How do I set up my project to call assembly functions

Hello,
I've been studying a lot C++ and 64-bit Assembly during my apprenticeship and would like to get into GUI programming with Qt.
Sadly I can't figure out how to get my project properly set up to call an extern assembly function from my .s or .asm file.

This is what I have tried:
.pro

Code:

---

QT       += core gui
 
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
 
TARGET = test---
TEMPLATE = app
 
DEFINES += QT_DEPRECATED_WARNINGS
 
 
QMAKE_EXTRA_COMPILERS += nasm
# or should I use QMAKE += nasm
 
SOURCES += main.cpp\
        mainwindow.cpp\
        asm.s
 
HEADERS  += mainwindow.h
 
FORMS    += mainwindow.ui
 
LIBS += asm.s

---

mainwindow.cpp

Code:

---

//code
 
extern "C" __int64 assembly();
 
//code
 
void MainWindow::on_pushButton_clicked()
{
    int zahl = assembly();  // for testing purposes I just want the value of rax to be returned and put into the variable zahl
}

---

asm.s

Code:

---

.code
.global
assembly proc
 
mov rax, 1
ret
 
xor rax, rax
 
assembly endp
end

---

Whenever I attempt to compile the program I get an error message stating that the symbol assembly cannot be found.
I'm really desperate and need someone help me with this problem :(
I've been browsing the internet for hours but couldn't get a decent solution