Fix: ImDrawList:PushClipRectFullScreen() was missing (drop target outside the window clip rect crashed); CalcItemSize() no longer writes to the caller's size (by value like upstream; fixes BeginTable UserOuterSize), scalar _CalcItemSizeXY for internal callers; t_fixes covers both

build/ImGui.linemap.json

@@ -1 +1 @@
-[[46, "imgui.lua"], [21389, "imgui_demo.lua"], [29807, "imgui_draw.lua"], [35745, "imgui_h.lua"], [38412, "imgui_impl_roblox.lua"], [40060, "imgui_impl_roblox_fonts.lua"], [46463, "imgui_internal.lua"], [49932, "imgui_tables.lua"], [54991, "imgui_widgets.lua"], [65631, "imstb_rectpack.lua"], [66295, "imstb_textedit.lua"], [67837, "imstb_truetype.lua"], [70625, "imstd_minstdio.lua"]]
+[[46, "imgui.lua"], [21395, "imgui_demo.lua"], [29813, "imgui_draw.lua"], [35756, "imgui_h.lua"], [38423, "imgui_impl_roblox.lua"], [40071, "imgui_impl_roblox_fonts.lua"], [46474, "imgui_internal.lua"], [49943, "imgui_tables.lua"], [55002, "imgui_widgets.lua"], [65642, "imstb_rectpack.lua"], [66306, "imstb_textedit.lua"], [67848, "imstb_truetype.lua"], [70636, "imstd_minstdio.lua"]]

build/ImGui.luau

@@ -6986,8 +6986,14 @@ end
 --- @param default_h float
 --- @return ImVec2
 function ImGui.CalcItemSize(size, default_w, default_h)
+    return ImVec2(ImGui._CalcItemSizeXY(size.x, size.y, default_w, default_h)) -- [Luau] 'size' is by value upstream: never written to
+end
+
+-- [Luau] scalar CalcItemSize(): callers that build 'size' themselves skip both ImVec2 allocations
+--- @return float, float
+function ImGui._CalcItemSizeXY(size_x, size_y, default_w, default_h)
     local avail_x, avail_y
-    if size.x < 0.0 or size.y < 0.0 then
+    if size_x < 0.0 or size_y < 0.0 then
         -- [Luau] scalar GetContentRegionAvail(), no temporary ImVec2
         local g = GImGui
         local window = g.CurrentWindow
@@ -6995,19 +7001,19 @@ function ImGui.CalcItemSize(size, default_w, default_h)
         avail_x = mx.x - window.DC.CursorPos.x; avail_y = mx.y - window.DC.CursorPos.y
     end
 
-    if size.x == 0.0 then
+    if size_x == 0.0 then
-        size.x = default_w
+        size_x = default_w
-    elseif size.x < 0.0 then
+    elseif size_x < 0.0 then
-        size.x = math.max(4.0, avail_x + size.x)  -- <-- size.x is negative here so we are subtracting
+        size_x = math.max(4.0, avail_x + size_x)  -- <-- size.x is negative here so we are subtracting
     end
 
-    if size.y == 0.0 then
+    if size_y == 0.0 then
-        size.y = default_h
+        size_y = default_h
-    elseif size.y < 0.0 then
+    elseif size_y < 0.0 then
-        size.y = math.max(4.0, avail_y + size.y)  -- <-- size.y is negative here so we are subtracting
+        size_y = math.max(4.0, avail_y + size_y)  -- <-- size.y is negative here so we are subtracting
     end
 
-    return size
+    return size_x, size_y
 end
 
 function ImGui.GetTextLineHeight()
@@ -34804,6 +34810,11 @@ function MT.ImDrawList:PushClipRect(cr_min, cr_max, intersect_with_current_clip_
     self:_OnChangedClipRect()
 end
 
+function MT.ImDrawList:PushClipRectFullScreen()
+    local cr = self._Data.ClipRectFullscreen
+    self:PushClipRect(ImVec2(cr.x, cr.y), ImVec2(cr.z, cr.w))
+end
+
 function MT.ImDrawList:PopClipRect()
     local stack = self._ClipRectStack
     assert(stack.Size > 0)
@@ -55064,6 +55075,7 @@ local IM_U32_MAX = UINT_MAX -- (0xFFFFFFFF)
 --- @param text_end? int
 --- @param flags?    ImGuiTextFlags
 local TextEx_bb = ImRect() -- [Luau] scratch, never escapes TextEx()
+local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize()/CalcItemSize() only read it
 
 @native
 function ImGui.TextEx(text, text_end, flags)
@@ -55264,7 +55276,7 @@ function ImGui.TextAligned(align_x, size_x, fmt, ...)
     local text = ImFormatString(fmt, ...)
     local text_end = #text + 1
     local text_size = ImGui.CalcTextSize(text, text_end)
-    size_x = ImGui.CalcItemSize(ImVec2(size_x, 0.0), 0.0, text_size.y).x
+    size_x = ImGui._CalcItemSizeXY(size_x, 0.0, 0.0, text_size.y)
 
     local pos = ImVec2(window.DC.CursorPos.x, window.DC.CursorPos.y + window.DC.CurrLineTextBaseOffset)
     local pos_max = ImVec2(pos.x + size_x, window.ClipRect.Max.y)
@@ -55732,7 +55744,7 @@ local ButtonEx_text_min, ButtonEx_text_max = ImVec2(), ImVec2()
 
 @native
 function ImGui.ButtonEx(label, size_arg, flags)
-    if size_arg == nil then size_arg = ImVec2(0, 0) end
+    if size_arg == nil then size_arg = LAYOUT_ZERO_SIZE end -- [Luau] shared read-only: CalcItemSize() only reads it
     if flags    == nil then flags    = 0            end
 
     local window = ImGui.GetCurrentWindow()
@@ -55823,7 +55835,7 @@ function ImGui.InvisibleButton(str_id, size_arg, flags)
     end
 
     -- Ensure zero-size fits to contents
-    local size = ImGui.CalcItemSize(ImVec2(size_arg.x ~= 0.0 and size_arg.x or -1.1754943508223e-38 --[[FLT_MIN]], size_arg.y ~= 0.0 and size_arg.y or -1.1754943508223e-38 --[[FLT_MIN]]), 0.0, 0.0)
+    local size = ImVec2(ImGui._CalcItemSizeXY(size_arg.x ~= 0.0 and size_arg.x or -1.1754943508223e-38 --[[FLT_MIN]], size_arg.y ~= 0.0 and size_arg.y or -1.1754943508223e-38 --[[FLT_MIN]], 0.0, 0.0))
 
     local id = window:GetID(str_id)
     local bb = ImRect(window.DC.CursorPos, window.DC.CursorPos + size)
@@ -56686,7 +56698,6 @@ end
 -- - Separator()
 -------------------------------------------------------------------------------
 
-local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize() only reads it
 local LayoutHelpers_size = ImVec2()   -- [Luau] scratch for ItemSize() arguments
 
 function ImGui.Spacing()

build/ImGuiTyped.luau

@@ -886,6 +886,7 @@ export type ImGuiAPI = {
     WindowSettingsAddSettingsHandler: (...any) -> ...any,
     WindowSyncOwnedViewport: (...any) -> ...any,
     _ByteArrayToString: (...any) -> ...any,
+    _CalcItemSizeXY: (...any) -> ...any,
     _GetTypeFunc: (...any) -> ...any,
     _SetCurrentContext_Internal: (...any) -> ...any,
     _SetCurrentContext_Tables: (...any) -> ...any,

build/imgui_love.linemap.json

@@ -1 +1 @@
-[[183, "imgui.lua"], [21526, "imgui_demo.lua"], [29944, "imgui_draw.lua"], [35882, "imgui_h.lua"], [38549, "imgui_impl_love.lua"], [39089, "imgui_internal.lua"], [42558, "imgui_tables.lua"], [47617, "imgui_widgets.lua"], [58257, "imstb_rectpack.lua"], [58921, "imstb_textedit.lua"], [60463, "imstb_truetype.lua"], [63251, "imstd_minstdio.lua"]]
+[[183, "imgui.lua"], [21532, "imgui_demo.lua"], [29950, "imgui_draw.lua"], [35893, "imgui_h.lua"], [38560, "imgui_impl_love.lua"], [39100, "imgui_internal.lua"], [42569, "imgui_tables.lua"], [47628, "imgui_widgets.lua"], [58268, "imstb_rectpack.lua"], [58932, "imstb_textedit.lua"], [60474, "imstb_truetype.lua"], [63262, "imstd_minstdio.lua"]]

build/imgui_love.lua

@@ -7123,8 +7123,14 @@ end
 --- @param default_h float
 --- @return ImVec2
 function ImGui.CalcItemSize(size, default_w, default_h)
+    return ImVec2(ImGui._CalcItemSizeXY(size.x, size.y, default_w, default_h)) -- [Luau] 'size' is by value upstream: never written to
+end
+
+-- [Luau] scalar CalcItemSize(): callers that build 'size' themselves skip both ImVec2 allocations
+--- @return float, float
+function ImGui._CalcItemSizeXY(size_x, size_y, default_w, default_h)
     local avail_x, avail_y
-    if size.x < 0.0 or size.y < 0.0 then
+    if size_x < 0.0 or size_y < 0.0 then
         -- [Luau] scalar GetContentRegionAvail(), no temporary ImVec2
         local g = GImGui
         local window = g.CurrentWindow
@@ -7132,19 +7138,19 @@ function ImGui.CalcItemSize(size, default_w, default_h)
         avail_x = mx.x - window.DC.CursorPos.x; avail_y = mx.y - window.DC.CursorPos.y
     end
 
-    if size.x == 0.0 then
+    if size_x == 0.0 then
-        size.x = default_w
+        size_x = default_w
-    elseif size.x < 0.0 then
+    elseif size_x < 0.0 then
-        size.x = math.max(4.0, avail_x + size.x)  -- <-- size.x is negative here so we are subtracting
+        size_x = math.max(4.0, avail_x + size_x)  -- <-- size.x is negative here so we are subtracting
     end
 
-    if size.y == 0.0 then
+    if size_y == 0.0 then
-        size.y = default_h
+        size_y = default_h
-    elseif size.y < 0.0 then
+    elseif size_y < 0.0 then
-        size.y = math.max(4.0, avail_y + size.y)  -- <-- size.y is negative here so we are subtracting
+        size_y = math.max(4.0, avail_y + size_y)  -- <-- size.y is negative here so we are subtracting
     end
 
-    return size
+    return size_x, size_y
 end
 
 function ImGui.GetTextLineHeight()
@@ -34941,6 +34947,11 @@ function MT.ImDrawList:PushClipRect(cr_min, cr_max, intersect_with_current_clip_
     self:_OnChangedClipRect()
 end
 
+function MT.ImDrawList:PushClipRectFullScreen()
+    local cr = self._Data.ClipRectFullscreen
+    self:PushClipRect(ImVec2(cr.x, cr.y), ImVec2(cr.z, cr.w))
+end
+
 function MT.ImDrawList:PopClipRect()
     local stack = self._ClipRectStack
     assert(stack.Size > 0)
@@ -47690,6 +47701,7 @@ local IM_U32_MAX = UINT_MAX -- (0xFFFFFFFF)
 --- @param text_end? int
 --- @param flags?    ImGuiTextFlags
 local TextEx_bb = ImRect() -- [Luau] scratch, never escapes TextEx()
+local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize()/CalcItemSize() only read it
 
 
 function ImGui.TextEx(text, text_end, flags)
@@ -47890,7 +47902,7 @@ function ImGui.TextAligned(align_x, size_x, fmt, ...)
     local text = ImFormatString(fmt, ...)
     local text_end = #text + 1
     local text_size = ImGui.CalcTextSize(text, text_end)
-    size_x = ImGui.CalcItemSize(ImVec2(size_x, 0.0), 0.0, text_size.y).x
+    size_x = ImGui._CalcItemSizeXY(size_x, 0.0, 0.0, text_size.y)
 
     local pos = ImVec2(window.DC.CursorPos.x, window.DC.CursorPos.y + window.DC.CurrLineTextBaseOffset)
     local pos_max = ImVec2(pos.x + size_x, window.ClipRect.Max.y)
@@ -48358,7 +48370,7 @@ local ButtonEx_text_min, ButtonEx_text_max = ImVec2(), ImVec2()
 
 
 function ImGui.ButtonEx(label, size_arg, flags)
-    if size_arg == nil then size_arg = ImVec2(0, 0) end
+    if size_arg == nil then size_arg = LAYOUT_ZERO_SIZE end -- [Luau] shared read-only: CalcItemSize() only reads it
     if flags    == nil then flags    = 0            end
 
     local window = ImGui.GetCurrentWindow()
@@ -48449,7 +48461,7 @@ function ImGui.InvisibleButton(str_id, size_arg, flags)
     end
 
     -- Ensure zero-size fits to contents
-    local size = ImGui.CalcItemSize(ImVec2(size_arg.x ~= 0.0 and size_arg.x or -1.1754943508223e-38 --[[FLT_MIN]], size_arg.y ~= 0.0 and size_arg.y or -1.1754943508223e-38 --[[FLT_MIN]]), 0.0, 0.0)
+    local size = ImVec2(ImGui._CalcItemSizeXY(size_arg.x ~= 0.0 and size_arg.x or -1.1754943508223e-38 --[[FLT_MIN]], size_arg.y ~= 0.0 and size_arg.y or -1.1754943508223e-38 --[[FLT_MIN]], 0.0, 0.0))
 
     local id = window:GetID(str_id)
     local bb = ImRect(window.DC.CursorPos, window.DC.CursorPos + size)
@@ -49312,7 +49324,6 @@ end
 -- - Separator()
 -------------------------------------------------------------------------------
 
-local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize() only reads it
 local LayoutHelpers_size = ImVec2()   -- [Luau] scratch for ItemSize() arguments
 
 function ImGui.Spacing()

imgui.lua

@@ -6941,8 +6941,14 @@ end
 --- @param default_h float
 --- @return ImVec2
 function ImGui.CalcItemSize(size, default_w, default_h)
+    return ImVec2(ImGui._CalcItemSizeXY(size.x, size.y, default_w, default_h)) -- [Luau] 'size' is by value upstream: never written to
+end
+
+-- [Luau] scalar CalcItemSize(): callers that build 'size' themselves skip both ImVec2 allocations
+--- @return float, float
+function ImGui._CalcItemSizeXY(size_x, size_y, default_w, default_h)
     local avail_x, avail_y
-    if size.x < 0.0 or size.y < 0.0 then
+    if size_x < 0.0 or size_y < 0.0 then
         -- [Luau] scalar GetContentRegionAvail(), no temporary ImVec2
         local g = GImGui
         local window = g.CurrentWindow
@@ -6950,19 +6956,19 @@ function ImGui.CalcItemSize(size, default_w, default_h)
         avail_x = mx.x - window.DC.CursorPos.x; avail_y = mx.y - window.DC.CursorPos.y
     end
 
-    if size.x == 0.0 then
+    if size_x == 0.0 then
-        size.x = default_w
+        size_x = default_w
-    elseif size.x < 0.0 then
+    elseif size_x < 0.0 then
-        size.x = math.max(4.0, avail_x + size.x)  -- <-- size.x is negative here so we are subtracting
+        size_x = math.max(4.0, avail_x + size_x)  -- <-- size.x is negative here so we are subtracting
     end
 
-    if size.y == 0.0 then
+    if size_y == 0.0 then
-        size.y = default_h
+        size_y = default_h
-    elseif size.y < 0.0 then
+    elseif size_y < 0.0 then
-        size.y = math.max(4.0, avail_y + size.y)  -- <-- size.y is negative here so we are subtracting
+        size_y = math.max(4.0, avail_y + size_y)  -- <-- size.y is negative here so we are subtracting
     end
 
-    return size
+    return size_x, size_y
 end
 
 function ImGui.GetTextLineHeight()

imgui_draw.lua

@@ -4998,6 +4998,11 @@ function MT.ImDrawList:PushClipRect(cr_min, cr_max, intersect_with_current_clip_
     self:_OnChangedClipRect()
 end
 
+function MT.ImDrawList:PushClipRectFullScreen()
+    local cr = self._Data.ClipRectFullscreen
+    self:PushClipRect(ImVec2(cr.x, cr.y), ImVec2(cr.z, cr.w))
+end
+
 function MT.ImDrawList:PopClipRect()
     local stack = self._ClipRectStack
     IM_ASSERT(stack.Size > 0)

imgui_widgets.lua

@@ -74,6 +74,7 @@ local IM_U32_MAX = UINT_MAX -- (0xFFFFFFFF)
 --- @param text_end? int
 --- @param flags?    ImGuiTextFlags
 local TextEx_bb = ImRect() -- [Luau] scratch, never escapes TextEx()
+local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize()/CalcItemSize() only read it
 
 @native
 function ImGui.TextEx(text, text_end, flags)
@@ -274,7 +275,7 @@ function ImGui.TextAligned(align_x, size_x, fmt, ...)
     local text = ImFormatString(fmt, ...)
     local text_end = #text + 1
     local text_size = ImGui.CalcTextSize(text, text_end)
-    size_x = ImGui.CalcItemSize(ImVec2(size_x, 0.0), 0.0, text_size.y).x
+    size_x = ImGui._CalcItemSizeXY(size_x, 0.0, 0.0, text_size.y)
 
     local pos = ImVec2(window.DC.CursorPos.x, window.DC.CursorPos.y + window.DC.CurrLineTextBaseOffset)
     local pos_max = ImVec2(pos.x + size_x, window.ClipRect.Max.y)
@@ -742,7 +743,7 @@ local ButtonEx_text_min, ButtonEx_text_max = ImVec2(), ImVec2()
 
 @native
 function ImGui.ButtonEx(label, size_arg, flags)
-    if size_arg == nil then size_arg = ImVec2(0, 0) end
+    if size_arg == nil then size_arg = LAYOUT_ZERO_SIZE end -- [Luau] shared read-only: CalcItemSize() only reads it
     if flags    == nil then flags    = 0            end
 
     local window = ImGui.GetCurrentWindow()
@@ -833,7 +834,7 @@ function ImGui.InvisibleButton(str_id, size_arg, flags)
     end
 
     -- Ensure zero-size fits to contents
-    local size = ImGui.CalcItemSize(ImVec2(size_arg.x ~= 0.0 and size_arg.x or -FLT_MIN, size_arg.y ~= 0.0 and size_arg.y or -FLT_MIN), 0.0, 0.0)
+    local size = ImVec2(ImGui._CalcItemSizeXY(size_arg.x ~= 0.0 and size_arg.x or -FLT_MIN, size_arg.y ~= 0.0 and size_arg.y or -FLT_MIN, 0.0, 0.0))
 
     local id = window:GetID(str_id)
     local bb = ImRect(window.DC.CursorPos, window.DC.CursorPos + size)
@@ -1696,7 +1697,6 @@ end
 -- - Separator()
 -------------------------------------------------------------------------------
 
-local LAYOUT_ZERO_SIZE = ImVec2(0, 0) -- [Luau] shared read-only: ItemSize() only reads it
 local LayoutHelpers_size = ImVec2()   -- [Luau] scratch for ItemSize() arguments
 
 function ImGui.Spacing()

tools/test/scripts/t_fixes.luau

@@ -1,4 +1,5 @@
--- Regressions vs upstream: clipboard paste filter (InputTextEx), ImParseFormatTrimDecorations (Ctrl+click temp input), ShrinkWidths tie order
+-- Regressions vs upstream: clipboard paste filter (InputTextEx), ImParseFormatTrimDecorations (Ctrl+click temp input), ShrinkWidths tie order,
+-- CalcItemSize by value, PushClipRectFullScreen (drop target outside clip rect)
 local G = require(game:GetService("ReplicatedStorage"):WaitForChild("ImGui"))
 local ImGui, ImVec2 = G.ImGui, G.ImVec2
 ImGui.CreateContext(); G.ImGui_ImplRoblox.Init()
@@ -48,6 +49,12 @@ game:GetService("RunService").Stepped:Connect(function()
     ImGui.InputText("##t", buf, 64); rects.t = rect()
     sf = ImGui.SliderFloat("##s", sf, 0.0, 100.0, "%.0f deg"); rects.s = rect()
     di = ImGui.DragInt("##d", di, 1, 0, 100, "%d%%"); rects.d = rect()
+    -- CalcItemSize takes 'size' by value: the caller's ImVec2 must not be written to
+    local bsz, csz = ImVec2(0, 0), ImVec2(-1, 40)
+    ImGui.Button("sz", bsz); check(bsz.x == 0 and bsz.y == 0, "Button wrote size_arg")
+    ImGui.BeginChild("c", csz); ImGui.EndChild(); check(csz.x == -1 and csz.y == 40, "BeginChild wrote size_arg")
+    -- drop target rect sticking out of the window clip rect pushes a full-screen clip rect
+    ImGui.RenderDragDropTargetRectForItem(G.ImRect(-50, -50, 900, 900))
     ImGui.End()
     ImGui.Render(); G.ImGui_ImplRoblox.RenderDrawData(ImGui.GetDrawData())
     if f == 8 then check(edit_text() == "abc\u{e9}", "paste: '" .. edit_text() .. "'") end