Tweak formatting engine to ignore elastic trivia for local functions.

src/EditorFeatures/CSharpTest/UseLocalFunction/UseLocalFunctionTests.cs

@@ -1777,6 +1777,59 @@ void Goo()
 }");
         }
 
+        [WorkItem(23872, "https://github.com/dotnet/roslyn/issues/23872")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsUseLocalFunction)]
+        public async Task TestSimpleInitialization_SingleLine4()
+        {
+            await TestInRegularAndScriptAsync(
+@"using System;
+
+class C
+{
+    void Goo()
+    {
+        Func<int, int[]> [||]onUpdateSolutionCancel = x => { return null; };
+    }
+}",
+@"using System;
+
+class C
+{
+    void Goo()
+    {
+        int[] onUpdateSolutionCancel(int x) { return null; }
+    }
+}");
+        }
+
+        [WorkItem(23872, "https://github.com/dotnet/roslyn/issues/23872")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsUseLocalFunction)]
+        public async Task TestSimpleInitialization_SingleLine5()
+        {
+
+            await TestInRegularAndScriptAsync(
+@"using System;
+using System.Threading.Tasks;
+
+class C
+{
+    void Goo()
+    {
+        Func<int, Task<int[]>> [||]onUpdateSolutionCancel = async x => { return null; };
+    }
+}",
+@"using System;
+using System.Threading.Tasks;
+
+class C
+{
+    void Goo()
+    {
+        async Task<int[]> onUpdateSolutionCancel(int x) { return null; }
+    }
+}");
+        }
+
         [WorkItem(23872, "https://github.com/dotnet/roslyn/issues/23872")]
         [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsUseLocalFunction)]
         public async Task TestCastInitialization_SingleLine1()

src/Features/CSharp/Portable/UseLocalFunction/CSharpUseLocalFunctionCodeFixProvider.cs

@@ -136,11 +136,7 @@ private LocalFunctionStatementSyntax CreateLocalFunctionStatement(
 
             var invokeMethod = delegateType.DelegateInvokeMethod;
 
-            // The presence of elastic trivia in the return type will cause the formatting engine 
-            // to wrap a local function that could stay on a single line.  Remove all the elastic
-            // trivia added by default to get good behavior for both single line and multiline
-            // lambdas.
-            var returnType = RemoveAllElasticTrivia(invokeMethod.GenerateReturnTypeSyntax());
+            var returnType = invokeMethod.GenerateReturnTypeSyntax();
 
             var identifier = localDeclaration.Declaration.Variables[0].Identifier;
             var typeParameterList = default(TypeParameterListSyntax);

src/Workspaces/CSharp/Portable/Formatting/Rules/SuppressFormattingRule.cs

@@ -127,8 +127,10 @@ private void AddSpecificNodesSuppressOperations(List<SuppressOperation> list, Sy
             if (node is AnonymousFunctionExpressionSyntax ||
                 node is LocalFunctionStatementSyntax)
             {
-                AddSuppressWrappingIfOnSingleLineOperation(
-                    list, node.GetFirstToken(includeZeroWidth: true), node.GetLastToken(includeZeroWidth: true));
+                AddSuppressWrappingIfOnSingleLineOperation(list,
+                    node.GetFirstToken(includeZeroWidth: true),
+                    node.GetLastToken(includeZeroWidth: true),
+                    SuppressOption.IgnoreElastic);
                 return;
             }