Also expose the deconstruction assignment in foreach loop control variable declaration

Fixes #16372

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

@@ -1251,7 +1251,7 @@ private IForEachLoopStatement CreateBoundForEachStatementOperation(BoundForEachS
             Lazy<IOperation> loopControlVariable;
             if (boundForEachStatement.DeconstructionOpt != null)
             {
-                loopControlVariable = new Lazy<IOperation>(() => Create(boundForEachStatement.DeconstructionOpt));
+                loopControlVariable = new Lazy<IOperation>(() => Create(boundForEachStatement.DeconstructionOpt.DeconstructionAssignment));
             }
             else if (locals.Length == 1)
             {

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

@@ -872,7 +872,14 @@ public static void M((int, int)[] x)
 IForEachLoopStatement (LoopKind.ForEach) (OperationKind.LoopStatement) (Syntax: 'foreach (va ... }')
   Locals: Local_1: System.Int32 a
     Local_2: System.Int32 b
-  LoopControlVariable: IOperation:  (OperationKind.None) (Syntax: 'var (a, b)')
+  LoopControlVariable: IDeconstructionAssignmentExpression (OperationKind.DeconstructionAssignmentExpression, Type: (System.Int32 a, System.Int32 b)) (Syntax: 'var (a, b)')
+      Left: ITupleExpression (OperationKind.TupleExpression, Type: (System.Int32 a, System.Int32 b)) (Syntax: 'var (a, b)')
+          Elements(2):
+              ILocalReferenceExpression: a (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.Int32) (Syntax: 'a')
+              ILocalReferenceExpression: b (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.Int32) (Syntax: 'b')
+      Right: IConversionExpression (Implicit, TryCast: False, Unchecked) (OperationKind.ConversionExpression, Type: (System.Int32 a, System.Int32 b)) (Syntax: 'x')
+          Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+          Operand: IPlaceholderExpression (OperationKind.None) (Syntax: 'x')
   Collection: IConversionExpression (Implicit, TryCast: False, Unchecked) (OperationKind.ConversionExpression, Type: System.Collections.IEnumerable) (Syntax: 'x')
       Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: True, IsUserDefined: False) (MethodSymbol: null)
       Operand: IParameterReferenceExpression: x (OperationKind.ParameterReferenceExpression, Type: (System.Int32, System.Int32)[]) (Syntax: 'x')
@@ -904,7 +911,17 @@ public static void M((int, (int, int))[] x)
   Locals: Local_1: System.Int32 a
     Local_2: System.Int32 b
     Local_3: System.Int32 c
-  LoopControlVariable: IOperation:  (OperationKind.None) (Syntax: 'var (a, (b, c))')
+  LoopControlVariable: IDeconstructionAssignmentExpression (OperationKind.DeconstructionAssignmentExpression, Type: (System.Int32 a, (System.Int32 b, System.Int32 c))) (Syntax: 'var (a, (b, c))')
+      Left: ITupleExpression (OperationKind.TupleExpression, Type: (System.Int32 a, (System.Int32 b, System.Int32 c))) (Syntax: 'var (a, (b, c))')
+          Elements(2):
+              ILocalReferenceExpression: a (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.Int32) (Syntax: 'a')
+              ITupleExpression (OperationKind.TupleExpression, Type: (System.Int32 b, System.Int32 c)) (Syntax: '(b, c)')
+                Elements(2):
+                    ILocalReferenceExpression: b (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.Int32) (Syntax: 'b')
+                    ILocalReferenceExpression: c (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.Int32) (Syntax: 'c')
+      Right: IConversionExpression (Implicit, TryCast: False, Unchecked) (OperationKind.ConversionExpression, Type: (System.Int32 a, (System.Int32 b, System.Int32 c))) (Syntax: 'x')
+          Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+          Operand: IPlaceholderExpression (OperationKind.None) (Syntax: 'x')
   Collection: IConversionExpression (Implicit, TryCast: False, Unchecked) (OperationKind.ConversionExpression, Type: System.Collections.IEnumerable) (Syntax: 'x')
       Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: True, IsUserDefined: False) (MethodSymbol: null)
       Operand: IParameterReferenceExpression: x (OperationKind.ParameterReferenceExpression, Type: (System.Int32, (System.Int32, System.Int32))[]) (Syntax: 'x')

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

@@ -986,7 +986,14 @@ public void M()
 IForEachLoopStatement (LoopKind.ForEach) (OperationKind.LoopStatement) (Syntax: 'foreach (va ... }')
   Locals: Local_1: System.UInt32 x
     Local_2: System.UInt32 y
-  LoopControlVariable: IOperation:  (OperationKind.None) (Syntax: 'var (x, y)')
+  LoopControlVariable: IDeconstructionAssignmentExpression (OperationKind.DeconstructionAssignmentExpression, Type: (System.UInt32 x, System.UInt32 y)) (Syntax: 'var (x, y)')
+      Left: ITupleExpression (OperationKind.TupleExpression, Type: (System.UInt32 x, System.UInt32 y)) (Syntax: 'var (x, y)')
+          Elements(2):
+              ILocalReferenceExpression: x (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.UInt32) (Syntax: 'x')
+              ILocalReferenceExpression: y (IsDeclaration: True) (OperationKind.LocalReferenceExpression, Type: System.UInt32) (Syntax: 'y')
+      Right: IConversionExpression (Implicit, TryCast: False, Unchecked) (OperationKind.ConversionExpression, Type: (System.UInt32 x, System.UInt32 y)) (Syntax: 'new Point[] ... int(0, 1) }')
+          Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: False, IsUserDefined: False) (MethodSymbol: null)
+          Operand: IPlaceholderExpression (OperationKind.None) (Syntax: 'new Point[] ... int(0, 1) }')
   Collection: IConversionExpression (Implicit, TryCast: False, Unchecked) (OperationKind.ConversionExpression, Type: System.Collections.IEnumerable) (Syntax: 'new Point[] ... int(0, 1) }')
       Conversion: CommonConversion (Exists: True, IsIdentity: False, IsNumeric: False, IsReference: True, IsUserDefined: False) (MethodSymbol: null)
       Operand: IArrayCreationExpression (OperationKind.ArrayCreationExpression, Type: Point[]) (Syntax: 'new Point[] ... int(0, 1) }')