On 25/12/2020 13:37, Tim Van den Langenbergh wrote:
> trace-calls-to-procedure is a low-level trace procedure that returns a 
> trap that you have to install in the trap state. You can either use the 
> add-trap! procedure from (use-modules system vm trap-state), or use the 
> add-trace-at-procedure-call! procedure from the same module.
> 
> That said, there seems to be a bug in add-trace-at-procedure-call! which 
> I'm having a hard time figuring out... c'est la vie.
> 
> Vale
> -Tim Van den Langenbergh

Update: the bug has already been addressed and a patch is awaiting merge:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=43102

I imagine this'll get in for 3.0.5.

Vale,
-Tim Van den Langenbergh