Rename variables with unclear naming (#14122)

* Rename var

* Add comments

src/transformers/modeling_utils.py

@@ -1494,13 +1494,13 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMix
 
         # key re-naming operations are never done on the keys
         # that are loaded, but always on the keys of the newly initialized model
-        remove_prefix = not has_prefix_module and expects_prefix_module
-        add_prefix = has_prefix_module and not expects_prefix_module
+        remove_prefix_from_model = not has_prefix_module and expects_prefix_module
+        add_prefix_to_model = has_prefix_module and not expects_prefix_module
 
-        if remove_prefix:
+        if remove_prefix_from_model:
             expected_keys_not_prefixed = [s for s in expected_keys if not s.startswith(prefix)]
             expected_keys = [".".join(s.split(".")[1:]) if s.startswith(prefix) else s for s in expected_keys]
-        elif add_prefix:
+        elif add_prefix_to_model:
             expected_keys = [".".join([prefix, s]) for s in expected_keys]
 
         missing_keys = list(set(expected_keys) - set(loaded_keys))
@@ -1512,9 +1512,11 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMix
         if ignore_mismatched_sizes:
             for checkpoint_key in loaded_keys:
                 model_key = checkpoint_key
-                if remove_prefix:
+                if remove_prefix_from_model:
+                    # The model key starts with `prefix` but `checkpoint_key` doesn't so we add it.
                     model_key = f"{prefix}.{checkpoint_key}"
-                elif add_prefix:
+                elif add_prefix_to_model:
+                    # The model key doesn't start with `prefix` but `checkpoint_key` does so we remove it.
                     model_key = ".".join(checkpoint_key.split(".")[1:])
 
                 if (
@@ -1539,7 +1541,7 @@ class PreTrainedModel(nn.Module, ModuleUtilsMixin, GenerationMixin, PushToHubMix
         if _fast_init:
             # retrieve unintialized modules and initialize
             uninitialized_modules = model.retrieve_modules_from_names(
-                missing_keys, add_prefix=add_prefix, remove_prefix=remove_prefix
+                missing_keys, add_prefix=add_prefix_to_model, remove_prefix=remove_prefix_from_model
             )
             for module in uninitialized_modules:
                 model._init_weights(module)