C:\Temp>type ConsoleApplication5.cpp
#include <iostream>
#include <mutex>
std::mutex mtx;

void testmethod() {
        std::scoped_lock lock{ mtx };
        std::cout << "lock worked!\n";
}
int main()
{
    std::cout << "Start!\n";
    testmethod();
    std::cout << "End!\n";
}

Microsoft (R) C/C++ Optimizing Compiler Version 19.40.33811 for x64
  Copyright (C) Microsoft Corporation.  All rights reserved.
  cl /c /Zi /W3 /WX- /diagnostics:column /sdl /O2 /Oi /GL /D NDEBUG /D _CONSOLE /D _UNICODE /D UNICODE /Gm- /EHsc /MD /GS /Gy /fp:precise /Zc:wchar_t /Zc:forScope /Zc:inline /std:c++17 /permissive- /Fo"x64\Release\\" /Fd"x64\Release\vc143.pdb" /external:W3 /Gd /TP /FC /errorReport:prompt ConsoleApplication5.cpp

C:\Temp>.\ConsoleApplication5.exe
Start!

C:\Temp>

C:\Temp>.\ConsoleApplication5.exe
Start!
lock worked!
End!

C:\Temp>

``