Revert "[ONNX] Remove the depreacated function _export (#109763)"

This reverts commit d7c05bb2e8.

Reverted https://github.com/pytorch/pytorch/pull/109763 on behalf of https://github.com/facebook-github-bot due to Diff reverted internally ([comment](https://github.com/pytorch/pytorch/pull/109763#issuecomment-1734201053))

test/onnx/test_export_modes.py

@@ -32,7 +32,7 @@ class TestExportModes(pytorch_test_common.ExportTestCase):
         torch_model = TestExportModes.MyModel()
         fake_input = Variable(torch.randn(1, 1, 224, 224), requires_grad=True)
         f = io.BytesIO()
-        torch.onnx.utils._export(
+        torch.onnx._export(
             torch_model,
             (fake_input),
             f,
@@ -44,7 +44,7 @@ class TestExportModes(pytorch_test_common.ExportTestCase):
         torch_model = TestExportModes.MyModel()
         fake_input = Variable(torch.randn(1, 1, 224, 224), requires_grad=True)
         f = io.BytesIO()
-        torch.onnx.utils._export(
+        torch.onnx._export(
             torch_model,
             (fake_input),
             f,
@@ -56,7 +56,7 @@ class TestExportModes(pytorch_test_common.ExportTestCase):
         torch_model = TestExportModes.MyModel()
         fake_input = Variable(torch.randn(1, 1, 224, 224), requires_grad=True)
         f = io.BytesIO()
-        torch.onnx.utils._export(
+        torch.onnx._export(
             torch_model,
             (fake_input),
             f,
@@ -68,7 +68,7 @@ class TestExportModes(pytorch_test_common.ExportTestCase):
         torch_model = TestExportModes.MyModel()
         fake_input = Variable(torch.randn(1, 1, 224, 224), requires_grad=True)
         d = tempfile.mkdtemp()
-        torch.onnx.utils._export(
+        torch.onnx._export(
             torch_model,
             (fake_input),
             d,

test/onnx/verify.py

@@ -377,7 +377,7 @@ def verify(
 
     with torch.onnx.select_model_mode_for_export(model, training):
         proto_bytes = io.BytesIO()
-        torch_out = torch.onnx.utils._export(
+        torch_out = torch.onnx._export(
             model,
             args,
             proto_bytes,
@@ -397,7 +397,7 @@ def verify(
 
         def run(args, remained_onnx_input_idx):
             alt_proto_bytes = io.BytesIO()
-            torch_out = torch.onnx.utils._export(
+            torch_out = torch.onnx._export(
                 model,
                 args,
                 alt_proto_bytes,

test/onnx_caffe2/export_onnx_tests_generator.py

@@ -101,7 +101,7 @@ def convert_tests(testcases, sets=1):
         try:
             input = gen_input(t)
             f = io.BytesIO()
-            torch.onnx.utils._export(
+            torch.onnx._export(
                 module,
                 input,
                 f,

test/onnx_caffe2/test_pytorch_onnx_caffe2.py

@@ -97,7 +97,7 @@ def skipIfNoEmbed(func):
 
 def do_export(model, inputs, *args, **kwargs):
     f = io.BytesIO()
-    out = torch.onnx.utils._export(model, inputs, f, *args, **kwargs)
+    out = torch.onnx._export(model, inputs, f, *args, **kwargs)
     if isinstance(model, torch.jit.ScriptModule):
         # Special case for common case of passing a single Tensor
         if isinstance(inputs, torch.Tensor):
@@ -320,7 +320,7 @@ class TestCaffe2Backend_opset9(pytorch_test_common.ExportTestCase):
         # Note that the export call explicitly sets the names of not just the input,
         # but also the parameters. This test checks that the model can be loaded and
         # executed in Caffe2 backend correctly.
-        torch.onnx.utils._export(
+        torch.onnx._export(
             model,
             input,
             f,
@@ -353,7 +353,7 @@ class TestCaffe2Backend_opset9(pytorch_test_common.ExportTestCase):
         # But note that the target first parameter name is the same as the second parameter name.
         # This test checks that given this edge condition, the model can be loaded and executed
         # in Caffe2 backend correctly.
-        torch.onnx.utils._export(
+        torch.onnx._export(
             model,
             input,
             f,
@@ -1613,7 +1613,7 @@ class TestCaffe2Backend_opset9(pytorch_test_common.ExportTestCase):
         f = io.BytesIO()
         from torch.onnx import ExportTypes
 
-        torch.onnx.utils._export(
+        torch.onnx._export(
             MyModel(),
             (torch.rand(3, 4),),
             f,

torch/onnx/__init__.py

@@ -8,6 +8,7 @@ from torch._C._onnx import (
 )
 
 from . import (  # usort:skip. Keep the order instead of sorting lexicographically
+    _deprecation,
     errors,
     symbolic_caffe2,
     symbolic_helper,
@@ -129,6 +130,13 @@ producer_name = "pytorch"
 producer_version = _C_onnx.PRODUCER_VERSION
 
 
+@_deprecation.deprecated(
+    since="1.12.0", removed_in="2.0", instructions="use `torch.onnx.export` instead"
+)
+def _export(*args, **kwargs):
+    return utils._export(*args, **kwargs)
+
+
 # TODO(justinchuby): Deprecate these logging functions in favor of the new diagnostic module.
 
 # Returns True iff ONNX logging is turned on.

torch/onnx/symbolic_opset9.py

@@ -5846,7 +5846,9 @@ def index(g: jit_utils.GraphContext, self, index):
             if rank is None:
                 return symbolic_helper._unimplemented(
                     "aten::index",
-                    "operator of advanced indexing on tensor of unknown rank.",
+                    "operator of advanced indexing on tensor of unknown rank. "
+                    "Try turning on shape inference during export: "
+                    "torch.onnx._export(..., onnx_shape_inference=True).",
                     self,
                 )
             # TODO: If indexing is supported natively in ONNX in future opsets,