# double-slash-root.m4 serial 4   -*- Autoconf -*-

dnl Copyright (C) 2006, 2008-2018 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_DOUBLE_SLASH_ROOT],

[

  AC_REQUIRE([AC_CANONICAL_HOST])

  AC_CACHE_CHECK([whether // is distinct from /], [gl_cv_double_slash_root],

    [ if test x"$cross_compiling" = xyes ; then

        # When cross-compiling, there is no way to tell whether // is special

        # short of a list of hosts.  However, the only known hosts to date

        # that have a distinct // are Apollo DomainOS (too old to port to),

        # Cygwin, and z/OS.  If anyone knows of another system for which // has

        # special semantics and is distinct from /, please report it to

        # <bug-gnulib@gnu.org>.

        case $host in

          *-cygwin | i370-ibm-openedition)

            gl_cv_double_slash_root=yes ;;

          *)

            # Be optimistic and assume that / and // are the same when we

            # don't know.

            gl_cv_double_slash_root='unknown, assuming no' ;;

        esac

      else

        set x `ls -di / // 2>/dev/null`

        if test "$[2]" = "$[4]" && wc //dev/null >/dev/null 2>&1; then

          gl_cv_double_slash_root=no

        else

          gl_cv_double_slash_root=yes

        fi

      fi])

  if test "$gl_cv_double_slash_root" = yes; then

    AC_DEFINE([DOUBLE_SLASH_IS_DISTINCT_ROOT], [1],

      [Define to 1 if // is a file system root distinct from /.])

  fi

])