VSCode doesnt build and debug pthreads code

Question

I got a few codes from https://computing.llnl.gov/tutorials/pthreads/ and I was trying to use the VSCode debugger to try to step through them but it doesnt seem to work.
Using tasks (ctrl+shift+B) I can build it just fine (I've added the -pthread flag) but when I try to debug it (F5) I get this error:

> Executing task: C/C++: gcc build active file <

Starting build...
Build finished with error:
/usr/bin/ld: /tmp/cc5vG56K.o: in function `main':
/home/xristosp59/Documents/Programming/condvar.c:98: undefined reference to `pthread_create'
/usr/bin/ld: /home/xristosp59/Documents/Programming/condvar.c:99: undefined reference to `pthread_create'
/usr/bin/ld: /home/xristosp59/Documents/Programming/condvar.c:100: undefined reference to `pthread_create'
/usr/bin/ld: /home/xristosp59/Documents/Programming/condvar.c:104: undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status 
The terminal process failed to launch (exit code: -1).

I've tried both -pthread and -lpthread flags in various places in my tasks.json but none seem to work, I always get this error.
Here is my current tasks.json: (this builds fine with tasks)

{
    "tasks": [
        {
            "type": "cppbuild",
            "label": "C/C++: gcc build active file",
            "command": "/usr/bin/gcc",
            "args": [
                "-g",
                "-pthread",
                "${file}",
                "-o",
                "${fileDirname}/${fileBasenameNoExtension}"
            ],
            "options": {
                "cwd": "/usr/bin"
            },
            "problemMatcher": [
                "$gcc"
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            },
            "detail": "Generated task by Debugger"
        }
    ],
    "version": "2.0.0"
}

I'm on pop_os 20.10 if that matters.

Answer 1

Ok so apparently vscode, when you first try to debug a c program, it creates a launch.json and tasks.json, the launch.json has a "preLaunchTask": "C/C++: gcc build active file" option and tasks.json has a "label": "C/C++: gcc build active file" option, which match, but I guess because C/C++: gcc build active file is already a task in vscode, it doesn't use the one in tasks (please correct me if I'm wrong). I changed the labels in both and now it works.