From 86ba1fc6c36653988bd1328a85f455c2e488a2e5 Mon Sep 17 00:00:00 2001
From: Leonard Hecker <lhecker@microsoft.com>
Date: Wed, 22 Sep 2021 21:39:34 +0200
Subject: [PATCH] Fix KeyChord constructor assertion failure during tab
 dragging (#11306)
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For some weird reason we sometimes receive a WM_KEYDOWN
message without vkey or scanCode if a user drags a tab.
The KeyChord constructor has a debug assertion ensuring that all KeyChord
either have a valid vkey/scanCode. This is important, because this prevents
accidential insertion of invalid KeyChords into classes like ActionMap.

## PR Checklist
* [x] Closes #11076
* [x] I work here
* [x] Tests added/passed

## Validation Steps Performed

* Tab dragging doesn't produce assertion failures anymore ✔️
---
 src/cascadia/TerminalControl/TermControl.cpp | 33 +++++++++++++-------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/cascadia/TerminalControl/TermControl.cpp b/src/cascadia/TerminalControl/TermControl.cpp
index fc74dd0a9..f90190a5d 100644
--- a/src/cascadia/TerminalControl/TermControl.cpp
+++ b/src/cascadia/TerminalControl/TermControl.cpp
@@ -848,6 +848,23 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             return;
         }
 
+        const auto keyStatus = e.KeyStatus();
+        const auto vkey = gsl::narrow_cast<WORD>(e.OriginalKey());
+        const auto scanCode = gsl::narrow_cast<WORD>(keyStatus.ScanCode);
+        auto modifiers = _GetPressedModifierKeys();
+
+        // GH#11076:
+        // For some weird reason we sometimes receive a WM_KEYDOWN
+        // message without vkey or scanCode if a user drags a tab.
+        // The KeyChord constructor has a debug assertion ensuring that all KeyChord
+        // either have a valid vkey/scanCode. This is important, because this prevents
+        // accidential insertion of invalid KeyChords into classes like ActionMap.
+        if (!vkey && !scanCode)
+        {
+            e.Handled(true);
+            return;
+        }
+
         // Mark the event as handled and do nothing if we're closing, or the key
         // was the Windows key.
         //
@@ -856,19 +873,12 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // win32-input-mode, then we'll send all these keystrokes to the
         // terminal - it's smart enough to ignore the keys it doesn't care
         // about.
-        if (_IsClosing() ||
-            e.OriginalKey() == VirtualKey::LeftWindows ||
-            e.OriginalKey() == VirtualKey::RightWindows)
-
+        if (_IsClosing() || vkey == VK_LWIN || vkey == VK_RWIN)
         {
             e.Handled(true);
             return;
         }
 
-        auto modifiers = _GetPressedModifierKeys();
-        const auto vkey = gsl::narrow_cast<WORD>(e.OriginalKey());
-        const auto scanCode = gsl::narrow_cast<WORD>(e.KeyStatus().ScanCode);
-
         // Short-circuit isReadOnly check to avoid warning dialog
         if (_core.IsInReadOnlyMode())
         {
@@ -876,7 +886,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
             return;
         }
 
-        if (e.KeyStatus().IsExtendedKey)
+        if (keyStatus.IsExtendedKey)
         {
             modifiers |= ControlKeyStates::EnhancedKey;
         }
@@ -886,8 +896,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // will be sent through the TSFInputControl. See GH#1401 for more
         // details
         if (modifiers.IsAltPressed() &&
-            (e.OriginalKey() >= VirtualKey::NumberPad0 && e.OriginalKey() <= VirtualKey::NumberPad9))
-
+            (vkey >= VK_NUMPAD0 && vkey <= VK_NUMPAD9))
         {
             e.Handled(true);
             return;
@@ -917,7 +926,7 @@ namespace winrt::Microsoft::Terminal::Control::implementation
         // Manually prevent keyboard navigation with tab. We want to send tab to
         // the terminal, and we don't want to be able to escape focus of the
         // control with tab.
-        e.Handled(e.OriginalKey() == VirtualKey::Tab);
+        e.Handled(vkey == VK_TAB);
     }
 
     // Method Description: