From d8451352737c08a5ee22b0d805415cb4a8327e5b Mon Sep 17 00:00:00 2001
From: omar <omarcornut@gmail.com>
Date: Sun, 23 Dec 2018 17:54:20 +0100
Subject: [PATCH] Error recovery: Extraneous/undesired calls to End() are now
 being caught by an assert in the End() function itself at the call site
 (instead of being reported in EndFrame). Past the assert, they don't lead to
 crashes any more. Missing calls to End(), pass the assert, should not lead to
 crashes any more, nor to the fallback/debug window appearing on screen.
 (#1651).

---
 docs/CHANGELOG.txt |  4 ++++
 imgui.cpp          | 19 ++++++++++++++++---
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index e2ac095f4..5d7bad6a8 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -62,6 +62,10 @@ Other Changes:
   This affects clamping window within the visible area: with this option enabled title bars need to be visible. (#899)
 - Window: Fixed using SetNextWindowPos() on a child window (which wasn't really documented) position the cursor as expected
   in the parent window, so there is no mismatch between the layout in parent and the position of the child window. 
+- Error recovery: Extraneous/undesired calls to End() are now being caught by an assert in the End() function itself 
+  at the call site (instead of being reported in EndFrame). Past the assert, they don't lead to crashes any more. (#1651)
+- Error recovery: Missing calls to End(), pass the assert, should not lead to crashes or to the fallback Debug window 
+  appearing on screen, (#1651).
 - IO: Added BackendPlatformUserData, BackendRendererUserData, BackendLanguageUserData void* for storage use by back-ends.
 - Style: Tweaked default value of style.DisplayWindowPadding from (20,20) to (19,19) so the default style as a value
   which is the same as the title bar height.
diff --git a/imgui.cpp b/imgui.cpp
index 1629ebac8..f33d7d5e3 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -3555,6 +3555,9 @@ void ImGui::EndFrame()
         return;
     IM_ASSERT(g.FrameScopeActive && "Forgot to call ImGui::NewFrame()?");
 
+    g.FrameScopeActive = false;
+    g.FrameCountEnded = g.FrameCount;
+
     // Notify OS when our Input Method Editor cursor has moved (e.g. CJK inputs using Microsoft IME)
     if (g.IO.ImeSetInputScreenPosFn && ImLengthSqr(g.PlatformImeLastPos - g.PlatformImePos) > 0.0001f)
     {
@@ -3567,9 +3570,15 @@ void ImGui::EndFrame()
     if (g.CurrentWindowStack.Size != 1)
     {
         if (g.CurrentWindowStack.Size > 1)
+        {
             IM_ASSERT(g.CurrentWindowStack.Size == 1 && "Mismatched Begin/BeginChild vs End/EndChild calls: did you forget to call End/EndChild?");
+            while (g.CurrentWindowStack.Size > 1) // FIXME-ERRORHANDLING
+                End();
+        }
         else
+        {
             IM_ASSERT(g.CurrentWindowStack.Size == 1 && "Mismatched Begin/BeginChild vs End/EndChild calls: did you call End/EndChild too much?");
+        }
     }
 
     // Hide implicit/fallback "Debug" window if it hasn't been used
@@ -3665,9 +3674,6 @@ void ImGui::EndFrame()
     g.IO.MouseWheel = g.IO.MouseWheelH = 0.0f;
     memset(g.IO.InputCharacters, 0, sizeof(g.IO.InputCharacters));
     memset(g.IO.NavInputs, 0, sizeof(g.IO.NavInputs));
-
-    g.FrameScopeActive = false;
-    g.FrameCountEnded = g.FrameCount;
 }
 
 void ImGui::Render()
@@ -5251,6 +5257,13 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_first_use,
 void ImGui::End()
 {
     ImGuiContext& g = *GImGui;
+
+    if (g.CurrentWindowStack.Size <= 1 && g.FrameScopeActive)
+    {
+        IM_ASSERT(g.CurrentWindowStack.Size > 1 && "Calling End() too many times!");
+        return; // FIXME-ERRORHANDLING
+    }
+
     ImGuiWindow* window = g.CurrentWindow;
 
     if (window->DC.ColumnsSet != NULL)