Error mutex does not name a type

 #include <iostream>
 #include <thread>
 #include <mutex>
 using namespace std;
 int x = 0; // shared variable

 void synchronized_procedure()
 {
    static std::mutex m;
    m.lock();
    x = x + 1;
    if (x < 5)
    {
       cout<<"hello";
    }
    m.unlock();

 }

int main()
{

   synchronized_procedure();
   x=x+2;
   cout<<"x is"<<x;
}

5

#include <iostream>  
#include  <thread>    // std::thread    
#include  <mutex>    // std::mutex    
mutex mtx;           // mutex for critical section

int main ()
{
    return 0;
}

arm-none-eabi-g++ -Os -Wall -std=c++11 -fno-rtti -fno-exceptions -c mt.cc

4

Что это вообще за зверь и с чем его едят? Гугл находит только шаманства, которые помогали людям в их специфических ситуациях (например, попытку задействовать как std::mutex реализацию из библиотеки boost), и поспешные оправдания в том, что это, мол, «local issue». А что за «local issue» и почему — нигде ничего не находится.

/usr/include/c++/6.2.0/bits/std_mutex.h на месте, в /usr/include/c++/6.2.0/mutex он упомянут, и «#include <mutex>» в исходниках (кстати, эмулятора MAME) совсем не забыто. Правда, там есть проверка на версию стандарта, но компилятор вызывается с «-std=c++14» и всё равно падает:

# make
GCC 6.2.0 detected
Precompiling src/emu/emu.h...
In file included from ../../../../../src/emu/emucore.h:37:0,
                 from ../../../../../src/emu/emu.h:29:
../../../../../src/emu/emualloc.h:128:7: ошибка: <<mutex>> в пространстве имен <<std>> не именует тип
  std::mutex              m_listlock;
       ^~~~~
make[2]: *** [precompile.make:270: ../../../../linux_gcc/obj/x64/Release/emu.h.gch] Ошибка 1
make[1]: *** [Makefile:55: precompile] Ошибка 2
make: *** [makefile:1170: linux_x64] Ошибка 2

Где может быть засада?

• 
• Forum
• General Programming Boards
• C++ Programming
• g++ 4.7.2 error: ‘mutex’ in namespace ‘std’ does not name a type

1. 03-11-2013

   
   

   #1

   

   
   Registered User
   

   ---

   g++ 4.7.2 error: ‘mutex’ in namespace ‘std’ does not name a type
   

   I’ve verified this on ubuntu 12.10 and on windows/mingw, and found that g++ version 4.7.2 seems to have broken thread/mutex support. has anyone else observed this?

   ---

2. 03-11-2013

   
   

   #2

   

   
   and the hat of int overfl
   

   

   ---

   Can you post your test case?

   ---

3. 03-11-2013

   
   

   #3

   

   
   Master Apprentice
   

   

   ---

   has anyone else observed this?

   I usually build my own package for «Windows», so maybe it is just my builds script, but that seems par for the course under «MinGW».

   I can’t speak to anything about «Ubuntu».

   My understanding, and only that, is that a lot of work needs to be done for «libstdc++» before the implementation has the proper safety the respect to the standard. You may not, and probably will not, be able to match your own expectations with «libstdc++» for a bit longer.

   Soma

   ---

4. 03-11-2013

   
   

   #4

   

   
   Registered User
   

   ---

   Originally Posted by Salem
   

   Can you post your test case?

   this was my actual test case

   Code:

   #include <iostream>
   #include <thread>
   #include <vector>
   #include <memory>
   
   std::mutex mutex;
   int mutexProtected = 0;
   
   void threadProc()
   {
       for (int i = 0; i < 5; ++i)
       {
   	std::lock_guard<std::mutex> lock(mutex);
   	std::cout << "Value: " << ++mutexProtected << std::endl;
       }
   }
   
   int main()
   {
       std::vector<std::shared_ptr<std::thread> > threadVector;
   
       for (int i = 0; i < 20; ++i)
       {
   	threadVector.push_back(std::shared_ptr<std::thread>(new std::thread(threadProc)));
       }
   
       for (auto& thread : threadVector)
       {
   	thread->join();
       }
   
       return 0;
   }

   my compile command is

   Code:

   g++ -pthread -std=c++0x -c main.cpp

   and the output I get on mingw is

   Code:

   main.cpp:6:1: error: 'mutex' in namespace 'std' does not name a type
   main.cpp: In function 'void threadProc()':
   main.cpp:13:2: error: 'lock_guard' is not a member of 'std'
   main.cpp:13:18: error: 'mutex' is not a member of 'std'
   main.cpp:13:35: error: 'mutex' was not declared in this scope
   main.cpp:13:40: error: 'lock' was not declared in this scope
   main.cpp: In function 'int main()':
   main.cpp:22:33: error: 'thread' is not a member of 'std'
   main.cpp:22:33: error: 'thread' is not a member of 'std'
   main.cpp:22:44: error: template argument 1 is invalid
   main.cpp:22:46: error: template argument 1 is invalid
   main.cpp:22:46: error: template argument 2 is invalid
   main.cpp:22:60: error: invalid type in declaration before ';' token
   main.cpp:26:15: error: request for member 'push_back' in 'threadVector', which is of non-class type 'int'
   main.cpp:26:41: error: 'thread' is not a member of 'std'
   main.cpp:26:41: error: 'thread' is not a member of 'std'
   main.cpp:26:52: error: template argument 1 is invalid
   main.cpp:26:58: error: expected type-specifier
   main.cpp:26:58: error: expected ')'
   main.cpp:29:25: error: no matching function for call to 'begin(int&)'
   more errors snipped...

   even a simple test case like this exhibits essentially the same behavior

   Code:

   #include <mutex>
   
   int main()
   {
       std::mutex mutex;
       return 0;
   }

   there were many more errors, but they were all related to the compiler’s inability to find a begin() or end() function for std::vector<std::shared_ptr<std::thread> >.

   after more digging, I determined that on ubuntu, modifying the code to include <mutex> solved the problem. it seems that <mutex> was included implicitly by <thread> in g++ 4.6.3 on fedora 15, and a recent move to ubuntu 12.10 (gcc 4.7.3) for my main dev machine exposed that fact.

   on mingw (gcc 4.7.3), including <mutex> did not solve the problem. it appears that the std::thread implementation in the official release of mingw version of g++ 4.7.3 is incomplete or nonexistent.

   ---

5. 03-11-2013

   
   

   #5

   

   
   Registered User
   

   ---

   You may want to include <mutex> to use the mutex class. After I add that include file your program compiles without errors for me. But I do use the -std=c++11 flag instead of -std=c++0x.

   Jim

   ---

6. 03-11-2013

   
   

   #6

   

   
   Registered User
   

   ---

   Originally Posted by jimblumberg
   

   You may want to include <mutex> to use the mutex class. After I add that include file your program compiles without errors for me.

   as I said in my last post, that fixes it on ubuntu, but not on windows.

   Originally Posted by jimblumberg
   

   But I do use the -std=c++11 flag instead of -std=c++0x.

   changing -std=c++0x to -std=c++11 makes no difference. my guess is that they are equivalent.

   ---

7. 03-11-2013

   
   

   #7

   

   
   Registered User
   

   ---

   changing -std=c++0x to -std=c++11 makes no difference. my guess is that they are equivalent.

   Not on my system. If I change to -std=c++0x I get these errors:

   /usr/include/c++/4.7/bits/c++0x_warning.h|32|error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support is currently experimental, and must be enabled with the -std=c++11 or -std=gnu++11 compiler options.|
   main.cpp||In function ‘int main()’:|
   main.cpp|5|error: ‘mutex’ is not a member of ‘std’|
   main.cpp|5|error: expected ‘;’ before ‘mutex’|
   ||=== Build finished: 3 errors, 0 warnings ===|

   Jim

   ---

8. 03-11-2013

   
   

   #8

   

   
   Registered User
   

   ---

   Originally Posted by jimblumberg
   

   changing -std=c++0x to -std=c++11 makes no difference. my guess is that they are equivalent.

   Not on my system. If I change to -std=c++0x I get these errors:

   Jim

   what actual version of gcc is it? (gcc —version)

   ---

9. 03-11-2013

   
   

   #9

   

   
   Registered User
   

   ---

   ---

10. 03-11-2013

    
    

    #10

    

    
    Registered User
    

    ---

    that’s interesting. both produce identical results on my ubuntu and mingw systems with 4.7.3.

    ---

11. 03-11-2013

    
    

    #11

    

    
    Registered User
    

    ---

    In my Code::Blocks with MinGW GCC (gcc version 4.7.1 (tdm-1)),
    _GLIBCXX_HAS_GTHREADS is not defined.

    From mutex header.

    Code:

    #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
    
    namespace std _GLIBCXX_VISIBILITY(default)
    {

    I am guessing that there is a option that compiles MinGW GCC with this _GLIBCXX_HAS_GTHREADS defined.

    Tim S.

    «…a computer is a stupid machine with the ability to do incredibly smart things, while computer programmers are smart people with the ability to do incredibly stupid things. They are,in short, a perfect match..» Bill Bryson

    ---

12. 03-13-2013

    
    

    #12

    

    
    Registered User
    

    ---

    MinGW-w64 does support C++11 threads, and despite its name, it is also for 32-bit (which I personally use):
    GCC for both x64 & x86 Windows! — MinGW-w64

    ---

Author
Topic: ‘ mutex ‘ in namespace ‘ std ‘ does not name a type  (Read 10365 times)

« Last Edit: August 05, 2017, 11:23:51 pm by BlueHazzard »

Logged

error: ‘mutex’ in
namespace ‘std’ does not name a type

     std::mutex m_mutex;

note: ‘std::mutex’
is defined in header ‘<mutex>’; did you forget to ‘#include
<mutex>’?

error: ‘mutex’ is
not a member of ‘std’

         std::lock_guard<std::mutex>
lock(m_mutex);

error: template
argument 1 is invalid

         std::lock_guard<std::mutex>
lock(m_mutex);

error: ‘m_mutex’ was
not declared in this scope

         std::lock_guard<std::mutex>
lock(m_mutex);

note: suggested
alternative: ‘uv_mutex_t’

         std::lock_guard<std::mutex>
lock(m_mutex);

                                         
^~~~~~~

                                         
uv_mutex_t

 warning: unused variable ‘lock’
[-Wunused-variable]

         std::lock_guard<std::mutex>
lock(m_mutex);

• Forum
• General C++ Programming
• C++0x mutex don’t compile on minGW

C++0x mutex don’t compile on minGW

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#include <thread>

using namespace std;

class TryMutex
{
    public:
        TryMutex();
        virtual ~TryMutex();
    protected:
    private:
    mutex myMutex;
};

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