Detect and report error when calling End() instead of EndPopup() on a popup. (#9351)

docs/CHANGELOG.txt

@@ -54,6 +54,7 @@ Other Changes:
 - Windows:
   - Fixed a single-axis auto-resizing feedback loop issue with nested containers
     and varying scrollbar visibility. (#9352)
+  - Detect and report error when calling End() instead of EndPopup() on a popup. (#9351)
 - Fonts:
   - imgui_freetype: add FreeType headers & compiled version in 'About Dear ImGui' details.
 - Clipper:

imgui.cpp

@@ -4154,7 +4154,7 @@ ImGuiContext::ImGuiContext(ImFontAtlas* shared_font_atlas)
     IO.Fonts = shared_font_atlas ? shared_font_atlas : IM_NEW(ImFontAtlas)();
     if (shared_font_atlas == NULL)
         IO.Fonts->OwnerContext = this;
-    WithinEndChildID = 0;
+    WithinEndChildID = WithinEndPopupID = 0;
     TestEngine = NULL;
 
     InputEventsNextMouseSource = ImGuiMouseSource_Mouse;
@@ -8207,6 +8207,8 @@ void ImGui::End()
     ImGuiWindowStackData& window_stack_data = g.CurrentWindowStack.back();
 
     // Error checking: verify that user doesn't directly call End() on a child window.
+    if (window->Flags & ImGuiWindowFlags_Popup)
+        IM_ASSERT_USER_ERROR(g.WithinEndPopupID == window->ID, "Must call EndPopup() and not End()!");
     if (window->Flags & ImGuiWindowFlags_ChildWindow)
         IM_ASSERT_USER_ERROR(g.WithinEndChildID == window->ID, "Must call EndChild() and not End()!");
 
@@ -12491,10 +12493,13 @@ void ImGui::EndPopup()
         NavMoveRequestTryWrapping(window, ImGuiNavMoveFlags_LoopY);
 
     // Child-popups don't need to be laid out
+    const ImGuiID backup_within_end_popup_id = g.WithinEndPopupID;
     const ImGuiID backup_within_end_child_id = g.WithinEndChildID;
+    g.WithinEndPopupID = window->ID;
     if (window->Flags & ImGuiWindowFlags_ChildWindow)
         g.WithinEndChildID = window->ID;
     End();
+    g.WithinEndPopupID = backup_within_end_popup_id;
     g.WithinEndChildID = backup_within_end_child_id;
 }
 

imgui_internal.h

@@ -2213,6 +2213,7 @@ struct ImGuiContext
     float                   CurrentDpiScale;                    // Current window/viewport DpiScale == CurrentViewport->DpiScale
     ImDrawListSharedData    DrawListSharedData;
     ImGuiID                 WithinEndChildID;                   // Set within EndChild()
+    ImGuiID                 WithinEndPopupID;                   // Set within EndPopup()
     void*                   TestEngine;                         // Test engine user data
 
     // Inputs