bypass null-deref warnings

libcudacxx/include/cuda/__utility/__basic_any/basic_any_value.h

@@ -342,6 +342,11 @@ struct _CCCL_TYPE_VISIBILITY_DEFAULT __basic_any : __basic_any_base<_Interface>
     return __get_vptr() != nullptr;
   }
 
+  // GCC cannot prove __query_interface returns non-null for __iunknown (the invariant guarantees it). This
+  // affects the reset() and type() methods.
+  _CCCL_DIAG_PUSH
+  _CCCL_DIAG_SUPPRESS_GCC("-Wnull-dereference")
+
   //! @brief Resets the `__basic_any` object to an empty state.
   //! @post `has_value() == false`
   _CCCL_API void reset() noexcept
@@ -367,6 +372,7 @@ struct _CCCL_TYPE_VISIBILITY_DEFAULT __basic_any : __basic_any_base<_Interface>
     }
     return _CCCL_TYPEID(void);
   }
+  _CCCL_DIAG_POP
 
   //! @brief Returns a reference to a type_info object representing the type of
   //! the dynamic interface.

libcudacxx/include/cuda/__utility/__basic_any/rtti.h

@@ -197,6 +197,10 @@ struct __rtti_ex : __rtti
   __base_info __base_vptr_array[_NbrInterfaces];
 };
 
+// GCC cannot prove __query_interface(__iunknown()) is non-null when inlined
+// (the __iunknown interface is always registered; the design guarantees non-null here)
+_CCCL_DIAG_PUSH
+_CCCL_DIAG_SUPPRESS_GCC("-Wnull-dereference")
 //!
 //! __try_vptr_cast
 //!
@@ -228,6 +232,7 @@ template <class _SrcInterface, class _DstInterface>
     return rtti->__query_interface(_DstInterface());
   }
 }
+_CCCL_DIAG_POP
 
 template <class _SrcInterface, class _DstInterface>
 [[nodiscard]] _CCCL_API auto __vptr_cast(__vptr_for<_SrcInterface> __src_vptr) //

libcudacxx/include/cuda/__utility/__basic_any/virtcall.h

@@ -105,6 +105,9 @@ inline constexpr bool __valid_virtcall = sizeof...(_Interface) == 1;
 template <auto _Mbr, class _Interface>
 inline constexpr bool __valid_virtcall<_Mbr, __ireference<_Interface const>> = __virtual_fn<_Mbr>::__const_fn;
 
+// GCC cannot prove __vptr is non-null (the type-erasure invariant guarantees it)
+_CCCL_DIAG_PUSH
+_CCCL_DIAG_SUPPRESS_GCC("-Wnull-dereference")
 template <auto _Mbr, class _Interface, class _Super, class _Self, class... _Args>
 _CCCL_API auto __virtcall(_Self* __self, _Args&&... __args) //
   noexcept(__virtual_fn<_Mbr>::__nothrow_fn) //
@@ -114,8 +117,10 @@ _CCCL_API auto __virtcall(_Self* __self, _Args&&... __args) //
   auto* __obj  = __basic_any_access::__get_optr(*__self);
   // map the member function pointer to the correct one if necessary
   using __virtual_fn_t = __virtual_fn_for<_Mbr, _Interface, _Super>;
+
   return __vptr->__virtual_fn_t::__fn_(__obj, static_cast<_Args&&>(__args)...);
 }
+_CCCL_DIAG_POP
 
 _CCCL_TEMPLATE(auto _Mbr, template <class...> class _Interface, class _Super, class... _Args)
 _CCCL_REQUIRES(__valid_virtcall<_Mbr, _Super>)

libcudacxx/test/CMakeLists.txt

@@ -57,6 +57,7 @@ if ("${CMAKE_CUDA_COMPILER_ID}" STREQUAL "NVIDIA")
       -Wall
       -Werror
       all-warnings
+      -Wnull-dereference
       -Wno-deprecated-gpu-targets
     )
   endif()
@@ -66,19 +67,20 @@ elseif ("${CMAKE_CUDA_COMPILER_ID}" STREQUAL "Clang")
     headertest_warning_levels_device
     -Wall
     -Werror
+    -Wnull-dereference
     -Wno-unknown-cuda-version
     -Xclang=-fcuda-allow-variadic-functions
   )
   # If the CMAKE_CUDA_COMPILER is unknown, try to use gcc style warnings
 else()
-  set(headertest_warning_levels_device -Wall -Werror)
+  set(headertest_warning_levels_device -Wall -Werror -Wnull-dereference)
 endif()
 
 # Set raw host/device warnings
 if (MSVC)
   set(headertest_warning_levels_host /W4 /WX)
 else()
-  set(headertest_warning_levels_host -Wall -Werror)
+  set(headertest_warning_levels_host -Wall -Werror -Wnull-dereference)
 endif()
 
 # Enable building the nvrtcc project if NVRTC is enabled