Add proper handling when a property’s backing field cannot be inferred or the unsafe accessor cannot be generated.

src/EFCore.Design/Scaffolding/Internal/CSharpRuntimeModelCodeGenerator.cs

@@ -1769,7 +1769,15 @@ private void RegisterPrivateAccessors(
         Dictionary<Type, HashSet<MemberInfo>> unsafeAccessorTypes,
         ref Dictionary<MemberInfo, QualifiedName>? memberAccessReplacements)
     {
-        var member = property.GetMemberInfo(forMaterialization, forSet);
+        if (!property.TryGetMemberInfo(forMaterialization, forSet, out var member, out var error))
+        {
+            throw new InvalidOperationException(error);
+        }
+
+        if (member == null)
+        {
+            return null;
+        }
         switch (member)
         {
             case FieldInfo field:
@@ -1799,6 +1807,7 @@ private void RegisterPrivateAccessors(
         }
 
         memberAccessReplacements ??= [];
+
         var methodName = LinqToCSharpSyntaxTranslator.GetUnsafeAccessorName(member);
 
         var declaringType = member.DeclaringType!;

test/EFCore.Cosmos.FunctionalTests/Scaffolding/CompiledModelCosmosTest.cs

@@ -689,6 +689,7 @@ protected override BuildSource AddReferences(BuildSource build, [CallerFilePath]
         IEnumerable<ScaffoldedFile>? additionalSourceFiles = null,
         Action<Assembly>? assertAssembly = null,
         string? expectedExceptionMessage = null,
+        bool skipValidation = false,
         [CallerMemberName] string testName = "")
         where TContext : class
         => base.Test(
@@ -706,5 +707,6 @@ protected override BuildSource AddReferences(BuildSource build, [CallerFilePath]
             additionalSourceFiles,
             assertAssembly,
             expectedExceptionMessage,
+            skipValidation,
             testName);
 }

test/EFCore.Specification.Tests/NonSharedModelTestBase.cs

@@ -86,7 +86,8 @@ protected virtual ContextFactory<TContext> CreateContextFactory<TContext>(
         Func<string, bool>? shouldLogCategory = null,
         Func<TestStore>? createTestStore = null,
         bool usePooling = true,
-        bool useServiceProvider = true)
+        bool useServiceProvider = true,
+        bool skipValidation = false)
         where TContext : DbContext
     {
         if (createTestStore != null)
@@ -110,7 +111,7 @@ protected virtual ContextFactory<TContext> CreateContextFactory<TContext>(
 
         if (onModelCreating != null)
         {
-            services = services.AddSingleton(TestModelSource.GetFactory(onModelCreating, configureConventions));
+            services = services.AddSingleton(TestModelSource.GetFactory(onModelCreating, configureConventions, skipValidation));
         }
 
         addServices?.Invoke(services);

test/EFCore.Specification.Tests/Scaffolding/CompiledModelTestBase.cs

@@ -1167,6 +1167,21 @@ public virtual Task ComplexTypes()
             },
             options: new CompiledModelCodeGenerationOptions { UseNullableReferenceTypes = true, ForNativeAot = true });
 
+    [ConditionalFact]
+    public virtual Task Throws_for_Backing_Field_Not_Found()
+        => Test(
+            modelBuilder =>
+            {
+                modelBuilder.Entity<EntityWithNoBackingFieldScalar>(eb =>
+                {
+                    eb.Property(e => e.Computed)
+                        .UsePropertyAccessMode(PropertyAccessMode.FieldDuringConstruction);
+                });
+            },
+            options: new CompiledModelCodeGenerationOptions { ForNativeAot = true },
+            expectedExceptionMessage: CoreStrings.NoFieldOrSetter("Computed", "EntityWithNoBackingFieldScalar"),
+            skipValidation: true);
+
     protected virtual void BuildComplexTypesModel(ModelBuilder modelBuilder)
     {
         modelBuilder.Entity<PrincipalBase>(eb =>
@@ -1790,6 +1805,12 @@ public class Data
         public byte[]? Blob { get; set; }
     }
 
+    public class EntityWithNoBackingFieldScalar
+    {
+        public int Id { get; set; }
+        public int Computed => 1;
+    }
+
     public class PrincipalBase : AbstractBase
     {
         public new long? Id { get; set; }
@@ -2007,6 +2028,7 @@ protected virtual Task Test(
         IEnumerable<ScaffoldedFile>? additionalSourceFiles = null,
         Action<Assembly>? assertAssembly = null,
         string? expectedExceptionMessage = null,
+        bool skipValidation = false,
         [CallerMemberName] string testName = "")
         => Test<DbContext>(
             onModelCreating,
@@ -2019,6 +2041,7 @@ protected virtual Task Test(
             additionalSourceFiles,
             assertAssembly,
             expectedExceptionMessage,
+            skipValidation,
             testName);
 
     protected virtual async Task<(TContext?, IModel?)> Test<TContext>(
@@ -2032,6 +2055,7 @@ protected virtual Task Test(
         IEnumerable<ScaffoldedFile>? additionalSourceFiles = null,
         Action<Assembly>? assertAssembly = null,
         string? expectedExceptionMessage = null,
+        bool skipValidation = false,
         [CallerMemberName] string testName = "")
         where TContext : DbContext
     {
@@ -2044,7 +2068,8 @@ protected virtual Task Test(
                 onModelCreating?.Invoke(modelBuilder);
             },
             onConfiguring,
-            addServices);
+            addServices,
+            skipValidation: skipValidation);
         using var context = contextFactory.CreateContext();
         var model = context.GetService<IDesignTimeModel>().Model;
 

test/EFCore.Specification.Tests/TestUtilities/TestModelSource.cs

@@ -9,15 +9,28 @@ public class TestModelSource : ModelSource
 {
     private readonly Action<ModelConfigurationBuilder>? _configureConventions;
     private readonly Action<ModelBuilder, DbContext> _onModelCreating;
+    private readonly bool _skipValidation;
 
     private TestModelSource(
         Action<ModelConfigurationBuilder>? configureConventions,
         Action<ModelBuilder, DbContext> onModelCreating,
-        ModelSourceDependencies dependencies)
+        ModelSourceDependencies dependencies,
+        bool skipValidation = false)
         : base(dependencies)
     {
         _configureConventions = configureConventions;
         _onModelCreating = onModelCreating;
+        _skipValidation = skipValidation;
+    }
+
+    public override IModel CreateModel(
+        DbContext context,
+        ModelCreationDependencies modelCreationDependencies,
+        bool designTime)
+    {
+        var model = CreateModel(context, modelCreationDependencies.ConventionSetBuilder, modelCreationDependencies.ModelDependencies);
+        return modelCreationDependencies.ModelRuntimeInitializer.Initialize(
+            model, designTime, _skipValidation ? null : modelCreationDependencies.ValidationLogger);
     }
 
     protected override IModel CreateModel(
@@ -41,17 +54,21 @@ protected override IModel CreateModel(
 
     public static Func<IServiceProvider, IModelSource> GetFactory(
         Action<ModelBuilder> onModelCreating,
-        Action<ModelConfigurationBuilder>? configureConventions = null)
+        Action<ModelConfigurationBuilder>? configureConventions = null,
+        bool skipValidation = false)
         => p => new TestModelSource(
             configureConventions,
             (mb, c) => onModelCreating(mb),
-            p.GetRequiredService<ModelSourceDependencies>());
+            p.GetRequiredService<ModelSourceDependencies>(),
+            skipValidation);
 
     public static Func<IServiceProvider, IModelSource> GetFactory(
         Action<ModelBuilder, DbContext> onModelCreating,
-        Action<ModelConfigurationBuilder>? configureConventions = null)
+        Action<ModelConfigurationBuilder>? configureConventions = null,
+        bool skipValidation = false)
         => p => new TestModelSource(
             configureConventions,
             onModelCreating,
-            p.GetRequiredService<ModelSourceDependencies>());
+            p.GetRequiredService<ModelSourceDependencies>(),
+            skipValidation);
 }