AC_PREREQ([2.57])

AC_INIT([libslirp],
	0.0.1,
	[],
	libslirp)

AM_INIT_AUTOMAKE([foreign dist-bzip2])
AM_MAINTAINER_MODE
AM_CONFIG_HEADER(config.h)

# Check for progs
AC_PROG_CC
AC_PROG_LIBTOOL
dnl If the first PKG_CHECK_MODULES appears inside a conditional, pkg-config
dnl must first be located explicitly.
PKG_PROG_PKG_CONFIG

dnl ===========================================================================
dnl check compiler flags

AC_DEFUN([SLIRP_CC_TRY_FLAG], [
  AC_MSG_CHECKING([whether $CC supports $1])

  slirp_save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS $1"

  AC_COMPILE_IFELSE([ ], [slirp_cc_flag=yes], [slirp_cc_flag=no])
  CFLAGS="$slirp_save_CFLAGS"

  if test "x$slirp_cc_flag" = "xyes"; then
    ifelse([$2], , :, [$2])
  else
    ifelse([$3], , :, [$3])
  fi
  AC_MSG_RESULT([$slirp_cc_flag])
])

dnl Use lots of warning flags with with gcc and compatible compilers

dnl Note: if you change the following variable, the cache is automatically
dnl skipped and all flags rechecked.  So there's no need to do anything
dnl else.  If for any reason you need to force a recheck, just change
dnl MAYBE_WARN in an ignorable way (like adding whitespace)

dnl MAYBE_WARN="-Wall -Wno-sign-compare -Werror -Wno-deprecated-declarations"

MAYBE_WARN="-Wall -Wno-sign-compare -Werror -Wno-deprecated-declarations"

# invalidate cached value if MAYBE_WARN has changed
if test "x$slirp_cv_warn_maybe" != "x$MAYBE_WARN"; then
	unset slirp_cv_warn_cflags
fi
AC_CACHE_CHECK([for supported warning flags], slirp_cv_warn_cflags, [
	echo
	WARN_CFLAGS=""

	# Some warning options are not supported by all versions of
	# gcc, so test all desired options against the current
	# compiler.
	#
	# Note that there are some order dependencies
	# here. Specifically, an option that disables a warning will
	# have no net effect if a later option then enables that
	# warnings, (perhaps implicitly). So we put some grouped
	# options (-Wall and -Wextra) up front and the -Wno options
	# last.

	for W in $MAYBE_WARN; do
		SLIRP_CC_TRY_FLAG([$W], [WARN_CFLAGS="$WARN_CFLAGS $W"])
	done

	slirp_cv_warn_cflags=$WARN_CFLAGS
	slirp_cv_warn_maybe=$MAYBE_WARN

	AC_MSG_CHECKING([which warning flags were supported])])
WARN_CFLAGS="$slirp_cv_warn_cflags"
SLIRP_CFLAGS="$SLIRP_CFLAGS $WARN_CFLAGS"

# We only wish to enable attribute(warn_unused_result) if we can prevent
# gcc from generating thousands of warnings about the misapplication of the
# attribute to void functions and variables.
AC_MSG_CHECKING([how to enable unused result warnings])
warn_unused_result=""
if echo $WARN_CFLAGS | grep -e '-Wno-attributes' >/dev/null; then
    AC_TRY_COMPILE([__attribute__((__warn_unused_result__))
	int f (int i) { return i; }], [],
	[warn_unused_result="__attribute__((__warn_unused_result__))"])
fi
AC_DEFINE_UNQUOTED([WARN_UNUSED_RESULT], [$warn_unused_result],
	  [Define to the value your compiler uses to support the warn-unused-result attribute])
AC_MSG_RESULT([$warn_unused_result])

AC_SUBST(WARN_CFLAGS)
AC_SUBST(CFLAGS_CFLAGS)

dnl =========================================================================
dnl -fvisibility stuff

have_gcc4=no
AC_MSG_CHECKING(for -fvisibility)
AC_COMPILE_IFELSE([
#if defined(__GNUC__) && (__GNUC__ >= 4)
#else
error Need GCC 4.0 for visibility
#endif
int main () { return 0; }
], have_gcc4=yes)

if test "x$have_gcc4" = "xyes"; then
   VISIBILITY_HIDDEN_CFLAGS="-fvisibility=hidden"
fi
AC_MSG_RESULT($have_gcc4)
AC_SUBST(VISIBILITY_HIDDEN_CFLAGS)

AC_OUTPUT([Makefile
	   slirp.pc])