convert : identify missing model files (ggml-org#9397)

Author: compilade

convert_hf_to_gguf.py

@@ -131,19 +131,22 @@ def set_vocab(self):
     def get_tensors(self) -> Iterator[tuple[str, Tensor]]:
         tensor_names_from_parts: set[str] = set()
 
-        if len(self.part_names) > 1:
+        index_name = "model.safetensors" if self.is_safetensors else "pytorch_model.bin"
+        index_name += ".index.json"
+        index_file = self.dir_model / index_name
+
+        if index_file.is_file():
             self.tensor_names = set()
-            index_name = "model.safetensors" if self.is_safetensors else "pytorch_model.bin"
-            index_name += ".index.json"
             logger.info(f"gguf: loading model weight map from '{index_name}'")
-            with open(self.dir_model / index_name, "r", encoding="utf-8") as f:
+            with open(index_file, "r", encoding="utf-8") as f:
                 index: dict[str, Any] = json.load(f)
                 weight_map = index.get("weight_map")
                 if weight_map is None or not isinstance(weight_map, dict):
                     raise ValueError(f"Can't load 'weight_map' from {index_name!r}")
                 self.tensor_names.update(weight_map.keys())
         else:
             self.tensor_names = tensor_names_from_parts
+            weight_map = {}
 
         for part_name in self.part_names:
             logger.info(f"gguf: loading model part '{part_name}'")
@@ -170,9 +173,17 @@ def get_tensors(self) -> Iterator[tuple[str, Tensor]]:
                             data = LazyTorchTensor.from_eager(data)
                     yield name, data
 
-        # only verify tensor name presence; it doesn't matter if they are not in the right files
-        if len(sym_diff := tensor_names_from_parts.symmetric_difference(self.tensor_names)) > 0:
-            raise ValueError(f"Mismatch between weight map and model parts for tensor names: {sym_diff}")
+        # verify tensor name presence and identify potentially missing files
+        if len(tensor_names_from_parts.symmetric_difference(self.tensor_names)) > 0:
+            missing = sorted(self.tensor_names.difference(tensor_names_from_parts))
+            extra = sorted(tensor_names_from_parts.difference(self.tensor_names))
+            missing_files = sorted(set(weight_map[n] for n in missing if n in weight_map))
+            if len(extra) == 0 and len(missing_files) > 0:
+                raise ValueError(f"Missing or incomplete model files: {missing_files}")
+            else:
+                raise ValueError("Mismatch between weight map and model parts for tensor names:\n"
+                                 f"Missing tensors: {missing}\n"
+                                 f"Extra tensors: {extra}")
 
     def format_tensor_name(self, key: gguf.MODEL_TENSOR, bid: int | None = None, suffix: str = ".weight") -> str:
         if key not in gguf.MODEL_TENSORS[self.model_arch]: