Merge pull request #22842 from 333fred/variable-declaration-refactor

Variable declaration refactor

src/Compilers/CSharp/Portable/Operations/CSharpOperationFactory.cs

@@ -278,9 +278,9 @@ private ImmutableArray<IOperation> GetIOperationChildren(BoundNode boundNode)
             return builder.ToImmutableAndFree();
         }
 
-        private IVariableDeclarationOperation CreateVariableDeclaration(BoundLocalDeclaration boundNode)
+        private IVariableDeclaratorOperation CreateVariableDeclarator(BoundLocalDeclaration boundNode)
         {
-            return (IVariableDeclarationOperation)_cache.GetOrAdd(boundNode, n => CreateVariableDeclarationInternal((BoundLocalDeclaration)n, n.Syntax));
+            return (IVariableDeclaratorOperation)_cache.GetOrAdd(boundNode, n => CreateVariableDeclaratorInternal((BoundLocalDeclaration)n, n.Syntax));
         }
 
         private IPlaceholderOperation CreateBoundDeconstructValuePlaceholderOperation(BoundDeconstructValuePlaceholder boundDeconstructValuePlaceholder)
@@ -311,7 +311,7 @@ private IOperation CreateBoundCallOperation(BoundCall boundCall)
             ITypeSymbol type = boundCall.Type;
             Optional<object> constantValue = ConvertToOptional(boundCall.ConstantValue);
             bool isImplicit = boundCall.WasCompilerGenerated;
-            
+
             if (!boundCall.OriginalMethodsOpt.IsDefault || boundCall.ResultKind == LookupResultKind.OverloadResolutionFailure || targetMethod == null || targetMethod.OriginalDefinition is ErrorMethodSymbol)
             {
                 return CreateInvalidExpressionForHasArgumentsExpression(boundCall.ReceiverOpt, boundCall.Arguments, null, syntax, type, constantValue, isImplicit);
@@ -401,7 +401,7 @@ private IOperation CreateBoundIndexerAccessOperation(BoundIndexerAccess boundInd
             MethodSymbol accessor = boundIndexerAccess.UseSetterForDefaultArgumentGeneration
                 ? property.GetOwnOrInheritedSetMethod()
                 : property.GetOwnOrInheritedGetMethod();
-            
+
             if (!boundIndexerAccess.OriginalIndexersOpt.IsDefault || boundIndexerAccess.ResultKind == LookupResultKind.OverloadResolutionFailure || accessor == null || accessor.OriginalDefinition is ErrorMethodSymbol)
             {
                 return CreateInvalidExpressionForHasArgumentsExpression(boundIndexerAccess.ReceiverOpt, boundIndexerAccess.Arguments, null, syntax, type, constantValue, isImplicit);
@@ -495,7 +495,7 @@ private IOperation CreateBoundObjectCreationExpressionOperation(BoundObjectCreat
             ITypeSymbol type = boundObjectCreationExpression.Type;
             Optional<object> constantValue = ConvertToOptional(boundObjectCreationExpression.ConstantValue);
             bool isImplicit = boundObjectCreationExpression.WasCompilerGenerated;
-            
+
             if (boundObjectCreationExpression.ResultKind == LookupResultKind.OverloadResolutionFailure || constructor == null || constructor.OriginalDefinition is ErrorMethodSymbol)
             {
                 return CreateInvalidExpressionForHasArgumentsExpression(null, boundObjectCreationExpression.Arguments, boundObjectCreationExpression.InitializerExpressionOpt, syntax, type, constantValue, isImplicit);
@@ -841,7 +841,7 @@ private IMethodReferenceOperation CreateBoundMethodGroupSingleMethodOperation(Bo
             bool isVirtual = (methodSymbol.IsAbstract || methodSymbol.IsOverride || methodSymbol.IsVirtual) && !suppressVirtualCalls;
             BoundExpression receiverOpt = boundMethodGroup.InstanceOpt;
 
-            if (methodSymbol.IsStatic && receiverOpt != null && 
+            if (methodSymbol.IsStatic && receiverOpt != null &&
                 receiverOpt.WasCompilerGenerated && receiverOpt.Kind == BoundKind.ThisReference)
             {
                 receiverOpt = null;
@@ -894,7 +894,7 @@ private IArrayCreationOperation CreateBoundArrayCreationOperation(BoundArrayCrea
             SyntaxNode syntax = boundArrayCreation.Syntax;
             ITypeSymbol type = boundArrayCreation.Type;
             Optional<object> constantValue = ConvertToOptional(boundArrayCreation.ConstantValue);
-            bool isImplicit = boundArrayCreation.WasCompilerGenerated || 
+            bool isImplicit = boundArrayCreation.WasCompilerGenerated ||
                               (boundArrayCreation.InitializerOpt?.Syntax == syntax && !boundArrayCreation.InitializerOpt.WasCompilerGenerated);
             return new LazyArrayCreationExpression(dimensionSizes, initializer, _semanticModel, syntax, type, constantValue, isImplicit);
         }
@@ -1419,7 +1419,7 @@ private ITryOperation CreateBoundTryStatementOperation(BoundTryStatement boundTr
         private ICatchClauseOperation CreateBoundCatchBlockOperation(BoundCatchBlock boundCatchBlock)
         {
             var exceptionSourceOpt = (BoundLocal)boundCatchBlock.ExceptionSourceOpt;
-            Lazy<IOperation> expressionDeclarationOrExpression = new Lazy<IOperation>(() => exceptionSourceOpt != null ? CreateVariableDeclaration(exceptionSourceOpt) : null);
+            Lazy<IOperation> expressionDeclarationOrExpression = new Lazy<IOperation>(() => exceptionSourceOpt != null ? CreateVariableDeclarator(exceptionSourceOpt) : null);
             ITypeSymbol exceptionType = boundCatchBlock.ExceptionTypeOpt;
             ImmutableArray<ILocalSymbol> locals = boundCatchBlock.Locals.As<ILocalSymbol>();
             Lazy<IOperation> filter = new Lazy<IOperation>(() => Create(boundCatchBlock.ExceptionFilterOpt));
@@ -1433,7 +1433,7 @@ private ICatchClauseOperation CreateBoundCatchBlockOperation(BoundCatchBlock bou
 
         private IFixedOperation CreateBoundFixedStatementOperation(BoundFixedStatement boundFixedStatement)
         {
-            Lazy<IVariableDeclarationsOperation> variables = new Lazy<IVariableDeclarationsOperation>(() => (IVariableDeclarationsOperation)Create(boundFixedStatement.Declarations));
+            Lazy<IVariableDeclarationGroupOperation> variables = new Lazy<IVariableDeclarationGroupOperation>(() => (IVariableDeclarationGroupOperation)Create(boundFixedStatement.Declarations));
             Lazy<IOperation> body = new Lazy<IOperation>(() => Create(boundFixedStatement.Body));
             SyntaxNode syntax = boundFixedStatement.Syntax;
             ITypeSymbol type = null;
@@ -1514,6 +1514,7 @@ private IOperation CreateBoundLocalDeclarationOperation(BoundLocalDeclaration bo
 
             SyntaxNode varStatement;
             SyntaxNode varDeclaration;
+            SyntaxNode varDeclarator;
             switch (kind)
             {
                 case SyntaxKind.LocalDeclarationStatement:
@@ -1524,18 +1525,22 @@ private IOperation CreateBoundLocalDeclarationOperation(BoundLocalDeclaration bo
                     // var statement points to LocalDeclarationStatementSyntax
                     varStatement = statement;
 
-                    // var declaration points to VariableDeclaratorSyntax
-                    varDeclaration = statement.Declaration.Variables.First();
+                    varDeclaration = statement.Declaration;
+
+                    varDeclarator = statement.Declaration.Variables.First();
                     break;
                 }
                 case SyntaxKind.VariableDeclarator:
                 {
                     // this happen for 'for loop' initializer
+                    // We generate a DeclarationGroup for this scenario to maintain tree shape consistency across IOperation.
                     // var statement points to VariableDeclarationSyntax
                     varStatement = node.Parent;
 
+                    varDeclaration = node.Parent;
+
                     // var declaration points to VariableDeclaratorSyntax
-                    varDeclaration = node;
+                    varDeclarator = node;
                     break;
                 }
                 default:
@@ -1543,27 +1548,47 @@ private IOperation CreateBoundLocalDeclarationOperation(BoundLocalDeclaration bo
                     Debug.Fail($"Unexpected syntax: {kind}");
 
                     // otherwise, they points to whatever bound nodes are pointing to.
-                    varStatement = varDeclaration = node;
+                    varStatement = varDeclaration = varDeclarator = node;
                     break;
                 }
             }
 
-            Lazy<ImmutableArray<IVariableDeclarationOperation>> declarations = new Lazy<ImmutableArray<IVariableDeclarationOperation>>(() => ImmutableArray.Create(CreateVariableDeclarationInternal(boundLocalDeclaration, varDeclaration)));
+            Lazy<ImmutableArray<IVariableDeclaratorOperation>> declarations = new Lazy<ImmutableArray<IVariableDeclaratorOperation>>(() => ImmutableArray.Create(CreateVariableDeclaratorInternal(boundLocalDeclaration, varDeclarator)));
+            bool multiVariableImplicit = boundLocalDeclaration.WasCompilerGenerated;
+            // In C#, the MultiVariable initializer will always be null, but we can't pass null as the actual lazy. We assume that all lazy elements always exist
+            Lazy<IVariableInitializerOperation> initializer = OperationFactory.EmptyInitializer;
+            IVariableDeclarationOperation multiVariableDeclaration = new LazyVariableDeclaration(declarations, initializer, _semanticModel, varDeclaration, null, default, multiVariableImplicit);
             ITypeSymbol type = null;
             Optional<object> constantValue = default(Optional<object>);
-            bool isImplicit = boundLocalDeclaration.WasCompilerGenerated;
-            return new LazyVariableDeclarationStatement(declarations, _semanticModel, varStatement, type, constantValue, isImplicit);
+            // In the case of a for loop, varStatement and varDeclaration will be the same syntax node.
+            // We can only have one explicit operation, so make sure this node is implicit in that scenario.
+            bool isImplicit = (varStatement == varDeclaration) || boundLocalDeclaration.WasCompilerGenerated;
+            return new VariableDeclarationGroupOperation(ImmutableArray.Create(multiVariableDeclaration), _semanticModel, varStatement, type, constantValue, isImplicit);
         }
 
-        private IVariableDeclarationsOperation CreateBoundMultipleLocalDeclarationsOperation(BoundMultipleLocalDeclarations boundMultipleLocalDeclarations)
+        private IVariableDeclarationGroupOperation CreateBoundMultipleLocalDeclarationsOperation(BoundMultipleLocalDeclarations boundMultipleLocalDeclarations)
         {
-            Lazy<ImmutableArray<IVariableDeclarationOperation>> declarations = new Lazy<ImmutableArray<IVariableDeclarationOperation>>(() =>
-                boundMultipleLocalDeclarations.LocalDeclarations.SelectAsArray(declaration => (IVariableDeclarationOperation)CreateVariableDeclaration(declaration)));
-            SyntaxNode syntax = boundMultipleLocalDeclarations.Syntax;
+            Lazy<ImmutableArray<IVariableDeclaratorOperation>> declarators = new Lazy<ImmutableArray<IVariableDeclaratorOperation>>(() =>
+                boundMultipleLocalDeclarations.LocalDeclarations.SelectAsArray(declaration => CreateVariableDeclarator(declaration)));
+            // In C#, the MultiVariable initializer will always be null, but we can't pass null as the actual lazy. We assume that all lazy elements always exist
+            Lazy<IVariableInitializerOperation> initializer = OperationFactory.EmptyInitializer;
+
+            // The syntax for the boundMultipleLocalDeclarations can either be a LocalDeclarationStatement or a VariableDeclaration, depending on the context
+            // (using/fixed statements vs variable declaration)
+            // We generate a DeclarationGroup for these scenarios (using/fixed) to maintain tree shape consistency across IOperation.
+            SyntaxNode declarationGroupSyntax = boundMultipleLocalDeclarations.Syntax;
+            SyntaxNode declarationSyntax = declarationGroupSyntax.IsKind(SyntaxKind.LocalDeclarationStatement) ?
+                    ((LocalDeclarationStatementSyntax)declarationGroupSyntax).Declaration :
+                    declarationGroupSyntax;
+            bool declarationIsImplicit = boundMultipleLocalDeclarations.WasCompilerGenerated;
+            IVariableDeclarationOperation multiVariableDeclaration = new LazyVariableDeclaration(declarators, initializer, _semanticModel, declarationSyntax, null, default, declarationIsImplicit);
+
             ITypeSymbol type = null;
             Optional<object> constantValue = default(Optional<object>);
-            bool isImplicit = boundMultipleLocalDeclarations.WasCompilerGenerated;
-            return new LazyVariableDeclarationStatement(declarations, _semanticModel, syntax, type, constantValue, isImplicit);
+            // If the syntax was the same, we're in a fixed statement or using statement. We make the Group operation implicit in this scenario, as the
+            // syntax itself is a VariableDeclaration
+            bool isImplicit = declarationGroupSyntax == declarationSyntax || boundMultipleLocalDeclarations.WasCompilerGenerated;
+            return new VariableDeclarationGroupOperation(ImmutableArray.Create(multiVariableDeclaration), _semanticModel, declarationGroupSyntax, type, constantValue, isImplicit);
         }
 
         private ILabeledOperation CreateBoundLabelStatementOperation(BoundLabelStatement boundLabelStatement)

src/Compilers/CSharp/Portable/Operations/CSharpOperationFactory_Methods.cs

@@ -51,14 +51,14 @@ internal IArgumentOperation CreateArgumentOperation(ArgumentKind kind, IParamete
                 isImplicit: expression.WasCompilerGenerated || argument == null);
         }
 
-        private IVariableDeclarationOperation CreateVariableDeclarationInternal(BoundLocalDeclaration boundLocalDeclaration, SyntaxNode syntax)
+        private IVariableDeclaratorOperation CreateVariableDeclaratorInternal(BoundLocalDeclaration boundLocalDeclaration, SyntaxNode syntax)
         {
             IVariableInitializerOperation initializer = null;
             if (boundLocalDeclaration.InitializerOpt != null)
             {
                 IOperation initializerValue = Create(boundLocalDeclaration.InitializerOpt);
                 SyntaxNode initializerSyntax = null;
-                bool isImplicit = false;
+                bool initializerIsImplicit = false;
                 if (syntax is VariableDeclaratorSyntax variableDeclarator)
                 {
                     initializerSyntax = variableDeclarator.Initializer;
@@ -72,18 +72,24 @@ private IVariableDeclarationOperation CreateVariableDeclarationInternal(BoundLoc
                 {
                     // There is no explicit syntax for the initializer, so we use the initializerValue's syntax and mark the operation as implicit.
                     initializerSyntax = initializerValue.Syntax;
-                    isImplicit = true;
+                    initializerIsImplicit = true;
                 }
 
-                initializer = OperationFactory.CreateVariableInitializer(initializerSyntax, initializerValue, _semanticModel, isImplicit);
+                initializer = OperationFactory.CreateVariableInitializer(initializerSyntax, initializerValue, _semanticModel, initializerIsImplicit);
             }
 
-            return OperationFactory.CreateVariableDeclaration(boundLocalDeclaration.LocalSymbol, initializer, _semanticModel, syntax);
+            ILocalSymbol symbol = boundLocalDeclaration.LocalSymbol;
+            SyntaxNode syntaxNode = boundLocalDeclaration.Syntax;
+            ITypeSymbol type = null;
+            Optional<object> constantValue = default;
+            bool isImplicit = false;
+
+            return new VariableDeclarator(symbol, initializer, _semanticModel, syntax, type, constantValue, isImplicit);
         }
 
-        private IVariableDeclarationOperation CreateVariableDeclaration(BoundLocal boundLocal)
+        private IVariableDeclaratorOperation CreateVariableDeclarator(BoundLocal boundLocal)
         {
-            return OperationFactory.CreateVariableDeclaration(boundLocal.LocalSymbol, initializer: null, semanticModel: _semanticModel, syntax: boundLocal.Syntax);
+            return new VariableDeclarator(boundLocal.LocalSymbol, initializer: null, semanticModel: _semanticModel, syntax: boundLocal.Syntax, type: null, constantValue: default, isImplicit: false);
         }
 
         private IOperation CreateBoundCallInstanceOperation(BoundCall boundCall)

src/Compilers/CSharp/Test/Semantic/Diagnostics/DiagnosticAnalyzerTests.cs

@@ -1995,7 +1995,7 @@ void MixMethod()
             compilation.VerifyDiagnostics();
 
             var syntaxKinds = ImmutableArray.Create(SyntaxKind.VariableDeclaration);
-            var operationKinds = ImmutableArray.Create(OperationKind.VariableDeclaration);
+            var operationKinds = ImmutableArray.Create(OperationKind.VariableDeclarator);
 
             var analyzers = new DiagnosticAnalyzer[] { new GeneratedCodeSyntaxAndOperationAnalyzer(GeneratedCodeAnalysisFlags.None, syntaxKinds, operationKinds) };
             compilation.VerifyAnalyzerDiagnostics(analyzers, null, null, true,

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

@@ -303,19 +303,22 @@ public void F(int dimension)
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int[] x = { 1, 2 };')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'x = { 1, 2 }')
-    Variables: Local_1: System.Int32[] x
-    Initializer: 
-      IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= { 1, 2 }')
-        IArrayCreationOperation (OperationKind.ArrayCreation, Type: System.Int32[], IsImplicit) (Syntax: '{ 1, 2 }')
-          Dimension Sizes(1):
-              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2, IsImplicit) (Syntax: '{ 1, 2 }')
+IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int[] x = { 1, 2 };')
+  IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int[] x = { 1, 2 }')
+    Declarators:
+        IVariableDeclaratorOperation (Symbol: System.Int32[] x) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'x = { 1, 2 }')
           Initializer: 
-            IArrayInitializerOperation (2 elements) (OperationKind.ArrayInitializer, Type: null) (Syntax: '{ 1, 2 }')
-              Element Values(2):
-                  ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
-                  ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
+            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= { 1, 2 }')
+              IArrayCreationOperation (OperationKind.ArrayCreation, Type: System.Int32[], IsImplicit) (Syntax: '{ 1, 2 }')
+                Dimension Sizes(1):
+                    ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2, IsImplicit) (Syntax: '{ 1, 2 }')
+                Initializer: 
+                  IArrayInitializerOperation (2 elements) (OperationKind.ArrayInitializer, Type: null) (Syntax: '{ 1, 2 }')
+                    Element Values(2):
+                        ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
+                        ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
+    Initializer: 
+      null
 ";
             var expectedDiagnostics = DiagnosticDescription.None;
 

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

@@ -200,9 +200,12 @@ static void M(Task<int> t)
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'await t;')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 't')
-    Variables: Local_1: await t
+IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid) (Syntax: 'await t;')
+  IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'await t')
+    Declarators:
+        IVariableDeclaratorOperation (Symbol: await t) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 't')
+          Initializer: 
+            null
     Initializer: 
       null
 ";

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

@@ -35,18 +35,21 @@ void M1()
             string expectedOperationTree = @"
 IOperation:  (OperationKind.None, Type: null) (Syntax: 'fixed(int * ... }')
   Children(2):
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int *p = &i')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p = &i')
-          Variables: Local_1: System.Int32* p
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'int *p = &i')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int *p = &i')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32* p) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p = &i')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i')
+                    IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i')
+                      Children(1):
+                          IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i')
+                            Reference: 
+                              IFieldReferenceOperation: System.Int32 C.i (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i')
+                                Instance Receiver: 
+                                  IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i')
-              IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i')
-                Children(1):
-                    IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i')
-                      Reference: 
-                        IFieldReferenceOperation: System.Int32 C.i (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i')
-                          Instance Receiver: 
-                            IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i')
+            null
       IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'Console.Wri ...  is {*p}"");')
           Expression: 
@@ -106,29 +109,31 @@ void M1()
             string expectedOperationTree = @"
 IOperation:  (OperationKind.None, Type: null) (Syntax: 'fixed (int* ... }')
   Children(2):
-      IVariableDeclarationsOperation (2 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int* p1 = &i1, p2 = &i2')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p1 = &i1')
-          Variables: Local_1: System.Int32* p1
-          Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i1')
-              IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i1')
-                Children(1):
-                    IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i1')
-                      Reference: 
-                        IFieldReferenceOperation: System.Int32 C.i1 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i1')
-                          Instance Receiver: 
-                            IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i1')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p2 = &i2')
-          Variables: Local_1: System.Int32* p2
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'int* p1 = &i1, p2 = &i2')
+        IVariableDeclarationOperation (2 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int* p1 = &i1, p2 = &i2')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32* p1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p1 = &i1')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i1')
+                    IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i1')
+                      Children(1):
+                          IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i1')
+                            Reference: 
+                              IFieldReferenceOperation: System.Int32 C.i1 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i1')
+                                Instance Receiver: 
+                                  IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i1')
+              IVariableDeclaratorOperation (Symbol: System.Int32* p2) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p2 = &i2')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i2')
+                    IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i2')
+                      Children(1):
+                          IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i2')
+                            Reference: 
+                              IFieldReferenceOperation: System.Int32 C.i2 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i2')
+                                Instance Receiver: 
+                                  IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i2')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i2')
-              IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i2')
-                Children(1):
-                    IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i2')
-                      Reference: 
-                        IFieldReferenceOperation: System.Int32 C.i2 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i2')
-                          Instance Receiver: 
-                            IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i2')
+            null
       IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'i3 = *p1 + *p2;')
           Expression: 
@@ -183,32 +188,38 @@ void M1()
             string expectedOperationTree = @"
 IOperation:  (OperationKind.None, Type: null) (Syntax: 'fixed (int* ... }')
   Children(2):
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int* p1 = &i1')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p1 = &i1')
-          Variables: Local_1: System.Int32* p1
-          Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i1')
-              IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i1')
-                Children(1):
-                    IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i1')
-                      Reference: 
-                        IFieldReferenceOperation: System.Int32 C.i1 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i1')
-                          Instance Receiver: 
-                            IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i1')
-      IOperation:  (OperationKind.None, Type: null) (Syntax: 'fixed (int* ... }')
-        Children(2):
-            IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int* p2 = &i2')
-              IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p2 = &i2')
-                Variables: Local_1: System.Int32* p2
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'int* p1 = &i1')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int* p1 = &i1')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32* p1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p1 = &i1')
                 Initializer: 
-                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i2')
-                    IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i2')
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i1')
+                    IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i1')
                       Children(1):
-                          IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i2')
+                          IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i1')
                             Reference: 
-                              IFieldReferenceOperation: System.Int32 C.i2 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i2')
+                              IFieldReferenceOperation: System.Int32 C.i1 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i1')
                                 Instance Receiver: 
-                                  IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i2')
+                                  IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i1')
+          Initializer: 
+            null
+      IOperation:  (OperationKind.None, Type: null) (Syntax: 'fixed (int* ... }')
+        Children(2):
+            IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'int* p2 = &i2')
+              IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int* p2 = &i2')
+                Declarators:
+                    IVariableDeclaratorOperation (Symbol: System.Int32* p2) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p2 = &i2')
+                      Initializer: 
+                        IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i2')
+                          IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i2')
+                            Children(1):
+                                IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i2')
+                                  Reference: 
+                                    IFieldReferenceOperation: System.Int32 C.i2 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i2')
+                                      Instance Receiver: 
+                                        IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i2')
+                Initializer: 
+                  null
             IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
               IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'i3 = *p1 + *p2;')
                 Expression: 
@@ -258,13 +269,16 @@ void M1()
             string expectedOperationTree = @"
 IOperation:  (OperationKind.None, Type: null, IsInvalid) (Syntax: 'fixed (int* ... }')
   Children(2):
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'int* p1 =')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'p1 =')
-          Variables: Local_1: System.Int32* p1
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid, IsImplicit) (Syntax: 'int* p1 =')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'int* p1 =')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32* p1) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'p1 =')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '=')
+                    IInvalidOperation (OperationKind.Invalid, Type: null, IsInvalid) (Syntax: '')
+                      Children(0)
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '=')
-              IInvalidOperation (OperationKind.Invalid, Type: null, IsInvalid) (Syntax: '')
-                Children(0)
+            null
       IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'i3 = *p1;')
           Expression: 
@@ -313,18 +327,21 @@ void M1()
             string expectedOperationTree = @"
 IOperation:  (OperationKind.None, Type: null, IsInvalid) (Syntax: 'fixed (int* ... }')
   Children(2):
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int* p1 = &i1')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p1 = &i1')
-          Variables: Local_1: System.Int32* p1
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'int* p1 = &i1')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int* p1 = &i1')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32* p1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p1 = &i1')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i1')
+                    IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i1')
+                      Children(1):
+                          IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i1')
+                            Reference: 
+                              IFieldReferenceOperation: System.Int32 C.i1 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i1')
+                                Instance Receiver: 
+                                  IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i1')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= &i1')
-              IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: '&i1')
-                Children(1):
-                    IAddressOfOperation (OperationKind.AddressOf, Type: System.Int32*) (Syntax: '&i1')
-                      Reference: 
-                        IFieldReferenceOperation: System.Int32 C.i1 (OperationKind.FieldReference, Type: System.Int32) (Syntax: 'i1')
-                          Instance Receiver: 
-                            IInstanceReferenceOperation (OperationKind.InstanceReference, Type: C, IsImplicit) (Syntax: 'i1')
+            null
       IBlockOperation (1 statements) (OperationKind.Block, Type: null, IsInvalid) (Syntax: '{ ... }')
         IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null, IsInvalid) (Syntax: 'i3 = &p1;')
           Expression: 

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

@@ -583,22 +583,25 @@ static void Main()
   Body: 
     IBlockOperation (1 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Boolean b
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'bool b = !x ... uals(null);')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'b = !x.Equals(null)')
-          Variables: Local_1: System.Boolean b
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'bool b = !x ... uals(null);')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'bool b = !x.Equals(null)')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Boolean b) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'b = !x.Equals(null)')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= !x.Equals(null)')
+                    IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.Boolean, IsImplicit) (Syntax: '!x.Equals(null)')
+                      Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+                      Operand: 
+                        IUnaryOperation (UnaryOperatorKind.Not) (OperationKind.UnaryOperator, Type: System.Object) (Syntax: '!x.Equals(null)')
+                          Operand: 
+                            IInvalidOperation (OperationKind.Invalid, Type: ?) (Syntax: 'x.Equals(null)')
+                              Children(2):
+                                  IOperation:  (OperationKind.None, Type: null) (Syntax: 'x.Equals')
+                                    Children(1):
+                                        ILocalReferenceOperation: x (OperationKind.LocalReference, Type: MissingType) (Syntax: 'x')
+                                  ILiteralOperation (OperationKind.Literal, Type: null, Constant: null) (Syntax: 'null')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= !x.Equals(null)')
-              IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.Boolean, IsImplicit) (Syntax: '!x.Equals(null)')
-                Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
-                Operand: 
-                  IUnaryOperation (UnaryOperatorKind.Not) (OperationKind.UnaryOperator, Type: System.Object) (Syntax: '!x.Equals(null)')
-                    Operand: 
-                      IInvalidOperation (OperationKind.Invalid, Type: ?) (Syntax: 'x.Equals(null)')
-                        Children(2):
-                            IOperation:  (OperationKind.None, Type: null) (Syntax: 'x.Equals')
-                              Children(1):
-                                  ILocalReferenceOperation: x (OperationKind.LocalReference, Type: MissingType) (Syntax: 'x')
-                            ILiteralOperation (OperationKind.Literal, Type: null, Constant: null) (Syntax: 'null')
+            null
   NextVariables(0)
 ";
             VerifyOperationTreeForTest<ForEachStatementSyntax>(source, expectedOperationTree);

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

@@ -476,8 +476,7 @@ public unsafe void M(int[] array)
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'p = array')
-  Variables: Local_1: System.Int32* p
+IVariableDeclaratorOperation (Symbol: System.Int32* p) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'p = array')
   Initializer: 
     IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= array')
       IOperation:  (OperationKind.None, Type: null, IsImplicit) (Syntax: 'array')
@@ -576,8 +575,7 @@ public void M(dynamic d, int x)
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'y = d[x]')
-  Variables: Local_1: dynamic y
+IVariableDeclaratorOperation (Symbol: dynamic y) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'y = d[x]')
   Initializer: 
     IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= d[x]')
       IDynamicIndexerAccessOperation (OperationKind.DynamicIndexerAccess, Type: dynamic) (Syntax: 'd[x]')

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

@@ -33,15 +33,18 @@ public static void M1()
             string expectedOperationTree = @"
 IUsingOperation (OperationKind.Using, Type: null) (Syntax: 'using (var  ... }')
   Resources: 
-    IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'var c = new C()')
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c = new C()')
-        Variables: Local_1: C c
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-              Arguments(0)
+    IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'var c = new C()')
+      IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'var c = new C()')
+        Declarators:
+            IVariableDeclaratorOperation (Symbol: C c) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c = new C()')
               Initializer: 
-                null
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+        Initializer: 
+          null
   Body: 
     IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'Console.Wri ... oString());')
@@ -89,23 +92,25 @@ public static void M1()
             string expectedOperationTree = @"
 IUsingOperation (OperationKind.Using, Type: null) (Syntax: 'using (C c1 ... }')
   Resources: 
-    IVariableDeclarationsOperation (2 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'C c1 = new  ... 2 = new C()')
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c1 = new C()')
-        Variables: Local_1: C c1
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-              Arguments(0)
+    IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'C c1 = new  ... 2 = new C()')
+      IVariableDeclarationOperation (2 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'C c1 = new  ... 2 = new C()')
+        Declarators:
+            IVariableDeclaratorOperation (Symbol: C c1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c1 = new C()')
               Initializer: 
-                null
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c2 = new C()')
-        Variables: Local_1: C c2
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-              Arguments(0)
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+            IVariableDeclaratorOperation (Symbol: C c2) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c2 = new C()')
               Initializer: 
-                null
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+        Initializer: 
+          null
   Body: 
     IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'Console.Wri ... oString());')
@@ -201,27 +206,33 @@ public static void M1()
             string expectedOperationTree = @"
 IUsingOperation (OperationKind.Using, Type: null) (Syntax: 'using (var  ... }')
   Resources: 
-    IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'var c1 = new C()')
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c1 = new C()')
-        Variables: Local_1: C c1
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-              Arguments(0)
+    IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'var c1 = new C()')
+      IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'var c1 = new C()')
+        Declarators:
+            IVariableDeclaratorOperation (Symbol: C c1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c1 = new C()')
               Initializer: 
-                null
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+        Initializer: 
+          null
   Body: 
     IUsingOperation (OperationKind.Using, Type: null) (Syntax: 'using (var  ... }')
       Resources: 
-        IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'var c2 = new C()')
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c2 = new C()')
-            Variables: Local_1: C c2
-            Initializer: 
-              IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-                IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-                  Arguments(0)
+        IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsImplicit) (Syntax: 'var c2 = new C()')
+          IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'var c2 = new C()')
+            Declarators:
+                IVariableDeclaratorOperation (Symbol: C c2) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c2 = new C()')
                   Initializer: 
-                    null
+                    IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                      IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                        Arguments(0)
+                        Initializer: 
+                          null
+            Initializer: 
+              null
       Body: 
         IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
           IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'Console.Wri ... oString());')
@@ -336,23 +347,25 @@ public static void M1()
             string expectedOperationTree = @"
 IUsingOperation (OperationKind.Using, Type: null, IsInvalid) (Syntax: 'using (var  ... }')
   Resources: 
-    IVariableDeclarationsOperation (2 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'var c1 = ne ... 2 = new C()')
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'c1 = new C()')
-        Variables: Local_1: C c1
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C, IsInvalid) (Syntax: 'new C()')
-              Arguments(0)
+    IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid, IsImplicit) (Syntax: 'var c1 = ne ... 2 = new C()')
+      IVariableDeclarationOperation (2 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'var c1 = ne ... 2 = new C()')
+        Declarators:
+            IVariableDeclaratorOperation (Symbol: C c1) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'c1 = new C()')
               Initializer: 
-                null
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'c2 = new C()')
-        Variables: Local_1: C c2
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C, IsInvalid) (Syntax: 'new C()')
-              Arguments(0)
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C, IsInvalid) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+            IVariableDeclaratorOperation (Symbol: C c2) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'c2 = new C()')
               Initializer: 
-                null
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C, IsInvalid) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+        Initializer: 
+          null
   Body: 
     IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'Console.Wri ... oString());')
@@ -415,24 +428,30 @@ public static void M1()
 IBlockOperation (5 statements, 2 locals) (OperationKind.Block, Type: null, IsInvalid) (Syntax: '{ ... }')
   Locals: Local_1: C c1
     Local_2: C c2
-  IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'var c1 = new C();')
-    IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c1 = new C()')
-      Variables: Local_1: C c1
-      Initializer: 
-        IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-          IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-            Arguments(0)
+  IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'var c1 = new C();')
+    IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'var c1 = new C()')
+      Declarators:
+          IVariableDeclaratorOperation (Symbol: C c1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c1 = new C()')
             Initializer: 
-              null
-  IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'var c2 = new C();')
-    IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c2 = new C()')
-      Variables: Local_1: C c2
+              IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                  Arguments(0)
+                  Initializer: 
+                    null
       Initializer: 
-        IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-          IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-            Arguments(0)
+        null
+  IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'var c2 = new C();')
+    IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'var c2 = new C()')
+      Declarators:
+          IVariableDeclaratorOperation (Symbol: C c2) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c2 = new C()')
             Initializer: 
-              null
+              IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+                IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+                  Arguments(0)
+                  Initializer: 
+                    null
+      Initializer: 
+        null
   IUsingOperation (OperationKind.Using, Type: null, IsInvalid) (Syntax: 'using (c1')
     Resources: 
       ILocalReferenceOperation: c1 (OperationKind.LocalReference, Type: C, IsInvalid) (Syntax: 'c1')
@@ -512,15 +531,18 @@ public static void M1()
             string expectedOperationTree = @"
 IUsingOperation (OperationKind.Using, Type: null, IsInvalid) (Syntax: 'using (var  ... }')
   Resources: 
-    IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'var c1 = new C()')
-      IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'c1 = new C()')
-        Variables: Local_1: C c1
-        Initializer: 
-          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= new C()')
-            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C, IsInvalid) (Syntax: 'new C()')
-              Arguments(0)
+    IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid, IsImplicit) (Syntax: 'var c1 = new C()')
+      IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'var c1 = new C()')
+        Declarators:
+            IVariableDeclaratorOperation (Symbol: C c1) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'c1 = new C()')
               Initializer: 
-                null
+                IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= new C()')
+                  IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C, IsInvalid) (Syntax: 'new C()')
+                    Arguments(0)
+                    Initializer: 
+                      null
+        Initializer: 
+          null
   Body: 
     IBlockOperation (1 statements) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       IExpressionStatementOperation (OperationKind.ExpressionStatement, Type: null) (Syntax: 'Console.Wri ... oString());')
@@ -767,15 +789,17 @@ public static void M1()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'var c = new C()')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c = new C()')
-    Variables: Local_1: C c
-    Initializer: 
-      IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
-        IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
-          Arguments(0)
-          Initializer: 
-            null
+IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'var c = new C()')
+  Declarators:
+      IVariableDeclaratorOperation (Symbol: C c) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c = new C()')
+        Initializer: 
+          IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
+            IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')
+              Arguments(0)
+              Initializer: 
+                null
+  Initializer: 
+    null
 ";
             var expectedDiagnostics = DiagnosticDescription.None;
 
@@ -880,8 +904,7 @@ public static void M1()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'c1 = new C()')
-  Variables: Local_1: C c1
+IVariableDeclaratorOperation (Symbol: C c1) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'c1 = new C()')
   Initializer: 
     IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= new C()')
       IObjectCreationOperation (Constructor: C..ctor()) (OperationKind.ObjectCreation, Type: C) (Syntax: 'new C()')

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

@@ -144,14 +144,17 @@ static void Main()
   Body: 
     IBlockOperation (2 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Int32 value
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int value = ++index;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'value = ++index')
-          Variables: Local_1: System.Int32 value
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int value = ++index;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int value = ++index')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 value) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'value = ++index')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
+                    IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
+                      Target: 
+                        ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
-              IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
-                Target: 
-                  ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
+            null
       IConditionalOperation (OperationKind.Conditional, Type: null) (Syntax: 'if (value > ... }')
         Condition: 
           IBinaryOperation (BinaryOperatorKind.GreaterThan) (OperationKind.BinaryOperator, Type: System.Boolean) (Syntax: 'value > 10')
@@ -206,14 +209,17 @@ static void Main()
   Body: 
     IBlockOperation (3 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Int32 value
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int value = ++index;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'value = ++index')
-          Variables: Local_1: System.Int32 value
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int value = ++index;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int value = ++index')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 value) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'value = ++index')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
+                    IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
+                      Target: 
+                        ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
-              IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
-                Target: 
-                  ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
+            null
       IConditionalOperation (OperationKind.Conditional, Type: null) (Syntax: 'if (value > ... }')
         Condition: 
           IBinaryOperation (BinaryOperatorKind.GreaterThan) (OperationKind.BinaryOperator, Type: System.Boolean) (Syntax: 'value > 5')
@@ -281,14 +287,17 @@ static void Main()
   Body: 
     IBlockOperation (3 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Int32 value
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int value = ++index;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'value = ++index')
-          Variables: Local_1: System.Int32 value
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int value = ++index;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int value = ++index')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 value) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'value = ++index')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
+                    IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
+                      Target: 
+                        ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
-              IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
-                Target: 
-                  ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
+            null
       IConditionalOperation (OperationKind.Conditional, Type: null) (Syntax: 'if (value > ... }')
         Condition: 
           IBinaryOperation (BinaryOperatorKind.GreaterThan) (OperationKind.BinaryOperator, Type: System.Boolean) (Syntax: 'value > 100')
@@ -571,14 +580,17 @@ static void Main()
   Body: 
     IBlockOperation (2 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Int32 value
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int value = ++index;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'value = ++index')
-          Variables: Local_1: System.Int32 value
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int value = ++index;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int value = ++index')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 value) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'value = ++index')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
+                    IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
+                      Target: 
+                        ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= ++index')
-              IIncrementOrDecrementOperation (Prefix) (OperationKind.Increment, Type: System.Int32) (Syntax: '++index')
-                Target: 
-                  ILocalReferenceOperation: index (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'index')
+            null
       IConditionalOperation (OperationKind.Conditional, Type: null) (Syntax: 'if (value > ... }')
         Condition: 
           IBinaryOperation (BinaryOperatorKind.GreaterThan) (OperationKind.BinaryOperator, Type: System.Boolean) (Syntax: 'value > 100')
@@ -735,12 +747,15 @@ static void Main()
           IIncrementOrDecrementOperation (Postfix) (OperationKind.Increment, Type: System.Int32) (Syntax: 'i++')
             Target: 
               ILocalReferenceOperation: i (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'i')
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int j = 0;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'j = 0')
-          Variables: Local_1: System.Int32 j
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int j = 0;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int j = 0')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 j) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'j = 0')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
+                    ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
-              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
+            null
       IWhileLoopOperation (LoopKind.While) (OperationKind.Loop, Type: null) (Syntax: 'while (j <  ... }')
         Condition: 
           IBinaryOperation (BinaryOperatorKind.LessThan) (OperationKind.BinaryOperator, Type: System.Boolean) (Syntax: 'j < 10')
@@ -820,12 +835,15 @@ static void Main()
           IIncrementOrDecrementOperation (Postfix) (OperationKind.Increment, Type: System.Int32) (Syntax: 'i++')
             Target: 
               ILocalReferenceOperation: i (OperationKind.LocalReference, Type: System.Int32) (Syntax: 'i')
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int j = 0;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'j = 0')
-          Variables: Local_1: System.Int32 j
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int j = 0;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int j = 0')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 j) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'j = 0')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
+                    ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
-              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
+            null
       IWhileLoopOperation (LoopKind.While) (OperationKind.Loop, Type: null) (Syntax: 'while (j <  ... }')
         Condition: 
           IBinaryOperation (BinaryOperatorKind.LessThan) (OperationKind.BinaryOperator, Type: System.Boolean) (Syntax: 'j < 10')

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

@@ -133,8 +133,7 @@ void F()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'y = x.MissingField')
-  Variables: Local_1: ? y
+IVariableDeclaratorOperation (Symbol: ? y) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'y = x.MissingField')
   Initializer: 
     IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= x.MissingField')
       IInvalidOperation (OperationKind.Invalid, Type: ?, IsInvalid) (Syntax: 'x.MissingField')
@@ -172,17 +171,20 @@ void F()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'string y = x.i1;')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'y = x.i1')
-    Variables: Local_1: System.String y
+IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid) (Syntax: 'string y = x.i1;')
+  IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'string y = x.i1')
+    Declarators:
+        IVariableDeclaratorOperation (Symbol: System.String y) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'y = x.i1')
+          Initializer: 
+            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= x.i1')
+              IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.String, IsInvalid, IsImplicit) (Syntax: 'x.i1')
+                Conversion: CommonConversion (Exists: False, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+                Operand: 
+                  IFieldReferenceOperation: System.Int32 Program.i1 (OperationKind.FieldReference, Type: System.Int32, IsInvalid) (Syntax: 'x.i1')
+                    Instance Receiver: 
+                      ILocalReferenceOperation: x (OperationKind.LocalReference, Type: Program, IsInvalid) (Syntax: 'x')
     Initializer: 
-      IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= x.i1')
-        IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: System.String, IsInvalid, IsImplicit) (Syntax: 'x.i1')
-          Conversion: CommonConversion (Exists: False, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
-          Operand: 
-            IFieldReferenceOperation: System.Int32 Program.i1 (OperationKind.FieldReference, Type: System.Int32, IsInvalid) (Syntax: 'x.i1')
-              Instance Receiver: 
-                ILocalReferenceOperation: x (OperationKind.LocalReference, Type: Program, IsInvalid) (Syntax: 'x')
+      null
 ";
             var expectedDiagnostics = new DiagnosticDescription[] {
                 // CS0029: Cannot implicitly convert type 'int' to 'string'
@@ -218,17 +220,20 @@ void F()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'Program y = ... ogram)x.i1;')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'y = (Program)x.i1')
-    Variables: Local_1: Program y
+IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid) (Syntax: 'Program y = ... ogram)x.i1;')
+  IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'Program y = ... rogram)x.i1')
+    Declarators:
+        IVariableDeclaratorOperation (Symbol: Program y) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'y = (Program)x.i1')
+          Initializer: 
+            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= (Program)x.i1')
+              IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: Program, IsInvalid) (Syntax: '(Program)x.i1')
+                Conversion: CommonConversion (Exists: False, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+                Operand: 
+                  IFieldReferenceOperation: System.Int32 Program.i1 (OperationKind.FieldReference, Type: System.Int32, IsInvalid) (Syntax: 'x.i1')
+                    Instance Receiver: 
+                      ILocalReferenceOperation: x (OperationKind.LocalReference, Type: Program, IsInvalid) (Syntax: 'x')
     Initializer: 
-      IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= (Program)x.i1')
-        IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: Program, IsInvalid) (Syntax: '(Program)x.i1')
-          Conversion: CommonConversion (Exists: False, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
-          Operand: 
-            IFieldReferenceOperation: System.Int32 Program.i1 (OperationKind.FieldReference, Type: System.Int32, IsInvalid) (Syntax: 'x.i1')
-              Instance Receiver: 
-                ILocalReferenceOperation: x (OperationKind.LocalReference, Type: Program, IsInvalid) (Syntax: 'x')
+      null
 ";
             var expectedDiagnostics = new DiagnosticDescription[] {
                 // CS0030: Cannot convert type 'int' to 'Program'
@@ -339,8 +344,7 @@ static void F()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'x = () => F()')
-  Variables: Local_1: var x
+IVariableDeclaratorOperation (Symbol: var x) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: 'x = () => F()')
   Initializer: 
     IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= () => F()')
       IAnonymousFunctionOperation (Symbol: lambda expression) (OperationKind.AnonymousFunction, Type: null, IsInvalid) (Syntax: '() => F()')

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

@@ -27,13 +27,15 @@ static void Main(string[] args)
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (2 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'int x, ( 1 );')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'x')
-    Variables: Local_1: System.Int32 x
-    Initializer: 
-      null
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: '( 1 ')
-    Variables: Local_1: System.Int32 
+IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid) (Syntax: 'int x, ( 1 );')
+  IVariableDeclarationOperation (2 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: 'int x, ( 1 ')
+    Declarators:
+        IVariableDeclaratorOperation (Symbol: System.Int32 x) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'x')
+          Initializer: 
+            null
+        IVariableDeclaratorOperation (Symbol: System.Int32 ) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: '( 1 ')
+          Initializer: 
+            null
     Initializer: 
       null
 ";

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

@@ -49,8 +49,7 @@ void M(int i)
       ICatchClauseOperation (Exception type: System.Exception) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Exce ... }')
         Locals: Local_1: System.Exception ex
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(Exception ex)')
-            Variables: Local_1: System.Exception ex
+          IVariableDeclaratorOperation (Symbol: System.Exception ex) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(Exception ex)')
             Initializer: 
               null
         Filter: 
@@ -120,8 +119,7 @@ void M(int i)
         ICatchClauseOperation (Exception type: System.Exception) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Exce ... }')
           Locals: Local_1: System.Exception ex
           ExceptionDeclarationOrExpression: 
-            IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(Exception ex)')
-              Variables: Local_1: System.Exception ex
+            IVariableDeclaratorOperation (Symbol: System.Exception ex) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(Exception ex)')
               Initializer: 
                 null
           Filter: 
@@ -175,8 +173,7 @@ static void Main()
       ICatchClauseOperation (Exception type: System.IO.IOException) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Syst ... }')
         Locals: Local_1: System.IO.IOException e
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.IO. ... xception e)')
-            Variables: Local_1: System.IO.IOException e
+          IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.IO. ... xception e)')
             Initializer: 
               null
         Filter: 
@@ -221,8 +218,7 @@ static void Main()
       ICatchClauseOperation (Exception type: System.IO.IOException) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Syst ... }')
         Locals: Local_1: System.IO.IOException e
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.IO. ... xception e)')
-            Variables: Local_1: System.IO.IOException e
+          IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.IO. ... xception e)')
             Initializer: 
               null
         Filter: 
@@ -275,8 +271,7 @@ static void Main()
       ICatchClauseOperation (Exception type: System.IO.IOException) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Syst ... }')
         Locals: Local_1: System.IO.IOException e
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.IO. ... xception e)')
-            Variables: Local_1: System.IO.IOException e
+          IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.IO. ... xception e)')
             Initializer: 
               null
         Filter: 
@@ -286,8 +281,7 @@ static void Main()
       ICatchClauseOperation (Exception type: System.Exception) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Syst ... }')
         Locals: Local_1: System.Exception e
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.Exception e)')
-            Variables: Local_1: System.Exception e
+          IVariableDeclaratorOperation (Symbol: System.Exception e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.Exception e)')
             Initializer: 
               null
         Filter: 
@@ -344,8 +338,7 @@ static void Main()
       ICatchClauseOperation (Exception type: System.IO.IOException) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Syst ... }')
         Locals: Local_1: System.IO.IOException e
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.IO. ... xception e)')
-            Variables: Local_1: System.IO.IOException e
+          IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.IO. ... xception e)')
             Initializer: 
               null
         Filter: 
@@ -355,8 +348,7 @@ static void Main()
       ICatchClauseOperation (Exception type: System.IO.IOException) (OperationKind.CatchClause, Type: null, IsInvalid) (Syntax: 'catch (Syst ... }')
         Locals: Local_1: System.IO.IOException e
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: '(System.IO. ... xception e)')
-            Variables: Local_1: System.IO.IOException e
+          IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: '(System.IO. ... xception e)')
             Initializer: 
               null
         Filter: 
@@ -535,12 +527,15 @@ static void M(string s)
   Body: 
     IBlockOperation (1 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Int32 i
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int i = 0;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'i = 0')
-          Variables: Local_1: System.Int32 i
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int i = 0;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int i = 0')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 i) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'i = 0')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
+                    ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
-              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
+            null
   Catch clauses(1):
       ICatchClauseOperation (Exception type: System.Exception) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Exce ... }')
         ExceptionDeclarationOrExpression: 
@@ -595,12 +590,15 @@ static void M(string s)
         Handler: 
           IBlockOperation (1 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
             Locals: Local_1: System.Int32 i
-            IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int i = 0;')
-              IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'i = 0')
-                Variables: Local_1: System.Int32 i
+            IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int i = 0;')
+              IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int i = 0')
+                Declarators:
+                    IVariableDeclaratorOperation (Symbol: System.Int32 i) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'i = 0')
+                      Initializer: 
+                        IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
+                          ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
                 Initializer: 
-                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
-                    ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
+                  null
   Finally: 
     null
 ";
@@ -687,8 +685,7 @@ static void M(object o)
         Locals: Local_1: System.Exception e
           Local_2: System.String s
         ExceptionDeclarationOrExpression: 
-          IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(Exception e)')
-            Variables: Local_1: System.Exception e
+          IVariableDeclaratorOperation (Symbol: System.Exception e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(Exception e)')
             Initializer: 
               null
         Filter: 
@@ -738,12 +735,15 @@ Catch clauses(0)
   Finally: 
     IBlockOperation (1 statements, 1 locals) (OperationKind.Block, Type: null) (Syntax: '{ ... }')
       Locals: Local_1: System.Int32 i
-      IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null) (Syntax: 'int i = 0;')
-        IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'i = 0')
-          Variables: Local_1: System.Int32 i
+      IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null) (Syntax: 'int i = 0;')
+        IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'int i = 0')
+          Declarators:
+              IVariableDeclaratorOperation (Symbol: System.Int32 i) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'i = 0')
+                Initializer: 
+                  IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
+                    ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
           Initializer: 
-            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= 0')
-              ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 0) (Syntax: '0')
+            null
 ";
             var expectedDiagnostics = new DiagnosticDescription[] {
                 // CS0219: The variable 'i' is assigned but its value is never used
@@ -776,8 +776,7 @@ static void Main()
 ICatchClauseOperation (Exception type: System.Int32) (OperationKind.CatchClause, Type: null, IsInvalid) (Syntax: 'catch (int  ... }')
   Locals: Local_1: System.Int32 e
   ExceptionDeclarationOrExpression: 
-    IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: '(int e)')
-      Variables: Local_1: System.Int32 e
+    IVariableDeclaratorOperation (Symbol: System.Int32 e) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: '(int e)')
       Initializer: 
         null
   Filter: 
@@ -819,8 +818,7 @@ static void Main()
 ICatchClauseOperation (Exception type: System.IO.IOException) (OperationKind.CatchClause, Type: null) (Syntax: 'catch (Syst ... }')
   Locals: Local_1: System.IO.IOException e
   ExceptionDeclarationOrExpression: 
-    IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.IO. ... xception e)')
-      Variables: Local_1: System.IO.IOException e
+    IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.IO. ... xception e)')
       Initializer: 
         null
   Filter: 
@@ -861,8 +859,7 @@ static void Main()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: '(System.IO. ... xception e)')
-  Variables: Local_1: System.IO.IOException e
+IVariableDeclaratorOperation (Symbol: System.IO.IOException e) (OperationKind.VariableDeclarator, Type: null) (Syntax: '(System.IO. ... xception e)')
   Initializer: 
     null
 ";

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

@@ -1828,8 +1828,7 @@ public void Deconstruct(out int x1, out int x2, out int x3, out int x4, out int
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null) (Syntax: 'y = (x, x,  ... ) = new C()')
-  Variables: Local_1: (System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64) y
+IVariableDeclaratorOperation (Symbol: (System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64) y) (OperationKind.VariableDeclarator, Type: null) (Syntax: 'y = (x, x,  ... ) = new C()')
   Initializer: 
     IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null) (Syntax: '= (x, x, x, ... ) = new C()')
       IDeconstructionAssignmentOperation (OperationKind.DeconstructionAssignment, Type: (System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64, System.Int64)) (Syntax: '(x, x, x, x ... ) = new C()')
@@ -3905,18 +3904,21 @@ static void Main()
 }
 ";
             string expectedOperationTree = @"
-IVariableDeclarationsOperation (1 declarations) (OperationKind.VariableDeclarations, Type: null, IsInvalid) (Syntax: 'const (int  ... ) = (1, 2);')
-  IVariableDeclarationOperation (1 variables) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: '= (1, 2)')
-    Variables: Local_1: (System.Int32 x, System.Int32 y) 
+IVariableDeclarationGroupOperation (1 declarations) (OperationKind.VariableDeclarationGroup, Type: null, IsInvalid) (Syntax: 'const (int  ... ) = (1, 2);')
+  IVariableDeclarationOperation (1 declarators) (OperationKind.VariableDeclaration, Type: null, IsInvalid) (Syntax: '(int x, int y) = (1, 2)')
+    Declarators:
+        IVariableDeclaratorOperation (Symbol: (System.Int32 x, System.Int32 y) ) (OperationKind.VariableDeclarator, Type: null, IsInvalid) (Syntax: '= (1, 2)')
+          Initializer: 
+            IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= (1, 2)')
+              IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: (System.Int32 x, System.Int32 y), IsImplicit) (Syntax: '(1, 2)')
+                Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+                Operand: 
+                  ITupleOperation (OperationKind.Tuple, Type: (System.Int32, System.Int32)) (Syntax: '(1, 2)')
+                    Elements(2):
+                        ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
+                        ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
     Initializer: 
-      IVariableInitializerOperation (OperationKind.VariableInitializer, Type: null, IsInvalid) (Syntax: '= (1, 2)')
-        IConversionOperation (TryCast: False, Unchecked) (OperationKind.Conversion, Type: (System.Int32 x, System.Int32 y), IsImplicit) (Syntax: '(1, 2)')
-          Conversion: CommonConversion (Exists: True, IsIdentity: True, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
-          Operand: 
-            ITupleOperation (OperationKind.Tuple, Type: (System.Int32, System.Int32)) (Syntax: '(1, 2)')
-              Elements(2):
-                  ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 1) (Syntax: '1')
-                  ILiteralOperation (OperationKind.Literal, Type: System.Int32, Constant: 2) (Syntax: '2')
+      null
 ";
             var expectedDiagnostics = new DiagnosticDescription[] {
                 // CS1001: Identifier expected

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

@@ -3,7 +3,7 @@
 namespace Microsoft.CodeAnalysis.Operations
 {
     /// <summary>
-    /// Represents a declaration expression operation. Unlike a regular variable declaration <see cref="IVariableDeclarationOperation"/>, this operation represents an "expression" declaring a variable.
+    /// Represents a declaration expression operation. Unlike a regular variable declaration <see cref="IVariableDeclaratorOperation"/> and <see cref="IVariableDeclarationOperation"/>, this operation represents an "expression" declaring a variable.
     /// <para>
     /// Current usage:
     ///  (1) C# declaration expression. For example,

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

@@ -17,7 +17,7 @@ internal interface IFixedOperation : IOperation
         /// <summary>
         /// Variables to be fixed.
         /// </summary>
-        IVariableDeclarationsOperation Variables { get; }
+        IVariableDeclarationGroupOperation Variables { get; }
         /// <summary>
         /// Body of the fixed, over which the variables are fixed.
         /// </summary>

src/Compilers/Core/Portable/Operations/IVariableDeclarationsOperation.cs → src/Compilers/Core/Portable/Operations/IVariableDeclarationGroupOperation.cs

@@ -5,23 +5,28 @@
 namespace Microsoft.CodeAnalysis.Operations
 {
     /// <summary>
-    /// Represents an operation with one or more <see cref="IVariableDeclarationOperation"/>.
+    /// Represents a variable declaration statement.
+    /// </summary>
     /// <para>
-    /// Current usage:
-    ///  (1) C# local declaration statement.
-    ///  (2) VB Dim statement.
+    /// Current Usage:
+    ///   (1) C# local declaration statement
+    ///   (2) C# fixed statement
+    ///   (3) C# using statement
+    ///   (4) VB Dim statement
+    ///   (5) VB Using statement
     /// </para>
-    /// </summary>
     /// <remarks>
     /// This interface is reserved for implementation by its associated APIs. We reserve the right to
     /// change it in the future.
     /// </remarks>
-    public interface IVariableDeclarationsOperation : IOperation
+    public interface IVariableDeclarationGroupOperation : IOperation
     {
         /// <summary>
-        /// Variables declared.
+        /// Variable declaration in the statement.
         /// </summary>
+        /// <remarks>
+        /// In C#, this will always be a single declaration, with all variables in <see cref="IVariableDeclarationOperation.Declarators"/>.
+        /// </remarks>
         ImmutableArray<IVariableDeclarationOperation> Declarations { get; }
     }
 }
-

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

@@ -5,29 +5,42 @@
 namespace Microsoft.CodeAnalysis.Operations
 {
     /// <summary>
-    /// Represents a local variable declaration.
+    /// Represents a declarator that declares multiple individual variables.
+    /// </summary>
     /// <para>
-    /// Current usage:
-    ///  (1) C# local variable declaration in local declaration statement, catch clause, etc.
-    ///  (2) VB local variable declaration in Dim statement, catch clause, etc.
+    /// Current Usage:
+    ///   (1) C# VariableDeclaration
+    ///   (2) C# fixed declarations
+    ///   (3) C# using declarations
+    ///   (4) VB Dim statement declaration groups
+    ///   (5) VB Using statement variable declarations
     /// </para>
-    /// </summary>
     /// <remarks>
+    /// The initializer of this node is applied to all individual declarations in <see cref="Declarators"/>. There cannot
+    /// be initializers in both locations except in invalid code scenarios.
+    /// In C#, this node will never have an initializer.
+    /// This corresponds to the VariableDeclarationSyntax in C#, and the VariableDeclaratorSyntax in Visual Basic.
+    ///
     /// This interface is reserved for implementation by its associated APIs. We reserve the right to
     /// change it in the future.
     /// </remarks>
     public interface IVariableDeclarationOperation : IOperation
     {
         /// <summary>
-        /// Symbols declared by the declaration. In VB, it's possible to declare multiple variables with the
-        /// same initializer. In C#, this will always have a single symbol.
+        /// Individual variable declarations declared by this multiple declaration.
         /// </summary>
-        ImmutableArray<ILocalSymbol> Variables { get; }
+        /// <remarks>
+        /// All <see cref="IVariableDeclarationGroupOperation"/> will have at least 1 <code>IVariableDeclarationOpertion</code>,
+        /// even if the declaration group only declares 1 variable.
+        /// </remarks>
+        ImmutableArray<IVariableDeclaratorOperation> Declarators { get; }
 
         /// <summary>
         /// Optional initializer of the variable.
         /// </summary>
+        /// <remarks>
+        /// In C#, this will always be null.
+        /// </remarks>
         IVariableInitializerOperation Initializer { get; }
     }
 }
-

src/Compilers/VisualBasic/Portable/BoundTree/BoundNodes.xml

@@ -1014,7 +1014,8 @@
   -->
     <Node Name="BoundLocalDeclaration" Base="BoundLocalDeclarationBase" HasValidate="true">
         <Field Name="LocalSymbol" Type="LocalSymbol"/>
-        <Field Name="InitializerOpt" Type="BoundExpression" Null="allow"/>
+        <Field Name="DeclarationInitializerOpt" Type="BoundExpression" Null="allow" />
+        <Field Name="IdentifierInitializerOpt" Type="BoundArrayCreation" Null="allow"/>
         <Field Name="InitializedByAsNew" Type="Boolean" />
     </Node>