Do not offer use-expr-body for properties with initializers

src/Analyzers/CSharp/Analyzers/UseExpressionBody/Helpers/UseExpressionBodyHelper`1.cs

@@ -153,10 +153,15 @@ protected bool TryConvertToExpressionBodyForBaseProperty(
         [NotNullWhen(true)] out ArrowExpressionClauseSyntax? arrowExpression,
         out SyntaxToken semicolonToken)
     {
+        arrowExpression = null;
+        semicolonToken = default;
+
+        // If we have `X Prop { ... } = ...;` we can't convert this as expr-bodied properties can't have initializers.
+        if (declaration is PropertyDeclarationSyntax { Initializer: not null })
+            return false;
+
         if (TryConvertToExpressionBodyWorker(declaration, conversionPreference, cancellationToken, out arrowExpression, out semicolonToken))
-        {
             return true;
-        }
 
         var getAccessor = GetSingleGetAccessor(declaration.AccessorList);
         if (getAccessor?.ExpressionBody != null &&

src/Analyzers/CSharp/Tests/UseExpressionBody/UseExpressionBodyForPropertiesAnalyzerTests.cs

@@ -2,10 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis.CodeStyle;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.CodeStyle;
+using Microsoft.CodeAnalysis.CSharp.Shared.Extensions;
 using Microsoft.CodeAnalysis.CSharp.UseExpressionBody;
 using Microsoft.CodeAnalysis.Editor.UnitTests.CodeActions;
 using Microsoft.CodeAnalysis.Test.Utilities;
@@ -22,7 +24,10 @@ namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.UseExpressionBody;
 [Trait(Traits.Feature, Traits.Features.CodeActionsUseExpressionBody)]
 public sealed class UseExpressionBodyForPropertiesAnalyzerTests
 {
-    private static async Task TestWithUseExpressionBody(string code, string fixedCode, LanguageVersion version = LanguageVersion.CSharp8)
+    private static async Task TestWithUseExpressionBody(
+        [StringSyntax(PredefinedEmbeddedLanguageNames.CSharpTest)] string code,
+        [StringSyntax(PredefinedEmbeddedLanguageNames.CSharpTest)] string fixedCode,
+        LanguageVersion version = LanguageVersion.CSharp8)
     {
         await new VerifyCS.Test
         {
@@ -38,7 +43,9 @@ private static async Task TestWithUseExpressionBody(string code, string fixedCod
         }.RunAsync();
     }
 
-    private static async Task TestWithUseBlockBody(string code, string fixedCode)
+    private static async Task TestWithUseBlockBody(
+        [StringSyntax(PredefinedEmbeddedLanguageNames.CSharpTest)] string code,
+        [StringSyntax(PredefinedEmbeddedLanguageNames.CSharpTest)] string fixedCode)
     {
         await new VerifyCS.Test
         {
@@ -580,4 +587,40 @@ public long Length                   //N
             """;
         await TestWithUseExpressionBody(code, fixedCode);
     }
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/77473")]
+    public async Task TestMissingWithInitializer1()
+    {
+        var code = """
+            class C
+            {
+                object Goo
+                {
+                    get
+                    {
+                        return field;
+                    }
+                } = new();
+            }
+            """;
+        await TestWithUseExpressionBody(code, code, LanguageVersionExtensions.CSharpNext);
+    }
+
+    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/77473")]
+    public async Task TestMissingWithInitializer2()
+    {
+        var code = """
+            class C
+            {
+                object Goo
+                {
+                    get
+                    {
+                        return field ??= new();
+                    }
+                } = new();
+            }
+            """;
+        await TestWithUseExpressionBody(code, code, LanguageVersionExtensions.CSharpNext);
+    }
 }