Cast this to (void*) in zero-clearing memset calls to fix -Wnontrivial-memcall (#9247, #8295, #8129, #8135)

Clang 20+ warns on memset(this, ...) for non-trivially copyable types via -Wnontrivial-memcall.
Should separately investigate -Wnonontrivial-memaccess vs -Wnonontrivial-memcall.

backends/imgui_impl_dx12.h

@@ -44,7 +44,7 @@ struct ImGui_ImplDX12_InitInfo
     D3D12_GPU_DESCRIPTOR_HANDLE LegacySingleSrvGpuDescriptor;
 #endif
 
-    ImGui_ImplDX12_InitInfo()   { memset(this, 0, sizeof(*this)); }
+    ImGui_ImplDX12_InitInfo()   { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Follow "Getting Started" link and check examples/ folder to learn about using backends!

imgui.cpp

@@ -1568,7 +1568,7 @@ void ImGuiStyle::ScaleAllSizes(float scale_factor)
 ImGuiIO::ImGuiIO()
 {
     // Most fields are initialized with zero
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     IM_STATIC_ASSERT(IM_COUNTOF(ImGuiIO::MouseDown) == ImGuiMouseButton_COUNT && IM_COUNTOF(ImGuiIO::MouseClicked) == ImGuiMouseButton_COUNT);
 
     // Settings
@@ -1974,7 +1974,7 @@ void ImGuiIO::AddFocusEvent(bool focused)
 ImGuiPlatformIO::ImGuiPlatformIO()
 {
     // Most fields are initialized with zero
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     Platform_LocaleDecimalPoint = '.';
 }
 
@@ -3231,7 +3231,7 @@ static void ImGuiListClipper_SeekCursorAndSetupPrevLine(ImGuiListClipper* clippe
 
 ImGuiListClipper::ImGuiListClipper()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
 }
 
 ImGuiListClipper::~ImGuiListClipper()
@@ -4525,7 +4525,7 @@ void ImGui::CallContextHooks(ImGuiContext* ctx, ImGuiContextHookType hook_type)
 // ImGuiWindow is mostly a dumb struct. It merely has a constructor and a few helper methods
 ImGuiWindow::ImGuiWindow(ImGuiContext* ctx, const char* name) : DrawListInst(NULL)
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     Ctx = ctx;
     Name = ImStrdup(name);
     NameBufLen = (int)ImStrlen(name) + 1;

imgui.h

@@ -2144,7 +2144,7 @@ struct ImGuiTableSortSpecs
     int                         SpecsCount;     // Sort spec count. Most often 1. May be > 1 when ImGuiTableFlags_SortMulti is enabled. May be == 0 when ImGuiTableFlags_SortTristate is enabled.
     bool                        SpecsDirty;     // Set to true when specs have changed since last time! Use this to sort again, then clear the flag.
 
-    ImGuiTableSortSpecs()       { memset(this, 0, sizeof(*this)); }
+    ImGuiTableSortSpecs()       { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Sorting specification for one column of a table (sizeof == 12 bytes)
@@ -2155,7 +2155,7 @@ struct ImGuiTableColumnSortSpecs
     ImS16                       SortOrder;          // Index within parent ImGuiTableSortSpecs (always stored in order starting from 0, tables sorted on a single criteria will always have a 0 here)
     ImGuiSortDirection          SortDirection;      // ImGuiSortDirection_Ascending or ImGuiSortDirection_Descending
 
-    ImGuiTableColumnSortSpecs() { memset(this, 0, sizeof(*this)); }
+    ImGuiTableColumnSortSpecs() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 //-----------------------------------------------------------------------------
@@ -2881,7 +2881,7 @@ struct ImGuiListClipper
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     //inline void IncludeRangeByIndices(int item_begin, int item_end)      { IncludeItemsByIndex(item_begin, item_end); } // [renamed in 1.89.9]
     //inline void ForceDisplayRangeByIndices(int item_begin, int item_end) { IncludeItemsByIndex(item_begin, item_end); } // [renamed in 1.89.6]
-    //inline ImGuiListClipper(int items_count, float items_height = -1.0f) { memset(this, 0, sizeof(*this)); ItemsCount = -1; Begin(items_count, items_height); } // [removed in 1.79]
+    //inline ImGuiListClipper(int items_count, float items_height = -1.0f) { memset((void*)this, 0, sizeof(*this)); ItemsCount = -1; Begin(items_count, items_height); } // [removed in 1.79]
 #endif
 };
 
@@ -3166,7 +3166,7 @@ struct ImDrawCmd
     int             UserCallbackDataSize;  // 4 // Size of callback user data when using storage, otherwise 0.
     int             UserCallbackDataOffset;// 4 // [Internal] Offset of callback user data when using storage, otherwise -1.
 
-    ImDrawCmd()     { memset(this, 0, sizeof(*this)); } // Also ensure our padding fields are zeroed
+    ImDrawCmd()     { memset((void*)this, 0, sizeof(*this)); } // Also ensure our padding fields are zeroed
 
     // Since 1.83: returns ImTextureID associated with this draw call. Warning: DO NOT assume this is always same as 'TextureId' (we will change this function for an upcoming feature)
     // Since 1.92: removed ImDrawCmd::TextureId field, the getter function must be used!
@@ -3212,7 +3212,7 @@ struct ImDrawListSplitter
     int                         _Count;      // Number of active channels (1+)
     ImVector<ImDrawChannel>     _Channels;   // Draw channels (not resized down so _Count might be < Channels.Size)
 
-    inline ImDrawListSplitter()  { memset(this, 0, sizeof(*this)); }
+    inline ImDrawListSplitter()  { memset((void*)this, 0, sizeof(*this)); }
     inline ~ImDrawListSplitter() { ClearFreeMemory(); }
     inline void                 Clear() { _Current = 0; _Count = 1; } // Do not clear Channels[] so our allocations are reused next frame
     IMGUI_API void              ClearFreeMemory();
@@ -3505,7 +3505,7 @@ struct ImTextureData
     bool                WantDestroyNextFrame;   // rw   -   // [Internal] Queued to set ImTextureStatus_WantDestroy next frame. May still be used in the current frame.
 
     // Functions
-    ImTextureData()     { memset(this, 0, sizeof(*this)); Status = ImTextureStatus_Destroyed; TexID = ImTextureID_Invalid; }
+    ImTextureData()     { memset((void*)this, 0, sizeof(*this)); Status = ImTextureStatus_Destroyed; TexID = ImTextureID_Invalid; }
     ~ImTextureData()    { DestroyPixels(); }
     IMGUI_API void      Create(ImTextureFormat format, int w, int h);
     IMGUI_API void      DestroyPixels();
@@ -3582,7 +3582,7 @@ struct ImFontGlyph
     float           U0, V0, U1, V1;     // Texture coordinates for the current value of ImFontAtlas->TexRef. Cached equivalent of calling GetCustomRect() with PackId.
     int             PackId;             // [Internal] ImFontAtlasRectId value (FIXME: Cold data, could be moved elsewhere?)
 
-    ImFontGlyph()   { memset(this, 0, sizeof(*this)); PackId = -1; }
+    ImFontGlyph()   { memset((void*)this, 0, sizeof(*this)); PackId = -1; }
 };
 
 // Helper to build glyph ranges from text/string data. Feed your application strings/characters to it then call BuildRanges().
@@ -3615,7 +3615,7 @@ struct ImFontAtlasRect
     unsigned short  w, h;               // Size
     ImVec2          uv0, uv1;           // UV coordinates (in current texture)
 
-    ImFontAtlasRect() { memset(this, 0, sizeof(*this)); }
+    ImFontAtlasRect() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Flags for ImFontAtlas build
@@ -3944,7 +3944,7 @@ struct ImGuiViewport
     void*               PlatformHandle;         // void* to hold higher-level, platform window handle (e.g. HWND, GLFWWindow*, SDL_Window*)
     void*               PlatformHandleRaw;      // void* to hold lower-level, platform-native window handle (under Win32 this is expected to be a HWND, unused for other platforms)
 
-    ImGuiViewport()     { memset(this, 0, sizeof(*this)); }
+    ImGuiViewport()     { memset((void*)this, 0, sizeof(*this)); }
 
     // Helpers
     ImVec2              GetCenter() const       { return ImVec2(Pos.x + Size.x * 0.5f, Pos.y + Size.y * 0.5f); }
@@ -4021,7 +4021,7 @@ struct ImGuiPlatformImeData
     float   InputLineHeight;        // Line height (for IME).
     ImGuiID ViewportId;             // ID of platform window/viewport.
 
-    ImGuiPlatformImeData()          { memset(this, 0, sizeof(*this)); }
+    ImGuiPlatformImeData()          { memset((void*)this, 0, sizeof(*this)); }
 };
 
 //-----------------------------------------------------------------------------

imgui_draw.cpp

@@ -392,7 +392,7 @@ void ImGui::StyleColorsLight(ImGuiStyle* dst)
 
 ImDrawListSharedData::ImDrawListSharedData()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     InitialFringeScale = 1.0f;
     for (int i = 0; i < IM_COUNTOF(ArcFastVtx); i++)
     {
@@ -424,7 +424,7 @@ void ImDrawListSharedData::SetCircleTessellationMaxError(float max_error)
 
 ImDrawList::ImDrawList(ImDrawListSharedData* shared_data)
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     _SetDrawListSharedData(shared_data);
 }
 
@@ -2417,7 +2417,7 @@ void ImGui::ShadeVertsTransformPos(ImDrawList* draw_list, int vert_start_idx, in
 // FIXME-NEWATLAS: Oversample specification could be more dynamic. For now, favoring automatic selection.
 ImFontConfig::ImFontConfig()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     FontDataOwnedByAtlas = true;
     OversampleH = 0; // Auto == 1 or 2 depending on size
     OversampleV = 0; // Auto == 1
@@ -2641,7 +2641,7 @@ static const ImVec2 FONT_ATLAS_DEFAULT_TEX_CURSOR_DATA[ImGuiMouseCursor_COUNT][3
 
 ImFontAtlas::ImFontAtlas()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     TexDesiredFormat = ImTextureFormat_RGBA32;
     TexGlyphPadding = 1;
     TexMinWidth = 512;
@@ -5134,7 +5134,7 @@ void ImFontGlyphRangesBuilder::BuildRanges(ImVector<ImWchar>* out_ranges)
 
 ImFontBaked::ImFontBaked()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     FallbackGlyphIndex = -1;
 }
 
@@ -5151,7 +5151,7 @@ void ImFontBaked::ClearOutputData()
 
 ImFont::ImFont()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     Scale = 1.0f;
 #endif

imgui_internal.h

@@ -708,7 +708,7 @@ struct ImSpanAllocator
     int     Offsets[CHUNKS];
     int     Sizes[CHUNKS];
 
-    ImSpanAllocator()                               { memset(this, 0, sizeof(*this)); }
+    ImSpanAllocator()                               { memset((void*)this, 0, sizeof(*this)); }
     inline void  Reserve(int n, size_t sz, int a=4) { IM_ASSERT(n == CurrIdx && n < CHUNKS); CurrOff = IM_MEMALIGN(CurrOff, a); Offsets[n] = CurrOff; Sizes[n] = (int)sz; CurrIdx++; CurrOff += (int)sz; }
     inline int   GetArenaSizeInBytes()              { return CurrOff; }
     inline void  SetArenaBasePtr(void* base_ptr)    { BasePtr = (char*)base_ptr; }
@@ -889,7 +889,7 @@ struct ImDrawDataBuilder
     ImVector<ImDrawList*>*  Layers[2];      // Pointers to global layers for: regular, tooltip. LayersP[0] is owned by DrawData.
     ImVector<ImDrawList*>   LayerData1;
 
-    ImDrawDataBuilder()                     { memset(this, 0, sizeof(*this)); }
+    ImDrawDataBuilder()                     { memset((void*)this, 0, sizeof(*this)); }
 };
 
 struct ImFontStackData
@@ -1164,7 +1164,7 @@ struct IMGUI_API ImGuiComboPreviewData
     float           BackupPrevLineTextBaseOffset;
     ImGuiLayoutType BackupLayout;
 
-    ImGuiComboPreviewData() { memset(this, 0, sizeof(*this)); }
+    ImGuiComboPreviewData() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Stacked storage data for BeginGroup()/EndGroup()
@@ -1198,7 +1198,7 @@ struct IMGUI_API ImGuiMenuColumns
     ImU16       OffsetMark;
     ImU16       Widths[4];          // Width of:   Icon, Label, Shortcut, Mark  (accumulators for current frame)
 
-    ImGuiMenuColumns() { memset(this, 0, sizeof(*this)); }
+    ImGuiMenuColumns() { memset((void*)this, 0, sizeof(*this)); }
     void        Update(float spacing, bool window_reappearing);
     float       DeclColumns(float w_icon, float w_label, float w_shortcut, float w_mark);
     void        CalcNextTotalWidth(bool update_offsets);
@@ -1210,7 +1210,7 @@ struct IMGUI_API ImGuiInputTextDeactivatedState
     ImGuiID            ID;              // widget id owning the text state (which just got deactivated)
     ImVector<char>     TextA;           // text buffer
 
-    ImGuiInputTextDeactivatedState()    { memset(this, 0, sizeof(*this)); }
+    ImGuiInputTextDeactivatedState()    { memset((void*)this, 0, sizeof(*this)); }
     void    ClearFreeMemory()           { ID = 0; TextA.clear(); }
 };
 
@@ -1336,7 +1336,7 @@ struct ImGuiNextWindowData
     ImVec2                      MenuBarOffsetMinVal;    // (Always on) This is not exposed publicly, so we don't clear it and it doesn't have a corresponding flag (could we? for consistency?)
     ImGuiWindowRefreshFlags     RefreshFlagsVal;
 
-    ImGuiNextWindowData()       { memset(this, 0, sizeof(*this)); }
+    ImGuiNextWindowData()       { memset((void*)this, 0, sizeof(*this)); }
     inline void ClearFlags()    { HasFlags = ImGuiNextWindowDataFlags_None; }
 };
 
@@ -1368,7 +1368,7 @@ struct ImGuiNextItemData
     ImGuiID                     StorageId;          // Set by SetNextItemStorageID()
     ImU32                       ColorMarker;        // Set by SetNextItemColorMarker(). Not exposed yet, supported by DragScalar,SliderScalar and for ImGuiSliderFlags_ColorMarkers.
 
-    ImGuiNextItemData()         { memset(this, 0, sizeof(*this)); SelectionUserData = -1; }
+    ImGuiNextItemData()         { memset((void*)this, 0, sizeof(*this)); SelectionUserData = -1; }
     inline void ClearFlags()    { HasFlags = ImGuiNextItemDataFlags_None; ItemFlags = ImGuiItemFlags_None; } // Also cleared manually by ItemAdd()!
 };
 
@@ -1385,7 +1385,7 @@ struct ImGuiLastItemData
     ImRect                  ClipRect;           // Clip rectangle at the time of submitting item. ONLY VALID IF (StatusFlags & ImGuiItemStatusFlags_HasClipRect) is set..
     ImGuiKeyChord           Shortcut;           // Shortcut at the time of submitting item. ONLY VALID IF (StatusFlags & ImGuiItemStatusFlags_HasShortcut) is set..
 
-    ImGuiLastItemData()     { memset(this, 0, sizeof(*this)); }
+    ImGuiLastItemData()     { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Store data emitted by TreeNode() for usage by TreePop()
@@ -1418,7 +1418,7 @@ struct IMGUI_API ImGuiErrorRecoveryState
     short   SizeOfBeginPopupStack;
     short   SizeOfDisabledStack;
 
-    ImGuiErrorRecoveryState() { memset(this, 0, sizeof(*this)); }
+    ImGuiErrorRecoveryState() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Data saved for each window pushed into the stack
@@ -1479,7 +1479,7 @@ struct ImGuiPopupData
     ImVec2              OpenPopupPos;   // Set on OpenPopup(), preferred popup position (typically == OpenMousePos when using mouse)
     ImVec2              OpenMousePos;   // Set on OpenPopup(), copy of mouse position at the time of opening popup
 
-    ImGuiPopupData()    { memset(this, 0, sizeof(*this)); ParentNavLayer = OpenFrameCount = -1; }
+    ImGuiPopupData()    { memset((void*)this, 0, sizeof(*this)); ParentNavLayer = OpenFrameCount = -1; }
 };
 
 //-----------------------------------------------------------------------------
@@ -1557,7 +1557,7 @@ struct ImGuiInputEvent
     };
     bool                            AddedByTestEngine;
 
-    ImGuiInputEvent() { memset(this, 0, sizeof(*this)); }
+    ImGuiInputEvent() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // Input function taking an 'ImGuiID owner_id' argument defaults to (ImGuiKeyOwner_Any == 0) aka don't test ownership, which matches legacy behavior.
@@ -1672,7 +1672,7 @@ struct ImGuiListClipperData
     int                             ItemsFrozen;
     ImVector<ImGuiListClipperRange> Ranges;
 
-    ImGuiListClipperData()          { memset(this, 0, sizeof(*this)); }
+    ImGuiListClipperData()          { memset((void*)this, 0, sizeof(*this)); }
     void                            Reset(ImGuiListClipper* clipper) { ListClipper = clipper; StepNo = ItemsFrozen = 0; Ranges.resize(0); }
 };
 
@@ -1807,7 +1807,7 @@ struct IMGUI_API ImGuiTypingSelectState
     float           LastRequestTime = 0.0f;
     bool            SingleCharModeLock = false; // After a certain single char repeat count we lock into SingleCharMode. Two benefits: 1) buffer never fill, 2) we can provide an immediate SingleChar mode without timer elapsing.
 
-    ImGuiTypingSelectState() { memset(this, 0, sizeof(*this)); }
+    ImGuiTypingSelectState() { memset((void*)this, 0, sizeof(*this)); }
     void            Clear()  { SearchBuffer[0] = 0; SingleCharModeLock = false; } // We preserve remaining data for easier debugging
 };
 
@@ -1843,7 +1843,7 @@ struct ImGuiOldColumnData
     ImGuiOldColumnFlags Flags;                  // Not exposed
     ImRect              ClipRect;
 
-    ImGuiOldColumnData() { memset(this, 0, sizeof(*this)); }
+    ImGuiOldColumnData() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 struct ImGuiOldColumns
@@ -1864,7 +1864,7 @@ struct ImGuiOldColumns
     ImVector<ImGuiOldColumnData> Columns;
     ImDrawListSplitter  Splitter;
 
-    ImGuiOldColumns()   { memset(this, 0, sizeof(*this)); }
+    ImGuiOldColumns()   { memset((void*)this, 0, sizeof(*this)); }
 };
 
 //-----------------------------------------------------------------------------
@@ -1892,7 +1892,7 @@ struct ImGuiBoxSelectState
     ImRect                  BoxSelectRectPrev;  // Selection rectangle in absolute coordinates (derived every frame from BoxSelectStartPosRel and MousePos)
     ImRect                  BoxSelectRectCurr;
 
-    ImGuiBoxSelectState()   { memset(this, 0, sizeof(*this)); }
+    ImGuiBoxSelectState()   { memset((void*)this, 0, sizeof(*this)); }
 };
 
 //-----------------------------------------------------------------------------
@@ -2003,7 +2003,7 @@ struct ImGuiWindowSettings
     bool        WantApply;      // Set when loaded from .ini data (to enable merging/loading .ini data into an already running context)
     bool        WantDelete;     // Set to invalidate/delete the settings entry
 
-    ImGuiWindowSettings()       { memset(this, 0, sizeof(*this)); }
+    ImGuiWindowSettings()       { memset((void*)this, 0, sizeof(*this)); }
     char* GetName()             { return (char*)(this + 1); }
 };
 
@@ -2019,7 +2019,7 @@ struct ImGuiSettingsHandler
     void        (*WriteAllFn)(ImGuiContext* ctx, ImGuiSettingsHandler* handler, ImGuiTextBuffer* out_buf);      // Write: Output every entries into 'out_buf'
     void*       UserData;
 
-    ImGuiSettingsHandler() { memset(this, 0, sizeof(*this)); }
+    ImGuiSettingsHandler() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 //-----------------------------------------------------------------------------
@@ -2108,7 +2108,7 @@ struct ImGuiDebugAllocInfo
     ImS16       LastEntriesIdx;             // Current index in buffer
     ImGuiDebugAllocEntry LastEntriesBuf[6]; // Track last 6 frames that had allocations
 
-    ImGuiDebugAllocInfo() { memset(this, 0, sizeof(*this)); }
+    ImGuiDebugAllocInfo() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 struct ImGuiMetricsConfig
@@ -2137,7 +2137,7 @@ struct ImGuiStackLevelInfo
     ImS8                    DataType;                   // ImGuiDataType
     int                     DescOffset;                 // -1 or offset into parent's ResultsPathsBuf
 
-    ImGuiStackLevelInfo()   { memset(this, 0, sizeof(*this)); DataType = -1; DescOffset = -1; }
+    ImGuiStackLevelInfo()   { memset((void*)this, 0, sizeof(*this)); DataType = -1; DescOffset = -1; }
 };
 
 struct ImGuiDebugItemPathQuery
@@ -2150,7 +2150,7 @@ struct ImGuiDebugItemPathQuery
     ImGuiTextBuffer         ResultsDescBuf;
     ImGuiTextBuffer         ResultPathBuf;
 
-    ImGuiDebugItemPathQuery() { memset(this, 0, sizeof(*this)); }
+    ImGuiDebugItemPathQuery() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 // State for ID Stack tool queries
@@ -2161,7 +2161,7 @@ struct ImGuiIDStackTool
     int                     LastActiveFrame;
     float                   CopyToClipboardLastTime;
 
-    ImGuiIDStackTool()      { memset(this, 0, sizeof(*this)); LastActiveFrame = -1; OptHexEncodeNonAsciiChars = true; CopyToClipboardLastTime = -FLT_MAX; }
+    ImGuiIDStackTool()      { memset((void*)this, 0, sizeof(*this)); LastActiveFrame = -1; OptHexEncodeNonAsciiChars = true; CopyToClipboardLastTime = -FLT_MAX; }
 };
 
 //-----------------------------------------------------------------------------
@@ -2179,7 +2179,7 @@ struct ImGuiContextHook
     ImGuiContextHookCallback    Callback;
     void*                       UserData;
 
-    ImGuiContextHook()          { memset(this, 0, sizeof(*this)); }
+    ImGuiContextHook()          { memset((void*)this, 0, sizeof(*this)); }
 };
 
 //-----------------------------------------------------------------------------
@@ -2806,7 +2806,7 @@ struct ImGuiTabItem
     ImS16               IndexDuringLayout;      // Index only used during TabBarLayout(). Tabs gets reordered so 'Tabs[n].IndexDuringLayout == n' but may mismatch during additions.
     bool                WantClose;              // Marked as closed by SetTabItemClosed()
 
-    ImGuiTabItem()      { memset(this, 0, sizeof(*this)); LastFrameVisible = LastFrameSelected = -1; RequestedWidth = -1.0f; NameOffset = -1; BeginOrder = IndexDuringLayout = -1; }
+    ImGuiTabItem()      { memset((void*)this, 0, sizeof(*this)); LastFrameVisible = LastFrameSelected = -1; RequestedWidth = -1.0f; NameOffset = -1; BeginOrder = IndexDuringLayout = -1; }
 };
 
 // Storage for a tab bar (sizeof() 160 bytes)
@@ -2911,7 +2911,7 @@ struct ImGuiTableColumn
 
     ImGuiTableColumn()
     {
-        memset(this, 0, sizeof(*this));
+        memset((void*)this, 0, sizeof(*this));
         StretchWeight = WidthRequest = -1.0f;
         NameOffset = -1;
         DisplayOrder = IndexWithinEnabledSet = -1;
@@ -3072,7 +3072,7 @@ struct IMGUI_API ImGuiTable
     bool                        MemoryCompacted;
     bool                        HostSkipItems;              // Backup of InnerWindow->SkipItem at the end of BeginTable(), because we will overwrite InnerWindow->SkipItem on a per-column basis
 
-    ImGuiTable()                { memset(this, 0, sizeof(*this)); LastFrameActive = -1; }
+    ImGuiTable()                { memset((void*)this, 0, sizeof(*this)); LastFrameActive = -1; }
     ~ImGuiTable()               { IM_FREE(RawData); }
 };
 
@@ -3101,7 +3101,7 @@ struct IMGUI_API ImGuiTableTempData
     float                       HostBackupItemWidth;        // Backup of OuterWindow->DC.ItemWidth at the end of BeginTable()
     int                         HostBackupItemWidthStackSize;//Backup of OuterWindow->DC.ItemWidthStack.Size at the end of BeginTable()
 
-    ImGuiTableTempData()        { memset(this, 0, sizeof(*this)); LastTimeActive = -1.0f; }
+    ImGuiTableTempData()        { memset((void*)this, 0, sizeof(*this)); LastTimeActive = -1.0f; }
 };
 
 // sizeof() ~ 16
@@ -3138,7 +3138,7 @@ struct ImGuiTableSettings
     ImGuiTableColumnIdx         ColumnsCountMax;        // Maximum number of columns this settings instance can store, we can recycle a settings instance with lower number of columns but not higher
     bool                        WantApply;              // Set when loaded from .ini data (to enable merging/loading .ini data into an already running context)
 
-    ImGuiTableSettings()        { memset(this, 0, sizeof(*this)); }
+    ImGuiTableSettings()        { memset((void*)this, 0, sizeof(*this)); }
     ImGuiTableColumnSettings*   GetColumnSettings()     { return (ImGuiTableColumnSettings*)(this + 1); }
 };
 
@@ -3789,7 +3789,7 @@ struct ImFontLoader
     // FIXME: At this point the two other types of buffers may be managed by core to be consistent?
     size_t          FontBakedSrcLoaderDataSize;
 
-    ImFontLoader()  { memset(this, 0, sizeof(*this)); }
+    ImFontLoader()  { memset((void*)this, 0, sizeof(*this)); }
 };
 
 #ifdef IMGUI_ENABLE_STB_TRUETYPE
@@ -3886,7 +3886,7 @@ struct ImFontAtlasBuilder
     ImFontAtlasRectId           PackIdMouseCursors;     // White pixel + mouse cursors. Also happen to be fallback in case of packing failure.
     ImFontAtlasRectId           PackIdLinesTexData;
 
-    ImFontAtlasBuilder()        { memset(this, 0, sizeof(*this)); FrameCount = -1; RectsIndexFreeListStart = -1; PackIdMouseCursors = PackIdLinesTexData = -1; }
+    ImFontAtlasBuilder()        { memset((void*)this, 0, sizeof(*this)); FrameCount = -1; RectsIndexFreeListStart = -1; PackIdMouseCursors = PackIdLinesTexData = -1; }
 };
 
 IMGUI_API void              ImFontAtlasBuildInit(ImFontAtlas* atlas);

imgui_widgets.cpp

@@ -4251,7 +4251,7 @@ static void stb_textedit_replace(ImGuiInputTextState* str, STB_TexteditState* st
 // We added an extra indirection where 'Stb' is heap-allocated, in order facilitate the work of bindings generators.
 ImGuiInputTextState::ImGuiInputTextState()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     Stb = IM_NEW(ImStbTexteditState);
     memset(Stb, 0, sizeof(*Stb));
 }
@@ -4301,7 +4301,7 @@ void ImGuiInputTextState::ReloadUserBufAndMoveToEnd()       { WantReloadUserBuf
 
 ImGuiInputTextCallbackData::ImGuiInputTextCallbackData()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
 }
 
 // Public API to manipulate UTF-8 text from within a callback.
@@ -9548,7 +9548,7 @@ struct ImGuiTabBarSection
     float               WidthAfterShrinkMinWidth;
     float               Spacing;                // Horizontal spacing at the end of the section.
 
-    ImGuiTabBarSection() { memset(this, 0, sizeof(*this)); }
+    ImGuiTabBarSection() { memset((void*)this, 0, sizeof(*this)); }
 };
 
 namespace ImGui
@@ -9564,7 +9564,7 @@ namespace ImGui
 
 ImGuiTabBar::ImGuiTabBar()
 {
-    memset(this, 0, sizeof(*this));
+    memset((void*)this, 0, sizeof(*this));
     CurrFrameVisible = PrevFrameVisible = -1;
     LastTabItemIdx = -1;
 }