From 3414c56b6c7c521d868c9a137ca2ace2e26b5b2e Mon Sep 17 00:00:00 2001
From: Alexander Grund <Flamefire@users.noreply.github.com>
Date: Sat, 21 Oct 2023 19:50:14 +0200
Subject: [PATCH 1/2] Workaround NVCC parse failure in `cast_op` (#4893)
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* Workaround NVCC parse failure in `cast_op`

There is a bug in some CUDA versions (observed in CUDA 12.1 and 11.7 w/ GCC 12.2),
that makes `cast_op` fail to compile:
  `cast.h:45:120: error: expected template-name before ‘<’ token`

Defining the nested type as an alias and using it allows this to work
without any change in semantics.

Fixes #4606

* style: pre-commit fixes

* Add comments to result_t referencing PR

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
---
 include/pybind11/cast.h | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index 3c9b7c927..8b5beb0ef 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -42,13 +42,15 @@ using make_caster = type_caster<intrinsic_t<type>>;
 // Shortcut for calling a caster's `cast_op_type` cast operator for casting a type_caster to a T
 template <typename T>
 typename make_caster<T>::template cast_op_type<T> cast_op(make_caster<T> &caster) {
-    return caster.operator typename make_caster<T>::template cast_op_type<T>();
+    using result_t = typename make_caster<T>::template cast_op_type<T>; // See PR #4893
+    return caster.operator result_t();
 }
 template <typename T>
 typename make_caster<T>::template cast_op_type<typename std::add_rvalue_reference<T>::type>
 cast_op(make_caster<T> &&caster) {
-    return std::move(caster).operator typename make_caster<T>::
-        template cast_op_type<typename std::add_rvalue_reference<T>::type>();
+    using result_t = typename make_caster<T>::template cast_op_type<
+        typename std::add_rvalue_reference<T>::type>; // See PR #4893
+    return std::move(caster).operator result_t();
 }
 
 template <typename type>

From bf88e29c95d20a94528637c1827df757821b5a88 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Mon, 23 Oct 2023 12:51:04 -0700
Subject: [PATCH 2/2] Bug fix: Replace bare `static exception<T>` with
 `gil_safe_call_once_and_store`. (#4897)

This is to ensure that `Py_DECREF()` is not called after the Python interpreter was finalized already:

https://github.com/pybind/pybind11/blob/3414c56b6c7c521d868c9a137ca2ace2e26b5b2e/include/pybind11/gil_safe_call_once.h#L19
---
 include/pybind11/pybind11.h | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index a94f6f0f1..95f7fa2eb 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -14,6 +14,7 @@
 #include "detail/init.h"
 #include "attr.h"
 #include "gil.h"
+#include "gil_safe_call_once.h"
 #include "options.h"
 #include "typing.h"
 
@@ -2609,23 +2610,14 @@ public:
 };
 
 PYBIND11_NAMESPACE_BEGIN(detail)
-// Returns a reference to a function-local static exception object used in the simple
-// register_exception approach below.  (It would be simpler to have the static local variable
-// directly in register_exception, but that makes clang <3.5 segfault - issue #1349).
-template <typename CppException>
-exception<CppException> &get_exception_object() {
-    static exception<CppException> ex;
-    return ex;
-}
 
 // Helper function for register_exception and register_local_exception
 template <typename CppException>
 exception<CppException> &
 register_exception_impl(handle scope, const char *name, handle base, bool isLocal) {
-    auto &ex = detail::get_exception_object<CppException>();
-    if (!ex) {
-        ex = exception<CppException>(scope, name, base);
-    }
+    PYBIND11_CONSTINIT static gil_safe_call_once_and_store<exception<CppException>> exc_storage;
+    exc_storage.call_once_and_store_result(
+        [&]() { return exception<CppException>(scope, name, base); });
 
     auto register_func
         = isLocal ? &register_local_exception_translator : &register_exception_translator;
@@ -2637,10 +2629,10 @@ register_exception_impl(handle scope, const char *name, handle base, bool isLoca
         try {
             std::rethrow_exception(p);
         } catch (const CppException &e) {
-            set_error(detail::get_exception_object<CppException>(), e.what());
+            set_error(exc_storage.get_stored(), e.what());
         }
     });
-    return ex;
+    return exc_storage.get_stored();
 }
 
 PYBIND11_NAMESPACE_END(detail)