Generalizing configure openmp treatment following data.table: part 2a

Author: eddelbuettel

configure

@@ -3324,7 +3324,7 @@ if test x"${SYSKERNEL}" = x"Darwin"; then
        { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether R CMD SHLIB can compile OpenMP programs using '-Xclang -fopenmp'" >&5
 printf %s "checking whether R CMD SHLIB can compile OpenMP programs using '-Xclang -fopenmp'... " >&6; }
 
-       PKG_CXXFLAGS=-Xclang -fopenmp PKG_LIBS="${PKG_LIBS} -lomp" "${R_HOME}/bin/R" CMD SHLIB -fopenmp test-omp.cpp >/dev/null 2>&1
+       CPPFLAGS="${CPPFLAGS} -Xclang -fopenmp" PKG_LIBS="${PKG_LIBS} -lomp" "${R_HOME}/bin/R" CMD SHLIB -fopenmp test-omp.cpp >/dev/null 2>&1
        if test x"$?" = x"0"; then
            { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 printf "%s\n" "yes" >&6; }

configure.ac

@@ -114,7 +114,8 @@ if test x"${SYSKERNEL}" = x"Darwin"; then
    if test x"${can_use_openmp}" = x"no"; then
        AC_MSG_CHECKING([whether R CMD SHLIB can compile OpenMP programs using '-Xclang -fopenmp'])
 
-       PKG_CXXFLAGS=-Xclang -fopenmp PKG_LIBS="${PKG_LIBS} -lomp" "${R_HOME}/bin/R" CMD SHLIB -fopenmp test-omp.cpp >/dev/null 2>&1
+       # >/dev/null 2>&1
+       PKG_CXXFLAGS="${PKG_CXXFLAGS} -Xclang -fopenmp" PKG_LIBS="${PKG_LIBS} -lomp" "${R_HOME}/bin/R" CMD SHLIB test-omp.cpp
        if test x"$?" = x"0"; then
            AC_MSG_RESULT([yes])
            openmp_already_works="yes"