Taken from https://salsa.debian.org/med-team/insighttoolkit/-/blob/itk-4.y/debian/patches/python3.8.diff

--- Modules/ThirdParty/pygccxml/src/pygccxml/declarations/scopedef.py
+++ Modules/ThirdParty/pygccxml/src/pygccxml/declarations/scopedef.py
@@ -293,7 +293,7 @@ class scopedef_t(declaration.declaration
         if self.name == '::':
             self._logger.debug(
                 "preparing data structures for query optimizer - started")
-        start_time = time.clock()
+        start_time = time.perf_counter()
 
         self.clear_optimizer()
 
@@ -327,7 +327,7 @@ class scopedef_t(declaration.declaration
         if self.name == '::':
             self._logger.debug((
                 "preparing data structures for query optimizer - " +
-                "done( %f seconds ). "), (time.clock() - start_time))
+                "done( %f seconds ). "), (time.perf_counter() - start_time))
         self._optimized = True
 
     @staticmethod
@@ -475,7 +475,7 @@ class scopedef_t(declaration.declaration
     def _find_single(self, match_class, **keywds):
         """implementation details"""
         self._logger.debug('find single query execution - started')
-        start_time = time.clock()
+        start_time = time.perf_counter()
         norm_keywds = self.__normalize_args(**keywds)
         decl_matcher = self.__create_matcher(match_class, **norm_keywds)
         dtype = self.__findout_decl_type(match_class, **norm_keywds)
@@ -484,13 +484,13 @@ class scopedef_t(declaration.declaration
         found = matcher.get_single(decl_matcher, decls, False)
         self._logger.debug(
             'find single query execution - done( %f seconds )',
-            (time.clock() - start_time))
+            (time.perf_counter() - start_time))
         return found
 
     def _find_multiple(self, match_class, **keywds):
         """implementation details"""
         self._logger.debug('find all query execution - started')
-        start_time = time.clock()
+        start_time = time.perf_counter()
         norm_keywds = self.__normalize_args(**keywds)
         decl_matcher = self.__create_matcher(match_class, **norm_keywds)
         dtype = self.__findout_decl_type(match_class, **norm_keywds)
@@ -502,7 +502,7 @@ class scopedef_t(declaration.declaration
         self._logger.debug('%d declaration(s) that match query', len(mfound))
         self._logger.debug(
             'find single query execution - done( %f seconds )',
-            (time.clock() - start_time))
+            (time.perf_counter() - start_time))
         if not mfound and not allow_empty:
             raise RuntimeError(
                 "Multi declaration query returned 0 declarations.")

--- Modules/ThirdParty/pygccxml/src/pygccxml/parser/declarations_cache.py
+++ Modules/ThirdParty/pygccxml/src/pygccxml/parser/declarations_cache.py
@@ -188,11 +188,11 @@ class file_cache_t(cache_base_t):
         cache_file_obj = open(file_name, 'rb')
         try:
             file_cache_t.logger.info('Loading cache file "%s".', file_name)
-            start_time = time.clock()
+            start_time = time.perf_counter()
             cache = pickle.load(cache_file_obj)
             file_cache_t.logger.debug(
                 "Cache file has been loaded in %.1f secs",
-                (time.clock() - start_time))
+                (time.perf_counter() - start_time))
             file_cache_t.logger.debug(
                 "Found cache in file: [%s]  entries: %s",
                 file_name, len(list(cache.keys())))

--- Modules/ThirdParty/pygccxml/src/pygccxml/parser/project_reader.py
+++ Modules/ThirdParty/pygccxml/src/pygccxml/parser/project_reader.py
@@ -316,11 +316,11 @@ class project_reader_t(object):
             namespaces.append(decls)
 
         self.logger.debug("Flushing cache... ")
-        start_time = time.clock()
+        start_time = time.perf_counter()
         self.__dcache.flush()
         self.logger.debug(
             "Cache has been flushed in %.1f secs",
-            (time.clock() - start_time))
+            (time.perf_counter() - start_time))
         answer = []
         self.logger.debug("Joining namespaces ...")
         for file_nss in namespaces: