namespace "std" has no member "mutex"

Question

I'm using mingw64 and even a simple program like this failed to compile. Moreover g++ is suggesting a revolutionary solution.

The code-

#include <mutex>

int main()
{
  std::mutex m;
}

The error-

test.cpp: In function 'int main()':
test.cpp:5:8: error: 'mutex' is not a member of 'std'
   std::mutex m;
    ^~~~~

The solution-

test.cpp:5:8: note: 'std::mutex' is defined in header '<mutex>'; did you forget to'#include <mutex>'?
test.cpp:2:1:
+#include <mutex>
 
test.cpp:5:8:
   std::mutex m;
        ^~~~~

How do I compile this?

What compiler version and C++ standard are you using? `std::mutex` is only available in C++11 or later — Brian61354270, Jul 29 '23 at 16:29
Also, are you certain that you saved your source file before compiling? — Brian61354270, Jul 29 '23 at 16:29
I was looking a source code in vs code and I encountered bunch of such errors regarding std::mutex and std::thread. So, I tested the above program certainly saving it! — vector X, Jul 29 '23 at 16:33
https://stackoverflow.com/questions/2519607/stdthread-error-thread-not-member-of-std This is similar. gcc does not fully support std::thread yet. Is std::mutex fully supported by gcc? — vector X, Jul 29 '23 at 16:38
@TedLyngmo g++ --version says "g++.exe (x86_64-win32-seh-rev0, Built by MinGW-W64 project) 8.1.0" By the way, can you compile? — vector X, Jul 29 '23 at 16:39
I see. It seems like there's something wrong with the mingw version of g++ then. Standard `g++` have had `std::mutex` for a very long time. Long before 8.1.0. — Ted Lyngmo, Jul 29 '23 at 16:45

score 0 · Accepted Answer · answered Jul 29 '23 at 17:07

Solved!

C++11 or C11 Multithreading features are only supported by POSIX threads

Threading I am using is win32 which does not support Multithreading. So, std::thread and std::mutex will not work!

However to get std::thread working, use this mingw-std-threads.

I simply replaced my initial mingw installation with x86_64-8.1.0-release-posix-seh-rt_v6-rev0.7z

You may find binaries here.

namespace "std" has no member "mutex"

1 Answers1