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emacs/m4/double-slash-root.m4
2023-01-01 05:31:12 -05:00

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# double-slash-root.m4 serial 4 -*- Autoconf -*-
dnl Copyright (C) 2006, 2008-2023 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
])