improve recursive scripting error message (#21841)

suo · facebook-github-bot · commit cdae8b93a759 · 2019-06-17T15:23:17.000-07:00
Summary: Pull Request resolved: #21841 ghimport-source-id: fbca813 Test Plan: Imported from OSS Reviewed By: zdevito Differential Revision: D15857569 Pulled By: suo fbshipit-source-id: 152eba10565cf7119508079e98512f116eb3a5a8
diff --git a/torch/jit/__init__.py b/torch/jit/__init__.py
@@ -995,6 +995,11 @@ def _try_compile_fn(fn):
         # Don't do anything for @ignore'd functions
         return None
 
+    if not inspect.isfunction(fn) and not inspect.ismethod(fn):
+        raise RuntimeError("`{}` is not a function. Recursive scripting only supports "
+                           "Python functions or methods currently.\n"
+                           "Consider manually annotating `{}` with @torch.jit.script.".format(fn))
+
     if isinstance(fn, torch.nn.Module):
         # Since modules are callable pybind recognizes them as functions, but
         # don't do anything for them
