fixes #6234

lib/system/gc.nim

@@ -259,6 +259,9 @@ proc nimGCunrefNoCycle(p: pointer) {.compilerProc, inline.} =
     sysAssert(allocInv(gch.region), "end nimGCunrefNoCycle 2")
   sysAssert(allocInv(gch.region), "end nimGCunrefNoCycle 5")
 
+proc nimGCunrefRC1(p: pointer) {.compilerProc, inline.} =
+  decRef(usrToCell(p))
+
 proc asgnRef(dest: PPointer, src: pointer) {.compilerProc, inline.} =
   # the code generator calls this proc!
   gcAssert(not isOnStack(dest), "asgnRef")

lib/system/mmdisp.nim

@@ -16,7 +16,7 @@
 const
   debugGC = false # we wish to debug the GC...
   logGC = false
-  traceGC = defined(smokeCycles) # extensive debugging
+  traceGC = false # extensive debugging
   alwaysCycleGC = defined(smokeCycles)
   alwaysGC = defined(fulldebug) # collect after every memory
                                 # allocation (for debugging)