Dawn WebGPU Strings

[nchavez324]

Version/Branch of Dear ImGui:

Version 1.91.4, Branch: master

Back-ends:

imgui_impl_wgpu.cpp + imgui_impl_glfw.cpp

Compiler, OS:

macOS 14.7 + Clang 15

Full config/build information:

No response

Details:

My Issue/Question:

When using Dawn for WebGPU at head (as of writing, this commit) with GLFW (also at head) on macOS targeting macOS with CMake, the following build errors are triggered:

[build] /Users/nickchavez/src/wgpu_imgui_bug/external/imgui/backends/imgui_impl_wgpu.cpp:281:27: error: no viable overloaded '='
[build]     stage_desc.entryPoint = "main";
[build]     ~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~
[build] /Users/nickchavez/src/wgpu_imgui_bug/build/default/external/dawn/gen/include/dawn/webgpu.h:2384:16: note: candidate function (the implicit copy assignment operator) not viable: no known conversion from 'const char[5]' to 'const WGPUStringView' for 1st argument
[build] typedef struct WGPUStringView {
[build]                ^
[build] /Users/nickchavez/src/wgpu_imgui_bug/build/default/external/dawn/gen/include/dawn/webgpu.h:2384:16: note: candidate function (the implicit move assignment operator) not viable: no known conversion from 'const char[5]' to 'WGPUStringView' for 1st argument
[build] 1 error generated.

and the similar:

[build] /Users/nickchavez/src/wgpu_imgui_bug/external/imgui/backends/imgui_impl_wgpu.cpp:532:24: error: no viable overloaded '='
[build]         tex_desc.label = "Dear ImGui Font Texture";
[build]         ~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~
[build] /Users/nickchavez/src/wgpu_imgui_bug/build/default/external/dawn/gen/include/dawn/webgpu.h:2384:16: note: candidate function (the implicit copy assignment operator) not viable: no known conversion from 'const char[24]' to 'const WGPUStringView' for 1st argument
[build] typedef struct WGPUStringView {
[build]                ^
[build] /Users/nickchavez/src/wgpu_imgui_bug/build/default/external/dawn/gen/include/dawn/webgpu.h:2384:16: note: candidate function (the implicit move assignment operator) not viable: no known conversion from 'const char[24]' to 'WGPUStringView' for 1st argument
[build] 1 error generated.

It seems that for the Dawn backend, these lines need to be rewritten as such:

#ifdef IMGUI_IMPL_WEBGPU_BACKEND_DAWN
    stage_desc.entryPoint = { "main", WGPU_STRLEN };
#else
    stage_desc.entryPoint = "main";
#endif

#ifdef IMGUI_IMPL_WEBGPU_BACKEND_DAWN
        tex_desc.label = { "Dear ImGui Font Texture", WGPU_STRLEN };
#else
        tex_desc.label = "Dear ImGui Font Texture";
#endif

Even when these are fixed however, the following runtime WGPU errors are produced:

Binding size (80) is larger than the size (0) of [Buffer "Dear ImGui Uniform buffer
Value 115200 is invalid for WGPUBufferUsage.
 - While calling [Device].CreateBuffer([BufferDescriptor ""Dear ImGui Vertex buffer

Value 22544 is invalid for WGPUBufferUsage.
 - While calling [Device].CreateBuffer([BufferDescriptor ""Dear ImGui Index buffer
 
[Invalid Buffer "Dear ImGui Vertex buffer
[Invalid Buffer "Dear ImGui Index buffer
Write range (bufferOffset: 0, size: 64) does not fit in [Buffer "Dear ImGui Uniform buffer
Write range (bufferOffset: 64, size: 4) does not fit in [Buffer "Dear ImGui Uniform buffer
[Invalid Buffer "Dear ImGui Vertex buffer
[Invalid CommandBuffer] is invalid.
 - While calling [Queue].Submit([[Invalid CommandBuffer]])

which point to the following lines, which likely should be corrected as:

  WGPUBufferDescriptor vb_desc =
  {
      nullptr,
      "Dear ImGui Vertex buffer", WGPU_STRLEN, // add WGPU_STRLEN here
      WGPUBufferUsage_CopyDst | WGPUBufferUsage_Vertex,
      MEMALIGN(fr->VertexBufferSize * sizeof(ImDrawVert), 4),
      false
  };
  WGPUBufferDescriptor ib_desc =
  {
      nullptr,
      "Dear ImGui Index buffer", WGPU_STRLEN, // add WGPU_STRLEN here
      WGPUBufferUsage_CopyDst | WGPUBufferUsage_Index,
      MEMALIGN(fr->IndexBufferSize * sizeof(ImDrawIdx), 4),
      false
  };
  WGPUBufferDescriptor ub_desc =
  {
      nullptr,
      "Dear ImGui Uniform buffer", WGPU_STRLEN, // add WGPU_STRLEN here
      WGPUBufferUsage_CopyDst | WGPUBufferUsage_Uniform,
      MEMALIGN(sizeof(Uniforms), 16),
      false
  };

Since WGPUBufferDescriptor's WGPU_BUFFER_DESCRIPTOR_INIT convenience initializer has a field label which has its own WGPU_STRING_VIEW_INIT convenience initializer which now takes 2 arguments, the label's value and its length.

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

Minimal code example: https://github.com/nchavez324/wgpu_imgui_bug/blob/main/main.cc