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# Some versions of gcc/libstdc++ require linking with -latomic if
# using the C++ atomic library.
# Copyright (c) 2015-2016 Tim Kosse <tim.kosse@filezilla-project.org>
# Copying and distribution of this file, with or without modification, are
# permitted in any medium without royalty provided the copyright notice
# and this notice are preserved. This file is offered as-is, without any
# warranty.
m4_define([_CHECK_ATOMIC_testbody], [[
#include <atomic>
#include <cstdint>
int main() {
std::atomic<int64_t> a{};
int64_t v = 5;
int64_t r = a.fetch_add(v);
return static_cast<int>(r);
}
]])
AC_DEFUN([CHECK_ATOMIC], [
AC_LANG_PUSH(C++)
AC_MSG_CHECKING([whether std::atomic can be used without link library])
AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_ATOMIC_testbody])],[
AC_MSG_RESULT([yes])
],[
AC_MSG_RESULT([no])
ATOMIC_LIBS=-latomic
AC_MSG_CHECKING([whether std::atomic needs -latomic])
AC_LINK_IFELSE([AC_LANG_SOURCE([_CHECK_ATOMIC_testbody])],[
AC_MSG_RESULT([yes])
],[
AC_MSG_RESULT([no])
AC_MSG_FAILURE([cannot figure out how to use std::atomic])
])
])
AC_LANG_POP
AC_SUBST([ATOMIC_LIBS])
])
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