Fix backward compatibility caused by missing eval metrics class (#3385)

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Co-authored-by: Mihir Patel <[email protected]>

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Co-authored-by: Daniel King <[email protected]>
Co-authored-by: Mihir Patel <[email protected]>

composer/metrics/nlp.py

@@ -178,3 +178,27 @@ def compute(self) -> Tensor:
         """Returns torch.exp() of the LanguageCrossEntropy."""
         avg_loss = super().compute()
         return torch.exp(avg_loss)
+
+
+# For backward compatibility
+class InContextLearningMetric:
+    """InContextLearningMetric only exists for backwards compatibility of checkpoints that contain pickled metrics."""
+
+    def __init__(self):
+        raise RuntimeError(
+            f'This class only exists for maintaining backward compatibility for checkpoints that contain pickled metrics. Please instead use https://github.com/mosaicml/llm-foundry/blob/main/scripts/eval/README.md.',
+        )
+
+    def __getstate__(self):
+        return None
+
+    def __setstate__(self, state):
+        pass
+
+
+InContextLearningCodeEvalAccuracy = InContextLearningMetric
+InContextLearningLMAccuracy = InContextLearningMetric
+InContextLearningLMExpectedCalibrationError = InContextLearningMetric
+InContextLearningMCExpectedCalibrationError = InContextLearningMetric
+InContextLearningQAAccuracy = InContextLearningMetric
+InContextLearningMultipleChoiceAccuracy = InContextLearningMetric