solidify validation and annotation

Author: sayakpaul

src/diffusers/quantizers/__init__.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import inspect
+from typing import Dict, List, Optional
 
 from ..utils import is_transformers_available, logging
 from .auto import DiffusersAutoQuantizer
@@ -28,9 +29,9 @@ class PipelineQuantizationConfig:
     def __init__(
         self,
         quant_backend: str = None,
-        quant_kwargs: dict = None,
-        modules_to_quantize: list = None,
-        quant_mapping: dict = None,
+        quant_kwargs: Dict[str, str] = None,
+        modules_to_quantize: Optional[List[str]] = None,
+        quant_mapping: Dict[str,] = None,
     ):
         self.quant_backend = quant_backend
         # Initialize kwargs to be {} to set to the defaults.
@@ -47,6 +48,9 @@ def post_init(self):
         self._validate_init_args()
 
     def _validate_init_args(self):
+        if self.quant_backend and self.quant_mapping:
+            raise ValueError("Both `quant_backend` and `quant_mapping` cannot be set.")
+
         if not self.quant_mapping and not self.quant_backend:
             raise ValueError("Must provide a `quant_backend` when not providing a `quant_mapping`.")
 
@@ -150,7 +154,8 @@ def _resolve_quant_config(self, is_diffusers: bool = True, module_name: str = No
                 logger.debug(f"Initializing quantization config class for {module_name}.")
                 mapping_to_use = quant_config_mapping_diffusers if is_diffusers else quant_config_mapping_transformers
                 quant_config_cls = mapping_to_use[self.quant_backend]
-                quant_kwargs = self.quant_kwargs
+                # If `quant_kwargs` is None we default to initializing with the defaults of `quant_config_cls`.
+                quant_kwargs = self.quant_kwargs or {}
                 return quant_config_cls(**quant_kwargs)
 
         # Fallback: no applicable configuration found.