configure: add minimal sanity check on user provided CFLAGS and CPPFLAGS

dnl

dnl LIBS should only specify libraries

dnl

tst_bad_libspec="no"

tst_bad_spec="no"

for word1 in $LIBS; do

  case "$word1" in

    -l*)

    -l* | --library=*)

      :

      ;;

    *)

      tst_bad_libspec="yes"

      tst_bad_spec="yes"

      ;;

  esac

done

if test "$tst_bad_libspec" = "yes"; then

  AC_MSG_ERROR([linker flags present in LIBS must be specified via LDFLAGS.])

if test "$tst_bad_spec" = "yes"; then

  AC_MSG_WARN([invalid LIBS: $LIBS])

  AC_MSG_ERROR([LIBS may only be used to specify libraries (-lname).])

fi

dnl

dnl LDFLAGS should only specify linker flags

dnl

tst_bad_libspec="no"

tst_bad_msg=""

tst_bad_spec="no"

for word1 in $LDFLAGS; do

  case "$word1" in

    -l*)

      tst_bad_libspec="yes"

    -D*)

      tst_bad_spec="yes"

      tst_bad_msg="not macro definitions. Use CPPFLAGS for these."

      ;;

    -U*)

      tst_bad_spec="yes"

      tst_bad_msg="not macro suppressions. Use CPPFLAGS for these."

      ;;

    -I*)

      tst_bad_spec="yes"

      tst_bad_msg="not include directories. Use CPPFLAGS for these."

      ;;

    -l* | --library=*)

      tst_bad_spec="yes"

      tst_bad_msg="not libraries. Use LIBS for these."

      ;;

  esac

done

if test "$tst_bad_spec" = "yes"; then

  AC_MSG_WARN([invalid LDFLAGS: $LDFLAGS])

  AC_MSG_ERROR([LDFLAGS may only be used to specify linker flags, $tst_bad_msg])

fi

dnl

dnl CPPFLAGS should only specify C preprocessor flags

dnl

tst_bad_msg=""

tst_bad_spec="no"

for word1 in $CPPFLAGS; do

  case "$word1" in

    -rpath*)

      tst_bad_spec="yes"

      tst_bad_msg="not library runtime directories. Use LDFLAGS for these."

      ;;

    -L* | --library-path=*)

      tst_bad_spec="yes"

      tst_bad_msg="not library directories. Use LDFLAGS for these."

      ;;

    -l* | --library=*)

      tst_bad_spec="yes"

      tst_bad_msg="not libraries. Use LIBS for these."

      ;;

  esac

done

if test "$tst_bad_spec" = "yes"; then

  AC_MSG_WARN([invalid CPPFLAGS: $CPPFLAGS])

  AC_MSG_ERROR([CPPFLAGS may only be used to specify C preprocessor flags, $tst_bad_msg])

fi

dnl

dnl CFLAGS should only specify C compiler flags

dnl

tst_bad_msg=""

tst_bad_spec="no"

for word1 in $CFLAGS; do

  case "$word1" in

    -D*)

      tst_bad_spec="yes"

      tst_bad_msg="not macro definitions. Use CPPFLAGS for these."

      ;;

    -U*)

      tst_bad_spec="yes"

      tst_bad_msg="not macro suppressions. Use CPPFLAGS for these."

      ;;

    -I*)

      tst_bad_spec="yes"

      tst_bad_msg="not include directories. Use CPPFLAGS for these."

      ;;

    -rpath*)

      tst_bad_spec="yes"

      tst_bad_msg="not library runtime directories. Use LDFLAGS for these."

      ;;

    -L* | --library-path=*)

      tst_bad_spec="yes"

      tst_bad_msg="not library directories. Use LDFLAGS for these."

      ;;

    -l* | --library=*)

      tst_bad_spec="yes"

      tst_bad_msg="not libraries. Use LIBS for these."

      ;;

  esac

done

if test "$tst_bad_libspec" = "yes"; then

  AC_MSG_ERROR([libraries present in LDFLAGS must be specified via LIBS.])

if test "$tst_bad_spec" = "yes"; then

  AC_MSG_WARN([invalid CFLAGS: $CFLAGS])

  AC_MSG_ERROR([CFLAGS may only be used to specify C compiler flags, $tst_bad_msg])

fi

dnl