tools/missing-macros/src/m4/as-ac-expand.m4

   1 dnl as-ac-expand.m4 0.2.0
   2 dnl autostars m4 macro for expanding directories using configure's prefix
   3 dnl thomas@apestaart.org
   4
   5 dnl AS_AC_EXPAND(VAR, CONFIGURE_VAR)
   6 dnl example
   7 dnl AS_AC_EXPAND(SYSCONFDIR, $sysconfdir)
   8 dnl will set SYSCONFDIR to /usr/local/etc if prefix=/usr/local
   9
  10 AC_DEFUN([AS_AC_EXPAND],
  11 [
  12   EXP_VAR=[$1]
  13   FROM_VAR=[$2]
  14
  15   dnl first expand prefix and exec_prefix if necessary
  16   prefix_save=$prefix
  17   exec_prefix_save=$exec_prefix
  18
  19   dnl if no prefix given, then use /usr/local, the default prefix
  20   if test "x$prefix" = "xNONE"; then
  21     prefix="$ac_default_prefix"
  22   fi
  23   dnl if no exec_prefix given, then use prefix
  24   if test "x$exec_prefix" = "xNONE"; then
  25     exec_prefix=$prefix
  26   fi
  27
  28   full_var="$FROM_VAR"
  29   dnl loop until it doesn't change anymore
  30   while true; do
  31     new_full_var="`eval echo $full_var`"
  32     if test "x$new_full_var" = "x$full_var"; then break; fi
  33     full_var=$new_full_var
  34   done
  35
  36   dnl clean up
  37   full_var=$new_full_var
  38   AC_SUBST([$1], "$full_var")
  39
  40   dnl restore prefix and exec_prefix
  41   prefix=$prefix_save
  42   exec_prefix=$exec_prefix_save
  43 ])