[clean-list] htoclean "cycle in spine detected"

[Tobias Neukom]

Hi everyone

I'm trying to make an SDL (Simple DirectMedia Layer) binding for Clean. 
But it seems that i don't understand htoclean:

events.h
-----------

void cleansdlPumpEvents();
Clean(cleansdlPumpEvents :: *World -> *World)

events.c
----------

void cleansdlPumpEvents()
{
}

window.icl
-------------

module window

import events
import StdEnv, StdFile, StdDebug

Start :: *World -> *World
Start w
    #    (c,w) =    trace_n "Create Console" (stdio w)
        w = trace_n "DO NOTHING" (cleansdlPumpEvents w)
        (ok,w) = trace_n "Close Console" (fclose c w)
    =     w

Output:

Close Console
DO NOTHING
Create Console
Run Time Warning: cycle in spine detected

What does this "cycle in spine detected" mean? And why does it happen?

Cheers Tobias