dash/build-aux/m4/l_filesystem.m4

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dnl Copyright (c) 2022 The Bitcoin Core developers
dnl Distributed under the MIT software license, see the accompanying
dnl file COPYING or http://www.opensource.org/licenses/mit-license.php.
# GCC 8.1 and earlier requires -lstdc++fs
# Clang 8.0.0 (libc++) and earlier requires -lc++fs
m4_define([_CHECK_FILESYSTEM_testbody], [[
#include <filesystem>
namespace fs = std::filesystem;
int main() {
(void)fs::current_path().root_name();
return 0;
}
]])
AC_DEFUN([CHECK_FILESYSTEM], [
AC_LANG_PUSH(C++)
AC_MSG_CHECKING([whether std::filesystem can be used without link library])
AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_FILESYSTEM_testbody])],[
AC_MSG_RESULT([yes])
],[
AC_MSG_RESULT([no])
SAVED_LIBS="$LIBS"
LIBS="$SAVED_LIBS -lstdc++fs"
AC_MSG_CHECKING([whether std::filesystem needs -lstdc++fs])
AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_FILESYSTEM_testbody])],[
AC_MSG_RESULT([yes])
],[
AC_MSG_RESULT([no])
AC_MSG_CHECKING([whether std::filesystem needs -lc++fs])
LIBS="$SAVED_LIBS -lc++fs"
AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_FILESYSTEM_testbody])],[
AC_MSG_RESULT([yes])
],[
AC_MSG_FAILURE([cannot figure out how to use std::filesystem])
])
])
])
AC_LANG_POP
])