cares-compilers.m4

        if test "$want_warnings" = "yes"; then
          dnl Activate all warnings
          tmp_CFLAGS="$tmp_CFLAGS -Wall"
          dnl Make string constants be of type const char *
          tmp_CFLAGS="$tmp_CFLAGS -Wwrite-strings"
          dnl Warn use of unsupported GCC features ignored by TCC
          tmp_CFLAGS="$tmp_CFLAGS -Wunsupported"
        fi
        ;;
        #
      WATCOM_UNIX_C)
        #
        if test "$want_warnings" = "yes"; then
          dnl Issue all warnings
          tmp_CFLAGS="$tmp_CFLAGS -Wall -Wextra"
        fi
        ;;
        #
      WATCOM_WINDOWS_C)
        #
        dnl Placeholder
        tmp_CFLAGS="$tmp_CFLAGS"
        ;;
        #
    esac
    #
    squeeze tmp_CPPFLAGS
    squeeze tmp_CFLAGS
    #
    if test ! -z "$tmp_CFLAGS" || test ! -z "$tmp_CPPFLAGS"; then
      AC_MSG_CHECKING([if compiler accepts strict warning options])
      CPPFLAGS="$tmp_save_CPPFLAGS $tmp_CPPFLAGS"
      CFLAGS="$tmp_save_CFLAGS $tmp_CFLAGS"
      squeeze CPPFLAGS
      squeeze CFLAGS
      CARES_COMPILER_WORKS_IFELSE([
        AC_MSG_RESULT([yes])
        AC_MSG_NOTICE([compiler options added: $tmp_CFLAGS $tmp_CPPFLAGS])
      ],[
        AC_MSG_RESULT([no])
        AC_MSG_WARN([compiler options rejected: $tmp_CFLAGS $tmp_CPPFLAGS])
        dnl restore initial settings
        CPPFLAGS="$tmp_save_CPPFLAGS"
        CFLAGS="$tmp_save_CFLAGS"
      ])
    fi
    #
  fi
])


dnl CARES_SHFUNC_SQUEEZE
dnl -------------------------------------------------
dnl Declares a shell function squeeze() which removes
dnl redundant whitespace out of a shell variable.

AC_DEFUN([CARES_SHFUNC_SQUEEZE], [
squeeze() {
  _sqz_result=""
  eval _sqz_input=\[$][$]1
  for _sqz_token in $_sqz_input; do
    if test -z "$_sqz_result"; then
      _sqz_result="$_sqz_token"
    else
      _sqz_result="$_sqz_result $_sqz_token"
    fi
  done
  eval [$]1=\$_sqz_result
  return 0
}
])


dnl CARES_CHECK_CURLDEBUG
dnl -------------------------------------------------
dnl Settings which depend on configure's curldebug given
dnl option, and other additional configure pre-requisites.
dnl Using the curl debug memory tracking feature in c-ares
dnl is a hack that actually can only be used/enabled when
dnl c-ares is built directly in curl's CVS tree, as a static
dnl library or as a shared one on those systems on which
dnl shared libraries support undefined symbols, along with
dnl an equally configured libcurl.

AC_DEFUN([CARES_CHECK_CURLDEBUG], [
  AC_REQUIRE([CARES_SHFUNC_SQUEEZE])dnl
  cares_builddir=`pwd`
  supports_curldebug="unknown"
  if test "$want_curldebug" = "yes"; then
    if test "x$enable_shared" != "xno" &&
      test "x$enable_shared" != "xyes"; then
      AC_MSG_WARN([unknown enable_shared setting.])
      supports_curldebug="no"
    fi
    if test "x$enable_static" != "xno" &&
      test "x$enable_static" != "xyes"; then
      AC_MSG_WARN([unknown enable_static setting.])
      supports_curldebug="no"
    fi
    if test "$supports_curldebug" != "no"; then
      if test "$enable_shared" = "yes" &&
        test "$need_no_undefined" = "yes"; then
        supports_curldebug="no"
        AC_MSG_WARN([shared library does not support undefined symbols.])
      fi
      if test ! -f "$srcdir/../include/curl/curlbuild.h.dist"; then
        AC_MSG_WARN([c-ares source not embedded in curl's CVS tree.])
        supports_curldebug="no"
      elif test ! -f "$srcdir/../include/curl/Makefile.in"; then
        AC_MSG_WARN([curl's buildconf has not been run.])
        supports_curldebug="no"
      elif test ! -f "$cares_builddir/../libcurl.pc" ||
        test ! -f "$cares_builddir/../include/curl/curlbuild.h"; then
        AC_MSG_WARN([curl's configure has not been run.])
        supports_curldebug="no"
      elif test ! -f "$cares_builddir/../lib/config.h"; then
        AC_MSG_WARN([libcurl's config.h is missing.])
        supports_curldebug="no"
      elif test ! -f "$cares_builddir/../config.status"; then
        AC_MSG_WARN([curl's config.status is missing.])
        supports_curldebug="no"
      fi
      if test "$supports_curldebug" != "no"; then
        grep '^#define USE_ARES' "$cares_builddir/../lib/config.h" >/dev/null
        if test "$?" -ne "0"; then
          AC_MSG_WARN([libcurl configured without c-ares support.])
          supports_curldebug="no"
        fi
      fi
      if test "$supports_curldebug" != "no"; then
        grep 'CPPFLAGS.*CURLDEBUG' "$cares_builddir/../config.status" >/dev/null
        if test "$?" -ne "0"; then
          AC_MSG_WARN([libcurl configured without curldebug support.])
          supports_curldebug="no"
        fi
      fi
    fi
  fi
  #
  if test "$want_curldebug" = "yes"; then
    AC_MSG_CHECKING([if curl debug memory tracking can be enabled])
    test "$supports_curldebug" = "no" || supports_curldebug="yes"
    AC_MSG_RESULT([$supports_curldebug])
    if test "$supports_curldebug" = "no"; then
      AC_MSG_WARN([cannot enable curl debug memory tracking.])
      want_curldebug="no"
    fi
  fi
  #
  if test "$want_curldebug" = "yes"; then
    dnl TODO: Verify if the BUILDING_LIBCURL definition is still required.
    AC_DEFINE(BUILDING_LIBCURL, 1, [when building as static part of libcurl])
    CPPFLAGS="$CPPFLAGS -DCURLDEBUG"
    squeeze CPPFLAGS
  fi
  #
  if test "$want_debug" = "yes"; then
    CPPFLAGS="$CPPFLAGS -DDEBUGBUILD"
    squeeze CPPFLAGS
  fi
])


dnl CARES_CHECK_NO_UNDEFINED
dnl -------------------------------------------------
dnl Checks if the -no-undefined flag must be used when
dnl building shared libraries. This is required on all
dnl systems on which shared libraries should not have
dnl references to undefined symbols. This check should
dnl not be done before AC-PROG-LIBTOOL.

AC_DEFUN([CARES_CHECK_NO_UNDEFINED], [
  AC_BEFORE([$0],[CARES_CHECK_CURLDEBUG])dnl
  AC_MSG_CHECKING([if shared libraries need -no-undefined])
  need_no_undefined="no"
  case $host in
    *-*-cygwin* | *-*-mingw* | *-*-pw32* | *-*-cegcc* | *-*-aix*)
      need_no_undefined="yes"
      ;;
  esac
  if test "x$allow_undefined" = "xno"; then
    need_no_undefined="yes"
  elif test "x$allow_undefined_flag" = "xunsupported"; then
    need_no_undefined="yes"
  fi
  AC_MSG_RESULT($need_no_undefined)
])


dnl CARES_CHECK_PROG_CC
dnl -------------------------------------------------
dnl Check for compiler program, preventing CFLAGS and
dnl CPPFLAGS from being unexpectedly changed.

AC_DEFUN([CARES_CHECK_PROG_CC], [
  ac_save_CFLAGS="$CFLAGS"
  ac_save_CPPFLAGS="$CPPFLAGS"
  AC_PROG_CC
  CFLAGS="$ac_save_CFLAGS"
  CPPFLAGS="$ac_save_CPPFLAGS"
])


dnl CARES_CHECK_COMPILER_HALT_ON_ERROR
dnl -------------------------------------------------
dnl Verifies if the compiler actually halts after the
dnl compilation phase without generating any object
dnl code file, when the source compiles with errors.

AC_DEFUN([CARES_CHECK_COMPILER_HALT_ON_ERROR], [
  AC_MSG_CHECKING([if compiler halts on compilation errors])
  AC_COMPILE_IFELSE([
    AC_LANG_PROGRAM([[
    ]],[[
      force compilation error
    ]])
  ],[
    AC_MSG_RESULT([no])
    AC_MSG_ERROR([compiler does not halt on compilation errors.])
  ],[
    AC_MSG_RESULT([yes])
  ])
])


dnl CARES_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE
dnl -------------------------------------------------
dnl Verifies if the compiler actually halts after the
dnl compilation phase without generating any object
dnl code file, when the source code tries to define a
dnl type for a constant array with negative dimension.

AC_DEFUN([CARES_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE], [
  AC_REQUIRE([CARES_CHECK_COMPILER_HALT_ON_ERROR])dnl
  AC_MSG_CHECKING([if compiler halts on negative sized arrays])
  AC_COMPILE_IFELSE([
    AC_LANG_PROGRAM([[
      typedef char bad_t[sizeof(char) == sizeof(int) ? -1 : -1 ];
    ]],[[
      bad_t dummy;
    ]])
  ],[
    AC_MSG_RESULT([no])
    AC_MSG_ERROR([compiler does not halt on negative sized arrays.])
  ],[
    AC_MSG_RESULT([yes])
  ])
])


dnl CARES_CHECK_COMPILER_STRUCT_MEMBER_SIZE
dnl -------------------------------------------------
dnl Verifies if the compiler is capable of handling the
dnl size of a struct member, struct which is a function
dnl result, as a compilation-time condition inside the
dnl type definition of a constant array.

AC_DEFUN([CARES_CHECK_COMPILER_STRUCT_MEMBER_SIZE], [
  AC_REQUIRE([CARES_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE])dnl
  AC_MSG_CHECKING([if compiler struct member size checking works])
  tst_compiler_check_one_works="unknown"
  AC_COMPILE_IFELSE([
    AC_LANG_PROGRAM([[
      struct mystruct {
        int  mi;
        char mc;
        struct mystruct *next;
      };
      struct mystruct myfunc();
      typedef char good_t1[sizeof(myfunc().mi) == sizeof(int)  ? 1 : -1 ];
      typedef char good_t2[sizeof(myfunc().mc) == sizeof(char) ? 1 : -1 ];
    ]],[[
      good_t1 dummy1;
      good_t2 dummy2;
    ]])
  ],[
    tst_compiler_check_one_works="yes"
  ],[
    tst_compiler_check_one_works="no"
    sed 's/^/cc-src: /' conftest.$ac_ext >&6
    sed 's/^/cc-err: /' conftest.err >&6
  ])
  tst_compiler_check_two_works="unknown"
  AC_COMPILE_IFELSE([
    AC_LANG_PROGRAM([[
      struct mystruct {
        int  mi;
        char mc;
        struct mystruct *next;
      };
      struct mystruct myfunc();
      typedef char bad_t1[sizeof(myfunc().mi) != sizeof(int)  ? 1 : -1 ];
      typedef char bad_t2[sizeof(myfunc().mc) != sizeof(char) ? 1 : -1 ];
    ]],[[
      bad_t1 dummy1;
      bad_t2 dummy2;
    ]])
  ],[
    tst_compiler_check_two_works="no"
  ],[
    tst_compiler_check_two_works="yes"
  ])
  if test "$tst_compiler_check_one_works" = "yes" &&
    test "$tst_compiler_check_two_works" = "yes"; then
    AC_MSG_RESULT([yes])
  else
    AC_MSG_RESULT([no])
    AC_MSG_ERROR([compiler fails struct member size checking.])
  fi
])


dnl CARES_VAR_MATCH (VARNAME, VALUE)
dnl -------------------------------------------------
dnl Verifies if shell variable VARNAME contains VALUE.
dnl Contents of variable VARNAME and VALUE are handled
dnl as whitespace separated lists of words. If at least
dnl one word of VALUE is present in VARNAME the match
dnl is considered positive, otherwise false.

AC_DEFUN([CARES_VAR_MATCH], [
  ac_var_match_word="no"
  for word1 in $[$1]; do
    for word2 in [$2]; do
      if test "$word1" = "$word2"; then
        ac_var_match_word="yes"
      fi
    done
  done
])


dnl CARES_VAR_MATCH_IFELSE (VARNAME, VALUE,
dnl                        [ACTION-IF-MATCH], [ACTION-IF-NOT-MATCH])
dnl -------------------------------------------------
dnl This performs a CURL_VAR_MATCH check and executes
dnl first branch if the match is positive, otherwise
dnl the second branch is executed.

AC_DEFUN([CARES_VAR_MATCH_IFELSE], [
  CARES_VAR_MATCH([$1],[$2])
  if test "$ac_var_match_word" = "yes"; then
  ifelse($3,,:,[$3])
  ifelse($4,,,[else
    $4])
  fi
])


dnl CARES_VAR_STRIP (VARNAME, VALUE)
dnl -------------------------------------------------
dnl Contents of variable VARNAME and VALUE are handled
dnl as whitespace separated lists of words. Each word
dnl from VALUE is removed from VARNAME when present.

AC_DEFUN([CARES_VAR_STRIP], [
  AC_REQUIRE([CARES_SHFUNC_SQUEEZE])dnl
  ac_var_stripped=""
  for word1 in $[$1]; do
    ac_var_strip_word="no"
    for word2 in [$2]; do
      if test "$word1" = "$word2"; then
        ac_var_strip_word="yes"
      fi
    done
    if test "$ac_var_strip_word" = "no"; then
      ac_var_stripped="$ac_var_stripped $word1"
    fi
  done
  dnl squeeze whitespace out of result
  [$1]="$ac_var_stripped"
  squeeze [$1]
])