error when BigInt required for Tensor.item, Tensor.data

Summary: Now that int64 / long are supported by the Dtype type, give users a helpful message when attempting to use them in an unsupported way

Reviewed By: raedle

Differential Revision: D37387583

fbshipit-source-id: f2e51a96a3724dcb3e605aa3c9439ee85e3944e7

react-native-pytorch-core/cxx/src/torchlive/torch/TensorHostObject.cpp

@@ -227,7 +227,10 @@ jsi::Value dataImpl(
   // BigIntArray
   if (type == torch_::kInt64) {
     throw jsi::JSError(
-        runtime, "the property 'data' of BigInt Tensor is not supported.");
+        runtime,
+        "the property 'data' for a tensor of dtype torch.int64 is not"
+        " supported. Work around this with .to({dtype: torch.int32})"
+        " This might alter the tensor values.");
   }
 
   std::string typedArrayName;
@@ -296,6 +299,16 @@ jsi::Value itemImpl(
     size_t count) {
   auto thiz =
       thisValue.asObject(runtime).asHostObject<TensorHostObject>(runtime);
+
+  // TODO(T113480543): enable BigInt once Hermes supports it
+  if (thiz->tensor.dtype() == torch_::kInt64) {
+    throw jsi::JSError(
+        runtime,
+        "the property 'item' for a tensor of dtype torch.int64 is not"
+        " supported. Work around this with .to({dtype: torch.int32})"
+        " This might alter the tensor values.");
+  }
+
   auto scalar = thiz->tensor.item();
   if (scalar.isIntegral(/*includeBool=*/false)) {
     return jsi::Value(scalar.toInt());

react-native-pytorch-core/cxx/test/TensorTests.cpp

@@ -245,7 +245,20 @@ TEST_F(TorchliveTensorRuntimeTest, TensorDataTest) {
         const tensor = torch.tensor([128, 255], {dtype: torch.long});
         tensor.data();
       )";
-  EXPECT_THROW(eval(tensorWithDtypeAsInt64), facebook::jsi::JSError);
+  EXPECT_THROW(
+      {
+        try {
+          eval(tensorWithDtypeAsInt64);
+        } catch (const facebook::jsi::JSError& e) {
+          EXPECT_TRUE(
+              std::string(e.what()).find(
+                  "property 'data' for a tensor of dtype torch.int64 is not supported.") !=
+              std::string::npos)
+              << e.what();
+          throw;
+        }
+      },
+      facebook::jsi::JSError);
 }
 
 TEST_F(TorchliveTensorRuntimeTest, TensorIndexing) {
@@ -746,6 +759,25 @@ TEST_F(TorchliveTensorRuntimeTest, TensorItemTest) {
     tensor.item();
   )";
   EXPECT_THROW(eval(tensorItemForMultiElementTensor), facebook::jsi::JSError);
+
+  std::string tensorItemInt64 = R"(
+    const tensor = torch.tensor(1, {dtype: torch.int64});
+    tensor.item();
+  )";
+  EXPECT_THROW(
+      {
+        try {
+          eval(tensorItemInt64);
+        } catch (const facebook::jsi::JSError& e) {
+          EXPECT_TRUE(
+              std::string(e.what()).find(
+                  "property 'item' for a tensor of dtype torch.int64 is not supported.") !=
+              std::string::npos)
+              << e.what();
+          throw;
+        }
+      },
+      facebook::jsi::JSError);
 }
 
 TEST_F(TorchliveTensorRuntimeTest, TensorSqrtTest) {