Ignore await in completion when triggers completion between two dots (#39302)

src/EditorFeatures/CSharpTest/Completion/CompletionProviders/SymbolCompletionProviderTests.cs

@@ -7178,6 +7178,89 @@ async Task<int> goo()
             await VerifyItemWithMscorlib45Async(markup, "goo", description, "C#");
         }
 
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public async Task AwaitableDotsLikeRangeExpression()
+        {
+            var markup = @"
+using System.IO;
+using System.Threading.Tasks;
+
+namespace N
+{
+    class C
+    {
+        async Task M()
+        {
+            var request = new Request();
+            var m = await request.$$.ReadAsStreamAsync();
+        }
+    }
+
+    class Request
+    {
+        public Task<Stream> ReadAsStreamAsync() => null;
+    }
+}";
+
+            await VerifyItemExistsAsync(markup, "ReadAsStreamAsync");
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public async Task AwaitableDotsLikeRangeExpressionWithParentheses()
+        {
+            var markup = @"
+using System.IO;
+using System.Threading.Tasks;
+
+namespace N
+{
+    class C
+    {
+        async Task M()
+        {
+            var request = new Request();
+            var m = (await request).$$.ReadAsStreamAsync();
+        }
+    }
+
+    class Request
+    {
+        public Task<Stream> ReadAsStreamAsync() => null;
+    }
+}";
+            // Nothing should be found: no awaiter for request.
+            await VerifyItemIsAbsentAsync(markup, "Result");
+            await VerifyItemIsAbsentAsync(markup, "ReadAsStreamAsync");
+        }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public async Task AwaitableDotsLikeRangeExpressionWithTaskAndParentheses()
+        {
+            var markup = @"
+using System.IO;
+using System.Threading.Tasks;
+
+namespace N
+{
+    class C
+    {
+        async Task M()
+        {
+            var request = new Task<Request>();
+            var m = (await request).$$.ReadAsStreamAsync();
+        }
+    }
+
+    class Request
+    {
+        public Task<Stream> ReadAsStreamAsync() => null;
+    }
+}";
+
+            await VerifyItemIsAbsentAsync(markup, "Result");
+            await VerifyItemExistsAsync(markup, "ReadAsStreamAsync");
+        }
+
         [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
         public async Task ObsoleteItem()
         {

src/Workspaces/CSharp/Portable/Recommendations/CSharpRecommendationServiceRunner.cs

@@ -323,7 +323,12 @@ private ImmutableArray<ISymbol> GetSymbolsOffOfName(NameSyntax name)
 
         private ImmutableArray<ISymbol> GetSymbolsOffOfExpression(ExpressionSyntax originalExpression)
         {
-            var expression = originalExpression.WalkDownParentheses();
+            // In case of 'await x$$', we want to move to 'x' to get it's members.
+            // To run GetSymbolInfo, we also need to get rid of parenthesis.
+            var expression = originalExpression is AwaitExpressionSyntax awaitExpression
+                ? awaitExpression.Expression.WalkDownParentheses()
+                : originalExpression.WalkDownParentheses();
+
             var leftHandBinding = _context.SemanticModel.GetSymbolInfo(expression, _cancellationToken);
             var container = _context.SemanticModel.GetTypeInfo(expression, _cancellationToken).Type;