Compile bug: ambiguous overload for ‘operator==’ (operand types are ‘vk::DeviceMemory’ and ‘std::nullptr_t’)

[mbaudier]

Git commit

28b5f19

Operating systems

Linux

GGML backends

Vulkan

Problem description & steps to reproduce

I am trying to compile llama.cpp b6435 with Vulkan support on an up-to-date Debian Bookworm (gcc 12) and the build fails with:

llama.cpp/ggml/src/ggml-vulkan/ggml-vulkan.cpp: In function ‘vk_buffer ggml_vk_create_buffer(vk_device&, size_t, const std::initializer_list<vk::Flags<vk::MemoryPropertyFlagBits> >&)’:
/home/mbaudier/dev/git/unstable/argeo-jjml/native/tp/llama.cpp/ggml/src/ggml-vulkan/ggml-vulkan.cpp:1963:28: error: ambiguous overload for ‘operator==’ (operand types are ‘vk::DeviceMemory’ and ‘std::nullptr_t’)
 1963 |     if (buf->device_memory == VK_NULL_HANDLE) {
      |                            ^

First Bad Commit

b97c9ed

Compile command

cmake -B build -DGGML_VULKAN=ON -DGGML_CCACHE=OFF

Relevant log output

llama.cpp/ggml/src/ggml-vulkan/ggml-vulkan.cpp: In function ‘vk_buffer ggml_vk_create_buffer(vk_device&, size_t, const std::initializer_list<vk::Flags<vk::MemoryPropertyFlagBits> >&)’:
/home/mbaudier/dev/git/unstable/argeo-jjml/native/tp/llama.cpp/ggml/src/ggml-vulkan/ggml-vulkan.cpp:1963:28: error: ambiguous overload for ‘operator==’ (operand types are ‘vk::DeviceMemory’ and ‘std::nullptr_t’)
 1963 |     if (buf->device_memory == VK_NULL_HANDLE) {
      |                            ^

[0cc4m]

As far as I can see, this is the correct way to check whether a vk::DeviceMemory is set, and it does work on Ubuntu 24, Arch and Windows. Do you have an unusual setup, for example something with 32-bit?

@jeffbolznv any ideas?

[jeffbolznv]

With vulkan-hpp I'm less sure, but maybe it would work to do !buf->device_memory?

[mbaudier]

No unusual setup, this is a Debian 12/bookworm development worksation with the standard packages:

$ sudo apt list libvulkan-dev gcc
gcc/oldstable,now 4:12.2.0-3 amd64 [installed]
gcc/oldstable 4:12.2.0-3 i386
libvulkan-dev/oldstable,now 1.3.239.0-1 amd64 [installed]
libvulkan-dev/oldstable 1.3.239.0-1 i386

With vulkan-hpp I'm less sure, but maybe it would work to do !buf->device_memory?

Yes, it works with if (!buf->device_memory) ! It now builds and I could run some quick tests with Vulkan enabled.

Do you want me to prepare a PR or do you prefer to change it directly?

Many thanks for your quick answers.

[jeffbolznv]

Please go ahead and make a PR.