g++ module compile fails with ‘_Atomic’ does not name a type

[JoshuaJCogliati]

BPO	23644
Nosy	@vstinner, @jpc2350
Files	min_example.tar.gz: Short example of swig files that will trigger the bug. atomic.cpp atomicfix.patch: Atomics compatibility for g++ and gcc pyatomic_cpp.patch pystate_cplusplus.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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assignee = None
closed_at = <Date 2020-06-25.09:28:48.938>
created_at = <Date 2015-03-12.14:59:00.785>
labels = []
title = 'g++ module compile fails with \xe2\x80\x98_Atomic\xe2\x80\x99 does not name a type'
updated_at = <Date 2020-06-25.09:28:48.938>
user = 'https://bugs.python.org/JoshuaJCogliati'

bugs.python.org fields:

activity = <Date 2020-06-25.09:28:48.938>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-06-25.09:28:48.938>
closer = 'vstinner'
components = []
creation = <Date 2015-03-12.14:59:00.785>
creator = 'Joshua.J.Cogliati'
dependencies = []
files = ['38453', '38458', '38508', '38518', '38519']
hgrepos = []
issue_num = 23644
keywords = ['patch']
message_count = 33.0
messages = ['237942', '237943', '237944', '237946', '237951', '237955', '237956', '237958', '238201', '238202', '238208', '238209', '238223', '238244', '238278', '238279', '238289', '238292', '238332', '238334', '238346', '238347', '269611', '297827', '297832', '297833', '297839', '297840', '297841', '297847', '297849', '305430', '372320']
nosy_count = 11.0
nosy_names = ['vstinner', 'Arfrever', 'jrincayc', 'python-dev', 'Joshua.J.Cogliati', 'Vitor.de.Lima', 'gustavotemple', 'lbianc', 'Martin Ritter', 'Melroy van den Berg', 'jpc2350']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue23644'
versions = ['Python 3.6']

[JoshuaJCogliati]

The attached example works fine with Python 3.4.2, but fails with Python 3.5.0a1 and 3.5.0a2

I am using:
$ g++ --version
g++ (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6)
$ swig -version

SWIG Version 3.0.5

Compiled with g++ [x86_64-redhat-linux-gnu]

Configured options: +pcre
$ python3 --version
Python 3.5.0a2

The output of trying the makefile with Python 3.5.0a2 is:

$ make
swig -c++ -python -py3 example.i
g++ -g -fPIC -c example.cxx example_wrap.cxx -I/local/python350a2/include/python3.5m -I/local/python350a2/include/python3.5m
In file included from /local/python350a2/include/python3.5m/pyatomic.h:10:0,
                 from /local/python350a2/include/python3.5m/Python.h:53,
                 from example_wrap.cxx:154:
/usr/include/c++/4.9.2/exception:161:34: error: missing binary operator before token "("
 #if (__cplusplus >= 201103L) && (ATOMIC_INT_LOCK_FREE > 1)
                                  ^
In file included from /local/python350a2/include/python3.5m/pyatomic.h:10:0,
                 from /local/python350a2/include/python3.5m/Python.h:53,
                 from example_wrap.cxx:154:
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:40:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic _Bool atomic_bool;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:41:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic char atomic_char;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:42:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic signed char atomic_schar;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:43:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic unsigned char atomic_uchar;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:44:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic short atomic_short;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:45:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic unsigned short atomic_ushort;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:46:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic int atomic_int;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:47:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic unsigned int atomic_uint;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:48:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic long atomic_long;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:49:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic unsigned long atomic_ulong;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:50:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic long long atomic_llong;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:51:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic unsigned long long atomic_ullong;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:52:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __CHAR16_TYPE__ atomic_char16_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:53:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __CHAR32_TYPE__ atomic_char32_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:54:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __WCHAR_TYPE__ atomic_wchar_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:55:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_LEAST8_TYPE__ atomic_int_least8_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:56:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_LEAST8_TYPE__ atomic_uint_least8_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:57:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_LEAST16_TYPE__ atomic_int_least16_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:58:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_LEAST16_TYPE__ atomic_uint_least16_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:59:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_LEAST32_TYPE__ atomic_int_least32_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:60:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_LEAST32_TYPE__ atomic_uint_least32_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:61:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_LEAST64_TYPE__ atomic_int_least64_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:62:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_LEAST64_TYPE__ atomic_uint_least64_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:63:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_FAST8_TYPE__ atomic_int_fast8_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:64:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_FAST8_TYPE__ atomic_uint_fast8_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:65:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_FAST16_TYPE__ atomic_int_fast16_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:66:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_FAST16_TYPE__ atomic_uint_fast16_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:67:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_FAST32_TYPE__ atomic_int_fast32_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:68:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_FAST32_TYPE__ atomic_uint_fast32_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:69:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INT_FAST64_TYPE__ atomic_int_fast64_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:70:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINT_FAST64_TYPE__ atomic_uint_fast64_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:71:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INTPTR_TYPE__ atomic_intptr_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:72:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINTPTR_TYPE__ atomic_uintptr_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:73:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __SIZE_TYPE__ atomic_size_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:74:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __PTRDIFF_TYPE__ atomic_ptrdiff_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:75:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __INTMAX_TYPE__ atomic_intmax_t;
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:76:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic __UINTMAX_TYPE__ atomic_uintmax_t;        
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:232:9: error: ‘_Atomic’ does not name a type
 typedef _Atomic struct
         ^
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include/stdatomic.h:239:3: error: ‘atomic_flag’ does not name a type
 } atomic_flag;
   ^
In file included from /local/python350a2/include/python3.5m/Python.h:53:0,
                 from example_wrap.cxx:154:
/local/python350a2/include/python3.5m/pyatomic.h:37:5: error: ‘_Atomic’ does not name a type
     _Atomic void *_value;
     ^
/local/python350a2/include/python3.5m/pyatomic.h:41:5: error: ‘atomic_int’ does not name a type
     atomic_int _value;
     ^
Makefile:4: recipe for target 'example.so' failed
make: *** [example.so] Error 1

The output with Python 3.4.2:
$ make
swig -c++ -python -py3 example.i
g++ -g -fPIC -c example.cxx example_wrap.cxx -I/local/python342m/include/python3.4m -I/local/python342m/include/python3.4m
g++ -g -shared *.o -o _example.so
$ python3.4 a_test.py
3

[vstinner]

_Atomic was added by the issue bpo-22038.

[python-dev]

New changeset eb48295e1f8b by Victor Stinner in branch 'default':
Issue bpo-23644, bpo-22038: Move #include <stdatomic.c> inside the extern "C" { ... }
https://hg.python.org/cpython/rev/eb48295e1f8b

[vstinner]

Can you please try with the latest development version?

[JoshuaJCogliati]

I have:
/local/python_fix/include/python3.5m/pyatomic.h
#ifndef Py_LIMITED_API
#ifndef Py_ATOMIC_H
#define Py_ATOMIC_H

#include "dynamic_annotations.h"

#include "pyconfig.h"

#ifdef __cplusplus
extern "C" {
#endif

#if defined(HAVE_STD_ATOMIC)
#include <stdatomic.h>
#endif

...

and still get:
In file included from /local/python_fix/include/python3.5m/pyatomic.h:14:0,
                 from /local/python_fix/include/python3.5m/Python.h:53,
                 from example_wrap.cxx:154:
/usr/include/c++/4.9.2/exception:161:34: error: missing binary operator before token "("
 #if (__cplusplus >= 201103L) && (ATOMIC_INT_LOCK_FREE > 1)

So the bug still seems to be there.

[vstinner]

The problem is more general than Python: #include <stdatomic.h> fails in C++. Try to compiled atomic.cpp with g++, you will get the same error.

The following bug report in the glibc has been closed as WONTFIX:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60932

It suggests to use the following code:

#ifdef __cplusplus
#include <atomic>
using namespace std;
#else
#include <stdatomic.h>
#endif

I don't know if it works.

[gustavotemple]

@Haypo, @lbianc will investigate this issue.

[JoshuaJCogliati]

If I change the header to:
#ifndef Py_LIMITED_API
#ifndef Py_ATOMIC_H
#define Py_ATOMIC_H

#include "dynamic_annotations.h"

#include "pyconfig.h"

#ifdef __cplusplus
extern "C" {
#endif

#if defined(HAVE_STD_ATOMIC)
#ifdef __cplusplus
#include <atomic>
using namespace std;
#else
#include <stdatomic.h>
#endif
#endif

... (rest same)

AND use -std=c++11
Then the error changes to:
In file included from /local/python_fix/include/python3.5m/Python.h:53:0,
from example_wrap.cxx:154:
/local/python_fix/include/python3.5m/pyatomic.h:42:5: error: ‘_Atomic’ does not name a type
_Atomic void *_value;
^

Basically, <atomic> does define std::atomic_int, but it does not define _Atomic, so the line:
_Atomic void *_value;
will also need to be changed.

[lbianc]

@Haypo

For adding compatibility for atomics based on @Joshua.J.Cogliati change, I propose:

#ifndef Py_LIMITED_API
#ifndef Py_ATOMIC_H
#define Py_ATOMIC_H

#include "dynamic_annotations.h"

#include "pyconfig.h"

#if defined(HAVE_STD_ATOMIC)
#ifdef __cplusplus
#include <atomic>
#define _Atomic(T) atomic<T>
using namespace std;
#else
#include <stdatomic.h>
#endif
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* This is modeled after the atomics interface from C1x, according to

• the draft at
• http://www.open-std.org/JTC1/SC22/wg14/www/docs/n1425.pdf.
• Operations and types are named the same except with a _Py_ prefix
• and have the same semantics.
• Beware, the implementations here are deep magic.
  */

#if defined(HAVE_STD_ATOMIC)

typedef enum _Py_memory_order {
_Py_memory_order_relaxed = memory_order_relaxed,
_Py_memory_order_acquire = memory_order_acquire,
_Py_memory_order_release = memory_order_release,
_Py_memory_order_acq_rel = memory_order_acq_rel,
_Py_memory_order_seq_cst = memory_order_seq_cst
} _Py_memory_order;

typedef struct _Py_atomic_address {
    _Atomic (void) *_value;
} _Py_atomic_address;

typedef struct _Py_atomic_int {
    atomic_int _value;
} _Py_atomic_int;

... (rest same)

[vstinner]

using namespace std;

Doing this in a header is ugly.

[JoshuaJCogliati]

> using namespace std;

Doing this in a header is ugly.

If you put it in the:
#ifdef __cplusplus
extern "C" {
#endif

then it would only apply till the end of the pyatomic header, and not to anything that includes it. Something like:

#ifdef __cplusplus
extern "C" {
#if defined(HAVE_STD_ATOMIC)
using namespace std;
#endif
#endif

But if you are already defining:
#define _Atomic(T) atomic<T>
maybe it should be:
#define _Atomic(T) std::atomic<T>

(I haven't checked any of this code, but they would get around the namespace std being changed in code that includes pyatomic.h problem. )

[vstinner]

#define _Atomic(T) std::atomic<T>

This looks better to me :-) Can you please write a patch?

[lbianc]

#define _Atomic(T) std::atomic<T>
Does not work, since there are definitions like "memory_order_relaxed" that are in std.

I tested the other one, and it works fine:

#ifdef __cplusplus
extern "C" {
#if defined(HAVE_STD_ATOMIC)
using namespace std;
#endif
#endif

@Haypo, what do you think?

[Arfrever]

So use std::memory_order_relaxed, std::memory_order_acquire etc.