Fix building with v143 toolchain (#10727)

Visual Studio 2022 Preview recently released the v143 toolchain.
C4189 is now flagging several unused variables, which breaks our build.

## PR Checklist

* [x] I work here
* [x] Tests added/passed

## Validation Steps Performed

* CascadiaPackage builds ✔️
* All tests build ✔️

src/buffer/out/textBuffer.cpp

@@ -418,7 +418,6 @@ bool TextBuffer::InsertCharacter(const std::wstring_view chars,
 
         // Store character and double byte data
         CharRow& charRow = Row.GetCharRow();
-        short const cBufferWidth = GetSize().Width();
 
         try
         {
@@ -1650,13 +1649,14 @@ const TextBuffer::TextAndColor TextBuffer::GetText(const bool includeCRLF,
 
             if (!cell.DbcsAttr().IsTrailing())
             {
-                selectionText.append(cell.Chars());
+                const auto chars = cell.Chars();
+                selectionText.append(chars);
 
                 if (copyTextColor)
                 {
                     const auto cellData = cell.TextAttr();
                     const auto [CellFgAttr, CellBkAttr] = GetAttributeColors(cellData);
-                    for (const wchar_t wch : cell.Chars())
+                    for (size_t j = 0; j < chars.size(); ++j)
                     {
                         selectionFgAttr.push_back(CellFgAttr);
                         selectionBkAttr.push_back(CellBkAttr);

src/cascadia/TerminalApp/Pane.cpp

@@ -911,7 +911,6 @@ winrt::fire_and_forget Pane::_CloseChildRoutine(const bool closeFirst)
         auto removedChild = closeFirst ? _firstChild : _secondChild;
         auto remainingChild = closeFirst ? _secondChild : _firstChild;
         const bool splitWidth = _splitState == SplitState::Vertical;
-        const auto totalSize = splitWidth ? _root.ActualWidth() : _root.ActualHeight();
 
         Size removedOriginalSize{
             ::base::saturated_cast<float>(removedChild->_root.ActualWidth()),

src/cascadia/TerminalCore/Terminal.cpp

@@ -230,16 +230,10 @@ void Terminal::UpdateAppearance(const ICoreAppearance& appearance)
     }
 
     const auto dx = ::base::ClampSub(viewportSize.X, oldDimensions.X);
-
-    const auto oldTop = _mutableViewport.Top();
-
     const short newBufferHeight = ::base::ClampAdd(viewportSize.Y, _scrollbackLines);
 
     COORD bufferSize{ viewportSize.X, newBufferHeight };
 
-    // Save cursor's relative height versus the viewport
-    const short sCursorHeightInViewportBefore = ::base::ClampSub(_buffer->GetCursor().GetPosition().Y, _mutableViewport.Top());
-
     // This will be used to determine where the viewport should be in the new buffer.
     const short oldViewportTop = _mutableViewport.Top();
     short newViewportTop = oldViewportTop;

src/cascadia/UnitTests_Remoting/RemotingTests.cpp

@@ -1656,7 +1656,7 @@ namespace RemotingUnitTests
 
         auto m0 = make_private<Remoting::implementation::Monarch>(monarch0PID);
         auto p1 = make_private<Remoting::implementation::Peasant>(peasant1PID);
-        auto p2 = make_private<Remoting::implementation::Peasant>(peasant1PID);
+        auto p2 = make_private<Remoting::implementation::Peasant>(peasant2PID);
 
         p1->WindowName(L"one");
         p2->WindowName(L"two");

src/cascadia/UnitTests_TerminalCore/ConptyRoundtripTests.cpp

@@ -1077,7 +1077,6 @@ void ConptyRoundtripTests::PassthroughClearAll()
     }
 
     auto verifyBuffer = [&](const TextBuffer& tb, const til::rectangle viewport, const bool afterClear = false) {
-        const auto firstRow = viewport.top<short>();
         const auto width = viewport.width<short>();
 
         // "~" rows
@@ -1781,7 +1780,6 @@ void ConptyRoundtripTests::ClearHostTrickeryTest()
     END_TEST_METHOD_PROPERTIES();
     constexpr int PaintEveryNewline = 0;
     constexpr int PaintAfterAllNewlines = 1;
-    constexpr int DontPaintAfterNewlines = 2;
 
     INIT_TEST_PROPERTY(int, paintEachNewline, L"Any of: manually PaintFrame after each newline is emitted, once at the end of all newlines, or not at all");
     INIT_TEST_PROPERTY(bool, cursorOnNextLine, L"Either leave the cursor on the first line, or place it on the second line of the buffer");
@@ -2562,7 +2560,6 @@ void ConptyRoundtripTests::ResizeRepaintVimExeBuffer()
         sm.ProcessString(L"BBB");
         sm.ProcessString(L"\r\n");
 
-        const auto end = 2 * hostView.Height();
         for (auto i = 2; i < hostView.BottomInclusive(); i++)
         {
             // IMPORTANT! The way vim writes these blank lines is as '~' followed by
@@ -2581,10 +2578,6 @@ void ConptyRoundtripTests::ResizeRepaintVimExeBuffer()
 
     drawVim();
 
-    const auto firstTextLength = TerminalViewWidth - 2;
-    const auto spacesLength = 3;
-    const auto secondTextLength = 1;
-
     auto verifyBuffer = [&](const TextBuffer& tb, const til::rectangle viewport) {
         const auto firstRow = viewport.top<short>();
         const auto width = viewport.width<short>();
@@ -2696,7 +2689,6 @@ void ConptyRoundtripTests::ClsAndClearHostClearsScrollbackTest()
     }
 
     auto verifyBuffer = [&](const TextBuffer& tb, const til::rectangle viewport, const bool afterClear = false) {
-        const auto firstRow = viewport.top<short>();
         const auto width = viewport.width<short>();
 
         // "~" rows
@@ -2910,8 +2902,6 @@ void ConptyRoundtripTests::ResizeInitializeBufferWithDefaultAttrs()
     //                                         { static_cast<BYTE>(XTERM_GREEN_ATTR) });
     terminalGreenAttrs.SetIndexedBackground(XTERM_GREEN_ATTR);
 
-    const size_t width = static_cast<size_t>(TerminalViewWidth);
-
     // Use an initial ^[[m to start printing with default-on-default
     sm.ProcessString(L"\x1b[m");
 
@@ -3043,8 +3033,6 @@ void ConptyRoundtripTests::NewLinesAtBottomWithBackground()
     terminalBlueAttrs.SetIndexedForeground(XTERM_GREEN_ATTR);
     terminalBlueAttrs.SetIndexedBackground(XTERM_BLUE_ATTR);
 
-    const size_t width = static_cast<size_t>(TerminalViewWidth);
-
     // We're going to print 4 more rows than the entire height of the viewport,
     // causing the buffer to circle 4 times. This is 2 extra iterations of the
     // two lines we're printing per iteration.
@@ -3162,7 +3150,6 @@ void ConptyRoundtripTests::WrapNewLineAtBottom()
     // timings for the frame affect the results. In this test we'll be printing
     // a bunch of paired lines. These values control when the PaintFrame calls
     // will occur:
-    constexpr int DontPaint = 0; // Only paint at the end of all the output
     constexpr int PaintAfterBothLines = 1; // Paint after each pair of lines is output
     constexpr int PaintEveryLine = 2; // Paint after each and every line is output.
 
@@ -3343,7 +3330,6 @@ void ConptyRoundtripTests::WrapNewLineAtBottomLikeMSYS()
     // timings for the frame affect the results. In this test we'll be printing
     // a bunch of paired lines. These values control when the PaintFrame calls
     // will occur:
-    constexpr int DontPaint = 0; // Only paint at the end of all the output
     constexpr int PaintAfterBothLines = 1; // Paint after each pair of lines is output
     constexpr int PaintEveryLine = 2; // Paint after each and every line is output.
 

src/cascadia/WindowsTerminal/IslandWindow.cpp

@@ -287,8 +287,6 @@ LRESULT IslandWindow::_OnMoving(const WPARAM /*wParam*/, const LPARAM lParam)
 
 void IslandWindow::Initialize()
 {
-    const bool initialized = (_interopWindowHandle != nullptr);
-
     _source = DesktopWindowXamlSource{};
 
     auto interop = _source.as<IDesktopWindowXamlSourceNative>();

src/host/stream.cpp

@@ -707,8 +707,6 @@ size_t RetrieveNumberOfSpaces(_In_ SHORT sOriginalCursorPositionX,
             return STATUS_BUFFER_TOO_SMALL;
         }
 
-        const size_t OutputBufferSize = buffer.size_bytes();
-
         if (readHandleState.IsInputPending())
         {
             return _ReadPendingInput(inputBuffer,

src/interactivity/base/EventSynthesis.cpp

@@ -181,7 +181,6 @@ std::deque<std::unique_ptr<KeyEvent>> Microsoft::Console::Interactivity::Synthes
                                                    UNICODE_NULL,
                                                    LEFT_ALT_PRESSED));
 
-    const int radix = 10;
     std::wstring wstr{ wch };
     const auto convertedChars = ConvertToA(codepage, wstr);
     if (convertedChars.size() == 1)

src/interactivity/win32/windowproc.cpp

@@ -181,7 +181,6 @@ using namespace Microsoft::Console::Types;
 
         // First retrieve the new DPI and the current DPI.
         DWORD const dpiProposed = (WORD)wParam;
-        DWORD const dpiCurrent = g.dpi;
 
         // Now we need to get what the font size *would be* if we had this new DPI. We need to ask the renderer about that.
         const FontInfo& fiCurrent = ScreenInfo.GetCurrentFont();

src/renderer/vt/state.cpp

@@ -163,8 +163,6 @@ VtEngine::VtEngine(_In_ wil::unique_hfile pipe,
 // - S_OK or suitable HRESULT error from writing pipe.
 [[nodiscard]] HRESULT VtEngine::_WriteTerminalAscii(const std::wstring_view wstr) noexcept
 {
-    const size_t cchActual = wstr.length();
-
     std::string needed;
     needed.reserve(wstr.size());
 

src/til/ut_til/MathTests.cpp

@@ -44,10 +44,7 @@ class MathTests
 
         _RunCases(til::math::truncating, cases);
 
-        const auto fn = []() {
-            const auto v = til::math::details::truncating_t::cast<ptrdiff_t>(NAN);
-        };
-        VERIFY_THROWS_SPECIFIC(fn(), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
+        VERIFY_THROWS_SPECIFIC(til::math::details::truncating_t::cast<ptrdiff_t>(NAN), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
     }
 
     TEST_METHOD(Ceiling)
@@ -65,10 +62,7 @@ class MathTests
 
         _RunCases(til::math::ceiling, cases);
 
-        const auto fn = []() {
-            const auto v = til::math::details::ceiling_t::cast<ptrdiff_t>(NAN);
-        };
-        VERIFY_THROWS_SPECIFIC(fn(), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
+        VERIFY_THROWS_SPECIFIC(til::math::details::ceiling_t::cast<ptrdiff_t>(NAN), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
     }
 
     TEST_METHOD(Flooring)
@@ -86,10 +80,7 @@ class MathTests
 
         _RunCases(til::math::flooring, cases);
 
-        const auto fn = []() {
-            const auto v = til::math::details::flooring_t::cast<ptrdiff_t>(NAN);
-        };
-        VERIFY_THROWS_SPECIFIC(fn(), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
+        VERIFY_THROWS_SPECIFIC(til::math::details::flooring_t::cast<ptrdiff_t>(NAN), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
     }
 
     TEST_METHOD(Rounding)
@@ -107,10 +98,7 @@ class MathTests
 
         _RunCases(til::math::rounding, cases);
 
-        const auto fn = []() {
-            const auto v = til::math::details::rounding_t::cast<ptrdiff_t>(NAN);
-        };
-        VERIFY_THROWS_SPECIFIC(fn(), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
+        VERIFY_THROWS_SPECIFIC(til::math::details::rounding_t::cast<ptrdiff_t>(NAN), wil::ResultException, [](wil::ResultException& e) { return e.GetErrorCode() == E_ABORT; });
     }
 
     TEST_METHOD(NormalIntegers)

src/til/ut_til/PointTests.cpp

@@ -765,7 +765,6 @@ class PointTests
 
         Log::Comment(L"4.) Division by zero");
         {
-            constexpr ptrdiff_t bigSize = std::numeric_limits<ptrdiff_t>().max();
             const til::point pt{ 1, 1 };
             const int scale = 0;