Make BoundUsingStatement.Declarations follow documentation in VB, updated tests to match.

src/Compilers/VisualBasic/Portable/BoundTree/Statement.vb

@@ -1461,7 +1461,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                 Return s_variablesMappings.GetValue(
                     Me,
                     Function(BoundUsing)
-                        Dim usingStatementSyntax = Syntax.ChildNodes().OfType(Of UsingStatementSyntax).SingleOrDefault()
+                        If (BoundUsing.ResourceList.IsDefault) Then
+                            Return Nothing
+                        End If
+                        Dim usingStatementSyntax = DirectCast(Syntax.ChildNodes()(0), UsingStatementSyntax)
                         Return New Variables(BoundUsing.ResourceList.As(Of IVariableDeclaration), usingStatementSyntax)
                     End Function)
             End Get

src/Compilers/VisualBasic/Test/Semantic/BasicCompilerSemanticTest.vbproj

@@ -128,6 +128,7 @@
     <Compile Include="FlowAnalysis\RegionAnalysisTestsWithStaticLocals.vb" />
     <Compile Include="FlowAnalysis\StructureAnalysisTests.vb" />
     <Compile Include="FlowAnalysis\TryLockUsingStatementTests.vb" />
+    <Compile Include="IOperation\IOperationTests_IUsingStatement.vb" />
     <Compile Include="IOperation\IOperationTests_IVariableDeclaration.vb" />
     <Compile Include="Resource.Designer.vb">
       <AutoGen>True</AutoGen>

src/Compilers/VisualBasic/Test/Semantic/IOperation/IOperationTests.vb

@@ -352,106 +352,5 @@ BC30581: 'AddressOf' expression cannot be converted to 'Integer' because 'Intege
     IObjectCreationExpression (Constructor: Sub System.Guid..ctor()) (OperationKind.ObjectCreationExpression, Type: System.Guid) (Syntax: 'New System.Guid()')
     IOperation:  (OperationKind.None) (Syntax: 'AddressOf Main')")
         End Sub
-
-        <Fact>
-        <WorkItem(19819, "https://github.com/dotnet/roslyn/issues/19819")>
-        Public Sub UsingDeclarationSyntaxNotNull()
-            Dim source = <compilation>
-                             <file name="c.vb">
-                                 <![CDATA[
-Imports System
-Module Module1
-    Class C1
-        Implements IDisposable
-        Public Sub Dispose() Implements IDisposable.Dispose
-            Throw New NotImplementedException()
-        End Sub
-    End Class
-    Sub S1()
-        Using D1 as New C1()
-        End Using
-    End Sub
-End Module
-]]>
-                             </file>
-                         </compilation>
-
-            Dim comp = CreateCompilationWithMscorlibAndVBRuntime(source, parseOptions:=TestOptions.RegularWithIOperationFeature)
-            Dim tree = comp.SyntaxTrees.Single()
-            Dim node = tree.GetRoot().DescendantNodes().OfType(Of UsingBlockSyntax).Single()
-            Dim op = DirectCast(comp.GetSemanticModel(tree).GetOperationInternal(node), IUsingStatement)
-
-            Assert.NotNull(op.Declaration.Syntax)
-            Assert.Equal("Using D1 as New C1()", op.Declaration.Syntax.ToString())
-        End Sub
-
-        <Fact>
-        <WorkItem(19819, "https://github.com/dotnet/roslyn/issues/19819")>
-        Public Sub UsingDeclarationIncompleteUsingNotNullSyntax()
-            Dim source = <compilation>
-                             <file name="c.vb">
-                                 <![CDATA[
-Imports System
-Module Module1
-    Class C1
-        Implements IDisposable
-        Public Sub Dispose() Implements IDisposable.Dispose
-            Throw New NotImplementedException()
-        End Sub
-    End Class
-    Sub S1()
-        Using
-        End Using
-    End Sub
-End Module
-]]>
-                             </file>
-                         </compilation>
-
-            Dim comp = CreateCompilationWithMscorlibAndVBRuntime(source, parseOptions:=TestOptions.RegularWithIOperationFeature)
-            Dim tree = comp.SyntaxTrees.Single()
-            Dim node = tree.GetRoot().DescendantNodes().OfType(Of UsingBlockSyntax).Single()
-            Dim op = DirectCast(comp.GetSemanticModel(tree).GetOperationInternal(node), IUsingStatement)
-
-            Assert.NotNull(op.Declaration.Syntax)
-            Assert.Equal("Using", op.Declaration.Syntax.ToString())
-        End Sub
-
-        <Fact>
-        Public Sub UsingDeclarationExistingVariableNonNullSyntax()
-            ' TODO: This will need to be removed when https://github.com/dotnet/roslyn/issues/19887 is fixed.
-            ' The docs for IUsingStatement.Declaration state that it should be returning null when the
-            ' using statement does not declare any variables. However, it currently does not. When that is
-            ' fixed, this test should be updated to correctly reflect that assertion.
-
-            Dim source = <compilation>
-                             <file name="c.vb">
-                                 <![CDATA[
-Imports System
-Module Module1
-    Class C1
-        Implements IDisposable
-        Public Sub Dispose() Implements IDisposable.Dispose
-            Throw New NotImplementedException()
-        End Sub
-    End Class
-    Sub S1()
-        Dim x = New C1()
-        Using x
-        End Using
-    End Sub
-End Module
-]]>
-                             </file>
-                         </compilation>
-
-            Dim comp = CreateCompilationWithMscorlibAndVBRuntime(source, parseOptions:=TestOptions.RegularWithIOperationFeature)
-            Dim tree = comp.SyntaxTrees.Single()
-            Dim node = tree.GetRoot().DescendantNodes().OfType(Of UsingBlockSyntax).Single()
-            Dim op = DirectCast(comp.GetSemanticModel(tree).GetOperationInternal(node), IUsingStatement)
-
-            Assert.NotNull(op.Declaration.Syntax)
-            Assert.Equal("Using x", op.Declaration.Syntax.ToString())
-        End Sub
     End Class
 End Namespace

src/Compilers/VisualBasic/Test/Semantic/IOperation/IOperationTests_IUsingStatement.vb

+Imports Microsoft.CodeAnalysis.Semantics
+Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
+Imports Roslyn.Test.Utilities
+
+Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests.Semantics
+    Partial Public Class IOperationTests
+        Inherits SemanticModelTestBase
+
+        <Fact>
+        <WorkItem(19819, "https://github.com/dotnet/roslyn/issues/19819")>
+        Public Sub UsingDeclarationSyntaxNotNull()
+            Dim source = <compilation>
+                             <file name="c.vb">
+                                 <![CDATA[
+Imports System
+Module Module1
+    Class C1
+        Implements IDisposable
+        Public Sub Dispose() Implements IDisposable.Dispose
+            Throw New NotImplementedException()
+        End Sub
+    End Class
+    Sub S1()
+        Using D1 as New C1()
+        End Using
+    End Sub
+End Module
+]]>
+                             </file>
+                         </compilation>
+
+            Dim comp = CreateCompilationWithMscorlibAndVBRuntime(source, parseOptions:=TestOptions.RegularWithIOperationFeature)
+            CompilationUtils.AssertNoDiagnostics(comp)
+
+            Dim tree = comp.SyntaxTrees.Single()
+            Dim node = tree.GetRoot().DescendantNodes().OfType(Of UsingBlockSyntax).Single()
+            Dim op = DirectCast(comp.GetSemanticModel(tree).GetOperationInternal(node), IUsingStatement)
+
+            Assert.NotNull(op.Declaration.Syntax)
+            Assert.Same(node.UsingStatement, op.Declaration.Syntax)
+        End Sub
+
+        <Fact>
+        <WorkItem(19887, "https://github.com/dotnet/roslyn/issues/19887")>
+        Public Sub UsingDeclarationIncompleteUsingNullDeclaration()
+            Dim source = <compilation>
+                             <file name="c.vb">
+                                 <![CDATA[
+Imports System
+Module Module1
+    Class C1
+        Implements IDisposable
+        Public Sub Dispose() Implements IDisposable.Dispose
+            Throw New NotImplementedException()
+        End Sub
+    End Class
+    Sub S1()
+        Using
+        End Using
+    End Sub
+End Module
+]]>
+                             </file>
+                         </compilation>
+
+            Dim comp = CreateCompilationWithMscorlibAndVBRuntime(source, parseOptions:=TestOptions.RegularWithIOperationFeature)
+            CompilationUtils.AssertTheseDiagnostics(comp,
+                                        <expected>
+BC30201: Expression expected.
+        Using
+             ~
+                                        </expected>)
+
+            Dim tree = comp.SyntaxTrees.Single()
+            Dim node = tree.GetRoot().DescendantNodes().OfType(Of UsingBlockSyntax).Single()
+            Dim op = DirectCast(comp.GetSemanticModel(tree).GetOperationInternal(node), IUsingStatement)
+
+            Assert.Null(op.Declaration)
+        End Sub
+
+        <Fact>
+        <WorkItem(19887, "https://github.com/dotnet/roslyn/issues/19887")>
+        Public Sub UsingDeclarationExistingVariableNullDeclaration()
+            Dim source = <compilation>
+                             <file name="c.vb">
+                                 <![CDATA[
+Imports System
+Module Module1
+    Class C1
+        Implements IDisposable
+        Public Sub Dispose() Implements IDisposable.Dispose
+            Throw New NotImplementedException()
+        End Sub
+    End Class
+    Sub S1()
+        Dim x = New C1()
+        Using x
+        End Using
+    End Sub
+End Module
+]]>
+                             </file>
+                         </compilation>
+
+            Dim comp = CreateCompilationWithMscorlibAndVBRuntime(source, parseOptions:=TestOptions.RegularWithIOperationFeature)
+            CompilationUtils.AssertNoDiagnostics(comp)
+
+            Dim tree = comp.SyntaxTrees.Single()
+            Dim node = tree.GetRoot().DescendantNodes().OfType(Of UsingBlockSyntax).Single()
+            Dim op = DirectCast(comp.GetSemanticModel(tree).GetOperationInternal(node), IUsingStatement)
+
+            Assert.Null(op.Declaration)
+        End Sub
+    End Class
+End Namespace