[Bugfix][Build] Patch stable string memleak fix from 2.14 for 2.13 (#51185)

Signed-off-by: Jane Xu <janeyx@meta.com>
Signed-off-by: Shengqi Chen <harry-chen@outlook.com>
Co-authored-by: Shengqi Chen <harry-chen@outlook.com>

CMakeLists.txt

@@ -395,6 +395,34 @@ if(VLLM_GPU_LANG STREQUAL "CUDA" OR VLLM_GPU_LANG STREQUAL "HIP")
   #
   # _C_stable_libtorch extension (ops registered via STABLE_TORCH_LIBRARY)
   #
+  if(Torch_VERSION VERSION_GREATER_EQUAL "2.13" AND
+     Torch_VERSION VERSION_LESS "2.14")
+    # hotfix for https://github.com/pytorch/pytorch/pull/190493
+    # delete after we bump to 2.14
+    list(GET TORCH_INCLUDE_DIRS 0 TORCH_INCLUDE_DIR)
+    set(_stable_hdr_rel "torch/csrc/stable/stableivalue_conversions.h")
+    file(READ "${TORCH_INCLUDE_DIR}/${_stable_hdr_rel}"
+      TORCH_STABLE_STRING_CONTENTS)
+
+    if(TORCH_STABLE_STRING_CONTENTS MATCHES "auto strptr = new std::string")
+      set(TORCH_SHADOW_INCLUDE_DIR
+        "${CMAKE_CURRENT_BINARY_DIR}/torch_patched_headers")
+
+      file(MAKE_DIRECTORY "${TORCH_SHADOW_INCLUDE_DIR}/torch/csrc/stable")
+      file(COPY_FILE
+        "${TORCH_INCLUDE_DIR}/${_stable_hdr_rel}"
+        "${TORCH_SHADOW_INCLUDE_DIR}/${_stable_hdr_rel}")
+
+      execute_process(
+        COMMAND patch --batch --forward -p1
+          "--input=${CMAKE_CURRENT_LIST_DIR}/cmake/patches/pytorch_stable_string.patch"
+        WORKING_DIRECTORY "${TORCH_SHADOW_INCLUDE_DIR}"
+        COMMAND_ERROR_IS_FATAL ANY)
+
+      include_directories(BEFORE "${TORCH_SHADOW_INCLUDE_DIR}")
+    endif()
+  endif()
+
   set(VLLM_STABLE_EXT_SRC
     "csrc/libtorch_stable/torch_bindings.cpp"
     "csrc/libtorch_stable/cuda_view.cu"

cmake/patches/pytorch_stable_string.patch

@@ -0,0 +1,15 @@
+diff --git a/torch/csrc/stable/stableivalue_conversions.h b/torch/csrc/stable/stableivalue_conversions.h
+--- a/torch/csrc/stable/stableivalue_conversions.h
++++ b/torch/csrc/stable/stableivalue_conversions.h
+@@ -807 +807 @@
+-// Returns a new std::string; the string in val is deleted.
++// Returns a std::string which owns its memory; the string in val is deleted.
+@@ -819 +819 @@
+-    auto strptr = new std::string(data, length);
++    const auto str = std::string(data, length);
+@@ -821 +821 @@
+-    // delete the old string before returning new string
++    // delete the old string
+@@ -823 +823 @@
+-    return *strptr;
++    return str;