Warning for RoBERTa sequences encoded without special tokens.

pytorch_transformers/modeling_roberta.py

@@ -165,6 +165,13 @@ class RobertaModel(BertModel):
         self.embeddings = RobertaEmbeddings(config)
         self.apply(self.init_weights)
 
+    def forward(self, input_ids, token_type_ids=None, attention_mask=None, position_ids=None, head_mask=None):
+        if input_ids[:, 0].sum().item() != 0:
+            logger.warning("A sequence with no special tokens has been passed to the RoBERTa model. "
+                           "This model requires special tokens in order to work. "
+                           "Please specify add_special_tokens=True in your encoding.")
+        return super(RobertaModel, self).forward(input_ids, token_type_ids, attention_mask, position_ids, head_mask)
+
 
 @add_start_docstrings("""RoBERTa Model with a `language modeling` head on top. """,
     ROBERTA_START_DOCSTRING, ROBERTA_INPUTS_DOCSTRING)