Clone the ivalue custom object smart pointers before passing them to the C++ side.

Author: LaurentMazare

src/wrappers/jit.rs

@@ -239,6 +239,7 @@ impl From<&str> for IValue {
 }
 
 impl IValue {
+    #![allow(unused_unsafe)]
     pub(super) fn to_c(&self) -> Result<*mut CIValue, TchError> {
         let c = unsafe_torch_err!(match self {
             IValue::Tensor(tensor) => ati_tensor(tensor.c_tensor),
@@ -296,7 +297,10 @@ impl IValue {
                 }
                 dict
             }
-            IValue::Object(Object { c_ivalue }) => *c_ivalue,
+            IValue::Object(Object { c_ivalue }) => {
+                // Clone the object if necessary before passing the pointer to the C++ side.
+                unsafe_torch_err!(ati_clone(*c_ivalue))
+            }
         });
         Ok(c)
     }

tests/jit_tests.rs

@@ -153,7 +153,10 @@ fn jit_double_free() {
             &Tensor::of_slice(&[4_f32, 5_f32, 6_f32]).into(),
         ],
     );
-    if false {
-        let _output = foo.method_is("add_them", &[&input.unwrap()]);
-    }
+    let result = foo.method_is("add_them", &[&input.unwrap()]);
+    let result = match result.unwrap() {
+        IValue::Tensor(tensor) => tensor,
+        result => panic!("expected a tensor got {:?}", result),
+    };
+    assert_eq!(Vec::<f64>::from(&result), [5.0, 7.0, 9.0])
 }

torch-sys/libtch/torch_api.cpp

@@ -1408,6 +1408,13 @@ ivalue ati_object_method_(ivalue i, char *method_name, ivalue *ivalues, int niva
   return nullptr;
 }
 
+ivalue ati_clone(ivalue i) {
+  PROTECT(
+    return new torch::jit::IValue(*i);
+  )
+  return nullptr;
+}
+
 void ati_free(ivalue i) {
   delete(i);
 }

torch-sys/libtch/torch_api.h

@@ -215,6 +215,7 @@ int ati_tag(ivalue);
 
 ivalue ati_object_method_(ivalue i, char *method_name, ivalue *ivalues, int nivalues);
 
+ivalue ati_clone(ivalue);
 void ati_free(ivalue);
 
 void at_set_graph_executor_optimize(bool);

torch-sys/src/lib.rs

@@ -238,6 +238,7 @@ extern "C" {
     pub fn ati_to_tensor_list(arg: *mut CIValue, outputs: *mut *mut C_tensor, n: c_int);
     pub fn ati_to_string(arg: *mut CIValue) -> *mut c_char;
 
+    pub fn ati_clone(arg: *mut CIValue) -> *mut CIValue;
     pub fn ati_free(arg: *mut CIValue);
 
     pub fn ati_object_method_(