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dnl as-compiler-flag.m4 0.1.0

dnl autostars m4 macro for detection of compiler flags

dnl David Schleef <ds@schleef.org>

dnl $Id: as-compiler-flag.m4,v 1.1 2005/06/18 18:02:46 burgerman Exp $

dnl AS_COMPILER_FLAG(CFLAGS, ACTION-IF-ACCEPTED, [ACTION-IF-NOT-ACCEPTED])
dnl Tries to compile with the given CFLAGS.
dnl Runs ACTION-IF-ACCEPTED if the compiler can compile with the flags,
dnl and ACTION-IF-NOT-ACCEPTED otherwise.

AC_DEFUN([AS_COMPILER_FLAG],[
  AC_MSG_CHECKING([to see if compiler understands $1])

  save_CFLAGS="$CFLAGS"
  CFLAGS="$CFLAGS $1"

  AC_TRY_COMPILE([ ], [], [flag_ok=yes], [flag_ok=no])
  CFLAGS="$save_CFLAGS"

  if test "X$flag_ok" = Xyes ; then
    $2
    true
  else
    $3
    true
  fi
  AC_MSG_RESULT([$flag_ok])
])

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dnl AS_AC_EXPAND(VAR, CONFIGURE_VAR)
dnl
dnl example
dnl AS_AC_EXPAND(SYSCONFDIR, $sysconfdir)
dnl will set SYSCONFDIR to /usr/local/etc if prefix=/usr/local

AC_DEFUN([AS_AC_EXPAND],[
  EXP_VAR=[$1]
  FROM_VAR=[$2]

  dnl first expand prefix and exec_prefix if necessary
  prefix_save=$prefix
  exec_prefix_save=$exec_prefix

  dnl if no prefix given, then use /usr/local, the default prefix
  if test "x$prefix" = "xNONE"; then
    prefix=$ac_default_prefix
  fi
  dnl if no exec_prefix given, then use prefix
  if test "x$exec_prefix" = "xNONE"; then
    exec_prefix=$prefix
  fi

  full_var="$FROM_VAR"
  dnl loop until it doesn't change anymore
  while true; do
    new_full_var="`eval echo $full_var`"
    if test "x$new_full_var"="x$full_var"; then break; fi
    full_var=$new_full_var
  done

  dnl clean up
  full_var=$new_full_var
  AC_SUBST([$1], "$full_var")

  dnl restore prefix and exec_prefix
  prefix=$prefix_save
  exec_prefix=$exec_prefix_save
])

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