ImVec2: added a check for cases where a custom IM_VEC2_CLASS_EXTRA macro adds an extra operator= to ImVec2

docs/CHANGELOG.txt

@@ -59,13 +59,17 @@ Autumn cleanup of stuff marked obsolete more than two years ago:
   - `io.GetClipboardTextFn`                --> `platform_io.Platform_GetClipboardTextFn`
   - `io.SetClipboardTextFn`                --> `platform_io.Platform_SetClipboardTextFn`
   - `io.ClipboardUserData`                 --> `platform_io.Platform_ClipboardUserData`
-
+- Please also try to get rid of calls to `GetContentRegionMax()`, `GetWindowContentRegionMin()`
-Please also try to get rid of calls to `GetContentRegionMax()`, `GetWindowContentRegionMin()`
+  and `GetWindowContentRegionMax()` will may be removed soon-ish: you should not
-and `GetWindowContentRegionMax()`: you do NOT need those functions. See #7838.
+  ever need those functions. See #7838.
 
 
 Other Changes:
 
+- ImVec2: added a check for cases where a custom `IM_VEC2_CLASS_EXTRA` macro
+  adds an extra `operator=` to ImVec2. This isn't supported but should not
+  be needed as you should have a constructor to convert from your type to ImVec2.
+
 
 -----------------------------------------------------------------------
  VERSION 1.93.0 (Released 2026-10-14)

imgui.cpp

@@ -11208,6 +11208,15 @@ static void ImGui::ErrorCheckNewFrameSanityChecks()
     // #define IM_ASSERT(EXPR)   do { if (SomeCode(EXPR)) SomeMoreCode(); } while (0)   // Correct!
     if (true) IM_ASSERT(1); else IM_ASSERT(0);
 
+    // Check user IM_VEC2_CLASS_EXTRA macro
+    // (IF YOU GET A "ambiguous overload" COMPILE ERROR HERE: does your IM_VEC2_CLASS_EXTRA macro contains an operator=?
+    //    e.g. ImVec2& operator=(const MyPoint & p) { x = p.x; y = p.y; return *this; }
+    //  You should be able to remove it if you have the corresponding constructor:
+    //    e.g. IM_NODEBUGSTEP constexpr inline ImVec2(const MyPoint& f) : x(f.x), y(f.y) {}
+    //  Allowing you to add this extra operator to ImVec2 would prevent our whole codebase from using v = {x,y} assignment style.
+    //  PLEASE GET IN TOUCH IF REMOVING THE operator= IS A PROBLEM TO YOU)
+    ImVec2 v; v = { 1.0f, 2.0f };
+
     // Emscripten backends are often imprecise in their submission of DeltaTime. (#6114, #3644)
     // Ideally the Emscripten app/backend should aim to fix or smooth this value and avoid feeding zero, but we tolerate it.
 #ifdef __EMSCRIPTEN__