fix bnb loading (#2529)

Author: vince62s

onmt/model_builder.py

@@ -95,13 +95,24 @@ def load_test_model(opt, device_id=0, model_path=None):
 
     model_opt = ArgumentParser.ckpt_model_opts(checkpoint["opt"])
 
-    if hasattr(model_opt, "quant_type") and model_opt.quant_type not in [
+    if hasattr(model_opt, "quant_type") and model_opt.quant_type in [
         "llm_awq",
         "aawq_gemm",
         "aawq_gemv",
-    ]:
+    ]:  # if the loaded model is a awq quantized one, inference config cannot overwrite this
+        if hasattr(opt, "quant_type") and opt.quant_type != model_opt.quant_type:
+            raise ValueError(
+                "Model is a awq quantized model, cannot overwrite with another quant method"
+            )
+
+    elif hasattr(opt, "quant_type") and opt.quant_type not in [
+        "llm_awq",
+        "aawq_gemm",
+        "aawq_gemv",
+    ]:  # we still want to be able to load fp16/32 models with bnb 4bit to minimize ram footprint
         model_opt.quant_layers = opt.quant_layers
         model_opt.quant_type = opt.quant_type
+        model_opt.lora_layers = []
 
     if opt.world_size > 1 and opt.parallel_mode == "tensor_parallel":
         model_opt.world_size = opt.world_size