How code global variable for a FreeRTOS Queue

Error message:
.pio/build/esp32dev/src/playMusicQueue.cpp.o:(.literal._Z14playMusicQueuePv+0x4): undefined reference to `xMusicQueue’
collect2: error: ld returned 1 exit status
*** [.pio/build/esp32dev/firmware.elf] Error 1

Code in github.

I’ve tried several way’s to code variable xMusicQueue as global, but I keep getting this error.

What is the way to do this?

You declare the existance of the global variable in

but there is no matching

QueueHandle_t xMusicQueue;

statement in the populateMusicQueue.cpp file. I suggest placing that in line 15. Otherwise it’s a declaration of a variable that was not defined.

Maximilian, That’s clear now, thank you.
But still:
QueueHandle_t xMusicQueue;
looks like a re-declaration to me, that’s why I didn’t try that one.

I’m still struggling with this issue, a good reliable explanation of the rules involved here would be very helpful.
I’ve found one: