Indicate support for OSC 52 in the DA1 report (#19034)

## Summary of the Pull Request
Some applications that make use of the `OSC 52` clipboard sequence will
only do so if they can be certain that the terminal actually has that
functionality. Indicating our support for `OSC 52` in the `DA1` report
will give them an easy way to detect that.

## References and Relevant Issues
`OSC 52` support was added to Windows Terminal in issue #5823, and to
ConHost in issue #18949.

## Detailed Description of the Pull Request / Additional comments
Support for writing to the clipboard is indicated in the primary device
attributes report by the extension parameter `52`. This is obviously not
a standard DEC extension, but it's one that's been agreed upon by a
number of modern terminals. The extension is only reported when writing
to the clipboard is actually permitted (Windows Terminal has an option
to disable that).

## Validation Steps Performed
I've updated the Device Attributes unit test to check that we're
reporting extension `52` when clipboard access is enabled, and not
reporting it when disabled.

## PR Checklist
- [x] Closes #19017
- [x] Tests added/passed

src/cascadia/TerminalCore/Terminal.cpp

@@ -94,7 +94,7 @@ void Terminal::UpdateSettings(ICoreSettings settings)
 
     if (_stateMachine)
     {
-        SetVtChecksumReportSupport(settings.AllowVtChecksumReport());
+        SetOptionalFeatures(settings);
     }
 
     _getTerminalInput().ForceDisableWin32InputMode(settings.ForceVTInput());
@@ -232,10 +232,13 @@ void Terminal::SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle)
     engine.Dispatch().SetCursorStyle(cursorStyle);
 }
 
-void Terminal::SetVtChecksumReportSupport(const bool enabled)
+void Terminal::SetOptionalFeatures(winrt::Microsoft::Terminal::Core::ICoreSettings settings)
 {
     auto& engine = reinterpret_cast<OutputStateMachineEngine&>(_stateMachine->Engine());
-    engine.Dispatch().SetVtChecksumReportSupport(enabled);
+    auto features = til::enumset<ITermDispatch::OptionalFeature>{};
+    features.set(ITermDispatch::OptionalFeature::ChecksumReport, settings.AllowVtChecksumReport());
+    features.set(ITermDispatch::OptionalFeature::ClipboardWrite, settings.AllowVtClipboardWrite());
+    engine.Dispatch().SetOptionalFeatures(features);
 }
 
 bool Terminal::IsXtermBracketedPasteModeEnabled() const noexcept

src/cascadia/TerminalCore/Terminal.hpp

@@ -95,7 +95,7 @@ public:
     void SetHighContrastMode(bool hc) noexcept;
     void SetFontInfo(const FontInfo& fontInfo);
     void SetCursorStyle(const ::Microsoft::Console::VirtualTerminal::DispatchTypes::CursorStyle cursorStyle);
-    void SetVtChecksumReportSupport(const bool enabled);
+    void SetOptionalFeatures(winrt::Microsoft::Terminal::Core::ICoreSettings settings);
     bool IsXtermBracketedPasteModeEnabled() const noexcept;
     std::wstring_view GetWorkingDirectory() noexcept;
 

src/terminal/adapter/ITermDispatch.hpp

@@ -25,6 +25,12 @@ class Microsoft::Console::VirtualTerminal::ITermDispatch
 public:
     using StringHandler = std::function<bool(const wchar_t)>;
 
+    enum class OptionalFeature
+    {
+        ChecksumReport,
+        ClipboardWrite,
+    };
+
 #pragma warning(push)
 #pragma warning(disable : 26432) // suppress rule of 5 violation on interface because tampering with this is fraught with peril
     virtual ~ITermDispatch() = 0;
@@ -133,7 +139,6 @@ public:
     virtual void ScreenAlignmentPattern() = 0; // DECALN
 
     virtual void SetCursorStyle(const DispatchTypes::CursorStyle cursorStyle) = 0; // DECSCUSR
-    virtual void SetVtChecksumReportSupport(const bool enabled) = 0;
 
     virtual void SetClipboard(wil::zwstring_view content) = 0; // OSCSetClipboard
 
@@ -185,6 +190,8 @@ public:
     virtual StringHandler RestorePresentationState(const DispatchTypes::PresentationReportFormat format) = 0; // DECRSPS
 
     virtual void PlaySounds(const VTParameters parameters) = 0; // DECPS
+
+    virtual void SetOptionalFeatures(const til::enumset<OptionalFeature> features) = 0;
 };
 inline Microsoft::Console::VirtualTerminal::ITermDispatch::~ITermDispatch() = default;
 #pragma warning(pop)

src/terminal/adapter/adaptDispatch.cpp

@@ -1297,11 +1297,6 @@ void AdaptDispatch::SelectAttributeChangeExtent(const DispatchTypes::ChangeExten
     }
 }
 
-void AdaptDispatch::SetVtChecksumReportSupport(const bool enabled) noexcept
-{
-    _vtChecksumReportEnabled = enabled;
-}
-
 // Routine Description:
 // - DECRQCRA - Computes and reports a checksum of the specified area of
 //   the buffer memory.
@@ -1318,7 +1313,7 @@ void AdaptDispatch::RequestChecksumRectangularArea(const VTInt id, const VTInt p
     // If this feature is not enabled, we'll just report a zero checksum.
     if constexpr (Feature_VtChecksumReport::IsEnabled())
     {
-        if (_vtChecksumReportEnabled)
+        if (_optionalFeatures.test(OptionalFeature::ChecksumReport))
         {
             // If the page number is 0, then we're meant to return a checksum of all
             // of the pages, but we have no need for that, so we'll just return 0.
@@ -1483,8 +1478,16 @@ void AdaptDispatch::DeviceAttributes()
     // 28 = Rectangular area operations
     // 32 = Text macros
     // 42 = ISO Latin-2 character set
+    // 52 = Clipboard access
 
-    _ReturnCsiResponse(L"?61;4;6;7;14;21;22;23;24;28;32;42c");
+    if (_optionalFeatures.test(OptionalFeature::ClipboardWrite))
+    {
+        _ReturnCsiResponse(L"?61;4;6;7;14;21;22;23;24;28;32;42;52c");
+    }
+    else
+    {
+        _ReturnCsiResponse(L"?61;4;6;7;14;21;22;23;24;28;32;42c");
+    }
 }
 
 // Routine Description:
@@ -4790,3 +4793,8 @@ void AdaptDispatch::PlaySounds(const VTParameters parameters)
         _api.PlayMidiNote(noteNumber, noteNumber == 71 ? 0 : velocity, duration);
     });
 }
+
+void AdaptDispatch::SetOptionalFeatures(const til::enumset<OptionalFeature> features) noexcept
+{
+    _optionalFeatures = features;
+}

src/terminal/adapter/adaptDispatch.hpp

@@ -188,7 +188,7 @@ namespace Microsoft::Console::VirtualTerminal
 
         void PlaySounds(const VTParameters parameters) override; // DECPS
 
-        void SetVtChecksumReportSupport(const bool enabled) noexcept override;
+        void SetOptionalFeatures(const til::enumset<OptionalFeature> features) noexcept override;
 
     private:
         enum class Mode
@@ -313,7 +313,7 @@ namespace Microsoft::Console::VirtualTerminal
         std::unique_ptr<FontBuffer> _fontBuffer;
         std::shared_ptr<MacroBuffer> _macroBuffer;
         std::optional<unsigned int> _initialCodePage;
-        bool _vtChecksumReportEnabled = false;
+        til::enumset<OptionalFeature> _optionalFeatures = { OptionalFeature::ClipboardWrite };
 
         // We have two instances of the saved cursor state, because we need
         // one for the main buffer (at index 0), and another for the alt buffer

src/terminal/adapter/termDispatch.hpp

@@ -178,7 +178,7 @@ public:
 
     void PlaySounds(const VTParameters /*parameters*/) override{}; // DECPS
 
-    void SetVtChecksumReportSupport(const bool /*enabled*/) override{};
+    void SetOptionalFeatures(const til::enumset<OptionalFeature> /*features*/) override{};
 };
 
 #pragma warning(default : 26440) // Restore "can be declared noexcept" warning

src/terminal/adapter/ut_adapter/adapterTest.cpp

@@ -415,7 +415,6 @@ public:
             auto& renderer = _testGetSet->_renderer;
             auto& renderSettings = renderer._renderSettings;
             auto adapter = std::make_unique<AdaptDispatch>(*_testGetSet, &renderer, renderSettings, _terminalInput);
-            adapter->SetVtChecksumReportSupport(true);
 
             fSuccess = adapter.get() != nullptr;
             if (fSuccess)
@@ -1737,11 +1736,15 @@ public:
         Log::Comment(L"Test 1: Verify normal response.");
         _testGetSet->PrepData();
         _pDispatch->DeviceAttributes();
+        _testGetSet->ValidateInputEvent(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42;52c");
 
-        auto pwszExpectedResponse = L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42c";
-        _testGetSet->ValidateInputEvent(pwszExpectedResponse);
+        Log::Comment(L"Test 2: Verify response with clipboard disabled.");
+        _testGetSet->PrepData();
+        _pDispatch->SetOptionalFeatures({});
+        _pDispatch->DeviceAttributes();
+        _testGetSet->ValidateInputEvent(L"\x1b[?61;4;6;7;14;21;22;23;24;28;32;42c");
 
-        Log::Comment(L"Test 2: Verify failure when ReturnResponse doesn't work.");
+        Log::Comment(L"Test 3: Verify failure when ReturnResponse doesn't work.");
         _testGetSet->PrepData();
         _testGetSet->_returnResponseResult = FALSE;
 
@@ -2187,6 +2190,8 @@ public:
 
         using namespace std::string_view_literals;
 
+        _pDispatch->SetOptionalFeatures(ITermDispatch::OptionalFeature::ChecksumReport);
+
         Log::Comment(L"Test 1: ASCII characters");
         outputText(L"A"sv);
         verifyChecksumReport(L"FF4F");