Use TerminateProcess to exit early

src/cascadia/WindowsTerminal/WindowEmperor.cpp

@@ -34,26 +34,6 @@ WindowEmperor::WindowEmperor() noexcept :
     });
 
     _dispatcher = winrt::Windows::System::DispatcherQueue::GetForCurrentThread();
-
-    // BODGY
-    //
-    // There's a mysterious crash in XAML on Windows 10 if you just let the App
-    // get dtor'd. By all accounts, it doesn't make sense. To mitigate this, we
-    // need to intentionally leak a reference to our App. Crazily, if you just
-    // let the app get cleaned up with the rest of the process when the process
-    // exits, then it doesn't crash. But if you let it get explicitly dtor'd, it
-    // absolutely will crash on exit.
-    //
-    // GH#15410 has more details.
-
-    auto a{ _app };
-    ::winrt::detach_abi(a);
-}
-
-WindowEmperor::~WindowEmperor()
-{
-    _app.Close();
-    _app = nullptr;
 }
 
 void _buildArgsFromCommandline(std::vector<winrt::hstring>& args)
@@ -78,7 +58,7 @@ void _buildArgsFromCommandline(std::vector<winrt::hstring>& args)
     }
 }
 
-bool WindowEmperor::HandleCommandlineArgs(int nCmdShow)
+void WindowEmperor::HandleCommandlineArgs(int nCmdShow)
 {
     std::vector<winrt::hstring> args;
     _buildArgsFromCommandline(args);
@@ -97,25 +77,30 @@ bool WindowEmperor::HandleCommandlineArgs(int nCmdShow)
     const Remoting::CommandlineArgs eventArgs{ args, cwd, gsl::narrow_cast<uint32_t>(nCmdShow), GetEnvironmentStringsW() };
     const auto isolatedMode{ _app.Logic().IsolatedMode() };
     const auto result = _manager.ProposeCommandline(eventArgs, isolatedMode);
+    int exitCode = 0;
 
-    const bool makeWindow = result.ShouldCreateWindow();
-    if (makeWindow)
+    if (result.ShouldCreateWindow())
     {
         _createNewWindowThread(Remoting::WindowRequestedArgs{ result, eventArgs });
-
         _becomeMonarch();
+        WaitForWindows();
     }
     else
     {
         const auto res = _app.Logic().GetParseCommandlineMessage(eventArgs.Commandline());
         if (!res.Message.empty())
         {
             AppHost::s_DisplayMessageBox(res);
-            std::quick_exit(res.ExitCode);
         }
+        exitCode = res.ExitCode;
     }
 
-    return makeWindow;
+    // There's a mysterious crash in XAML on Windows 10 if you just let _app get destroyed (GH#15410).
+    // We also need to ensure that all UI threads exit before WindowEmperor leaves the scope on the main thread (MSFT:46744208).
+    // Both problems can be solved and the shutdown accelerated by using TerminateProcess.
+    // std::exit(), etc., cannot be used here, because those use ExitProcess for unpackaged applications.
+    TerminateProcess(GetCurrentProcess(), gsl::narrow_cast<UINT>(exitCode));
+    __assume(false);
 }
 
 void WindowEmperor::WaitForWindows()
@@ -568,15 +553,6 @@ LRESULT WindowEmperor::_messageHandler(UINT const message, WPARAM const wParam,
 // we'll undoubtedly crash.
 winrt::fire_and_forget WindowEmperor::_close()
 {
-    {
-        auto fridge{ _oldThreads.lock() };
-        for (auto& window : *fridge)
-        {
-            window->ThrowAway();
-        }
-        fridge->clear();
-    }
-
     // Important! Switch back to the main thread for the emperor. That way, the
     // quit will go to the emperor's message pump.
     co_await wil::resume_foreground(_dispatcher);

src/cascadia/WindowsTerminal/WindowEmperor.h

@@ -24,10 +24,9 @@ class WindowEmperor : public std::enable_shared_from_this<WindowEmperor>
 {
 public:
     WindowEmperor() noexcept;
-    ~WindowEmperor();
     void WaitForWindows();
 
-    bool HandleCommandlineArgs(int nCmdShow);
+    void HandleCommandlineArgs(int nCmdShow);
 
 private:
     void _createNewWindowThread(const winrt::Microsoft::Terminal::Remoting::WindowRequestedArgs& args);

src/cascadia/WindowsTerminal/main.cpp

@@ -115,8 +115,5 @@ int __stdcall wWinMain(HINSTANCE, HINSTANCE, LPWSTR, int nCmdShow)
     winrt::init_apartment(winrt::apartment_type::single_threaded);
 
     const auto emperor = std::make_shared<::WindowEmperor>();
-    if (emperor->HandleCommandlineArgs(nCmdShow))
-    {
-        emperor->WaitForWindows();
-    }
+    emperor->HandleCommandlineArgs(nCmdShow);
 }