From 3ec21f6fab20ab4c95ef1e9ec9f453a832259f37 Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrusn@microsoft.com>
Date: Fri, 23 May 2025 19:29:17 +0200
Subject: [PATCH 1/2] Fix crash with introduce local within a compilation unit

---
 .../CSharpInlineMethodRefactoringProvider.cs  | 21 ++++---
 .../CSharpIntroduceVariableService.cs         | 23 ++++----
 .../IntroduceVariableTests.cs                 | 33 +++++++++++
 .../AbstractIntroduceVariableService.cs       | 57 ++++++-------------
 .../VisualBasicIntroduceVariableService.vb    |  4 ++
 5 files changed, 73 insertions(+), 65 deletions(-)

diff --git a/src/Features/CSharp/Portable/CodeRefactorings/InlineMethod/CSharpInlineMethodRefactoringProvider.cs b/src/Features/CSharp/Portable/CodeRefactorings/InlineMethod/CSharpInlineMethodRefactoringProvider.cs
index 400a1438d45e9..65949c1b36341 100644
--- a/src/Features/CSharp/Portable/CodeRefactorings/InlineMethod/CSharpInlineMethodRefactoringProvider.cs
+++ b/src/Features/CSharp/Portable/CodeRefactorings/InlineMethod/CSharpInlineMethodRefactoringProvider.cs
@@ -85,17 +85,16 @@ protected override bool IsValidExpressionUnderExpressionStatement(ExpressionSynt
         //     ;
         var isNullConditionalInvocationExpression = IsNullConditionalInvocationExpression(expressionNode);
 
-        return expressionNode.IsKind(SyntaxKind.InvocationExpression)
-               || isNullConditionalInvocationExpression
-               || expressionNode is AssignmentExpressionSyntax
-               || expressionNode.Kind()
-                    is SyntaxKind.InvocationExpression
-                    or SyntaxKind.ObjectCreationExpression
-                    or SyntaxKind.PreIncrementExpression
-                    or SyntaxKind.PreDecrementExpression
-                    or SyntaxKind.PostIncrementExpression
-                    or SyntaxKind.PostDecrementExpression
-                    or SyntaxKind.AwaitExpression;
+        return isNullConditionalInvocationExpression
+            || expressionNode is AssignmentExpressionSyntax
+            || expressionNode.Kind()
+                is SyntaxKind.InvocationExpression
+                or SyntaxKind.ObjectCreationExpression
+                or SyntaxKind.PreIncrementExpression
+                or SyntaxKind.PreDecrementExpression
+                or SyntaxKind.PostIncrementExpression
+                or SyntaxKind.PostDecrementExpression
+                or SyntaxKind.AwaitExpression;
     }
 
     protected override bool CanBeReplacedByThrowExpression(SyntaxNode syntaxNode)
diff --git a/src/Features/CSharp/Portable/IntroduceVariable/CSharpIntroduceVariableService.cs b/src/Features/CSharp/Portable/IntroduceVariable/CSharpIntroduceVariableService.cs
index 8e783027e7240..cac25638ca343 100644
--- a/src/Features/CSharp/Portable/IntroduceVariable/CSharpIntroduceVariableService.cs
+++ b/src/Features/CSharp/Portable/IntroduceVariable/CSharpIntroduceVariableService.cs
@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 using System;
 using System.Collections.Generic;
 using System.Composition;
@@ -11,22 +9,22 @@
 using System.Threading;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Extensions;
+using Microsoft.CodeAnalysis.CSharp.LanguageService;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Host.Mef;
 using Microsoft.CodeAnalysis.IntroduceVariable;
+using Microsoft.CodeAnalysis.LanguageService;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 
 namespace Microsoft.CodeAnalysis.CSharp.IntroduceVariable;
 
 [ExportLanguageService(typeof(IIntroduceVariableService), LanguageNames.CSharp), Shared]
-internal sealed partial class CSharpIntroduceVariableService :
+[method: ImportingConstructor]
+[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
+internal sealed partial class CSharpIntroduceVariableService() :
     AbstractIntroduceVariableService<CSharpIntroduceVariableService, ExpressionSyntax, TypeSyntax, TypeDeclarationSyntax, QueryExpressionSyntax, NameSyntax>
 {
-    [ImportingConstructor]
-    [Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
-    public CSharpIntroduceVariableService()
-    {
-    }
+    protected override ISyntaxFacts SyntaxFacts => CSharpSyntaxFacts.Instance;
 
     protected override bool IsInNonFirstQueryClause(ExpressionSyntax expression)
     {
@@ -45,10 +43,9 @@ protected override bool IsInNonFirstQueryClause(ExpressionSyntax expression)
     }
 
     protected override bool IsInFieldInitializer(ExpressionSyntax expression)
-    {
-        return expression.GetAncestorOrThis<VariableDeclaratorSyntax>()
-                         .GetAncestorOrThis<FieldDeclarationSyntax>() != null;
-    }
+        => expression
+            .GetAncestorOrThis<VariableDeclaratorSyntax>()
+            .GetAncestorOrThis<FieldDeclarationSyntax>() != null;
 
     protected override bool IsInParameterInitializer(ExpressionSyntax expression)
         => expression.GetAncestorOrThis<EqualsValueClauseSyntax>().IsParentKind(SyntaxKind.Parameter);
@@ -62,7 +59,7 @@ protected override bool IsInAutoPropertyInitializer(ExpressionSyntax expression)
     protected override bool IsInExpressionBodiedMember(ExpressionSyntax expression)
     {
         // walk up until we find a nearest enclosing block or arrow expression.
-        for (SyntaxNode node = expression; node != null; node = node.Parent)
+        for (SyntaxNode? node = expression; node != null; node = node.Parent)
         {
             // If we are in an expression bodied member and if the expression has a block body, then,
             // act as if we're in a block context and not in an expression body context at all.
diff --git a/src/Features/CSharpTest/IntroduceVariable/IntroduceVariableTests.cs b/src/Features/CSharpTest/IntroduceVariable/IntroduceVariableTests.cs
index 34fa0af9300fa..c0fc56fb1ba84 100644
--- a/src/Features/CSharpTest/IntroduceVariable/IntroduceVariableTests.cs
+++ b/src/Features/CSharpTest/IntroduceVariable/IntroduceVariableTests.cs
@@ -9535,4 +9535,37 @@ void M()
             }
             """);
     }
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/78680")]
+    public async Task FixReferenceInMemberAccessNameInTopLevel()
+    {
+        await TestAsync(
+            """
+            C c = null;
+            C d = null;
+            Console.WriteLine([|c.c|]);
+            Console.WriteLine(d.c.c);
+
+            class C
+            {
+                public C c;
+            }
+            """,
+            """
+            C c = null;
+            C d = null;
+            
+            C {|Rename:c1|} = c.c;
+
+            Console.WriteLine(c1);
+            Console.WriteLine(d.c.c);
+
+            class C
+            {
+                public C c;
+            }
+            """,
+            parseOptions: null,
+            index: 1);
+    }
 }
diff --git a/src/Features/Core/Portable/IntroduceVariable/AbstractIntroduceVariableService.cs b/src/Features/Core/Portable/IntroduceVariable/AbstractIntroduceVariableService.cs
index e109d42cf8e86..8a08783135d93 100644
--- a/src/Features/Core/Portable/IntroduceVariable/AbstractIntroduceVariableService.cs
+++ b/src/Features/Core/Portable/IntroduceVariable/AbstractIntroduceVariableService.cs
@@ -15,7 +15,6 @@
 using Microsoft.CodeAnalysis.Editing;
 using Microsoft.CodeAnalysis.Internal.Log;
 using Microsoft.CodeAnalysis.LanguageService;
-using Microsoft.CodeAnalysis.Operations;
 using Microsoft.CodeAnalysis.PooledObjects;
 using Microsoft.CodeAnalysis.Shared.Extensions;
 using Microsoft.CodeAnalysis.Simplification;
@@ -32,6 +31,8 @@ internal abstract partial class AbstractIntroduceVariableService<TService, TExpr
     where TQueryExpressionSyntax : TExpressionSyntax
     where TNameSyntax : TTypeSyntax
 {
+    protected abstract ISyntaxFacts SyntaxFacts { get; }
+
     protected abstract bool IsInNonFirstQueryClause(TExpressionSyntax expression);
     protected abstract bool IsInFieldInitializer(TExpressionSyntax expression);
     protected abstract bool IsInParameterInitializer(TExpressionSyntax expression);
@@ -319,54 +320,28 @@ private bool NodeMatchesExpression(
     {
         cancellationToken.ThrowIfCancellationRequested();
         if (nodeInCurrent == expressionInOriginal)
-        {
             return true;
-        }
 
-        if (allOccurrences && CanReplace(nodeInCurrent))
+        var syntaxFacts = this.SyntaxFacts;
+        if (syntaxFacts.IsNameOfAnyMemberAccessExpression(nodeInCurrent) ||
+            syntaxFacts.IsMemberInitializerNamedAssignmentIdentifier(nodeInCurrent))
         {
-            // Original expression and current node being semantically equivalent isn't enough when the original expression 
-            // is a member access via instance reference (either implicit or explicit), the check only ensures that the expression
-            // and current node are both backed by the same member symbol. So in this case, in addition to SemanticEquivalence check, 
-            // we also check if expression and current node are both instance member access.
-            //
-            // For example, even though the first `c` binds to a field and we are introducing a local for it,
-            // we don't want other references to that field to be replaced as well (i.e. the second `c` in the expression).
-            //
-            //  class C
-            //  {
-            //      C c;
-            //      void Test()
-            //      {
-            //          var x = [|c|].c;
-            //      }
-            //  }
-
-            if (SemanticEquivalence.AreEquivalent(originalSemanticModel, currentSemanticModel, expressionInOriginal, nodeInCurrent))
-            {
-                var originalOperation = originalSemanticModel.GetOperation(expressionInOriginal, cancellationToken);
-                if (IsInstanceMemberReference(originalOperation))
-                {
-                    var currentOperation = currentSemanticModel.GetOperation(nodeInCurrent, cancellationToken);
-                    return IsInstanceMemberReference(currentOperation);
-                }
+            return false;
+        }
 
-                // If the original expression is within a static local function, further checks are unnecessary since our scope has already been narrowed down to within the local function.
-                // If the original expression is not within a static local function, we need to further check whether the expression we're comparing against is within a static local
-                // function. If so, the expression is not a valid match since we cannot refer to instance variables from within static local functions.
-                if (!IsExpressionInStaticLocalFunction(expressionInOriginal))
-                {
-                    return !IsExpressionInStaticLocalFunction(nodeInCurrent);
-                }
+        if (allOccurrences && CanReplace(nodeInCurrent) &&
+            SemanticEquivalence.AreEquivalent(originalSemanticModel, currentSemanticModel, expressionInOriginal, nodeInCurrent))
+        {
+            // If the original expression is within a static local function, further checks are unnecessary since our scope has already been narrowed down to within the local function.
+            // If the original expression is not within a static local function, we need to further check whether the expression we're comparing against is within a static local
+            // function. If so, the expression is not a valid match since we cannot refer to instance variables from within static local functions.
+            if (!IsExpressionInStaticLocalFunction(expressionInOriginal))
+                return !IsExpressionInStaticLocalFunction(nodeInCurrent);
 
-                return true;
-            }
+            return true;
         }
 
         return false;
-
-        static bool IsInstanceMemberReference(IOperation operation)
-            => operation is IMemberReferenceOperation { Instance.Kind: OperationKind.InstanceReference };
     }
 
     protected TNode Rewrite<TNode>(
diff --git a/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb b/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb
index 1500f8128a0b6..928e170d0308c 100644
--- a/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb
+++ b/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb
@@ -9,6 +9,8 @@ Imports Microsoft.CodeAnalysis.Host.Mef
 Imports Microsoft.CodeAnalysis.Text
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 Imports System.Composition
+Imports Microsoft.CodeAnalysis.LanguageService
+Imports Microsoft.CodeAnalysis.VisualBasic.LanguageService
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.IntroduceVariable
     <ExportLanguageService(GetType(IIntroduceVariableService), LanguageNames.VisualBasic), [Shared]>
@@ -20,6 +22,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.IntroduceVariable
         Public Sub New()
         End Sub
 
+        Protected Overrides ReadOnly Property SyntaxFacts As ISyntaxFacts = VisualBasicSyntaxFacts.Instance
+
         Protected Overrides Function GetContainingExecutableBlocks(expression As ExpressionSyntax) As IEnumerable(Of SyntaxNode)
             Return expression.GetContainingExecutableBlocks()
         End Function

From 14844516b75a3a4b6e7afb7f7d33727eb49138df Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrusn@microsoft.com>
Date: Fri, 23 May 2025 19:30:59 +0200
Subject: [PATCH 2/2] Sort

---
 .../VisualBasicIntroduceVariableService.vb                | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb b/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb
index 928e170d0308c..541e715f7810e 100644
--- a/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb
+++ b/src/Features/VisualBasic/Portable/IntroduceVariable/VisualBasicIntroduceVariableService.vb
@@ -2,15 +2,15 @@
 ' The .NET Foundation licenses this file to you under the MIT license.
 ' See the LICENSE file in the project root for more information.
 
+Imports System.Composition
 Imports System.Threading
 Imports Microsoft.CodeAnalysis
-Imports Microsoft.CodeAnalysis.IntroduceVariable
 Imports Microsoft.CodeAnalysis.Host.Mef
-Imports Microsoft.CodeAnalysis.Text
-Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
-Imports System.Composition
+Imports Microsoft.CodeAnalysis.IntroduceVariable
 Imports Microsoft.CodeAnalysis.LanguageService
+Imports Microsoft.CodeAnalysis.Text
 Imports Microsoft.CodeAnalysis.VisualBasic.LanguageService
+Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.IntroduceVariable
     <ExportLanguageService(GetType(IIntroduceVariableService), LanguageNames.VisualBasic), [Shared]>