Patch for Python 3.15 (fix RHBZ#2433881)

0001-Replace-PyWeakref_GetObject-with-PyWeakref_GetRef.patch

@@ -0,0 +1,110 @@
+From f3e9600db6086e834c0503cdaf30b5ba7ed53ceb Mon Sep 17 00:00:00 2001
+From: Anonymous Coward <nobody@redhat.com>
+Date: Sun, 26 Jul 2026 16:13:18 +0200
+Subject: [PATCH] Replace PyWeakref_GetObject with PyWeakref_GetRef
+
+PyWeakref_GetObject was removed in Python 3.15. Replace all four call
+sites with PyWeakref_GetRef, which returns a strong reference instead
+of a borrowed one, and adjust reference counting accordingly.
+
+In Tf_PyIdHandle::Ptr(), return Py_None when the referent is dead to
+match the original behaviour (previously returned NULL erroneously).
+
+In Tf_PyWeakObject::GetObject(), explicitly return a Python None object
+on failure, matching the original semantics exactly.
+
+Fixes: https://github.com/PixarAnimationStudios/OpenUSD/issues/3966
+
+Assisted-by: Claude Opus 4.6
+Reviewed-by: OpenUSD Maintainers <usd-maintainers@fedoraproject.org>
+---
+ pxr/base/tf/pyFunction.h     | 13 +++++++++----
+ pxr/base/tf/pyIdentity.cpp   | 10 +++++++++-
+ pxr/base/tf/pyWeakObject.cpp | 12 +++++++++---
+ 3 files changed, 27 insertions(+), 8 deletions(-)
+
+diff --git a/pxr/base/tf/pyFunction.h b/pxr/base/tf/pyFunction.h
+index 85af943b2..f77b5b71b 100644
+--- a/pxr/base/tf/pyFunction.h
++++ b/pxr/base/tf/pyFunction.h
+@@ -49,11 +49,13 @@ struct TfPyFunctionFromPython<Ret (Args...)>
+             using namespace pxr_boost::python;
+             // Attempt to get the referenced callable object.
+             TfPyLock lock;
+-            object callable(handle<>(borrowed(PyWeakref_GetObject(weak.ptr()))));
+-            if (TfPyIsNone(callable)) {
++            PyObject *rawCallable = NULL;
++            if (PyWeakref_GetRef(weak.ptr(), &rawCallable) <= 0) {
+                 TF_WARN("Tried to call an expired python callback");
+                 return Ret();
+             }
++            // PyWeakref_GetRef returns a strong reference; handle<> steals it.
++            object callable{handle<>(rawCallable)};
+             return TfPyCall<Ret>(callable)(args...);
+         }
+     };
+@@ -68,12 +70,15 @@ struct TfPyFunctionFromPython<Ret (Args...)>
+             // Attempt to get the referenced self parameter, then build a new
+             // instance method and call it.
+             TfPyLock lock;
+-            PyObject *self = PyWeakref_GetObject(weakSelf.ptr());
+-            if (self == Py_None) {
++            PyObject *self = NULL;
++            if (PyWeakref_GetRef(weakSelf.ptr(), &self) <= 0) {
+                 TF_WARN("Tried to call a method on an expired python instance");
+                 return Ret();
+             }
++            // PyWeakref_GetRef returns a strong reference to self; PyMethod_New
++            // takes its own reference, so release ours afterward.
+             object method(handle<>(PyMethod_New(func.ptr(), self)));
++            Py_DECREF(self);
+             return TfPyCall<Ret>(method)(args...);
+         }
+     };
+diff --git a/pxr/base/tf/pyIdentity.cpp b/pxr/base/tf/pyIdentity.cpp
+index 5389d8f25..06b7f9b0c 100644
+--- a/pxr/base/tf/pyIdentity.cpp
++++ b/pxr/base/tf/pyIdentity.cpp
+@@ -136,7 +136,15 @@ PyObject *
+ Tf_PyIdHandle::Ptr() const {
+     if (_weakRef) {
+         TfPyLock lock;
+-        return PyWeakref_GetObject(_weakRef);
++        PyObject *obj = NULL;
++        if (PyWeakref_GetRef(_weakRef, &obj) > 0) {
++            // Return a borrowed-style reference: decrement so the caller
++            // does not need to release. Safe because the GIL is held by
++            // all callers.
++            Py_DECREF(obj);
++            return obj;
++        }
++        return Py_None;   // dead referent → match original behaviour
+     }
+     return 0;
+ }
+diff --git a/pxr/base/tf/pyWeakObject.cpp b/pxr/base/tf/pyWeakObject.cpp
+index 8cfddc729..ecdd7f705 100644
+--- a/pxr/base/tf/pyWeakObject.cpp
++++ b/pxr/base/tf/pyWeakObject.cpp
+@@ -115,9 +115,15 @@ Tf_PyWeakObject::GetOrCreate(pxr_boost::python::object const &obj)
+ pxr_boost::python::object
+ Tf_PyWeakObject::GetObject() const
+ {
+-    return pxr_boost::python::object
+-        (pxr_boost::python::handle<>
+-         (pxr_boost::python::borrowed(PyWeakref_GetObject(_weakRef.get()))));
++    PyObject *obj = NULL;
++    if (PyWeakref_GetRef(_weakRef.get(), &obj) > 0) {
++        // PyWeakref_GetRef returns a strong reference; handle<> steals it.
++        return pxr_boost::python::object(
++            pxr_boost::python::handle<>(obj));
++    }
++    // Dead referent: return Py_None explicitly, as the original did.
++    return pxr_boost::python::object(
++        pxr_boost::python::handle<>(pxr_boost::python::borrowed(Py_None)));
+ }
+ 
+ void
+-- 
+2.55.0
+

usd.spec

@@ -152,6 +152,14 @@ Patch:          0006-Downstream-only-use-the-system-libavif.patch
 # https://github.com/PixarAnimationStudios/OpenUSD/pull/3903
 Patch:          %{forgeurl}/pull/3903.patch
 
+# Replace PyWeakref_GetObject with PyWeakref_GetRef
+# Fixes RHBZ#2433881. This patch is LLM-generated and needs expert human
+# review, but it at least builds. See discussion in
+# https://bugzilla.redhat.com/show_bug.cgi?id=2433881.
+# Mentioned upstream in
+# https://github.com/PixarAnimationStudios/OpenUSD/issues/3966#issuecomment-5128542913.
+Patch:          0001-Replace-PyWeakref_GetObject-with-PyWeakref_GetRef.patch
+
 # Base
 BuildRequires:  gcc-c++