Fix WasPropertyBackingFieldAccessChecked assertion with query continuations

src/Compilers/CSharp/Portable/Binder/Binder.ValueChecks.cs

@@ -759,11 +759,11 @@ private BoundExpression CheckValue(BoundExpression expr, BindValueKind valueKind
                     return expr;
 
                 case BoundKind.PropertyAccess:
+                    var propertyAccess = (BoundPropertyAccess)expr;
                     if (!InAttributeArgument)
                     {
                         // If the property has a synthesized backing field, record the accessor kind of the property
                         // access for determining whether the property access can use the backing field directly.
-                        var propertyAccess = (BoundPropertyAccess)expr;
                         if (HasSynthesizedBackingField(propertyAccess.PropertySymbol, out _))
                         {
                             expr = propertyAccess.Update(
@@ -774,8 +774,24 @@ private BoundExpression CheckValue(BoundExpression expr, BindValueKind valueKind
                                 propertyAccess.ResultKind,
                                 propertyAccess.Type);
                         }
+#if DEBUG
+                        else
+                        {
+                            // Under DEBUG, create a new node to mark as checked, rather than mutating the original.
+                            // This allows the original node to be passed to CheckValue multiple times safely, without
+                            // asserting in WasPropertyBackingFieldAccessChecked.
+                            expr = propertyAccess.Clone();
+                        }
+#endif
                     }
 #if DEBUG
+                    else
+                    {
+                        // Under DEBUG, create a new node to mark as checked, rather than mutating the original.
+                        // This allows the original node to be passed to CheckValue multiple times safely, without
+                        // asserting in WasPropertyBackingFieldAccessChecked.
+                        expr = propertyAccess.Clone();
+                    }
                     expr.WasPropertyBackingFieldAccessChecked = true;
 #endif
                     break;

src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs

@@ -7755,7 +7755,7 @@ private BoundExpression BindDynamicMemberAccess(
         /// </summary>
         /// <remarks>
         /// If new checks are added to this method, they will also need to be added to
-        /// <see cref="MakeQueryInvocation(CSharpSyntaxNode, BoundExpression, bool, string, SeparatedSyntaxList{TypeSyntax}, ImmutableArray{TypeWithAnnotations}, ImmutableArray{BoundExpression}, BindingDiagnosticBag, string?)"/>.
+        /// <see cref="MakeQueryInvocation(CSharpSyntaxNode, BoundExpression, string, SeparatedSyntaxList{TypeSyntax}, ImmutableArray{TypeWithAnnotations}, ImmutableArray{BoundExpression}, BindingDiagnosticBag, string?)"/>.
         /// </remarks>
 #else
         /// <summary>
@@ -7764,7 +7764,7 @@ private BoundExpression BindDynamicMemberAccess(
         /// </summary>
         /// <remarks>
         /// If new checks are added to this method, they will also need to be added to
-        /// <see cref="MakeQueryInvocation(CSharpSyntaxNode, BoundExpression, bool, string, SeparatedSyntaxList{TypeSyntax}, ImmutableArray{TypeWithAnnotations}, ImmutableArray{BoundExpression}, BindingDiagnosticBag)"/>.
+        /// <see cref="MakeQueryInvocation(CSharpSyntaxNode, BoundExpression, string, SeparatedSyntaxList{TypeSyntax}, ImmutableArray{TypeWithAnnotations}, ImmutableArray{BoundExpression}, BindingDiagnosticBag)"/>.
         /// </remarks>
 #endif
         private BoundExpression BindMemberAccessWithBoundLeft(

src/Compilers/CSharp/Portable/Binder/Binder_Query.cs

@@ -54,7 +54,7 @@ internal BoundExpression BindQuery(QueryExpressionSyntax node, BindingDiagnostic
             if (fromClause.Type != null)
             {
                 var typeRestriction = BindTypeArgument(fromClause.Type, diagnostics);
-                cast = MakeQueryInvocation(fromClause, state.fromExpression, receiverIsCheckedForRValue: false, "Cast", fromClause.Type, typeRestriction, diagnostics
+                cast = MakeQueryInvocation(fromClause, state.fromExpression, "Cast", fromClause.Type, typeRestriction, diagnostics
 #if DEBUG
                     , state.nextInvokedMethodName
 #endif
@@ -230,7 +230,7 @@ private BoundExpression FinalTranslation(QueryTranslationState state, BindingDia
                         var e = state.fromExpression;
                         var v = selectClause.Expression;
                         var lambda = MakeQueryUnboundLambda(state.RangeVariableMap(), x, v, diagnostics.AccumulatesDependencies);
-                        var result = MakeQueryInvocation(state.selectOrGroup, e, receiverIsCheckedForRValue: false, "Select", lambda, diagnostics
+                        var result = MakeQueryInvocation(state.selectOrGroup, e, "Select", lambda, diagnostics
 #if DEBUG
                                         , state.nextInvokedMethodName
 #endif
@@ -260,7 +260,7 @@ private BoundExpression FinalTranslation(QueryTranslationState state, BindingDia
                         // this is the unoptimized form (when v is not the identifier x)
                         var d = BindingDiagnosticBag.GetInstance(diagnostics);
                         BoundExpression lambdaRight = MakeQueryUnboundLambda(state.RangeVariableMap(), x, v, diagnostics.AccumulatesDependencies);
-                        result = MakeQueryInvocation(state.selectOrGroup, e, receiverIsCheckedForRValue: false, "GroupBy", ImmutableArray.Create(lambdaLeft, lambdaRight), d
+                        result = MakeQueryInvocation(state.selectOrGroup, e, "GroupBy", ImmutableArray.Create(lambdaLeft, lambdaRight), d
 #if DEBUG
                             , state.nextInvokedMethodName
 #endif
@@ -276,7 +276,7 @@ private BoundExpression FinalTranslation(QueryTranslationState state, BindingDia
                         {
                             // The optimized form.  We store the unoptimized form for analysis
                             unoptimizedForm = result;
-                            result = MakeQueryInvocation(state.selectOrGroup, e, receiverIsCheckedForRValue: false, "GroupBy", lambdaLeft, diagnostics
+                            result = MakeQueryInvocation(state.selectOrGroup, e, "GroupBy", lambdaLeft, diagnostics
 #if DEBUG
                                 , state.nextInvokedMethodName
 #endif
@@ -364,7 +364,7 @@ private void ReduceWhere(WhereClauseSyntax where, QueryTranslationState state, B
             // is translated into
             //     from x in ( e ) . Where ( x => f )
             var lambda = MakeQueryUnboundLambda(state.RangeVariableMap(), state.rangeVariable, where.Condition, diagnostics.AccumulatesDependencies);
-            var invocation = MakeQueryInvocation(where, state.fromExpression, receiverIsCheckedForRValue: false, "Where", lambda, diagnostics
+            var invocation = MakeQueryInvocation(where, state.fromExpression, "Where", lambda, diagnostics
 #if DEBUG
                 , state.nextInvokedMethodName
 #endif
@@ -395,7 +395,7 @@ private void ReduceJoin(JoinClauseSyntax join, QueryTranslationState state, Bind
                 // is translated into
                 //     join x in ( e ) . Cast < T > ( ) on k1 equals k2
                 var castType = BindTypeArgument(join.Type, diagnostics);
-                castInvocation = MakeQueryInvocation(join, inExpression, receiverIsCheckedForRValue: false, "Cast", join.Type, castType, diagnostics
+                castInvocation = MakeQueryInvocation(join, inExpression, "Cast", join.Type, castType, diagnostics
 #if DEBUG
                     , expectedMethodName: null
 #endif
@@ -426,7 +426,6 @@ private void ReduceJoin(JoinClauseSyntax join, QueryTranslationState state, Bind
                     invocation = MakeQueryInvocation(
                         join,
                         state.fromExpression,
-                        receiverIsCheckedForRValue: false,
                         "Join",
                         ImmutableArray.Create(inExpression, outerKeySelectorLambda, innerKeySelectorLambda, resultSelectorLambda),
                         diagnostics
@@ -455,7 +454,6 @@ private void ReduceJoin(JoinClauseSyntax join, QueryTranslationState state, Bind
                     invocation = MakeQueryInvocation(
                         join,
                         state.fromExpression,
-                        receiverIsCheckedForRValue: false,
                         "GroupJoin",
                         ImmutableArray.Create(inExpression, outerKeySelectorLambda, innerKeySelectorLambda, resultSelectorLambda),
                         diagnostics
@@ -496,7 +494,6 @@ private void ReduceJoin(JoinClauseSyntax join, QueryTranslationState state, Bind
                     invocation = MakeQueryInvocation(
                         join,
                         state.fromExpression,
-                        receiverIsCheckedForRValue: false,
                         "Join",
                         ImmutableArray.Create(inExpression, outerKeySelectorLambda, innerKeySelectorLambda, resultSelectorLambda),
                         diagnostics
@@ -527,7 +524,6 @@ private void ReduceJoin(JoinClauseSyntax join, QueryTranslationState state, Bind
                     invocation = MakeQueryInvocation(
                         join,
                         state.fromExpression,
-                        receiverIsCheckedForRValue: false,
                         "GroupJoin",
                         ImmutableArray.Create(inExpression, outerKeySelectorLambda, innerKeySelectorLambda, resultSelectorLambda),
                         diagnostics
@@ -569,7 +565,7 @@ private void ReduceOrderBy(OrderByClauseSyntax orderby, QueryTranslationState st
             {
                 string methodName = (first ? "OrderBy" : "ThenBy") + (ordering.IsKind(SyntaxKind.DescendingOrdering) ? "Descending" : "");
                 var lambda = MakeQueryUnboundLambda(state.RangeVariableMap(), state.rangeVariable, ordering.Expression, diagnostics.AccumulatesDependencies);
-                var invocation = MakeQueryInvocation(ordering, state.fromExpression, receiverIsCheckedForRValue: false, methodName, lambda, diagnostics
+                var invocation = MakeQueryInvocation(ordering, state.fromExpression, methodName, lambda, diagnostics
 #if DEBUG
                     , state.nextInvokedMethodName
 #endif
@@ -615,7 +611,6 @@ private void ReduceFrom(FromClauseSyntax from, QueryTranslationState state, Bind
                 var invocation = MakeQueryInvocation(
                     from,
                     state.fromExpression,
-                    receiverIsCheckedForRValue: false,
                     "SelectMany",
                     ImmutableArray.Create(collectionSelectorLambda, resultSelectorLambda),
                     diagnostics
@@ -663,7 +658,6 @@ private void ReduceFrom(FromClauseSyntax from, QueryTranslationState state, Bind
                 var invocation = MakeQueryInvocation(
                     from,
                     state.fromExpression,
-                    receiverIsCheckedForRValue: false,
                     "SelectMany",
                     ImmutableArray.Create(collectionSelectorLambda, resultSelectorLambda),
                     diagnostics
@@ -765,7 +759,7 @@ private void ReduceLet(LetClauseSyntax let, QueryTranslationState state, Binding
             state.AddTransparentIdentifier(x.Name);
             var y = state.AddRangeVariable(this, let.Identifier, diagnostics);
             state.allRangeVariables[y].Add(let.Identifier.ValueText);
-            var invocation = MakeQueryInvocation(let, state.fromExpression, receiverIsCheckedForRValue: false, "Select", lambda, diagnostics
+            var invocation = MakeQueryInvocation(let, state.fromExpression, "Select", lambda, diagnostics
 #if DEBUG
                                                  , state.nextInvokedMethodName
 #endif
@@ -858,7 +852,7 @@ private UnboundLambda MakeQueryUnboundLambdaWithCast(RangeVariableMap qvm, Range
                 BoundExpression boundExpression = lambdaBodyBinder.BindValue(expression, diagnostics, BindValueKind.RValue);
 
                 // We transform the expression from "expr" to "expr.Cast<castTypeOpt>()".
-                boundExpression = lambdaBodyBinder.MakeQueryInvocation(expression, boundExpression, receiverIsCheckedForRValue: true, "Cast", castTypeSyntax, castType, diagnostics
+                boundExpression = lambdaBodyBinder.MakeQueryInvocation(expression, boundExpression, "Cast", castTypeSyntax, castType, diagnostics
 #if DEBUG
                     , expectedMethodName: null
 #endif
@@ -882,46 +876,46 @@ private static UnboundLambda MakeQueryUnboundLambda(CSharpSyntaxNode node, Query
             return lambda;
         }
 
-        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, bool receiverIsCheckedForRValue, string methodName, BoundExpression arg, BindingDiagnosticBag diagnostics
+        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, string methodName, BoundExpression arg, BindingDiagnosticBag diagnostics
 #if DEBUG
             , string? expectedMethodName
 #endif
             )
         {
-            return MakeQueryInvocation(node, receiver, receiverIsCheckedForRValue, methodName, default(SeparatedSyntaxList<TypeSyntax>), default(ImmutableArray<TypeWithAnnotations>), ImmutableArray.Create(arg), diagnostics
+            return MakeQueryInvocation(node, receiver, methodName, default(SeparatedSyntaxList<TypeSyntax>), default(ImmutableArray<TypeWithAnnotations>), ImmutableArray.Create(arg), diagnostics
 #if DEBUG
                 , expectedMethodName
 #endif
                 );
         }
 
-        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, bool receiverIsCheckedForRValue, string methodName, ImmutableArray<BoundExpression> args, BindingDiagnosticBag diagnostics
+        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, string methodName, ImmutableArray<BoundExpression> args, BindingDiagnosticBag diagnostics
 #if DEBUG
             , string? expectedMethodName
 #endif
             )
         {
-            return MakeQueryInvocation(node, receiver, receiverIsCheckedForRValue, methodName, default(SeparatedSyntaxList<TypeSyntax>), default(ImmutableArray<TypeWithAnnotations>), args, diagnostics
+            return MakeQueryInvocation(node, receiver, methodName, default(SeparatedSyntaxList<TypeSyntax>), default(ImmutableArray<TypeWithAnnotations>), args, diagnostics
 #if DEBUG
                 , expectedMethodName
 #endif
                 );
         }
 
-        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, bool receiverIsCheckedForRValue, string methodName, TypeSyntax typeArgSyntax, TypeWithAnnotations typeArg, BindingDiagnosticBag diagnostics
+        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, string methodName, TypeSyntax typeArgSyntax, TypeWithAnnotations typeArg, BindingDiagnosticBag diagnostics
 #if DEBUG
             , string? expectedMethodName
 #endif
             )
         {
-            return MakeQueryInvocation(node, receiver, receiverIsCheckedForRValue, methodName, new SeparatedSyntaxList<TypeSyntax>(new SyntaxNodeOrTokenList(typeArgSyntax, 0)), ImmutableArray.Create(typeArg), ImmutableArray<BoundExpression>.Empty, diagnostics
+            return MakeQueryInvocation(node, receiver, methodName, new SeparatedSyntaxList<TypeSyntax>(new SyntaxNodeOrTokenList(typeArgSyntax, 0)), ImmutableArray.Create(typeArg), ImmutableArray<BoundExpression>.Empty, diagnostics
 #if DEBUG
                 , expectedMethodName
 #endif
                 );
         }
 
-        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, bool receiverIsCheckedForRValue, string methodName, SeparatedSyntaxList<TypeSyntax> typeArgsSyntax, ImmutableArray<TypeWithAnnotations> typeArgs, ImmutableArray<BoundExpression> args, BindingDiagnosticBag diagnostics
+        protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression receiver, string methodName, SeparatedSyntaxList<TypeSyntax> typeArgsSyntax, ImmutableArray<TypeWithAnnotations> typeArgs, ImmutableArray<BoundExpression> args, BindingDiagnosticBag diagnostics
 #if DEBUG
             , string? expectedMethodName
 #endif
@@ -993,17 +987,10 @@ protected BoundCall MakeQueryInvocation(CSharpSyntaxNode node, BoundExpression r
             }
             else
             {
-                if (!receiverIsCheckedForRValue)
+                var checkedUltimateReceiver = CheckValue(ultimateReceiver, BindValueKind.RValue, diagnostics);
+                if (checkedUltimateReceiver != ultimateReceiver)
                 {
-                    var checkedUltimateReceiver = CheckValue(ultimateReceiver, BindValueKind.RValue, diagnostics);
-                    if (checkedUltimateReceiver != ultimateReceiver)
-                    {
-                        receiver = updateUltimateReceiver(receiver, ultimateReceiver, checkedUltimateReceiver);
-                    }
-                }
-                else
-                {
-                    Debug.Assert(ultimateReceiver is not BoundQueryClause);
+                    receiver = updateUltimateReceiver(receiver, ultimateReceiver, checkedUltimateReceiver);
                 }
             }
 

src/Compilers/CSharp/Portable/BoundTree/BoundPropertyAccess.cs

@@ -0,0 +1,11 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.CodeAnalysis.CSharp;
+
+internal partial class BoundPropertyAccess
+{
+    public BoundPropertyAccess Clone()
+        => (BoundPropertyAccess)this.MemberwiseClone();
+}

src/Compilers/CSharp/Test/Semantic/Semantics/QueryTests.cs

@@ -4480,6 +4480,33 @@ public void SetOnlyProperty()
 var test = from i in c.Prop
            select i;
 
+public class C {
+    public IEnumerable<int> Prop
+    {
+        set {}
+    }
+}
+", options: TestOptions.ReleaseExe);
+
+            comp.VerifyDiagnostics(
+                // (6,22): error CS0154: The property or indexer 'C.Prop' cannot be used in this context because it lacks the get accessor
+                // var test = from i in c.Prop
+                Diagnostic(ErrorCode.ERR_PropertyLacksGet, "c.Prop").WithArguments("C.Prop").WithLocation(6, 22)
+            );
+        }
+
+        [Fact, WorkItem(50316, "https://github.com/dotnet/roslyn/issues/50316")]
+        public void SetOnlyProperty_GroupByContinuation()
+        {
+            var comp = CreateCompilation(@"
+using System.Collections.Generic;
+using System.Linq;
+
+var c = new C();
+var test = from i in c.Prop
+           group i by i into g
+           select g;
+
 public class C {
     public IEnumerable<int> Prop
     {
@@ -4786,5 +4813,22 @@ public static class F
             var comp = CreateCompilation(code);
             CompileAndVerify(code, expectedOutput: "ran").VerifyDiagnostics();
         }
+
+        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/81709")]
+        public void PropertyAccess_AnonymousType_GroupBy()
+        {
+            var code = """
+                using System.Linq;
+
+                var x = new { A = new[] { new { B = 1 } } };
+
+                var y = from a in x.A
+                        group a by a.B into g
+                        select 1;
+                """;
+
+            var comp = CreateCompilation(code);
+            comp.VerifyDiagnostics();
+        }
     }
 }