Replace IProcess.WaitForProcessExitAsync with WaitForExitAsync

kudos to @vjdw

GitCommands/Git/Executable.cs

@@ -4,6 +4,7 @@
 using GitExtUtils;
 using GitUI;
 using GitUIPluginInterfaces;
+using Microsoft.VisualStudio.Threading;
 
 namespace GitCommands
 {
@@ -220,10 +221,7 @@ public StreamReader StandardError
             public Task<int> WaitForExitAsync() => _exitTaskCompletionSource.Task;
 
             /// <inheritdoc />
-            public Task WaitForProcessExitAsync(CancellationToken token)
-            {
-                return _process.WaitForExitAsync(token);
-            }
+            public Task<int> WaitForExitAsync(CancellationToken token) => WaitForExitAsync().WithCancellation(token);
 
             /// <inheritdoc />
             public int WaitForExit()

GitCommands/Git/ExecutableExtensions.cs

@@ -318,16 +318,13 @@ string ComposeOutput()
             }
 #endif
 
-            // Wait for the process to exit (or be cancelled)
-            await process.WaitForProcessExitAsync(cancellationToken);
-
-            // Await the output and exit status
-            var exitTask = process.WaitForExitAsync();
+            // Wait for the process to exit (or be cancelled) and for the output
+            Task<int> exitTask = process.WaitForExitAsync(cancellationToken);
             await Task.WhenAll(outputTask, errorTask, exitTask);
 
             var output = outputEncoding.GetString(outputBuffer.GetBuffer(), 0, (int)outputBuffer.Length);
             var error = outputEncoding.GetString(errorBuffer.GetBuffer(), 0, (int)errorBuffer.Length);
-            var exitCode = await process.WaitForExitAsync();
+            int exitCode = await exitTask;
 
             if (cache is not null && exitCode == 0)
             {

Plugins/GitUIPluginInterfaces/IProcess.cs

@@ -53,12 +53,10 @@ public interface IProcess : IDisposable
         Task<int> WaitForExitAsync();
 
         /// <summary>
-        /// Instructs the process component to wait for the associated process to exit, or for the cancellationToken to be cancelled (cancells the process).
-        /// Note that the exit task must be awaited too.
+        /// Returns a cancellable task that completes when the process exits, or when this object is disposed.
         /// </summary>
-        /// <param name="token">An optional token to cancel the asynchronous operation.</param>
-        /// <returns>A task that will complete when the process has exited, cancellation has been requested, or an error occurs.</returns>
-        Task WaitForProcessExitAsync(CancellationToken token);
+        /// <returns>A task that yields the process's exit code, or <c>null</c> if this object was disposed before the process exited.</returns>
+        Task<int> WaitForExitAsync(CancellationToken token);
 
         /// <summary>
         /// Waits for the process to reach an idle state.

UnitTests/CommonTestUtils/MockExecutable.cs

@@ -136,9 +136,9 @@ public Task<int> WaitForExitAsync()
                 }
             }
 
-            public Task WaitForProcessExitAsync(CancellationToken token)
+            public Task<int> WaitForExitAsync(CancellationToken token)
             {
-                return Task.CompletedTask;
+                return Task.FromResult(0);
             }
 
             public void WaitForInputIdle()