for lora, raise error when no target modules in base model

src/peft/tuners/lora.py

@@ -118,6 +118,7 @@ class LoraModel(torch.nn.Module):
         self.forward = self.model.forward
 
     def _find_and_replace(self):
+        is_target_modules_in_base_model = False
         kwargs = {
             "r": self.peft_config.r,
             "lora_alpha": self.peft_config.lora_alpha,
@@ -128,6 +129,8 @@ class LoraModel(torch.nn.Module):
         key_list = [key for key, _ in self.model.named_modules()]
         for key in key_list:
             if any(key.endswith(target_key) for target_key in self.peft_config.target_modules):
+                if not is_target_modules_in_base_model:
+                    is_target_modules_in_base_model = True
                 parent, target, target_name = self._get_submodules(key)
                 bias = target.bias is not None
                 if isinstance(target, bnb.nn.Linear8bitLt) and self.peft_config.enable_lora is None:
@@ -156,6 +159,11 @@ class LoraModel(torch.nn.Module):
                             kwargs["fan_in_fan_out"] = False
                     new_module = MergedLinear(in_features, out_features, bias=bias, **kwargs)
                 self._replace_module(parent, target_name, new_module, target)
+        if not is_target_modules_in_base_model:
+            raise ValueError(
+                f"Target modules {self.peft_config.target_modules} not found in the base model. "
+                f"Please check the target modules and try again."
+            )
 
     def _get_submodules(self, key):
         parent = self.model.get_submodule(".".join(key.split(".")[:-1]))