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src/Features/Core/Portable/GenerateConstructorFromMembers/ConstructorDelegatingCodeAction.cs

@@ -64,36 +64,15 @@ protected override async Task<Document> GetChangedDocumentAsync(CancellationToke
                 {
                     var symbolName = _state.SelectedMembers[i].Name;
                     var parameter = _state.Parameters[i];
-                    var parameterName = parameter.Name;
-
-                    var shouldAddNullCheck = _addNullChecks && parameter.Type.CanAddNullCheck();
-                    if (shouldAddNullCheck && useThrowExpressions)
-                    {
-                        // Generate 'this.a = a ?? throw...
-                        assignStatements.Add(factory.CreateAssignWithNullCheckStatement(
-                            compilation, parameter,
-                            fieldAccess: factory.MemberAccessExpression(
-                                factory.ThisExpression(),
-                                factory.IdentifierName(symbolName))));
-                    }
-                    else
-                    {
-                        if (shouldAddNullCheck)
-                        {
-                            // generate: if (p == null) throw ...
-                            nullCheckStatements.Add(
-                                factory.CreateIfNullThrowStatement(compilation, parameter));
-                        }
-
-                        // generate: this.p = p;
-                        assignStatements.Add(
-                            factory.ExpressionStatement(
-                                factory.AssignmentStatement(
-                                    factory.MemberAccessExpression(
-                                        factory.ThisExpression(),
-                                        factory.IdentifierName(symbolName)),
-                                    factory.IdentifierName(parameterName))));
-                    }
+
+                    var fieldAccess = factory.MemberAccessExpression(
+                        factory.ThisExpression(),
+                        factory.IdentifierName(symbolName));
+
+                    factory.AddAssignmentStatements(
+                        compilation, parameter, fieldAccess,
+                        _addNullChecks, useThrowExpressions,
+                        nullCheckStatements, assignStatements);
                 }
 
                 var syntaxTree = await _document.GetSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);

src/Workspaces/Core/Portable/Shared/Extensions/ICodeDefinitionFactoryExtensions.cs

@@ -233,25 +233,10 @@ private static bool TryGetValue(IDictionary<string, ISymbol> dictionary, string
                         var fieldAccess = factory.MemberAccessExpression(factory.ThisExpression(), factory.IdentifierName(fieldName))
                                                  .WithAdditionalAnnotations(Simplifier.Annotation);
 
-                        var shouldAddNullCheck = addNullChecks && parameterType.CanAddNullCheck();
-                        if (shouldAddNullCheck && preferThrowExpression)
-                        {
-                            var statement = CreateAssignWithNullCheckStatement(factory, compilation, parameter, fieldAccess);
-                            assignStatements.Add(statement);
-                        }
-                        else
-                        {
-                            if (shouldAddNullCheck)
-                            {
-                                nullCheckStatements.Add(
-                                    factory.CreateIfNullThrowStatement(compilation, parameter));
-                            }
-
-                            var assignExpression = factory.AssignmentStatement(
-                                fieldAccess, factory.IdentifierName(parameterName));
-                            var statement = factory.ExpressionStatement(assignExpression);
-                            assignStatements.Add(statement);
-                        }
+                        factory.AddAssignmentStatements(
+                            compilation, parameter, fieldAccess,
+                            addNullChecks, preferThrowExpression,
+                            nullCheckStatements, assignStatements);
                     }
                 }
             }
@@ -259,6 +244,41 @@ private static bool TryGetValue(IDictionary<string, ISymbol> dictionary, string
             return nullCheckStatements.ToImmutableAndFree().Concat(assignStatements.ToImmutableAndFree());
         }
 
+        public static void AddAssignmentStatements(
+             this SyntaxGenerator factory,
+             Compilation compilation,
+             IParameterSymbol parameter,
+             SyntaxNode fieldAccess,
+             bool addNullChecks,
+             bool preferThrowExpression,
+             ArrayBuilder<SyntaxNode> nullCheckStatements,
+             ArrayBuilder<SyntaxNode> assignStatements)
+        {
+            var shouldAddNullCheck = addNullChecks && parameter.Type.CanAddNullCheck();
+            if (shouldAddNullCheck && preferThrowExpression)
+            {
+                // Generate: this.x = x ?? throw ...
+                assignStatements.Add(CreateAssignWithNullCheckStatement(
+                    factory, compilation, parameter, fieldAccess));
+            }
+            else
+            {
+                if (shouldAddNullCheck)
+                {
+                    // generate: if (x == null) throw ...
+                    nullCheckStatements.Add(
+                        factory.CreateIfNullThrowStatement(compilation, parameter));
+                }
+
+                // generate: this.x = x;
+                assignStatements.Add(
+                    factory.ExpressionStatement(
+                        factory.AssignmentStatement(
+                            fieldAccess,
+                            factory.IdentifierName(parameter.Name))));
+            }
+        }
+
         public static SyntaxNode CreateAssignWithNullCheckStatement(
             this SyntaxGenerator factory, Compilation compilation, IParameterSymbol parameter, SyntaxNode fieldAccess)
         {