,6 +198,7 @@ jobs:
             compiler: lfortran
             version: 0.64
             container: ghcr.io/lfortran/lfortran:v0.64.0
+            CONFIGURE_ARGS: --without-cxx # just for argument coverage
 
           - os: ubuntu-22.04
             compiler: lfortran
@@ -524,7 +527,7 @@ jobs:
       run: |
         echo "FC=gfortran-${COMPILER_VERSION}" >> "$GITHUB_ENV"
         echo "CC=gcc-${COMPILER_VERSION}" >> "$GITHUB_ENV"
-        echo "CXX=g++-${COMPILER_VERSION}" >> "$GITHUB_ENV"
+        grep -q without-cxx <<< "$CONFIGURE_ARGS" || echo "CXX=g++-${COMPILER_VERSION}" >> "$GITHUB_ENV"
         # XCode 26 / gfortran bug workaround
         if [[ ${{ matrix.os }} =~ macos-26 ]] ; then
           echo "CONFIGURE_ARGS=$CONFIGURE_ARGS --enable-force-posix-realtime" >> "$GITHUB_ENV"
@@ -540,7 +543,7 @@ jobs:
             echo "FC=flang" >> "$GITHUB_ENV"
           fi
           echo "CC=clang" >> "$GITHUB_ENV"
-          echo "CXX=clang++" >> "$GITHUB_ENV"
+          grep -q without-cxx <<< "$CONFIGURE_ARGS" || echo "CXX=clang++" >> "$GITHUB_ENV"
         fi
 
     - name: Setup lfortran dependencies and variables
@@ -554,7 +557,7 @@ jobs:
         fi
         echo "FC=lfortran" >> "$GITHUB_ENV" 
         echo "CC=clang" >> "$GITHUB_ENV"
-        echo "CXX=clang++" >> "$GITHUB_ENV"
+        grep -q without-cxx <<< "$CONFIGURE_ARGS" || echo "CXX=clang++" >> "$GITHUB_ENV"
         ls -R $(lfortran --print-c-include-dir)
         #find / -name $HEADER_NAME -exec ls -al {} \; -exec md5sum {} \; -exec head {} \; -exec echo --- \;
 

install.sh

@@ -29,13 +29,15 @@ Options:
                     thread-safe GASNet, for use in threaded do-concurrent.
  --enable-cmake or --disable-fpm 
                     Build Caffeine library using CMake instead of FPM (the default).
+ --without-cxx      Disable optional use of the C++ compiler
 
 All unrecognized arguments will be passed to GASNet's configure.
 
 Some influential environment variables:
   FC          Fortran compiler command
   FFLAGS      Fortran compiler flags
   CC          C compiler command
+  CXX         C++ compiler command (optional)
   CFLAGS      C compiler flags
   CPPFLAGS    C preprocessor flags, e.g. -I<include dir> if you have
               headers in a nonstandard directory <include dir>
@@ -217,6 +219,8 @@ while [ "$1" != "" ]; do
         --enable-debug)  GASNET_CODEMODE=debug ; append_gasnet_configure_arg "$orig_arg" ;;
         --disable-debug) GASNET_CODEMODE=opt ;   append_gasnet_configure_arg "$orig_arg" ;;
 
+        --without-cxx)   CXX=false ; append_gasnet_configure_arg "$orig_arg" ;;
+
         *) # Pass unrecognized args unmodified to GASNet configure
             append_gasnet_configure_arg "$orig_arg"
             ;;
@@ -469,7 +473,9 @@ EOF
     # Homebrew does not inject clang/clang++ into PATH on macOS
     export PATH="$BREW_PREFIX/opt/llvm/bin:$PATH"
     CC="clang"
-    CXX="clang++"
+    if [ -z ${CXX:+x} ] || [[ $(basename ${CXX}) != false ]] ; then
+      CXX="clang++"
+    fi
     FC="flang-new"
     for tool in CC CXX FC ; do
       if ! type -P ${!tool} > /dev/null 2>&1 ; then
@@ -661,15 +667,18 @@ if ! $PKG_CONFIG $pkg ; then
       cd $GASNET_DIR
       cmd="set -x ; ./configure --prefix=\"$PREFIX\""
       # user-provided overrides:
-      cmd="$cmd $GASNET_CONFIGURE_ARGS"
+      cmd+=" $GASNET_CONFIGURE_ARGS"
       # pass-thru compiler settings:
-      cmd="$cmd --with-cc=\"$CC\" --with-cxx=\"$CXX\""
+      cmd+=" --with-cc=\"$CC\""
+      if [[ $(basename ${CXX}) != false ]] ; then
+        cmd+=" --with-cxx=\"$CXX\""
+      fi
       # select the GASNet config settings Caffeine requires, and disable unused features:
-      cmd="$cmd --enable-$GASNET_CONDUIT"
-      cmd="$cmd --enable-seq --enable-par --disable-parsync"
-      cmd="$cmd --disable-segment-everything"
+      cmd+=" --enable-$GASNET_CONDUIT"
+      cmd+=" --enable-seq --enable-par --disable-parsync"
+      cmd+=" --disable-segment-everything"
       # TEMPORARY: disable MPI compatibility until we figure out how to support in fpm
-      cmd="$cmd --disable-mpi-compat"
+      cmd+=" --disable-mpi-compat"
       eval $cmd
       $MAKE -j 8 all
       $MAKE -j 8 install
@@ -891,7 +900,7 @@ info)
   echo NATIVEFLAGS=\$NATIVEFLAGS
   echo CFLAGS=\$CFLAGS
   echo LDFLAGS=\$LDFLAGS
-  grep -e link \$SRCDIR/fpm.toml
+  echo '$FPM_TOML_LINK_ENTRY'
   echo GASNET=\$GASNETDIR
   echo GASNET_CONDUIT=$GASNET_CONDUIT
   echo GASNET_CODEMODE=$GASNET_CODEMODE