Backends: all backends + demo now call IMGUI_CHECKVERSION() to verify ABI compatibility between caller code and compiled version of dear imgui. (#7568)

backends/imgui_impl_allegro5.cpp

@@ -423,6 +423,7 @@ static ImGuiKey ImGui_ImplAllegro5_KeyCodeToImGuiKey(int key_code)
 bool ImGui_ImplAllegro5_Init(ALLEGRO_DISPLAY* display)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_android.cpp

@@ -263,6 +263,8 @@ int32_t ImGui_ImplAndroid_HandleInputEvent(const AInputEvent* input_event)
 
 bool ImGui_ImplAndroid_Init(ANativeWindow* window)
 {
+    IMGUI_CHECKVERSION();
+
     g_Window = window;
     g_Time = 0.0;
 

backends/imgui_impl_dx10.cpp

@@ -534,6 +534,7 @@ void    ImGui_ImplDX10_InvalidateDeviceObjects()
 bool    ImGui_ImplDX10_Init(ID3D10Device* device)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_dx11.cpp

@@ -546,6 +546,7 @@ void    ImGui_ImplDX11_InvalidateDeviceObjects()
 bool    ImGui_ImplDX11_Init(ID3D11Device* device, ID3D11DeviceContext* device_context)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_dx12.cpp

@@ -702,6 +702,7 @@ bool ImGui_ImplDX12_Init(ID3D12Device* device, int num_frames_in_flight, DXGI_FO
                          D3D12_CPU_DESCRIPTOR_HANDLE font_srv_cpu_desc_handle, D3D12_GPU_DESCRIPTOR_HANDLE font_srv_gpu_desc_handle)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_dx9.cpp

@@ -285,6 +285,7 @@ void ImGui_ImplDX9_RenderDrawData(ImDrawData* draw_data)
 bool ImGui_ImplDX9_Init(IDirect3DDevice9* device)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_glfw.cpp

@@ -556,6 +556,7 @@ void ImGui_ImplGlfw_SetCallbacksChainForAllWindows(bool chain_for_all_windows)
 static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, GlfwClientApi client_api)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");
     //printf("GLFW_VERSION: %d.%d.%d (%d)", GLFW_VERSION_MAJOR, GLFW_VERSION_MINOR, GLFW_VERSION_REVISION, GLFW_VERSION_COMBINED);
 

backends/imgui_impl_glut.cpp

@@ -167,6 +167,7 @@ static ImGuiKey ImGui_ImplGLUT_KeyToImGuiKey(int key)
 bool ImGui_ImplGLUT_Init()
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
 
 #ifdef FREEGLUT
     io.BackendPlatformName = "imgui_impl_glut (freeglut)";

backends/imgui_impl_metal.mm

@@ -79,7 +79,6 @@ struct ImGui_ImplMetal_Data
     ImGui_ImplMetal_Data()      { memset(this, 0, sizeof(*this)); }
 };
 
-static ImGui_ImplMetal_Data*    ImGui_ImplMetal_CreateBackendData() { return IM_NEW(ImGui_ImplMetal_Data)(); }
 static ImGui_ImplMetal_Data*    ImGui_ImplMetal_GetBackendData()    { return ImGui::GetCurrentContext() ? (ImGui_ImplMetal_Data*)ImGui::GetIO().BackendRendererUserData : nullptr; }
 static void                     ImGui_ImplMetal_DestroyBackendData(){ IM_DELETE(ImGui_ImplMetal_GetBackendData()); }
 
@@ -125,8 +124,11 @@ bool ImGui_ImplMetal_CreateDeviceObjects(MTL::Device* device)
 
 bool ImGui_ImplMetal_Init(id<MTLDevice> device)
 {
-    ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_CreateBackendData();
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
+    IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
+
+    ImGui_ImplMetal_Data* bd = IM_NEW(ImGui_ImplMetal_Data)();
     io.BackendRendererUserData = (void*)bd;
     io.BackendRendererName = "imgui_impl_metal";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.

backends/imgui_impl_opengl2.cpp

@@ -83,6 +83,7 @@ static ImGui_ImplOpenGL2_Data* ImGui_ImplOpenGL2_GetBackendData()
 bool    ImGui_ImplOpenGL2_Init()
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_opengl3.cpp

@@ -275,6 +275,7 @@ struct ImGui_ImplOpenGL3_VtxAttribState
 bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Initialize our loader

backends/imgui_impl_osx.mm

@@ -84,7 +84,6 @@ struct ImGui_ImplOSX_Data
     ImGui_ImplOSX_Data()        { memset(this, 0, sizeof(*this)); }
 };
 
-static ImGui_ImplOSX_Data*      ImGui_ImplOSX_CreateBackendData()   { return IM_NEW(ImGui_ImplOSX_Data)(); }
 static ImGui_ImplOSX_Data*      ImGui_ImplOSX_GetBackendData()      { return (ImGui_ImplOSX_Data*)ImGui::GetIO().BackendPlatformUserData; }
 static void                     ImGui_ImplOSX_DestroyBackendData()  { IM_DELETE(ImGui_ImplOSX_GetBackendData()); }
 
@@ -392,13 +391,15 @@ IMGUI_IMPL_API void ImGui_ImplOSX_NewFrame(void* _Nullable view) {
 bool ImGui_ImplOSX_Init(NSView* view)
 {
     ImGuiIO& io = ImGui::GetIO();
-    ImGui_ImplOSX_Data* bd = ImGui_ImplOSX_CreateBackendData();
+    IMGUI_CHECKVERSION();
-    io.BackendPlatformUserData = (void*)bd;
+    IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");
 
     // Setup backend capabilities flags
+    ImGui_ImplOSX_Data* bd = IM_NEW(ImGui_ImplOSX_Data)();
+    io.BackendPlatformUserData = (void*)bd;
+    io.BackendPlatformName = "imgui_impl_osx";
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;           // We can honor GetMouseCursor() values (optional)
     //io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
-    io.BackendPlatformName = "imgui_impl_osx";
 
     bd->Observer = [ImGuiObserver new];
 

backends/imgui_impl_sdl2.cpp

@@ -400,6 +400,7 @@ bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
 static bool ImGui_ImplSDL2_Init(SDL_Window* window, SDL_Renderer* renderer)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");
 
     // Check and store if we are on a SDL backend that supports global mouse position

backends/imgui_impl_sdl3.cpp

@@ -369,6 +369,7 @@ static void ImGui_ImplSDL3_SetupPlatformHandles(ImGuiViewport* viewport, SDL_Win
 static bool ImGui_ImplSDL3_Init(SDL_Window* window, SDL_Renderer* renderer, void* sdl_gl_context)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");
     IM_UNUSED(sdl_gl_context); // Unused in this branch
 

backends/imgui_impl_sdlrenderer2.cpp

@@ -63,6 +63,7 @@ static ImGui_ImplSDLRenderer2_Data* ImGui_ImplSDLRenderer2_GetBackendData()
 bool ImGui_ImplSDLRenderer2_Init(SDL_Renderer* renderer)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
     IM_ASSERT(renderer != nullptr && "SDL_Renderer not initialized!");
 

backends/imgui_impl_sdlrenderer3.cpp

@@ -59,6 +59,7 @@ static ImGui_ImplSDLRenderer3_Data* ImGui_ImplSDLRenderer3_GetBackendData()
 bool ImGui_ImplSDLRenderer3_Init(SDL_Renderer* renderer)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
     IM_ASSERT(renderer != nullptr && "SDL_Renderer not initialized!");
 

backends/imgui_impl_vulkan.cpp

@@ -1092,6 +1092,7 @@ bool    ImGui_ImplVulkan_Init(ImGui_ImplVulkan_InitInfo* info)
     }
 
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_wgpu.cpp

@@ -724,6 +724,7 @@ void ImGui_ImplWGPU_InvalidateDeviceObjects()
 bool ImGui_ImplWGPU_Init(ImGui_ImplWGPU_InitInfo* init_info)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!");
 
     // Setup backend capabilities flags

backends/imgui_impl_win32.cpp

@@ -146,6 +146,7 @@ static void ImGui_ImplWin32_UpdateKeyboardCodePage()
 static bool ImGui_ImplWin32_InitEx(void* hwnd, bool platform_has_own_dc)
 {
     ImGuiIO& io = ImGui::GetIO();
+    IMGUI_CHECKVERSION();
     IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");
 
     INT64 perf_frequency, perf_counter;

docs/CHANGELOG.txt

@@ -44,6 +44,9 @@ Breaking changes:
 Other changes:
 
 - Tables: fixed cell background of fully clipped row overlapping with header. (#7575, #7041) [@prabuinet]
+- Backends: all backends + demo now call IMGUI_CHECKVERSION() to verify ABI compatibility between caller
+  code and compiled version of Dear ImGui. If you get an assert it most likely mean you have a build issue,
+  read comments near the assert. (#7568)
 
 
 -----------------------------------------------------------------------

imgui.cpp

@@ -9639,8 +9639,8 @@ bool ImGui::Shortcut(ImGuiKeyChord key_chord, ImGuiID owner_id, ImGuiInputFlags
 // [SECTION] ERROR CHECKING
 //-----------------------------------------------------------------------------
 
-// Helper function to verify ABI compatibility between caller code and compiled version of Dear ImGui.
+// Verify ABI compatibility between caller code and compiled version of Dear ImGui. This helps detects some build issues.
-// This is called by IMGUI_CHECKVERSION().
+// Called by IMGUI_CHECKVERSION().
 // Verify that the type sizes are matching between the calling file's compilation unit and imgui.cpp's compilation unit
 // If this triggers you have mismatched headers and compiled code versions.
 // - It could be because of a build issue (using new headers with old compiled code)
@@ -9653,12 +9653,12 @@ bool ImGui::DebugCheckVersionAndDataLayout(const char* version, size_t sz_io, si
 {
     bool error = false;
     if (strcmp(version, IMGUI_VERSION) != 0) { error = true; IM_ASSERT(strcmp(version, IMGUI_VERSION) == 0 && "Mismatched version string!"); }
-    if (sz_io != sizeof(ImGuiIO)) { error = true; IM_ASSERT(sz_io == sizeof(ImGuiIO) && "Mismatched struct layout!"); }
+    if (sz_io    != sizeof(ImGuiIO))    { error = true; IM_ASSERT(sz_io == sizeof(ImGuiIO) && "Mismatched struct layout!"); }
     if (sz_style != sizeof(ImGuiStyle)) { error = true; IM_ASSERT(sz_style == sizeof(ImGuiStyle) && "Mismatched struct layout!"); }
-    if (sz_vec2 != sizeof(ImVec2)) { error = true; IM_ASSERT(sz_vec2 == sizeof(ImVec2) && "Mismatched struct layout!"); }
+    if (sz_vec2  != sizeof(ImVec2))     { error = true; IM_ASSERT(sz_vec2 == sizeof(ImVec2) && "Mismatched struct layout!"); }
-    if (sz_vec4 != sizeof(ImVec4)) { error = true; IM_ASSERT(sz_vec4 == sizeof(ImVec4) && "Mismatched struct layout!"); }
+    if (sz_vec4  != sizeof(ImVec4))     { error = true; IM_ASSERT(sz_vec4 == sizeof(ImVec4) && "Mismatched struct layout!"); }
-    if (sz_vert != sizeof(ImDrawVert)) { error = true; IM_ASSERT(sz_vert == sizeof(ImDrawVert) && "Mismatched struct layout!"); }
+    if (sz_vert  != sizeof(ImDrawVert)) { error = true; IM_ASSERT(sz_vert == sizeof(ImDrawVert) && "Mismatched struct layout!"); }
-    if (sz_idx != sizeof(ImDrawIdx)) { error = true; IM_ASSERT(sz_idx == sizeof(ImDrawIdx) && "Mismatched struct layout!"); }
+    if (sz_idx   != sizeof(ImDrawIdx))  { error = true; IM_ASSERT(sz_idx == sizeof(ImDrawIdx) && "Mismatched struct layout!"); }
     return !error;
 }
 

imgui.h

@@ -90,6 +90,8 @@ Index of this file:
 #endif
 #define IM_ARRAYSIZE(_ARR)          ((int)(sizeof(_ARR) / sizeof(*(_ARR))))     // Size of a static C-style array. Don't use on pointers!
 #define IM_UNUSED(_VAR)             ((void)(_VAR))                              // Used to silence "unused variable warnings". Often useful as asserts may be stripped out from final builds.
+
+// Check that version and structures layouts are matching between compiled imgui code and caller. Read comments above DebugCheckVersionAndDataLayout() for details.
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 
 // Helper Macros - IM_FMTARGS, IM_FMTLIST: Apply printf-style warnings to our formatting functions.

imgui_demo.cpp

@@ -266,6 +266,9 @@ void ImGui::ShowDemoWindow(bool* p_open)
     // Most functions would normally just assert/crash if the context is missing.
     IM_ASSERT(ImGui::GetCurrentContext() != NULL && "Missing Dear ImGui context. Refer to examples app!");
 
+    // Verify ABI compatibility between caller code and compiled version of Dear ImGui. This helps detects some build issues.
+    IMGUI_CHECKVERSION();
+
     // Examples Apps (accessible from the "Examples" menu)
     static bool show_app_main_menu_bar = false;
     static bool show_app_console = false;