Error check: clarified that carriage returns are emitted by our code. Added helper default callback. Comments. (#1651)

(doesn't affect test engine hook for it as trailing \n are trimmed anyhow)

imgui.cpp

@@ -79,7 +79,7 @@ CODE
 // [SECTION] MAIN CODE (most of the code! lots of stuff, needs tidying up!)
 // [SECTION] ID STACK
 // [SECTION] INPUTS
-// [SECTION] ERROR CHECKING
+// [SECTION] ERROR CHECKING, STATE RECOVERY
 // [SECTION] ITEM SUBMISSION
 // [SECTION] LAYOUT
 // [SECTION] SCROLLING
@@ -7734,7 +7734,8 @@ void ImGui::PopItemFlag()
 // - Those can be nested but it cannot be used to enable an already disabled section (a single BeginDisabled(true) in the stack is enough to keep everything disabled)
 // - Visually this is currently altering alpha, but it is expected that in a future styling system this would work differently.
 // - Feedback welcome at https://github.com/ocornut/imgui/issues/211
-// - BeginDisabled(false) essentially does nothing useful but is provided to facilitate use of boolean expressions. If you can avoid calling BeginDisabled(False)/EndDisabled() best to avoid it.
+// - BeginDisabled(false) essentially does nothing useful but is provided to facilitate use of boolean expressions.
+//   (as a micro-optimisation if you can avoid calling BeginDisabled(false)/EndDisabled() tens of thousands of times by doing a local check, it won't hurt)
 // - Optimized shortcuts instead of PushStyleVar() + PushItemFlag()
 // - Note: mixing up BeginDisabled() and PushItemFlag(ImGuiItemFlags_Disabled) is currently NOT SUPPORTED.
 void ImGui::BeginDisabled(bool disabled)
@@ -10069,7 +10070,15 @@ bool ImGui::Shortcut(ImGuiKeyChord key_chord, ImGuiInputFlags flags, ImGuiID own
 
 
 //-----------------------------------------------------------------------------
-// [SECTION] ERROR CHECKING
+// [SECTION] ERROR CHECKING, STATE RECOVERY
+//-----------------------------------------------------------------------------
+// - DebugCheckVersionAndDataLayout() (called via IMGUI_CHECKVERSION() macros)
+// - ErrorCheckUsingSetCursorPosToExtendParentBoundaries()
+// - ErrorCheckNewFrameSanityChecks()
+// - ErrorCheckEndFrameSanityChecks()
+// - ErrorCheckEndFrameRecover()
+// - ErrorCheckEndWindowRecover()
+// - ImGuiStackSizes
 //-----------------------------------------------------------------------------
 
 // Verify ABI compatibility between caller code and compiled version of Dear ImGui. This helps detects some build issues.
@@ -10215,6 +10224,15 @@ static void ImGui::ErrorCheckEndFrameSanityChecks()
     IM_ASSERT_USER_ERROR(g.GroupStack.Size == 0, "Missing EndGroup call!");
 }
 
+// Default implementation of ImGuiErrorLogCallback that pipe errors to DebugLog: appears in tty + Tools->DebugLog
+void    ImGui::ErrorLogCallbackToDebugLog(void*, const char* fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+    ImGui::DebugLogV(fmt, args);
+    va_end(args);
+}
+
 // Experimental recovery from incorrect usage of BeginXXX/EndXXX/PushXXX/PopXXX calls.
 // Must be called during or before EndFrame().
 // This is generally flawed as we are not necessarily End/Popping things in the right order.
@@ -10235,12 +10253,12 @@ void    ImGui::ErrorCheckEndFrameRecover(ImGuiErrorLogCallback log_callback, voi
         }
         if (window->Flags & ImGuiWindowFlags_ChildWindow)
         {
-            if (log_callback) log_callback(user_data, "Recovered from missing EndChild() for '%s'", window->Name);
+            if (log_callback) log_callback(user_data, "Recovered from missing EndChild() for '%s'\n", window->Name);
             EndChild();
         }
         else
         {
-            if (log_callback) log_callback(user_data, "Recovered from missing End() for '%s'", window->Name);
+            if (log_callback) log_callback(user_data, "Recovered from missing End() for '%s'\n", window->Name);
             End();
         }
     }
@@ -10252,7 +10270,7 @@ void    ImGui::ErrorCheckEndWindowRecover(ImGuiErrorLogCallback log_callback, vo
     ImGuiContext& g = *GImGui;
     while (g.CurrentTable && (g.CurrentTable->OuterWindow == g.CurrentWindow || g.CurrentTable->InnerWindow == g.CurrentWindow))
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing EndTable() in '%s'", g.CurrentTable->OuterWindow->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing EndTable() in '%s'\n", g.CurrentTable->OuterWindow->Name);
         EndTable();
     }
 
@@ -10261,32 +10279,32 @@ void    ImGui::ErrorCheckEndWindowRecover(ImGuiErrorLogCallback log_callback, vo
     IM_ASSERT(window != NULL);
     while (g.CurrentTabBar != NULL) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing EndTabBar() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing EndTabBar() in '%s'\n", window->Name);
         EndTabBar();
     }
     while (g.CurrentMultiSelect != NULL && g.CurrentMultiSelect->Storage->Window == window)
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing EndMultiSelect() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing EndMultiSelect() in '%s'\n", window->Name);
         EndMultiSelect();
     }
     while (window->DC.TreeDepth > 0)
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing TreePop() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing TreePop() in '%s'\n", window->Name);
         TreePop();
     }
     while (g.GroupStack.Size > stack_sizes->SizeOfGroupStack) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing EndGroup() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing EndGroup() in '%s'\n", window->Name);
         EndGroup();
     }
     while (window->IDStack.Size > 1)
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing PopID() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing PopID() in '%s'\n", window->Name);
         PopID();
     }
     while (g.DisabledStackSize > stack_sizes->SizeOfDisabledStack) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing EndDisabled() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing EndDisabled() in '%s'\n", window->Name);
         if (g.CurrentItemFlags & ImGuiItemFlags_Disabled)
             EndDisabled();
         else
@@ -10297,27 +10315,27 @@ void    ImGui::ErrorCheckEndWindowRecover(ImGuiErrorLogCallback log_callback, vo
     }
     while (g.ColorStack.Size > stack_sizes->SizeOfColorStack)
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing PopStyleColor() in '%s' for ImGuiCol_%s", window->Name, GetStyleColorName(g.ColorStack.back().Col));
+        if (log_callback) log_callback(user_data, "Recovered from missing PopStyleColor() in '%s' for ImGuiCol_%s\n", window->Name, GetStyleColorName(g.ColorStack.back().Col));
         PopStyleColor();
     }
     while (g.ItemFlagsStack.Size > stack_sizes->SizeOfItemFlagsStack) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing PopItemFlag() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing PopItemFlag() in '%s'\n", window->Name);
         PopItemFlag();
     }
     while (g.StyleVarStack.Size > stack_sizes->SizeOfStyleVarStack) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing PopStyleVar() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing PopStyleVar() in '%s'\n", window->Name);
         PopStyleVar();
     }
     while (g.FontStack.Size > stack_sizes->SizeOfFontStack) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing PopFont() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing PopFont() in '%s'\n", window->Name);
         PopFont();
     }
     while (g.FocusScopeStack.Size > stack_sizes->SizeOfFocusScopeStack + 1) //-V1044
     {
-        if (log_callback) log_callback(user_data, "Recovered from missing PopFocusScope() in '%s'", window->Name);
+        if (log_callback) log_callback(user_data, "Recovered from missing PopFocusScope() in '%s'\n", window->Name);
         PopFocusScope();
     }
 }

imgui_internal.h

@@ -1259,6 +1259,7 @@ struct ImGuiTreeNodeStackData
     ImRect                  NavRect;    // Used for nav landing
 };
 
+// sizeof() = 18
 struct IMGUI_API ImGuiStackSizes
 {
     short   SizeOfIDStack;
@@ -3606,11 +3607,14 @@ namespace ImGui
     IMGUI_API void          GcCompactTransientWindowBuffers(ImGuiWindow* window);
     IMGUI_API void          GcAwakeTransientWindowBuffers(ImGuiWindow* window);
 
-    // Debug Tools
+    // Error Checking, State Recovery
-    IMGUI_API void          DebugAllocHook(ImGuiDebugAllocInfo* info, int frame_count, void* ptr, size_t size); // size >= 0 : alloc, size = -1 : free
+    IMGUI_API void          ErrorLogCallbackToDebugLog(void* user_data, const char* fmt, ...);
     IMGUI_API void          ErrorCheckEndFrameRecover(ImGuiErrorLogCallback log_callback, void* user_data = NULL);
     IMGUI_API void          ErrorCheckEndWindowRecover(ImGuiErrorLogCallback log_callback, void* user_data = NULL);
     IMGUI_API void          ErrorCheckUsingSetCursorPosToExtendParentBoundaries();
+
+    // Debug Tools
+    IMGUI_API void          DebugAllocHook(ImGuiDebugAllocInfo* info, int frame_count, void* ptr, size_t size); // size >= 0 : alloc, size = -1 : free
     IMGUI_API void          DebugDrawCursorPos(ImU32 col = IM_COL32(255, 0, 0, 255));
     IMGUI_API void          DebugDrawLineExtents(ImU32 col = IM_COL32(255, 0, 0, 255));
     IMGUI_API void          DebugDrawItemRect(ImU32 col = IM_COL32(255, 0, 0, 255));