Merge #8563: Add configure check for -latomic

878faac Add configure check for -latomic (Anthony Towns)
This commit is contained in:
Wladimir J. van der Laan 2016-09-09 08:57:08 +02:00 committed by Alexander Block
parent c2a601f507
commit b90d7611ab
2 changed files with 42 additions and 0 deletions

40
build-aux/m4/l_atomic.m4 Normal file
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@ -0,0 +1,40 @@
# Some versions of gcc/libstdc++ require linking with -latomic if
# using the C++ atomic library.
#
# Sourced from http://bugs.debian.org/797228
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])
LIBS="$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 our how to use std::atomic])
])
])
AC_LANG_POP
])

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@ -56,6 +56,8 @@ case $host in
esac
dnl Require C++11 compiler (no GNU extensions)
AX_CXX_COMPILE_STDCXX([11], [noext], [mandatory], [nodefault])
dnl Check if -latomic is required for <std::atomic>
CHECK_ATOMIC
dnl Unless the user specified OBJCXX, force it to be the same as CXX. This ensures
dnl that we get the same -std flags for both.