Ensure that IOperations nodes within a C# local function are part of …

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

@@ -854,16 +854,18 @@ public override TResult Accept<TArgument, TResult>(OperationVisitor<TArgument, T
 
     partial class BoundLocalFunctionStatement
     {
-        protected override OperationKind StatementKind => OperationKind.LocalFunctionStatement;
+        protected override OperationKind StatementKind => OperationKind.None;
+
+        protected override ImmutableArray<IOperation> Children => ImmutableArray.Create<IOperation>(this.Body);
 
         public override void Accept(OperationVisitor visitor)
         {
-            visitor.VisitLocalFunctionStatement(this);
+            visitor.VisitNoneOperation(this);
         }
 
         public override TResult Accept<TArgument, TResult>(OperationVisitor<TArgument, TResult> visitor, TArgument argument)
         {
-            return visitor.VisitLocalFunctionStatement(this, argument);
+            return visitor.VisitNoneOperation(this, argument);
         }
     }
 

src/Compilers/CSharp/Test/Semantic/IOperation/IOperationTests_IParameterReferenceExpression.cs

@@ -850,5 +850,48 @@ public void Method1(object x)
 
             VerifyOperationTreeAndDiagnosticsForTest<IsPatternExpressionSyntax>(source, expectedOperationTree, expectedDiagnostics);
         }
+
+        [Fact, WorkItem(19902, "https://github.com/dotnet/roslyn/issues/19902")]
+        public void ParameterReference_LocalFunctionStatement()
+        {
+            string source = @"
+using System;
+using System.Collections.Generic;
+
+class Class
+{
+    static IEnumerable<T> MyIterator<T>(IEnumerable<T> source, Func<T, bool> predicate)
+    {
+        /*<bind>*/IEnumerable<T> Iterator()
+        {
+            foreach (var element in source)
+                if (predicate(element))
+                    yield return element;
+        }/*</bind>*/
+
+        return Iterator();
+    }
+}
+
+";
+            string expectedOperationTree = @"
+IOperation:  (OperationKind.None) (Syntax: 'IEnumerable ... }')
+  Children(1): IBlockStatement (2 statements) (OperationKind.BlockStatement) (Syntax: '{ ... }')
+      IForEachLoopStatement (Iteration variable: T element) (LoopKind.ForEach) (OperationKind.LoopStatement) (Syntax: 'foreach (va ... rn element;')
+        Collection: IConversionExpression (ConversionKind.Cast, Implicit) (OperationKind.ConversionExpression, Type: System.Collections.Generic.IEnumerable<T>) (Syntax: 'source')
+            IParameterReferenceExpression: source (OperationKind.ParameterReferenceExpression, Type: System.Collections.Generic.IEnumerable<T>) (Syntax: 'source')
+        Body: IIfStatement (OperationKind.IfStatement) (Syntax: 'if (predica ... rn element;')
+            Condition: IInvocationExpression (virtual System.Boolean System.Func<T, System.Boolean>.Invoke(T arg)) (OperationKind.InvocationExpression, Type: System.Boolean) (Syntax: 'predicate(element)')
+                Instance Receiver: IParameterReferenceExpression: predicate (OperationKind.ParameterReferenceExpression, Type: System.Func<T, System.Boolean>) (Syntax: 'predicate')
+                Arguments(1): IArgument (ArgumentKind.Explicit, Matching Parameter: arg) (OperationKind.Argument) (Syntax: 'element')
+                    ILocalReferenceExpression: element (OperationKind.LocalReferenceExpression, Type: T) (Syntax: 'element')
+            IfTrue: IReturnStatement (OperationKind.YieldReturnStatement) (Syntax: 'yield return element;')
+                ILocalReferenceExpression: element (OperationKind.LocalReferenceExpression, Type: T) (Syntax: 'element')
+      YieldBreakStatement (OperationKind.YieldBreakStatement) (Syntax: '{ ... }')
+";
+            var expectedDiagnostics = DiagnosticDescription.None;
+
+            VerifyOperationTreeAndDiagnosticsForTest<LocalFunctionStatementSyntax>(source, expectedOperationTree, expectedDiagnostics);
+        }
     }
 }

src/Compilers/Core/Portable/Operations/OperationVisitor.cs

@@ -389,11 +389,6 @@ public virtual void VisitInvalidExpression(IInvalidExpression operation)
         {
             DefaultVisit(operation);
         }
-
-        public virtual void VisitLocalFunctionStatement(IOperation operation)
-        {
-            DefaultVisit(operation);
-        }
     }
 
     /// <summary>
@@ -789,10 +784,5 @@ public virtual TResult VisitInvalidExpression(IInvalidExpression operation, TArg
         {
             return DefaultVisit(operation, argument);
         }
-
-        public virtual TResult VisitLocalFunctionStatement(IOperation operation, TArgument argument)
-        {
-            return DefaultVisit(operation, argument);
-        }
     }
 }

src/Compilers/Core/Portable/PublicAPI.Unshipped.txt

@@ -804,7 +804,6 @@ virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLabelStatement(Mi
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLambdaExpression(Microsoft.CodeAnalysis.Semantics.ILambdaExpression operation) -> void
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLateBoundMemberReferenceExpression(Microsoft.CodeAnalysis.Semantics.ILateBoundMemberReferenceExpression operation) -> void
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLiteralExpression(Microsoft.CodeAnalysis.Semantics.ILiteralExpression operation) -> void
-virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLocalFunctionStatement(Microsoft.CodeAnalysis.IOperation operation) -> void
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLocalReferenceExpression(Microsoft.CodeAnalysis.Semantics.ILocalReferenceExpression operation) -> void
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitLockStatement(Microsoft.CodeAnalysis.Semantics.ILockStatement operation) -> void
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor.VisitMethodBindingExpression(Microsoft.CodeAnalysis.Semantics.IMethodBindingExpression operation) -> void
@@ -880,7 +879,6 @@ virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.Vi
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitLambdaExpression(Microsoft.CodeAnalysis.Semantics.ILambdaExpression operation, TArgument argument) -> TResult
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitLateBoundMemberReferenceExpression(Microsoft.CodeAnalysis.Semantics.ILateBoundMemberReferenceExpression operation, TArgument argument) -> TResult
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitLiteralExpression(Microsoft.CodeAnalysis.Semantics.ILiteralExpression operation, TArgument argument) -> TResult
-virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitLocalFunctionStatement(Microsoft.CodeAnalysis.IOperation operation, TArgument argument) -> TResult
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitLocalReferenceExpression(Microsoft.CodeAnalysis.Semantics.ILocalReferenceExpression operation, TArgument argument) -> TResult
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitLockStatement(Microsoft.CodeAnalysis.Semantics.ILockStatement operation, TArgument argument) -> TResult
 virtual Microsoft.CodeAnalysis.Semantics.OperationVisitor<TArgument, TResult>.VisitMethodBindingExpression(Microsoft.CodeAnalysis.Semantics.IMethodBindingExpression operation, TArgument argument) -> TResult

src/Test/Utilities/Portable/Compilation/OperationTreeVerifier.cs

@@ -1058,12 +1058,6 @@ public override void VisitIfStatement(IIfStatement operation)
             Visit(operation.IfFalseStatement, "IfFalse");
         }
 
-        public override void VisitLocalFunctionStatement(IOperation operation)
-        {
-            LogString(nameof(VisitLocalFunctionStatement));
-            LogCommonPropertiesAndNewLine(operation);
-        }
-
         private void LogCaseClauseCommon(ICaseClause operation)
         {
             var kindStr = $"{nameof(CaseKind)}.{operation.CaseKind}";