pytorch
diff --git a/‎test/cpp/jit/test_save_load.cpp
Lines changed: 11 additions & 0 deletions b/‎test/cpp/jit/test_save_load.cpp
Lines changed: 11 additions & 0 deletions
diff --git a/‎torch/csrc/jit/serialization/unpickler.cpp
Lines changed: 18 additions & 8 deletions b/‎torch/csrc/jit/serialization/unpickler.cpp
Lines changed: 18 additions & 8 deletions
diff --git a/‎torch/csrc/jit/serialization/unpickler.h
Lines changed: 1 addition & 0 deletions b/‎torch/csrc/jit/serialization/unpickler.h
Lines changed: 1 addition & 0 deletions
@@ -11,6 +11,7 @@
 #include <torch/csrc/jit/serialization/export_bytecode.h>
 #include <torch/csrc/jit/serialization/import.h>
 #include <torch/csrc/jit/serialization/import_source.h>
+#include <torch/script.h>
 #include <torch/torch.h>
 
 #include "caffe2/serialize/istream_adapter.h"
@@ -318,5 +319,15 @@ TEST(TestSaveLoad, LoadWithoutDebugInfo) { // NOLINT (use =delete in gtest)
   ASSERT_THROWS_WITH_MESSAGE(m3.run_method("exception"), error2);
 }
 
+TEST(SerializationTest, TestPickleAppend) {
+  auto data = std::vector<char>({'\x80', char(2), ']', 'K', char(2), 'a', '.'});
+
+  torch::IValue actual = torch::jit::unpickle(data.data(), data.size());
+
+  torch::IValue expected = c10::impl::GenericList(at::AnyType::get());
+  expected.toList().push_back(2);
+  ASSERT_EQ(expected, actual);
+}
+
 } // namespace jit
 } // namespace torch
@@ -10,6 +10,7 @@
 #include <torch/csrc/jit/serialization/unpickler.h>
 #include <torch/csrc/utils/byte_order.h>
 #include <string>
+#include <utility>
 
 namespace torch::jit {
 
@@ -406,7 +407,7 @@ PickleOpCode Unpickler::readInstruction() {
     } break;
     case PickleOpCode::TUPLE1: {
       TORCH_CHECK(
-          stack_.size() > 0,
+          !stack_.empty(),
           "Parsing error: stack_ contains ",
           stack_.size(),
           " elements, at least 1 expected");
@@ -451,6 +452,12 @@ PickleOpCode Unpickler::readInstruction() {
       auto list_ivalue = stack_.at(start - 1);
       readList(list_ivalue);
     } break;
+    case PickleOpCode::APPEND: {
+      TORCH_CHECK(
+          stack_.size() >= 2, "Parsing error: missing elements in stack_.");
+      auto list_ivalue = stack_.at(stack_.size() - 2);
+      readListElements(list_ivalue, stack_.size() - 1);
+    } break;
     case PickleOpCode::LIST: {
       IValue list_ivalue = c10::impl::GenericList(AnyType::get());
       readList(list_ivalue);
@@ -1118,12 +1125,7 @@ std::string Unpickler::readBytes(size_t length) {
   return data;
 }
 
-// Pop all the list items off of the stack and append them to the list at
-// the corresponding MARK
-void Unpickler::readList(IValue list_ivalue) {
-  TORCH_CHECK(!marks_.empty(), "Parsing error: marks_ is empty");
-  size_t start = marks_.back();
-  marks_.pop_back();
+void Unpickler::readListElements(IValue list_ivalue, size_t start) {
   auto num_elements = stack_.size() - start;
   auto elements = c10::ArrayRef<IValue>(stack_).slice(start);
   if (list_ivalue.isIntList()) {
@@ -1159,10 +1161,18 @@ void Unpickler::readList(IValue list_ivalue) {
   } else {
     AT_ERROR("Unknown IValue list kind: ", list_ivalue.tagKind());
   }
-
   stack_.erase(stack_.begin() + start, stack_.end());
 }
 
+// Pop all the list items off of the stack and append them to the list at
+// the corresponding MARK
+void Unpickler::readList(IValue list_ivalue) {
+  TORCH_CHECK(!marks_.empty(), "Parsing error: marks_ is empty");
+  size_t start = marks_.back();
+  marks_.pop_back();
+  readListElements(std::move(list_ivalue), start);
+}
+
 inline bool is_valid_python_id_char(char c) {
   return c == '_' || c == '.' || (c >= '0' && c <= '9') ||
       (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
 
@@ -131,6 +131,7 @@ class TORCH_API Unpickler {
   }
   std::string readString();
   void readList(IValue list_ivalue);
+  void readListElements(IValue list_ivalue, size_t start);
   void setInput(size_t memo_id);
   void run();
Original file line number	Diff line number	Diff line change
`@@ -131,6 +131,7 @@ class TORCH_API Unpickler {`
`131`	`131`	`}`
`132`	`132`	`std::string readString();`
`133`	`133`	`void readList(IValue list_ivalue);`
	`134`	`+ void readListElements(IValue list_ivalue, size_t start);`
`134`	`135`	`void setInput(size_t memo_id);`
`135`	`136`	`void run();`
`136`	`137`