Simplify code.

src/Features/Core/Portable/MoveDeclarationNearReference/AbstractMoveDeclarationNearReferenceCodeRefactoringProvider.cs

@@ -32,36 +32,42 @@ internal abstract partial class AbstractMoveDeclarationNearReferenceService<
         protected abstract Task<bool> TypesAreCompatibleAsync(Document document, ILocalSymbol localSymbol, TLocalDeclarationStatementSyntax declarationStatement, SyntaxNode right, CancellationToken cancellationToken);
 
         public async Task<bool> CanMoveDeclarationNearReferenceAsync(Document document, SyntaxNode node, CancellationToken cancellationToken)
+        {
+            var state = await ComputeStateAsync(document, node, cancellationToken).ConfigureAwait(false);
+            return state != null;
+        }
+
+        private async Task<State> ComputeStateAsync(Document document, SyntaxNode node, CancellationToken cancellationToken)
         {
             if (!(node is TLocalDeclarationStatementSyntax statement))
             {
-                return false;
+                return null;
             }
 
-
             var state = await State.GenerateAsync((TService)this, document, statement, cancellationToken).ConfigureAwait(false);
             if (state == null)
             {
-                return false;
+                return null;
             }
 
             if (!CanMoveToBlock(state.LocalSymbol, state.OutermostBlock, state.InnermostBlock))
             {
-                return false;
+                return null;
             }
 
-            return true;
+            return state;
         }
 
         public async Task<Document> MoveDeclarationNearReferenceAsync(
             Document document, SyntaxNode localDeclarationStatement, CancellationToken cancellationToken)
         {
-            Debug.Assert(await CanMoveDeclarationNearReferenceAsync(document, localDeclarationStatement, cancellationToken));
+            var state = await ComputeStateAsync(document, localDeclarationStatement, cancellationToken);
+            if (state == null)
+            {
+                return document;
+            }
 
-            var statement = (TLocalDeclarationStatementSyntax)localDeclarationStatement;
             var root = await document.GetSyntaxRootAsync(cancellationToken);
-            var state = await State.GenerateAsync((TService)this, document, statement, cancellationToken).ConfigureAwait(false);
-
             var editor = new SyntaxEditor(root, document.Project.Solution.Workspace);
 
             var crossesMeaningfulBlock = CrossesMeaningfulBlock(state);

src/Features/Core/Portable/MoveDeclarationNearReference/IMoveDeclarationNearReferenceService.cs

@@ -17,7 +17,8 @@ internal interface IMoveDeclarationNearReferenceService : ILanguageService
         /// <summary>
         /// Moves true if <paramref name="localDeclarationStatement"/> closer to its first
         /// reference. Only applicable if <see cref="CanMoveDeclarationNearReferenceAsync"/>
-        /// returned <code>true</code>.
+        /// returned <code>true</code>.  If not, then the original document will be returned
+        /// unchanged.
         /// </summary>
         Task<Document> MoveDeclarationNearReferenceAsync(Document document, SyntaxNode localDeclarationStatement, CancellationToken cancellationToken);
     }