Add null checks in AwaitExpressionInfo

dotnet · Dec 30, 2018 · 6f98b20 · 6f98b20
1 parent bff68d6
commit 6f98b20
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Showing 3 changed files with 24 additions and 4 deletions.
diff --git a/src/Compilers/CSharp/Portable/Compilation/AwaitExpressionInfo.cs b/src/Compilers/CSharp/Portable/Compilation/AwaitExpressionInfo.cs
@@ -13,13 +13,13 @@ public struct AwaitExpressionInfo : IEquatable<AwaitExpressionInfo>
     {
         private readonly AwaitableInfo _awaitableInfo;
 
-        public IMethodSymbol GetAwaiterMethod => _awaitableInfo.GetAwaiter;
+        public IMethodSymbol GetAwaiterMethod => _awaitableInfo?.GetAwaiter;
 
-        public IPropertySymbol IsCompletedProperty => _awaitableInfo.IsCompleted;
+        public IPropertySymbol IsCompletedProperty => _awaitableInfo?.IsCompleted;
 
-        public IMethodSymbol GetResultMethod => _awaitableInfo.GetResult;
+        public IMethodSymbol GetResultMethod => _awaitableInfo?.GetResult;
 
-        public bool IsDynamic => _awaitableInfo.IsDynamic;
+        public bool IsDynamic => _awaitableInfo?.IsDynamic == true;
 
         internal AwaitExpressionInfo(AwaitableInfo awaitableInfo)
         {

diff --git a/src/Compilers/CSharp/Test/Semantic/Semantics/AwaitExpressionTests.cs b/src/Compilers/CSharp/Test/Semantic/Semantics/AwaitExpressionTests.cs
@@ -54,6 +54,17 @@ public C(Task<int> t) {
             Assert.Equal("System.Boolean System.Runtime.CompilerServices.TaskAwaiter<System.Int32>.IsCompleted { get; }", info.IsCompletedProperty.ToTestDisplayString());
         }
 
+        [Fact]
+        [WorkItem(744146, "https://devdiv.visualstudio.com/DevDiv/_workitems/edit/744146")]
+        public void DefaultAwaitExpressionInfo()
+        {
+            AwaitExpressionInfo info = default;
+            Assert.Null(info.GetAwaiterMethod);
+            Assert.Null(info.GetResultMethod);
+            Assert.Null(info.IsCompletedProperty);
+            Assert.False(info.IsDynamic);
+        }
+
         private AwaitExpressionInfo GetAwaitExpressionInfo(string text, out CSharpCompilation compilation, params DiagnosticDescription[] diagnostics)
         {
             var tree = Parse(text, options: CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp5));

diff --git a/src/Compilers/VisualBasic/Test/Semantic/Semantics/AsyncAwait.vb b/src/Compilers/VisualBasic/Test/Semantic/Semantics/AsyncAwait.vb
@@ -42,6 +42,15 @@ End Module
             AssertTheseDiagnostics(compilation, <expected></expected>)
         End Sub
 
+        <Fact, WorkItem(744146, "https://devdiv.visualstudio.com/DevDiv/_workitems/edit/744146")>
+        Public Sub DefaultAwaitExpressionInfo()
+            Dim awaitInfo As AwaitExpressionInfo = Nothing
+
+            Assert.Null(awaitInfo.GetAwaiterMethod)
+            Assert.Null(awaitInfo.IsCompletedProperty)
+            Assert.Null(awaitInfo.GetResultMethod)
+        End Sub
+
         <Fact()>
         Public Sub AwaitableType01()
             Dim source =