Merge pull request #91 from Holt59/fix-ifiletree-sharedptr

Fix deletion of shared_ptr created from C++.

src/runner/gamefeatureswrappers.cpp

@@ -9,6 +9,7 @@
 #include <isavegame.h>
 #include <isavegameinfowidget.h>
 
+#include "shared_ptr_converter.h"
 #include "ifiletree.h"
 #include "pythonwrapperutilities.h"
 
@@ -108,7 +109,9 @@ ModDataChecker::CheckReturn ModDataCheckerWrapper::dataLooksValid(std::shared_pt
 }
 
 std::shared_ptr<MOBase::IFileTree> ModDataCheckerWrapper::fix(std::shared_ptr<MOBase::IFileTree> fileTree) const {
-  return basicWrapperFunctionImplementationWithDefault<std::shared_ptr<MOBase::IFileTree>>(this, [](auto&&... args) { return nullptr; }, "fix", fileTree);
+  return utils::clean_shared_ptr(
+    basicWrapperFunctionImplementationWithDefault<std::shared_ptr<MOBase::IFileTree>>(
+      this, [](auto&&... args) { return nullptr; }, "fix", fileTree));
 }
 
 /// end ModDataChecker Wrapper

src/runner/proxypluginwrappers.cpp

@@ -4,6 +4,7 @@
 #include <QUrl>
 #include <QWidget>
 
+#include "shared_ptr_converter.h"
 #include "pythonwrapperutilities.h"
 #include "uibasewrappers.h"
 
@@ -330,10 +331,10 @@ IPluginInstaller::EInstallResult IPluginInstallerSimpleWrapper::install(
   using return_type = std::variant<
     IPluginInstaller::EInstallResult,
     std::shared_ptr<IFileTree>,
-    std::tuple<IPluginInstaller::EInstallResult, std::shared_ptr<IFileTree>, QString, int>> ;
+    std::tuple<IPluginInstaller::EInstallResult, std::shared_ptr<IFileTree>, QString, int>>;
   auto ret = basicWrapperFunctionImplementation<return_type>(this, "install", boost::ref(modName), tree, version, nexusID);
 
-  return std::visit([&](auto const& t) {
+  auto result = std::visit([&](auto const& t) {
     using type = std::decay_t<decltype(t)>;
     if constexpr (std::is_same_v<type, IPluginInstaller::EInstallResult>) {
       return t;
@@ -349,6 +350,9 @@ IPluginInstaller::EInstallResult IPluginInstallerSimpleWrapper::install(
       return std::get<0>(t);
     }
   }, ret);
+
+  tree = utils::clean_shared_ptr(tree);
+  return result;
 }
 
 /// end IPluginInstallerSimple Wrapper

src/runner/shared_ptr_converter.h

@@ -96,6 +96,30 @@ namespace utils {
     }
   };
 
+  // release the bpy::object associated with the deleter of the given shared_ptr,
+  // if the given shared_ptr has a Boost.Python deleter
+  //
+  // this should only be used when returning from Python objects that have been created
+  // on the C++ side, e.g. if IFileTree.createOrphanTree() from Python and then return
+  // the tree
+  //
+  // for reason yet to be known, Boost.Python had a custom deleter in this case that tries
+  // to delete the bpy::object and fails, so we have to release the object manually
+  //
+  template <class SharedPtr>
+  SharedPtr clean_shared_ptr(SharedPtr&& ptr) {
+    if (auto* d = get_deleter<boost::python::converter::shared_ptr_deleter>(ptr); d != nullptr) {
+      // we cannot do a proper reset() here, even with the GIL lock, for unknown reason,
+      // so we only release
+      //
+      // this might create lost references to Python object but this should not happen
+      // too often so hopefully it's not a big issue
+      //
+      d->owner.release();
+    }
+    return ptr;
+  }
+
 }
 
 #endif