dnl Synopsis
dnl 
dnl         AC_CC_WARNINGS([ANSI]) 
dnl 
dnl Version
dnl 
dnl         1.1 (2000/12/31) 
dnl 
dnl Author
dnl 
dnl         Ville Laurikari <vl@iki.fi> 
dnl 
dnl Description
dnl 
dnl         Enables a reasonable set of warnings for the C compiler. 
dnl         Optionally, if the first argument is nonempty, turns on 
dnl         flags which enforce and/or enable proper ANSI C if such 
dnl         flags are known to the compiler used. 
dnl 
dnl         Currently this macro knows about GCC, Solaris C compiler, 
dnl         Digital Unix C compiler, C for AIX Compiler, HP-UX C
dnl         compiler, and IRIX C compiler.

AC_DEFUN([AC_CC_WARNINGS], [
  ansi=$1
  if test -z "$ansi"; then
    msg="for C compiler warning flags"
  else
    msg="for C compiler warning and ANSI conformance flags"
  fi
  AC_CACHE_CHECK($msg, ac_cv_prog_cc_warnings, [
    if test -n "$CC"; then
      cat > conftest.c <<EOF
int main(int argc, char **argv) { return 0; }
EOF

      dnl GCC
      if test "$GCC" = "yes"; then
        if test -z "$ansi"; then
          ac_cv_prog_cc_warnings="-Wall"
        else
          ac_cv_prog_cc_warnings="-Wall -ansi -pedantic"
        fi

      dnl Solaris C compiler
      elif $CC -flags 2>&1 | grep "Xc.*strict ANSI C" > /dev/null 2>&1 &&
           $CC -c -v -Xc conftest.c > /dev/null 2>&1 &&
           test -f conftest.o; then
        if test -z "$ansi"; then
          ac_cv_prog_cc_warnings="-v"
        else
          ac_cv_prog_cc_warnings="-v -Xc"
        fi

      dnl HP-UX C compiler
      elif $CC > /dev/null 2>&1 &&
           $CC -c -Aa +w1 conftest.c > /dev/null 2>&1 &&
           test -f conftest.o; then
        if test -z "$ansi"; then
          ac_cv_prog_cc_warnings="+w1"
        else
          ac_cv_prog_cc_warnings="+w1 -Aa"
        fi

      dnl Digital Unix C compiler
      elif ! $CC > /dev/null 2>&1 &&
           $CC -c -verbose -w0 -warnprotos -std1 conftest.c > /dev/null 2>&1 &&
           test -f conftest.o; then
        if test -z "$ansi"; then
          ac_cv_prog_cc_warnings="-verbose -w0 -warnprotos"
        else
          ac_cv_prog_cc_warnings="-verbose -w0 -warnprotos -std1"
        fi

      dnl C for AIX Compiler
      elif $CC > /dev/null 2>&1 | grep AIX > /dev/null 2>&1 &&
           $CC -c -qlanglvl=ansi -qinfo=all conftest.c > /dev/null 2>&1 &&
           test -f conftest.o; then
        if test -z "$ansi"; then
          ac_cv_prog_cc_warnings="-qsrcmsg -qinfo=all:noppt:noppc:noobs:nocnd"
        else
          ac_cv_prog_cc_warnings="-qsrcmsg -qinfo=all:noppt:noppc:noobs:nocnd -qlanglvl=ansi"
        fi

      dnl IRIX C compiler
      elif $CC -fullwarn -ansi -ansiE > /dev/null 2>&1 &&
           test -f conftest.o; then
        if test -z "$ansi"; then
          ac_cv_prog_cc_warnings="-fullwarn"
        else
          ac_cv_prog_cc_warnings="-fullwarn -ansi -ansiE"
        fi

      fi
      rm -f conftest.*
    fi
    if test -n "$ac_cv_prog_cc_warnings"; then
      CFLAGS="$CFLAGS $ac_cv_prog_cc_warnings"
      CXXFLAGS="$CXXFLAGS $ac_cv_prog_cc_warnings"
    else
      ac_cv_prog_cc_warnings="unknown"
    fi
  ])
])