[Python] Set memory policy to "strict"

.github/workflows/root-ci-config/buildconfig/alma9-march_native.txt

@@ -7,6 +7,7 @@ builtin_veccore=ON
 builtin_zlib=ON
 builtin_zstd=ON
 pythia8=ON
+tmva-pymva=ON
 tmva-sofie=ON
 veccore=ON
 vc=ON

.github/workflows/root-ci-config/buildconfig/alma9.txt

@@ -1,3 +1,4 @@
 builtin_vdt=ON
+davix=OFF
 pythia8=ON
 tmva-sofie=ON

.github/workflows/root-ci-config/buildconfig/global.txt

@@ -12,7 +12,6 @@ builtin_fftw3=OFF
 builtin_freetype=OFF
 builtin_ftgl=OFF
 builtin_gl2ps=OFF
-builtin_glew=OFF
 builtin_gsl=OFF
 builtin_llvm=ON
 builtin_lz4=OFF

.github/workflows/root-ci-config/buildconfig/mac-beta.txt

@@ -6,7 +6,6 @@ builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
 builtin_gl2ps=ON
-builtin_glew=ON
 builtin_gsl=ON
 builtin_gtest=ON
 builtin_lz4=ON

.github/workflows/root-ci-config/buildconfig/mac14.txt

@@ -8,7 +8,6 @@ builtin_freetype=ON
 builtin_ftgl=ON
 builtin_gif=ON
 builtin_gl2ps=ON
-builtin_glew=ON
 builtin_gsl=ON
 builtin_gtest=ON
 builtin_jpeg=ON

.github/workflows/root-ci-config/buildconfig/mac15.txt

@@ -1,11 +1,9 @@
 builtin_cfitsio=ON
 builtin_cppzmq=ON
-builtin_davix=ON
 builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
 builtin_gl2ps=ON
-builtin_glew=ON
 builtin_gsl=ON
 builtin_gtest=ON
 builtin_lz4=ON
@@ -21,6 +19,7 @@ builtin_xxhash=ON
 builtin_zeromq=ON
 builtin_zstd=ON
 cocoa=ON
+davix=OFF
 minuit2_omp=OFF
 r=OFF
 tmva-sofie=ON

.github/workflows/root-ci-config/buildconfig/mac26.txt

@@ -6,7 +6,6 @@ builtin_fftw3=ON
 builtin_freetype=ON
 builtin_ftgl=ON
 builtin_gl2ps=ON
-builtin_glew=ON
 builtin_gsl=ON
 builtin_gtest=ON
 builtin_lz4=ON

.github/workflows/root-ci-config/buildconfig/ubuntu2604.txt

@@ -1 +1,2 @@
 CMAKE_CXX_STANDARD=23
+davix=OFF

.github/workflows/root-ci-config/buildconfig/windows10.txt

@@ -4,7 +4,6 @@ builtin_freetype=ON
 builtin_ftgl=ON
 builtin_gif=ON
 builtin_gl2ps=ON
-builtin_glew=ON
 builtin_gtest=ON
 builtin_jpeg=ON
 builtin_lz4=ON

.github/workflows/root-ci.yml

@@ -198,7 +198,7 @@ jobs:
           [ -d "${VIRTUAL_ENV_DIR}" ] && source ${VIRTUAL_ENV_DIR}/bin/activate
           echo "Python is now $(which python3) $(python3 --version)"
           src/.github/workflows/root-ci-config/build_root.py  \
-                    --buildtype      Release                  \
+                    --buildtype      RelWithDebInfo           \
                     --platform       ${{ matrix.platform }}   \
                     --incremental    false                    \
                     --binaries       true                     \
@@ -548,7 +548,7 @@ jobs:
       - name: Nightly build
         if:   github.event_name == 'schedule'
         run: ".github/workflows/root-ci-config/build_root.py
-                    --buildtype      Release
+                    --buildtype      RelWithDebInfo
                     --platform       ${{ matrix.image }}
                     --platform_config ${{ matrix.platform_config }}
                     --incremental    false

.github/workflows/visual-studio-latest.yml

@@ -10,16 +10,14 @@ on:
         type: choice
         options:
         - Update
-        - Reboot
         - Build
   schedule:
-    - cron: '0  1 * * 3'
-    - cron: '30 1 * * 3'
-    - cron: '0  2 * * 3'
+    - cron: '0  6 * * 3'
+    - cron: '0  7 * * 3'
 
 jobs:
   update-visualstudio-latest:
-    if: ${{ github.event.schedule == '0  1 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Update') }}
+    if: ${{ github.event.schedule == '0  6 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Update') }}
 
     name: Update Visual Studio - Latest
 
@@ -30,28 +28,20 @@ jobs:
       - latest
 
     steps:
-    - name: Update Visual Studio
+    - name: Update Visual Studio Latest
       shell: cmd
       run: "C:\\bin\\vs_update.bat"
 
-  reboot-after-update:
-    if: ${{ github.event.schedule == '30 1 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Reboot') }}
-
-    name: Reboot after update
-
-    runs-on:
-      - self-hosted
-      - windows
-      - x64
-      - latest
+    - name: Display Update Log - Visual Studio Latest
+      shell: cmd
+      run: "timeout 30 > NUL & type C:\\ROOT-CI\\VS-Update.log"
 
-    steps:
-    - name: Reboot
+    - name: Reboot after update - Visual Studio Latest
       shell: cmd
-      run: "shutdown /r"
+      run: "timeout 30 > NUL & shutdown /r"
 
   build-windows:
-    if: ${{ github.event.schedule == '0  2 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Build') }}
+    if: ${{ github.event.schedule == '0  7 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Build') }}
 
     permissions:
       contents: read
@@ -73,8 +63,7 @@ jobs:
         with:
           ref: master
 
-      - name: Wednesday build
-        if: (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch')
+      - name: Build after VS update
         shell: cmd
         run: "C:\\setenv.bat x64 &&
               python .github/workflows/root-ci-config/build_root.py

.github/workflows/visual-studio-preview.yml

@@ -10,16 +10,14 @@ on:
         type: choice
         options:
         - Update
-        - Reboot
         - Build
   schedule:
-    - cron: '0  1 * * 3'
-    - cron: '30 1 * * 3'
-    - cron: '0  2 * * 3'
+    - cron: '0  6 * * 3'
+    - cron: '0  7 * * 3'
 
 jobs:
   update-visualstudio-preview:
-    if: ${{ github.event.schedule == '0  1 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Update') }}
+    if: ${{ github.event.schedule == '0  6 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Update') }}
 
     name: Update Visual Studio - Preview (Insiders)
 
@@ -30,28 +28,20 @@ jobs:
       - preview
 
     steps:
-    - name: Update Visual Studio
+    - name: Update Visual Studio Preview
       shell: cmd
       run: "C:\\bin\\vs_update.bat"
 
-  reboot-after-update:
-    if: ${{ github.event.schedule == '30 1 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Reboot') }}
-
-    name: Reboot after update
-
-    runs-on:
-      - self-hosted
-      - windows
-      - x64
-      - latest
+    - name: Display Update Log - Visual Studio Preview
+      shell: cmd
+      run: "timeout 30 > NUL & type C:\\ROOT-CI\\VS-Update.log"
 
-    steps:
-    - name: Reboot
+    - name: Reboot after update - Visual Studio Preview
       shell: cmd
-      run: "shutdown /r"
+      run: "timeout 30 > NUL & shutdown /r"
 
   build-windows:
-    if: ${{ github.event.schedule == '0  2 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Build') }}
+    if: ${{ github.event.schedule == '0  7 * * 3' || (github.event_name == 'workflow_dispatch' && inputs.selected-job == 'Build') }}
 
     permissions:
       contents: read
@@ -73,8 +63,7 @@ jobs:
         with:
           ref: master
 
-      - name: Wednesday build
-        if: (github.event_name == 'schedule' || github.event_name == 'workflow_dispatch')
+      - name: Build after VS update
         shell: cmd
         run: "C:\\setenv.bat x64 &&
               python .github/workflows/root-ci-config/build_root.py

README/ReleaseNotes/v640/index.md

@@ -45,7 +45,7 @@ The following people have contributed to this new version:
 ## Removals
 
 * The `TH1K` class was removed. `TMath::KNNDensity` can be used in its stead.
-* The `TObject` equality operator pythonization (`TObject.__eq__`) that was deprecated in ROOT 6.38 and scheduled for removal in ROOT 6.40 is removed.
+* The `TObject` equality operator Pythonization (`TObject.__eq__`) that was deprecated in ROOT 6.38 and scheduled for removal in ROOT 6.40 is removed.
 * Comparing C++ `nullptr` objects with `None` in Python now raises a `TypeError`, as announced in the ROOT 6.38 release notes. Use truth-value checks like `if not x` or `x is None` instead.
 * The `TGLIncludes.h` and `TGLWSIncludes.h` that were deprecated in ROOT 6.38 and scheduled for removal are gone now. Please include your required headers like `<GL/gl.h>` or `<GL/glu.h>` directly.
 * The GLEW headers (`GL/eglew.h`, `GL/glew.h`, `GL/glxew.h`, and `GL/wglew.h`) that were installed when building ROOT with `builtin_glew=ON` are no longer installed. This is done because ROOT is moving away from GLEW for loading OpenGL extensions.
@@ -236,6 +236,113 @@ The new implementation is statistically consistent and recommended.
 
 - ROOT dropped support for Python 3.9, meaning ROOT now requires at least Python 3.10.
 
+
+### Change in memory ownership heuristics
+
+In previous ROOT versions, if a C++ member function took a non-`const` raw pointer, e.g.
+```C++
+MyClass::add(T* obj)
+```
+then calling this method from Python on an instance
+```Python
+my_instance.add(obj)
+```
+would assume that ownership of `obj` is transferred to `my_instance`.
+
+In practice, many such functions do not actually take ownership.
+As a result, this heuristic caused several memory leaks.
+
+Starting with ROOT 6.40, the ROOT Python interfaces no longer assumes ownership transfer for non-`const` raw pointer arguments.
+
+#### What does this mean for you?
+
+Because Python no longer automatically relinquishes ownership, some code that previously relied on the old heuristic may now expose:
+
+  * **Dangling references** on the C++ side
+  * **Double deletes**
+
+These issues must now be fixed by managing object lifetimes explicitly.
+
+#### Dangling references
+
+A dangling reference occurs when C++ holds a pointer or reference to an object that has already been deleted on the Python side.
+
+*Example*
+```Python
+obj = ROOT.MyClass()
+my_instance.foo(obj)
+del obj  # C++ may still hold a pointer: dangling reference
+```
+
+When the Python object is deleted, the memory associated with the C++ object
+ is also freed. But the C++ side may want to delete the object as well, for
+instance if the destructor of the class of `my_instance` also calls `delete obj`.
+
+*Possible remedies*
+
+ 1. **Keep the Python object alive**
+
+    Assign the object to a Python variable that lives at least as long as the C++ reference.
+
+    *Example:* Python lifeline
+    ```Python
+    obj = ROOT.MyClass()
+    my_instance.foo(obj)
+    # Setting `obj` as an attribute of `my_instance` makes sure that it's not
+    # garbage collected before `my_instance` is deleted:
+    my_instance._owned_obj = obj
+    del obj  # Reference counter for `obj` doesn't hit zero here
+    ```
+    Setting the lifeline reference could also be done in a user-side Pythonization of `MyClass::foo`.
+
+ 3. **Transfer ownership explicitly to C++**
+      * Drop the ownership on the Python side:
+        ```Python
+        ROOT.SetOwnership(obj, False)
+        ```
+      * Ensure that the C++ side will take ownership instead, e.g. by explicitly calling `delete` in the class destructor or using smart pointers like `std::unique_ptr`.
+
+ 3. **Rely on Pythonizations that imply ownership transfer**
+
+    If the object is stored in a non-owning collection such as a default-constructed `TCollection` (e.g. `TList`), you can make the collection owning before adding any elements:
+    ```Python
+    coll.SetOwner(True)
+    ```
+    This will imply ownership transfer to the C++ side when adding elements with `TCollection::Add()`.
+
+#### Note on **TCollection** Pythonization
+
+`TCollection`-derived classes are Pythonized such that when an object is added to an owning collection via `TCollection::Add()`, Python ownership is automatically dropped.
+
+If you identify other cases where such a Pythonization would be beneficial, please report them via a GitHub issue. Users can also implement custom Pythonizations outside ROOT if needed.
+
+#### Double deletes
+
+A double delete indicates that C++ already owns the object, but Python still attempts to delete it.
+
+In this case, you do not need to ensure C++ ownership, as it already exists.
+Instead, ensure that Python does not delete the object.
+
+*Possible remedies*
+
+ 1. Drop Python ownership explicitly:
+    ```Python
+    ROOT.SetOwnership(obj, False)
+    ```
+
+ 2. Pythonize the relevant member function to automatically drop ownership on the Python side (similar to the `TCollection` Pythonization described above).
+
+#### Temporary compatibility option
+
+You can temporarily restore the old heuristic by calling:
+```Python
+ROOT.SetHeuristicMemoryPolicy(True)
+```
+
+after importing ROOT.
+
+This option is intended **for debugging only and will be removed in ROOT 6.44**.
+
 ### UHI
 #### Backwards incompatible changes
 - `TH1.values()` now returns a **read-only** NumPy array by default. Previously it returned a writable array that allowed modifying histogram contents implicitly.
@@ -274,7 +381,7 @@ h_from_uhi = ROOT.TH1D(json.loads(json_str, , object_hook=uhi.io.json.object_hoo
 ## Command-line utilities
 
 - `rootls` has a new flag: `-c / --allCycles`, which displays all cycles of each object in the inspected file/directory even in normal mode (cycles are already displayed by default with `-l` or `-t`).
-- `rootcp` has a new native implementation, which should make it significantly faster to startup and usable even without Python.
+- `rootcp` and `rootrm` have a new native implementation, which should make them significantly faster to startup and usable even without Python.
 
 ## JavaScript ROOT
 

SECURITY.md

@@ -2,6 +2,6 @@
 
 ## Reporting a Vulnerability
 
-If you would like to report a security issue, we would appreciate you give us a "reasonable" warning time by contacting us privately. We will respond to you privately, providing context and explanations if required.
+If you would like to report a security issue, we would appreciate you give us a warning time by contacting us privately. We will respond to you privately, providing context and explanations if required.
 
-To contact us, please use the following email address rootdev@cern.ch.
+To contact us, please use the following email address rootdev∂cern.ch.

bindings/pyroot/cppyy/CPyCppyy/include/CPyCppyy/PyResult.h

@@ -57,7 +57,7 @@ class CPYCPPYY_CLASS_EXTERN PyResult {
     operator PyObject*() const;
 
 private:
-    PyObject* fPyObject;            //! actual python object
+    PyObject* fPyObject;            ///<! actual python object
 };
 
 } // namespace CPyCppyy

bindings/pyroot/cppyy/CPyCppyy/include/CPyCppyy/TPyArg.h

@@ -46,7 +46,7 @@ class CPYCPPYY_CLASS_EXTERN TPyArg {
     static void CallDestructor(PyObject*& pyself);
 
 private:
-    mutable PyObject* fPyObject;        //! converted C++ value as python object
+    mutable PyObject* fPyObject;        ///<! converted C++ value as python object
 };
 
 #endif // !CPYCPPYY_TPYARG_H

bindings/pyroot/pythonizations/inc/TPyDispatcher.h

@@ -130,7 +130,7 @@ class TPyDispatcher : public TObject {
    PyObject *Dispatch(const char *name, const TList *attr);
 
 private:
-   PyObject *fCallable; //! callable object to be dispatched
+   PyObject *fCallable; ///<! callable object to be dispatched
 };
 
 #endif