Address PROTOTYPE comment in ExtensionMethodBodyRewriter

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

@@ -249,7 +249,7 @@ protected BoundTreeRewriterWithStackGuardWithoutRecursionOnTheLeftOfBinaryOperat
 
             if (child.Kind != BoundKind.BinaryOperator)
             {
-                return base.VisitBinaryOperator(node);
+                return node.Update(node.OperatorKind, VisitBinaryOperatorData(node), node.ResultKind, (BoundExpression)this.Visit(node.Left), (BoundExpression)this.Visit(node.Right), this.VisitType(node.Type));
             }
 
             var stack = ArrayBuilder<BoundBinaryOperator>.GetInstance();
@@ -279,7 +279,7 @@ protected BoundTreeRewriterWithStackGuardWithoutRecursionOnTheLeftOfBinaryOperat
                 var right = (BoundExpression?)this.Visit(binary.Right);
                 Debug.Assert(right is { });
                 var type = this.VisitType(binary.Type);
-                left = binary.Update(binary.OperatorKind, binary.Data, binary.ResultKind, left, right, type);
+                left = binary.Update(binary.OperatorKind, VisitBinaryOperatorData(binary), binary.ResultKind, left, right, type);
             }
             while (stack.Count > 0);
 
@@ -289,6 +289,11 @@ protected BoundTreeRewriterWithStackGuardWithoutRecursionOnTheLeftOfBinaryOperat
             return left;
         }
 
+        protected virtual BoundBinaryOperator.UncommonData? VisitBinaryOperatorData(BoundBinaryOperator node)
+        {
+            return node.Data;
+        }
+
         public sealed override BoundNode? VisitIfStatement(BoundIfStatement node)
         {
             if (node.AlternativeOpt is not BoundIfStatement ifStatement)

src/Compilers/CSharp/Portable/Lowering/BoundTreeToDifferentEnclosingContextRewriter.cs

@@ -16,7 +16,7 @@ namespace Microsoft.CodeAnalysis.CSharp
     /// a bound node rewriter that rewrites types properly (which in some cases the automatically-generated
     /// base class does not).  This is used in the lambda rewriter, the iterator rewriter, and the async rewriter.
     /// </summary>
-    internal abstract class BoundTreeToDifferentEnclosingContextRewriter : BoundTreeRewriterWithStackGuard
+    internal abstract class BoundTreeToDifferentEnclosingContextRewriter : BoundTreeRewriterWithStackGuardWithoutRecursionOnTheLeftOfBinaryOperator
     {
         // A mapping from every local variable to its replacement local variable.  Local variables are replaced when
         // their types change due to being inside of a generic method.  Otherwise we reuse the original local (even
@@ -111,20 +111,12 @@ protected BoundBlock VisitBlock(BoundBlock node, bool removeInstrumentation)
             return TypeMap.SubstituteType(type).Type;
         }
 
-        public override BoundNode VisitBinaryOperator(BoundBinaryOperator node)
+        protected override BoundBinaryOperator.UncommonData? VisitBinaryOperatorData(BoundBinaryOperator node)
         {
             // Local rewriter should have already rewritten interpolated strings into their final form of calls and gotos
             Debug.Assert(node.InterpolatedStringHandlerData is null);
 
-            return node.Update(
-                node.OperatorKind,
-                node.ConstantValueOpt,
-                VisitMethodSymbol(node.Method),
-                VisitType(node.ConstrainedToType),
-                node.ResultKind,
-                (BoundExpression)Visit(node.Left),
-                (BoundExpression)Visit(node.Right),
-                VisitType(node.Type));
+            return BoundBinaryOperator.UncommonData.CreateIfNeeded(node.ConstantValueOpt, VisitMethodSymbol(node.Method), VisitType(node.ConstrainedToType), node.OriginalUserDefinedOperatorsOpt);
         }
 
         public override BoundNode? VisitConversion(BoundConversion node)

src/Compilers/CSharp/Portable/Lowering/ExtensionMethodBodyRewriter.cs

@@ -187,7 +187,5 @@ public override BoundNode VisitFunctionPointerLoad(BoundFunctionPointerLoad node
         {
             return ExtensionMethodReferenceRewriter.VisitFunctionPointerLoad(this, node);
         }
-
-        // PROTOTYPE: Handle deep recursion on long chain of binary operators, etc.
     }
 }

src/Compilers/CSharp/Portable/Lowering/ExtensionMethodReferenceRewriter.cs

@@ -228,5 +228,13 @@ public static BoundNode VisitFunctionPointerLoad(BoundTreeRewriter rewriter, Bou
             TypeSymbol? type = rewriter.VisitType(node.Type);
             return node.Update(targetMethod, constrainedToTypeOpt, type);
         }
+
+        protected override BoundBinaryOperator.UncommonData? VisitBinaryOperatorData(BoundBinaryOperator node)
+        {
+            Debug.Assert(node.Method is null ||
+                         (!node.Method.IsExtensionMethod && !node.Method.GetIsNewExtensionMember())); // Expression tree context. At the moment an operator cannot be an extension method
+
+            return base.VisitBinaryOperatorData(node);
+        }
     }
 }