Linker can't find WinMain entry point

Question

Error: undefined reference to `WinMain'
collect2.exe: error: ld returned 1 exit status

Code:

#include <windows.h>

HWND hwnd;
COLORREF dotColor = RGB(0, 0, 0); 

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
void PaintDot(HWND hwnd, int x, int y);

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
    WNDCLASSEX wc;
    MSG msg;

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.style = 0;
    wc.lpfnWndProc = WndProc;
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hInstance = hInstance;
    wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wc.lpszMenuName = NULL;
    wc.lpszClassName = "PaintDots";
    wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

    if (!RegisterClassEx(&wc)) {
        MessageBox(NULL, "Window Registration Failed!", "Error", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        "PaintDots",
        "Paint Dots",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 640, 480,
        NULL, NULL, hInstance, NULL);

    if (hwnd == NULL) {
        MessageBox(NULL, "Window Creation Failed!", "Error", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    while (GetMessage(&msg, NULL, 0, 0) > 0) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam) {
    switch (msg) {
        case WM_PAINT:
            {
                PAINTSTRUCT ps;
                HDC hdc = BeginPaint(hwnd, &ps);
                // Handle paint event here
                EndPaint(hwnd, &ps);
            }
            break;
        case WM_LBUTTONDOWN:
            {
                int x = LOWORD(lParam);
                int y = HIWORD(lParam);
                PaintDot(hwnd, x, y);
            }
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

void PaintDot(HWND hwnd, int x, int y) {
    HDC hdc = GetDC(hwnd);
    SetPixel(hdc, x, y, dotColor);
    ReleaseDC(hwnd, hdc);
}

Build Command:

gcc GPTpaint.c -o paintdots.exe -mwindows 

Compiler: GCC (installed using MSYS2)

Note: I've tried entering in the MSYS2 terminal 'pacman -Su' which would update all packages, including GCC and it seems to have no need to do that. I also notice that wWinMain is not an accepted entry point even though the only difference between them is ASCII and Unicode. There seems to be an issue regarding w_char_t and LPSTR (one of the entry point parameters which is a type) and I've had code that had successfully surpassed this error but then gained those aforementioned errors.