Bugfix: GetAwaitExpressionInfo ignores BoundConversion

src/Compilers/CSharp/Portable/Compilation/MemberSemanticModel.cs

@@ -899,7 +899,7 @@ public override AwaitExpressionInfo GetAwaitExpressionInfo(AwaitExpressionSyntax
  throw new ArgumentException("node.Kind==" + node.Kind());
  }
 
- var bound = GetUpperBoundNode(node);
+ var bound = GetLowerBoundNode(node);
  BoundAwaitableInfo awaitableInfo = (((bound as BoundExpressionStatement)?.Expression ?? bound) as BoundAwaitExpression)?.AwaitableInfo;
  if (awaitableInfo == null)
  {

src/Compilers/CSharp/Test/Semantic/Semantics/AwaitExpressionTests.cs

@@ -20,6 +20,85 @@ namespace Microsoft.CodeAnalysis.CSharp.UnitTests
  /// </summary>
  public class AwaitExpressionTests : CompilingTestBase
  {
+ [Fact]
+ public void TestAwaitInfoExtensionMethod()
+ {
+ var text =
+@"using System;
+using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
+
+static class App{
+ public static async Task Main(){
+ var x = new MyAwaitable();
+ x.SetValue(42);
+
+ Console.WriteLine(await x + ""!"");
+ }
+}
+
+struct MyAwaitable
+{
+ private ValueTask<int> task;
+ private TaskCompletionSource<int> source;
+
+ private TaskCompletionSource<int> Source
+ {
+ get
+ {
+ if (source == null)
+ {
+ source = new TaskCompletionSource<int>();
+ task = new ValueTask<int>(source.Task);
+ }
+ return source;
+ }
+ }
+ internal ValueTask<int> Task
+ {
+ get
+ {
+ _ = Source;
+ return task;
+ }
+ }
+
+ public void SetValue(int i)
+ {
+ Source.SetResult(i);
+ }
+}
+
+static class MyAwaitableExtension
+{
+ public static System.Runtime.CompilerServices.ValueTaskAwaiter<int> GetAwaiter(this MyAwaitable a)
+ {
+ return a.Task.GetAwaiter();
+ }
+}";
+
+ var csCompilation = CreateCompilation(text, targetFramework: TargetFramework.NetCoreAppAndCSharp);
+ var tree = csCompilation.SyntaxTrees.Single();
+
+ var model = csCompilation.GetSemanticModel(tree);
+ var awaitExpression = tree.GetRoot().DescendantNodes().OfType<AwaitExpressionSyntax>().First();
+ Assert.Equal("await x", awaitExpression.ToString());
+
+ var info = model.GetAwaitExpressionInfo(awaitExpression);
+ Assert.Equal(
+ "System.Runtime.CompilerServices.ValueTaskAwaiter<System.Int32> MyAwaitableExtension.GetAwaiter(this MyAwaitable a)",
+ info.GetAwaiterMethod.ToTestDisplayString()
+ );
+ Assert.Equal(
+ "System.Int32 System.Runtime.CompilerServices.ValueTaskAwaiter<System.Int32>.GetResult()",
+ info.GetResultMethod.ToTestDisplayString()
+ );
+ Assert.Equal(
+ "System.Boolean System.Runtime.CompilerServices.ValueTaskAwaiter<System.Int32>.IsCompleted { get; }",
+ info.IsCompletedProperty.ToTestDisplayString()
+ );
+ }
+
  [Fact]
  [WorkItem(711413, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/711413")]
  public void TestAwaitInfo()