unable to compile c++ code in macbook due to __GLIBC__ issue - c++

Question

g++ -std=c++11 -Wall -g threads.cpp -o threads.out
In file included from threads.cpp:1:
In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/iostream:37:
In file included from /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/ios:215:
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__locale:401:32: error: use of undeclared identifier '_ISspace'
static const mask space = _ISspace;
^
Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__locale:402:32: error: use of undeclared identifier '_ISprint'
static const mask print = _ISprint;
^
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__locale:403:32: error: use of undeclared identifier '_IScntrl'
static const mask cntrl = _IScntrl;
^
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__locale:404:32: error: use of undeclared identifier '_ISupper'
static const mask upper = _ISupper;
^
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__locale:405:32: error: use of undeclared identifier '_ISlower'
static const mask lower = _ISlower;
^
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/__locale:406:32: error: use of undeclared identifier '_ISalpha'
static const mask alpha = _ISalpha;
can you please help me to resolve this __locale issue while compiling the c++ code.
#include <iostream>
#include <thread>
using namespace std;
void fun(void)
{
cout << "Vaule " << 10 << endl;
}
int main()
{
thread t1(fun);
thread t2(fun);
return 0;
}
compiling command:
g++ -std=c++11 -Wall -g thread.cpp -o thread.out

Answer 1

Two things fix the problem you're having.
Thing the first, add the compiler option -pthread. My compile command: clang++ -Wall -Wextra -std=c++11 -pthread main.cpp
Thing the second, join your threads before ending the program.
t1.join();
t2.join();
Something it does not fix, is that your std::cout statement will likely be jumbled because the threads simply dump their data into the single stream as they please. For an example, my output was the following:
Vaule Vaule 10
10
In order to fix that, you'll likely need to place a lock(mutex) around the std::cout statement.
As I said in my comment, I do not recommend using g++ unless you installed it yourself. The command you're using is an alias that doesn't behave, because of some text you left out.
❯ g++ --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin20.3.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
Contrast with clang++
❯ clang++ --version
Apple clang version 12.0.0 (clang-1200.0.32.29)
Target: x86_64-apple-darwin20.3.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
Of note in the g++ section is the 'Configured with' line. It uses a Standard Library from gcc 4.2.1, which is pre-C++11. You should not have left that information out.