Merge pull request #15564 from rchande/fix15443

Don't show builder after dot

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

@@ -718,6 +718,17 @@ class C {
             await VerifyNotBuilderAsync(markup);
         }
 
+        [WorkItem(15443, "https://github.com/dotnet/roslyn/issues/15443")]
+        [Fact, Trait(Traits.Feature, Traits.Features.Completion)]
+        public async Task NotBuilderWhenDelegateInferredRightOfDotInInvocation()
+        {
+            var markup = @"
+class C {
+	Action a = Task.$$
+}";
+            await VerifyNotBuilderAsync(markup);
+        }
+
         private async Task VerifyNotBuilderAsync(string markup)
         {
             await VerifyWorkerAsync(markup, isBuilder: false);

src/Features/CSharp/Portable/Completion/SuggestionMode/CSharpSuggestionModeCompletionProvider.cs

@@ -152,10 +152,19 @@ private bool IsLambdaExpression(SemanticModel semanticModel, int position, Synta
                 position = token.Parent.SpanStart;
             }
 
+            // In the following situation, the type inferrer will infer Task to support target type preselection
+            // Action a = Task.$$
+            // We need to explicitly exclude invocation/member access from suggestion mode
+            var previousToken = token.GetPreviousTokenIfTouchingWord(position);
+            if (previousToken.IsKind(SyntaxKind.DotToken) &&
+                previousToken.Parent.IsKind(SyntaxKind.SimpleMemberAccessExpression))
+            {
+                return false;
+            }
+
             // If we're an argument to a function with multiple overloads, 
             // open the builder if any overload takes a delegate at our argument position
             var inferredTypeInfo = typeInferrer.GetTypeInferenceInfo(semanticModel, position, cancellationToken: cancellationToken);
-
             return inferredTypeInfo.Any(type => GetDelegateType(type, semanticModel.Compilation).IsDelegateType());
         }