Fix pipeline+peft interaction (#36480)

* Fix pipeline-peft interaction

* once again you have committed a debug breakpoint

* Remove extra testing line

* Add a test to check adapter loading

* Correct adapter path

* make fixup

* Remove unnecessary check

* Make check a little more stringent

src/transformers/pipelines/__init__.py

@@ -824,6 +824,7 @@ def pipeline(
 
     # Config is the primordial information item.
     # Instantiate config if needed
+    adapter_path = None
     if isinstance(config, str):
         config = AutoConfig.from_pretrained(
             config, _from_pipeline=task, code_revision=code_revision, **hub_kwargs, **model_kwargs
@@ -844,6 +845,7 @@ def pipeline(
             if maybe_adapter_path is not None:
                 with open(maybe_adapter_path, "r", encoding="utf-8") as f:
                     adapter_config = json.load(f)
+                    adapter_path = model
                     model = adapter_config["base_model_name_or_path"]
 
         config = AutoConfig.from_pretrained(
@@ -938,7 +940,7 @@ def pipeline(
     if isinstance(model, str) or framework is None:
         model_classes = {"tf": targeted_task["tf"], "pt": targeted_task["pt"]}
         framework, model = infer_framework_load_model(
-            model,
+            adapter_path if adapter_path is not None else model,
             model_classes=model_classes,
             config=config,
             framework=framework,

tests/peft_integration/test_peft_integration.py

@@ -526,9 +526,13 @@ class PeftIntegrationTester(unittest.TestCase, PeftTesterMixin):
         """
         from transformers import pipeline
 
-        for model_id in self.peft_test_model_ids:
-            pipe = pipeline("text-generation", model_id)
-            _ = pipe("Hello")
+        for adapter_id, base_model_id in zip(self.peft_test_model_ids, self.transformers_test_model_ids):
+            peft_pipe = pipeline("text-generation", adapter_id)
+            base_pipe = pipeline("text-generation", base_model_id)
+            peft_params = list(peft_pipe.model.parameters())
+            base_params = list(base_pipe.model.parameters())
+            self.assertNotEqual(len(peft_params), len(base_params))  # Assert we actually loaded the adapter too
+            _ = peft_pipe("Hello")
 
     def test_peft_add_adapter_with_state_dict(self):
         """