fix cast in newer cppyy included in e.g. ROOT 6.32.08. See wlav/cppyy…

…#278

py/mattak/backends/pyroot/dataset.py

@@ -21,6 +21,10 @@
 
 cppyy.cppdef(" bool is_nully(void *p) { return !p; }")
 
+# this is needed for newer versions of cppyy to remain backwards compatible, due to changes in uint8_t handling
+cppyy.cppdef(" uint8_t* cast_uint8_t(void * x) { return (uint8_t*) x; }")
+cast_uint8_t  = cppyy.gbl.cast_uint8_t
+
 def isNully(p):
     return p is None or ROOT.AddressOf(p) == 0 or cppyy.gbl.is_nully(p)
 
@@ -164,8 +168,9 @@ def _eventInfo(self, i : int) -> Optional[mattak.Dataset.EventInfo]:
         # The `numpy.copy(...)`` is strictly necessary. Otherwise group access via `dataset.eventInfo()`
         # results in the same `radiantStartWindows` for each event (only for the last event it is correct)
         radiantStartWindows = numpy.copy(numpy.frombuffer(
-            cppyy.ll.cast['uint8_t*'](hdr.trigger_info.radiant_info.start_windows),
-            dtype='uint8', count=self.NUM_CHANNELS * 2).reshape(self.NUM_CHANNELS, 2))
+                cast_uint8_t(hdr.trigger_info.radiant_info.start_windows),
+                dtype='uint8', count=self.NUM_CHANNELS * 2).reshape(self.NUM_CHANNELS, 2))
+
 
         readout_delay = numpy.copy(numpy.around(numpy.frombuffer(
             cppyy.ll.reinterpret_cast['float*'](self.ds.radiantReadoutDelays()),