Merge branch 'dev15.6' of https://github.com/dotnet/roslyn into remoteCancellation

build/Rulesets/NonShippingProject_BuildRules.ruleset

@@ -26,4 +26,9 @@
     <!-- Do not use generic CodeAction.Create to create CodeAction - not useful for tests -->
     <Rule Id="RS0005" Action="None" />
   </Rules>
+  
+  <Rules AnalyzerId="Microsoft.CodeQuality.Analyzers.QualityGuidelines" RuleNamespace="Microsoft.CodeQuality.Analyzers.QualityGuidelines">
+    <!-- Mark constant field as 'const' instead of static readonly - not useful for tests -->
+    <Rule Id="CA1802" Action="None" />
+  </Rules>  
 </RuleSet>
\ No newline at end of file

build/Rulesets/Roslyn_BuildRules.ruleset

@@ -36,15 +36,15 @@
     <Rule Id="CA1720" Action="None" />
     <Rule Id="CA1721" Action="None" />
     <Rule Id="CA1724" Action="None" />
-    <Rule Id="CA1801" Action="None" /> <!-- unused parameters: broken due to https://github.com/dotnet/roslyn/issues/8884 -->
-    <Rule Id="CA1802" Action="None" /> <!-- broken due to https://github.com/dotnet/roslyn-analyzers/issues/1175 -->
-    <Rule Id="CA1804" Action="None" /> <!-- broken due to incomplete IOperation support -->
+    <Rule Id="CA1801" Action="None" /> <!-- https://github.com/dotnet/roslyn/issues/20405: Enable rule CA1801 (remove unused parameter) in Roslyn.sln once we have a fixer for it -->
+    <Rule Id="CA1802" Action="Warning" />
+    <Rule Id="CA1804" Action="None" /> <!-- https://github.com/dotnet/roslyn/issues/20406: Enable rule CA1804 (remove unused local) in Roslyn.sln once we have a fixer for it -->
     <Rule Id="CA1806" Action="None" /> <!-- "do not ignore results": we do this in many places, for example fire-and-forget async or HRESULTs we don't care about -->
     <Rule Id="CA1812" Action="None" /> <!-- disabled as we create many internal types via reflection-based mechanisms -->
     <Rule Id="CA1814" Action="None" /> <!-- prefer jagged arrays to multidimensional: a silly piece of advice -->
     <Rule Id="CA1815" Action="None" />
-    <Rule Id="CA1821" Action="None" /> <!-- broken due to https://github.com/dotnet/roslyn-analyzers/issues/1176 -->
-    <Rule Id="CA1823" Action="None" /> <!-- "avoid unused private fields": many issues including https://github.com/dotnet/roslyn-analyzers/issues/933 -->
+    <Rule Id="CA1821" Action="Warning" />
+    <Rule Id="CA1823" Action="None" /> <!-- https://github.com/dotnet/roslyn/issues/20404: Enable rule CA1823 (remove unused field) once we have a fixer for it -->
     <Rule Id="CA1824" Action="None" /> <!-- mark assemblies with NeutralResourcesLanguageAttribute -->
     <Rule Id="CA2007" Action="Warning" />
     <Rule Id="CA2211" Action="None" />
@@ -94,7 +94,7 @@
     <Rule Id="RS0027" Action="Error" />
   </Rules>
   <Rules AnalyzerId="System.Collections.Immutable.Analyzers" RuleNamespace="System.Collections.Immutable.Analyzers">
-    <Rule Id="RS0012" Action="None" />
+    <Rule Id="RS0012" Action="Warning" />
   </Rules>
   <Rules AnalyzerId="System.Runtime.Analyzers" RuleNamespace="System.Runtime.Analyzers">
     <Rule Id="CA1305" Action="None" />
@@ -102,7 +102,7 @@
     <Rule Id="CA1308" Action="None" />
     <Rule Id="CA1810" Action="None" />
     <Rule Id="CA1816" Action="None" />
-    <Rule Id="CA1825" Action="None" />
+    <Rule Id="CA1825" Action="Warning" />
     <Rule Id="CA2002" Action="None" />
     <Rule Id="CA2207" Action="None" />
     <Rule Id="CA2208" Action="None" />
@@ -110,7 +110,7 @@
     <Rule Id="CA2219" Action="None" />
     <Rule Id="CA2241" Action="None" />
     <Rule Id="CA2242" Action="None" />
-    <Rule Id="RS0014" Action="None" />
+    <Rule Id="RS0014" Action="Warning" />
   </Rules>
   <Rules AnalyzerId="System.Runtime.InteropServices.Analyzers" RuleNamespace="System.Runtime.InteropServices.Analyzers">
     <Rule Id="CA1401" Action="None" />

build/Targets/Packages.props

@@ -46,7 +46,7 @@
     <MicrosoftMetadataVisualizerVersion>1.0.0-beta1-61531-03</MicrosoftMetadataVisualizerVersion>
     <MicrosoftMSXMLVersion>8.0.0.0-alpha</MicrosoftMSXMLVersion>
     <MicrosoftNetCompilersVersion>2.3.0-beta3-61821-14</MicrosoftNetCompilersVersion>
-    <MicrosoftNetRoslynDiagnosticsVersion>2.0.0-beta1-61628-06</MicrosoftNetRoslynDiagnosticsVersion>
+    <MicrosoftNetRoslynDiagnosticsVersion>2.3.0-beta1</MicrosoftNetRoslynDiagnosticsVersion>
     <MicrosoftNetCoreILAsmVersion>1.1.0</MicrosoftNetCoreILAsmVersion>
     <MicrosoftNETCoreCompilersVersion>2.3.0-beta3-61821-14</MicrosoftNETCoreCompilersVersion>
     <MicrosoftNETCoreVersion>5.0.0</MicrosoftNETCoreVersion>

build/Targets/Settings.props

@@ -15,7 +15,7 @@
     <VSIXExpInstallerPackageName>RoslynTools.Microsoft.VSIXExpInstaller</VSIXExpInstallerPackageName>
     <VSIXExpInstallerPackageVersion>0.2.1-beta</VSIXExpInstallerPackageVersion>
     <RoslynDiagnosticsNugetPackageVersion>$(MicrosoftNetRoslynDiagnosticsVersion)</RoslynDiagnosticsNugetPackageVersion>
-    <RoslynDiagnosticsPropsFilePath>$(NuGetPackageRoot)\Microsoft.Net.RoslynDiagnostics\$(RoslynDiagnosticsNugetPackageVersion)\build\Microsoft.Net.RoslynDiagnostics.props</RoslynDiagnosticsPropsFilePath>
+    <RoslynDiagnosticsPropsFilePath>$(NuGetPackageRoot)\Microsoft.Net.RoslynDiagnostics\$(RoslynDiagnosticsNugetPackageVersion)\roslyn\Microsoft.Net.RoslynDiagnostics.props</RoslynDiagnosticsPropsFilePath>
     <RoslynBuildUtilFilePath>$(NuGetPackageRoot)\Roslyn.Build.Util\0.9.4-portable\lib\dotnet\Roslyn.MSBuild.Util.dll</RoslynBuildUtilFilePath>
     <RoslynRuntimeIdentifier Condition="'$(RoslynRuntimeIdentifier)' == '' AND '$(OS)' == 'Windows_NT'">win7-x64</RoslynRuntimeIdentifier>
     <Features>strict,IOperation</Features>

src/Compilers/CSharp/Portable/Errors/ErrorFacts.cs

@@ -11,8 +11,8 @@ namespace Microsoft.CodeAnalysis.CSharp
 {
     internal static partial class ErrorFacts
     {
-        private static readonly string s_titleSuffix = "_Title";
-        private static readonly string s_descriptionSuffix = "_Description";
+        private const string s_titleSuffix = "_Title";
+        private const string s_descriptionSuffix = "_Description";
         private static readonly Lazy<ImmutableDictionary<ErrorCode, string>> s_helpLinksMap = new Lazy<ImmutableDictionary<ErrorCode, string>>(CreateHelpLinks);
         private static readonly Lazy<ImmutableDictionary<ErrorCode, string>> s_categoriesMap = new Lazy<ImmutableDictionary<ErrorCode, string>>(CreateCategoriesMap);
 

src/Compilers/CSharp/Portable/Lowering/StateMachineRewriter/StateMachineStates.cs

@@ -4,8 +4,8 @@ namespace Microsoft.CodeAnalysis.CSharp
 {
     internal static class StateMachineStates
     {
-        internal readonly static int FinishedStateMachine = -2;
-        internal readonly static int NotStartedStateMachine = -1;
-        internal readonly static int FirstUnusedState = 0;
+        internal const int FinishedStateMachine = -2;
+        internal const int NotStartedStateMachine = -1;
+        internal const int FirstUnusedState = 0;
     }
 }

src/Compilers/CSharp/Portable/Symbols/TypeSymbol.cs

@@ -28,7 +28,7 @@ internal abstract partial class TypeSymbol : NamespaceOrTypeSymbol, ITypeSymbol
         // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
         // TODO (tomat): Consider changing this to an empty name. This name shouldn't ever leak to the user in error messages.
-        internal static readonly string ImplicitTypeName = "<invalid-global-code>";
+        internal const string ImplicitTypeName = "<invalid-global-code>";
 
         // InterfaceInfo for a common case of a type not implementing anything directly or indirectly.
         private static readonly InterfaceInfo s_noInterfaces = new InterfaceInfo();

src/Compilers/CSharp/Portable/Syntax/InternalSyntax/SyntaxToken.cs

@@ -131,8 +131,8 @@ internal static SyntaxToken CreateMissing(SyntaxKind kind, GreenNode leading, Gr
             return new MissingTokenWithTrivia(kind, leading, trailing);
         }
 
-        internal static readonly SyntaxKind FirstTokenWithWellKnownText = SyntaxKind.TildeToken;
-        internal static readonly SyntaxKind LastTokenWithWellKnownText = SyntaxKind.EndOfFileToken;
+        internal const SyntaxKind FirstTokenWithWellKnownText = SyntaxKind.TildeToken;
+        internal const SyntaxKind LastTokenWithWellKnownText = SyntaxKind.EndOfFileToken;
 
         // TODO: eliminate the blank space before the first interesting element?
         private static readonly ArrayElement<SyntaxToken>[] s_tokensWithNoTrivia = new ArrayElement<SyntaxToken>[(int)LastTokenWithWellKnownText + 1];

src/Compilers/CSharp/Test/Symbol/Symbols/Metadata/MetadataMemberTests.cs

@@ -14,7 +14,7 @@ namespace Microsoft.CodeAnalysis.CSharp.UnitTests
 {
     public class MetadataMemberTests : CSharpTestBase
     {
-        private static readonly string VTableGapClassIL = @"
+        private const string VTableGapClassIL = @"
 .class public auto ansi beforefieldinit Class
        extends [mscorlib]System.Object
 {

src/Compilers/CSharp/Test/Symbol/Symbols/Retargeting/NoPia.cs

@@ -17,7 +17,7 @@ public class NoPia : CSharpTestBase
         /// Translation of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\Pia1.vb
         /// Disassembly of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\Pia1.dll
         /// </summary>
-        private static readonly string s_sourcePia1 =
+        private const string s_sourcePia1 =
 @"
 using System;
 using System.Reflection;
@@ -58,7 +58,7 @@ public struct S2
         /// <summary>
         /// Disassembly of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\LocalTypes1.dll
         /// </summary>
-        private static readonly string s_sourceLocalTypes1_IL =
+        private const string s_sourceLocalTypes1_IL =
 @"
 using System;
 using System.Runtime.CompilerServices;
@@ -91,7 +91,7 @@ public interface I2
         /// <summary>
         /// Translation of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\LocalTypes1.vb
         /// </summary>
-        private static readonly string s_sourceLocalTypes1 =
+        private const string s_sourceLocalTypes1 =
 @"
 using NS1;
 
@@ -106,7 +106,7 @@ public void Test1(I1 x, I2 y)
         /// <summary>
         /// Disassembly of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\LocalTypes2.dll
         /// </summary>
-        private static readonly string s_sourceLocalTypes2_IL =
+        private const string s_sourceLocalTypes2_IL =
 @"
 using NS1;
 using System;
@@ -139,7 +139,7 @@ public struct S2
         /// <summary>
         /// Translation of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\LocalTypes2.vb
         /// </summary>
-        private static readonly string s_sourceLocalTypes2 =
+        private const string s_sourceLocalTypes2 =
 @"
 using NS1;
 
@@ -154,7 +154,7 @@ public void Test2(S1 x, S2 y)
         /// <summary>
         /// Disassembly of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\LocalTypes3.dll
         /// </summary>
-        private static readonly string s_sourceLocalTypes3_IL =
+        private const string s_sourceLocalTypes3_IL =
 @"
 using System;
 using System.Reflection;
@@ -219,7 +219,7 @@ public List<I1> Test6()
         /// <summary>
         /// Translation of Roslyn\Main\Open\Compilers\Test\Resources\Core\SymbolsTests\NoPia\LocalTypes3.vb
         /// </summary>
-        private static readonly string s_sourceLocalTypes3 =
+        private const string s_sourceLocalTypes3 =
 @"
 using System;
 using System.Collections.Generic;

src/Compilers/CSharp/Test/Symbol/Symbols/Source/SourcePlusMetadataTests.cs

@@ -171,7 +171,7 @@ struct Name5 {}
         }
 
         [WorkItem(527531, "http://vstfdevdiv:8080/DevDiv2/DevDiv/_workitems/edit/527531")]
-        [Fact]
+        [Fact(Skip = "https://github.com/dotnet/roslyn/issues/18985")]
         public void InterfaceName()
         {
             var text = @"

src/Compilers/CSharp/Test/Symbol/Symbols/SymbolErrorTests.cs

@@ -7841,7 +7841,7 @@ public static int Main()
                 new ErrorDescription { Code = (int)ErrorCode.ERR_CantOverrideNonVirtual, Line = 13, Column = 29 });
         }
 
-        private static readonly string s_typeWithMixedProperty = @"
+        private const string s_typeWithMixedProperty = @"
 .class public auto ansi beforefieldinit Base_VirtGet_Set
        extends [mscorlib]System.Object
 {

src/Compilers/Core/Portable/CodeGen/PermissionSetAttribute.cs

@@ -29,8 +29,8 @@ internal class PermissionSetAttributeWithFileReference : Cci.ICustomAttribute
     {
         private readonly Cci.ICustomAttribute _sourceAttribute;
         private readonly string _resolvedPermissionSetFilePath;
-        internal static readonly string FilePropertyName = "File";
-        internal static readonly string HexPropertyName = "Hex";
+        internal const string FilePropertyName = "File";
+        internal const string HexPropertyName = "Hex";
 
         public PermissionSetAttributeWithFileReference(Cci.ICustomAttribute sourceAttribute, string resolvedPermissionSetFilePath)
         {

src/Compilers/Core/Portable/Compilation/Compilation.cs

@@ -1094,7 +1094,7 @@ protected static ImmutableArray<string> CheckTupleElementNames(int cardinality,
 
         #region Diagnostics
 
-        internal static readonly CompilationStage DefaultDiagnosticsStage = CompilationStage.Compile;
+        internal const CompilationStage DefaultDiagnosticsStage = CompilationStage.Compile;
 
         /// <summary>
         /// Gets the diagnostics produced during the parsing stage.

src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerDriver.cs

@@ -51,7 +51,7 @@ internal abstract partial class AnalyzerDriver : IDisposable
         /// This mode should always guarantee that analyzer action callbacks are enabled for generated code, i.e. <see cref="GeneratedCodeAnalysisFlags.Analyze"/> is set.
         /// However, the default diagnostic reporting mode is liable to change in future.
         /// </remarks>
-        internal static readonly GeneratedCodeAnalysisFlags DefaultGeneratedCodeAnalysisFlags = GeneratedCodeAnalysisFlags.Analyze | GeneratedCodeAnalysisFlags.ReportDiagnostics;
+        internal const GeneratedCodeAnalysisFlags DefaultGeneratedCodeAnalysisFlags = GeneratedCodeAnalysisFlags.Analyze | GeneratedCodeAnalysisFlags.ReportDiagnostics;
 
         /// <summary>
         /// Map from non-concurrent analyzers to the gate guarding callback into the analyzer. 

src/Compilers/Core/Portable/FileSystem/PathUtilities.cs

@@ -17,9 +17,9 @@ internal static class PathUtilities
         // We consider '/' a directory separator on Unix like systems. 
         // On Windows both / and \ are equally accepted.
         internal static readonly char DirectorySeparatorChar = PlatformInformation.IsUnix ? '/' : '\\';
-        internal static readonly char AltDirectorySeparatorChar = '/';
-        internal static readonly string ParentRelativeDirectory = "..";
-        internal static readonly string ThisDirectory = ".";
+        internal const char AltDirectorySeparatorChar = '/';
+        internal const string ParentRelativeDirectory = "..";
+        internal const string ThisDirectory = ".";
         internal static readonly string DirectorySeparatorStr = new string(DirectorySeparatorChar, 1);
         internal const char VolumeSeparatorChar = ':';
         internal static bool IsUnixLikePlatform => PlatformInformation.IsUnix;

src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs

@@ -455,8 +455,8 @@ private bool IsMinimalDelta
 
         // Well known dummy cor library types whose refs are used for attaching assembly attributes off within net modules
         // There is no guarantee the types actually exist in a cor library
-        internal static readonly string dummyAssemblyAttributeParentNamespace = "System.Runtime.CompilerServices";
-        internal static readonly string dummyAssemblyAttributeParentName = "AssemblyAttributesGoHere";
+        internal const string dummyAssemblyAttributeParentNamespace = "System.Runtime.CompilerServices";
+        internal const string dummyAssemblyAttributeParentName = "AssemblyAttributesGoHere";
         internal static readonly string[,] dummyAssemblyAttributeParentQualifier = { { "", "M" }, { "S", "SM" } };
         private readonly TypeReferenceHandle[,] _dummyAssemblyAttributeParent = { { default(TypeReferenceHandle), default(TypeReferenceHandle) }, { default(TypeReferenceHandle), default(TypeReferenceHandle) } };
 

src/Compilers/Core/Portable/Serialization/ObjectWriter.cs

@@ -842,22 +842,22 @@ static ObjectWriter()
         /// <summary>
         /// byte marker mask for encoding compressed uint 
         /// </summary>
-        internal static readonly byte ByteMarkerMask = 3 << 6;
+        internal const byte ByteMarkerMask = 3 << 6;
 
         /// <summary>
         /// byte marker bits for uint encoded in 1 byte.
         /// </summary>
-        internal static readonly byte Byte1Marker = 0;
+        internal const byte Byte1Marker = 0;
 
         /// <summary>
         /// byte marker bits for uint encoded in 2 bytes.
         /// </summary>
-        internal static readonly byte Byte2Marker = 1 << 6;
+        internal const byte Byte2Marker = 1 << 6;
 
         /// <summary>
         /// byte marker bits for uint encoded in 4 bytes.
         /// </summary>
-        internal static readonly byte Byte4Marker = 2 << 6;
+        internal const byte Byte4Marker = 2 << 6;
 
         internal enum EncodingKind : byte
         {

src/Compilers/Core/Portable/Symbols/Attributes/WellKnownAttributeData.cs

@@ -16,7 +16,7 @@ internal abstract class WellKnownAttributeData
         /// For some well-known attributes, the latter case will return string stored in <see cref="StringMissingValue"/>
         /// field.
         /// </summary>
-        public static readonly string StringMissingValue = nameof(StringMissingValue);
+        public const string StringMissingValue = nameof(StringMissingValue);
 
 #if DEBUG
         private bool _isSealed;

src/Compilers/VisualBasic/Portable/Compilation/LookupSymbolsInfo.vb

@@ -8,7 +8,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
         Inherits AbstractLookupSymbolsInfo(Of Symbol)
 
         ' TODO: tune pool size
-        Private Shared ReadOnly s_poolSize As Integer = 64
+        Private Const s_poolSize As Integer = 64
         Private Shared ReadOnly s_pool As New ObjectPool(Of LookupSymbolsInfo)(Function() New LookupSymbolsInfo(), s_poolSize)
 
         Private Sub New()

src/Compilers/VisualBasic/Portable/Lowering/StateMachineRewriter/StateMachineStates.vb

@@ -8,9 +8,9 @@ Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 Namespace Microsoft.CodeAnalysis.VisualBasic
 
     Friend Module StateMachineStates
-        Public ReadOnly FinishedStateMachine As Integer = -2
-        Public ReadOnly NotStartedStateMachine As Integer = -1
-        Public ReadOnly FirstUnusedState As Integer = 0
+        Public FinishedStateMachine As Integer = -2
+        Public NotStartedStateMachine As Integer = -1
+        Public FirstUnusedState As Integer = 0
     End Module
 
 End Namespace

src/Compilers/VisualBasic/Portable/Symbols/TypeSymbol.vb

@@ -26,7 +26,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
         ' !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
         ' TODO (tomat): Consider changing this to an empty name. This name shouldn't ever leak to the user in error messages.
-        Friend Shared ReadOnly ImplicitTypeName As String = "<invalid-global-code>"
+        Friend Const ImplicitTypeName As String = "<invalid-global-code>"
 
         Private Shared ReadOnly s_EmptyTypeSymbols() As TypeSymbol = Array.Empty(Of TypeSymbol)
 

src/Compilers/VisualBasic/Test/Emit/Attributes/AttributeTests_Conditional.vb

@@ -546,7 +546,7 @@ End Class
     End Module
     ]]>.Value
 
-        Private Shared ReadOnly s_commonExpectedOutput_ConditionalMethodsTest As String =
+        Private Const s_commonExpectedOutput_ConditionalMethodsTest As String =
             "Z.PreservedCalls_AppliedConditional_Method" & vbCrLf &
             "Z.PreservedCalls_InheritedConditional_Method" & vbCrLf &
             "Z.PreservedCalls_MultipleConditional_Method" & vbCrLf &

src/Compilers/VisualBasic/Test/Semantic/Semantics/Conversions.vb

@@ -18,7 +18,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.UnitTests.Semantics
     Public Class ConversionsTests
         Inherits BasicTestBase
 
-        Private Shared ReadOnly s_noConversion As ConversionKind = Nothing
+        Private Const s_noConversion As ConversionKind = Nothing
 
         <Fact()>
         Public Sub TryCastDirectCastConversions()

src/EditorFeatures/CSharpTest/AddUsing/AddUsingTests.cs

@@ -1431,7 +1431,9 @@ void Method()
         public async Task TestSimpleSystemUnsortedUsings1()
         {
             await TestAsync(
-@"using B;
+@"
+using C;
+using B;
 using System;
 
 class Class
@@ -1451,7 +1453,9 @@ public static void Bar()
         }
     }
 }",
-@"using B;
+@"
+using C;
+using B;
 using System;
 using A;
 
@@ -1636,7 +1640,9 @@ void Method()
         public async Task TestSimpleSystemUnsortedUsings4()
         {
             await TestAsync(
-@"using System;
+@"
+using C;
+using System;
 using B;
 
 class Class
@@ -1656,7 +1662,9 @@ public static void Bar()
         }
     }
 }",
-@"using System;
+@"
+using C;
+using System;
 using B;
 using A;
 
@@ -4671,6 +4679,111 @@ private void GetEvaluationRuleNames()
         IEnumerable < Int32 >
         return ImmutableArray.CreateRange();
     }
+}");
+        }
+
+        [WorkItem(19796, "https://github.com/dotnet/roslyn/issues/19796")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsAddImport)]
+        public async Task TestWhenInRome1()
+        {
+            // System is set to be sorted first, but the actual file shows it at the end.
+            // Keep things sorted, but respect that 'System' is at the end.
+            await TestAsync(
+@"
+using B;
+using System;
+
+class Class
+{
+    void Method()
+    {
+        [|Foo|].Bar();
+    }
+}
+
+namespace A
+{
+    class Foo
+    {
+        public static void Bar()
+        {
+        }
+    }
+}",
+@"
+using A;
+using B;
+using System;
+
+class Class
+{
+    void Method()
+    {
+        Foo.Bar();
+    }
+}
+
+namespace A
+{
+    class Foo
+    {
+        public static void Bar()
+        {
+        }
+    }
+}",
+systemSpecialCase: true);
+        }
+
+        [WorkItem(19796, "https://github.com/dotnet/roslyn/issues/19796")]
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsAddImport)]
+        public async Task TestWhenInRome2()
+        {
+            // System is set to not be sorted first, but the actual file shows it sorted first.
+            // Keep things sorted, but respect that 'System' is at the beginning.
+            await TestAsync(
+@"
+using System;
+using B;
+
+class Class
+{
+    void Method()
+    {
+        [|Foo|].Bar();
+    }
+}
+
+namespace A
+{
+    class Foo
+    {
+        public static void Bar()
+        {
+        }
+    }
+}",
+@"
+using System;
+using A;
+using B;
+
+class Class
+{
+    void Method()
+    {
+        Foo.Bar();
+    }
+}
+
+namespace A
+{
+    class Foo
+    {
+        public static void Bar()
+        {
+        }
+    }
 }");
         }
     }

src/EditorFeatures/CSharpTest/ImplementInterface/ImplementInterfaceTests.cs

@@ -180,7 +180,7 @@ class Class : IInterface
 }");
         }
 
-        private static readonly string s_tupleElementNamesAttribute =
+        private const string s_tupleElementNamesAttribute =
 @"namespace System.Runtime.CompilerServices
 {
     [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Event )]

src/EditorFeatures/Core/EditorFeatures.csproj

@@ -127,6 +127,14 @@
     <InternalsVisibleTo Include="Microsoft.CodeAnalysis.Remote.ServiceHub" />
     <InternalsVisibleToTest Include="Microsoft.CodeAnalysis.Editor.UI.Wpf" />
     <InternalsVisibleTo Include="Roslyn.Hosting.Diagnostics" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.Ide" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.Refactoring" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.CSharpBinding" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.VBNetBinding" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.Ide.Tests" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.Refactoring.Tests" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.CSharpBinding.Tests" />
+    <InternalsVisibleToMonodevelop Include="MonoDevelop.VBNetBinding.Tests" />
     <InternalsVisibleToTest Include="Roslyn.InteractiveWindow.UnitTests" />
     <InternalsVisibleToTest Include="Roslyn.Services.Editor.CSharp.UnitTests" />
     <InternalsVisibleToTest Include="Roslyn.Services.Editor.UnitTests" />

src/EditorFeatures/Core/Implementation/IntelliSense/Completion/Presentation/CustomCommitCompletion.cs

@@ -15,7 +15,7 @@ namespace Microsoft.CodeAnalysis.Editor.Implementation.IntelliSense.Completion.P
 {
     internal sealed class CustomCommitCompletion : Completion3, ICustomCommit
     {
-        private static readonly string s_glyphCompletionWarning = "GlyphCompletionWarning";
+        private const string s_glyphCompletionWarning = "GlyphCompletionWarning";
         private readonly CompletionPresenterSession _completionPresenterSession;
         internal readonly CompletionItem CompletionItem;
         private readonly ImageMoniker _imageMoniker;

src/EditorFeatures/VisualBasicTest/Diagnostics/AddImport/AddImportTests.vb

@@ -3,6 +3,7 @@
 Imports Microsoft.CodeAnalysis.CodeActions
 Imports Microsoft.CodeAnalysis.CodeFixes
 Imports Microsoft.CodeAnalysis.Diagnostics
+Imports Microsoft.CodeAnalysis.Editing
 Imports Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.Diagnostics
 Imports Microsoft.CodeAnalysis.Remote
 Imports Microsoft.CodeAnalysis.Test.Utilities.RemoteHost
@@ -17,9 +18,10 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.CodeActions.AddImp
                                                   expectedMarkup As String,
                                                   Optional index As Integer = 0,
                                                   Optional ignoreTrivia As Boolean = True,
-                                                  Optional priority As CodeActionPriority? = Nothing) As Task
-            Await TestAsync(initialMarkup, expectedMarkup, index, ignoreTrivia, priority, outOfProcess:=False)
-            Await TestAsync(initialMarkup, expectedMarkup, index, ignoreTrivia, priority, outOfProcess:=True)
+                                                  Optional priority As CodeActionPriority? = Nothing,
+                                                  Optional placeSystemFirst As Boolean = True) As Task
+            Await TestAsync(initialMarkup, expectedMarkup, index, ignoreTrivia, priority, placeSystemFirst, outOfProcess:=False)
+            Await TestAsync(initialMarkup, expectedMarkup, index, ignoreTrivia, priority, placeSystemFirst, outOfProcess:=True)
         End Function
 
         Friend Overloads Async Function TestAsync(initialMarkup As String,
@@ -27,10 +29,13 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.CodeActions.AddImp
                                                   index As Integer,
                                                   ignoreTrivia As Boolean,
                                                   priority As CodeActionPriority?,
+                                                  placeSystemFirst As Boolean,
                                                   outOfProcess As Boolean) As Task
             Await TestInRegularAndScript1Async(
                 initialMarkup, expectedMarkup, index, ignoreTrivia, priority,
-                parameters:=New TestParameters(fixProviderData:=outOfProcess))
+                parameters:=New TestParameters(
+                    options:=[Option](GenerationOptions.PlaceSystemNamespaceFirst, placeSystemFirst),
+                    fixProviderData:=outOfProcess))
         End Function
     End Class
 
@@ -2355,6 +2360,64 @@ Namespace Y
     End Module
 End Namespace")
         End Function
+
+        <WorkItem(19796, "https://github.com/dotnet/roslyn/issues/19796")>
+        <Fact, Trait(Traits.Feature, Traits.Features.CodeActionsAddImport)>
+        Public Async Function TestWhenInRome1() As Task
+            Await TestAsync(
+"
+Imports System
+Imports B
+
+Class Class1
+    Dim v As [|AType|]
+End Class
+Namespace A
+    Public Class AType
+    End Class
+End Namespace",
+"
+Imports System
+Imports A
+Imports B
+
+Class Class1
+    Dim v As AType
+End Class
+Namespace A
+    Public Class AType
+    End Class
+End Namespace", placeSystemFirst:=False)
+        End Function
+
+        <WorkItem(19796, "https://github.com/dotnet/roslyn/issues/19796")>
+        <Fact, Trait(Traits.Feature, Traits.Features.CodeActionsAddImport)>
+        Public Async Function TestWhenInRome2() As Task
+            Await TestAsync(
+"
+Imports B
+Imports System
+
+Class Class1
+    Dim v As [|AType|]
+End Class
+Namespace A
+    Public Class AType
+    End Class
+End Namespace",
+"
+Imports A
+Imports B
+Imports System
+
+Class Class1
+    Dim v As AType
+End Class
+Namespace A
+    Public Class AType
+    End Class
+End Namespace", placeSystemFirst:=True)
+        End Function
     End Class
 
     Public Class AddImportTestsWithAddImportDiagnosticProvider

src/EditorFeatures/VisualBasicTest/GenerateEqualsAndGetHashCodeFromMembers/GenerateEqualsAndGetHashCodeFromMembersTests.vb

@@ -219,7 +219,7 @@ End structure",
 Imports System
 Imports System.Collections.Generic
 
-Structure Program
+structure Program
     Implements IEquatable(Of Program)
 
     Public s As String
@@ -231,7 +231,7 @@ Structure Program
     Public Function Equals(other As Program) As Boolean Implements IEquatable(Of Program).Equals
         Return s = other.s
     End Function
-End Structure",
+End structure",
 chosenSymbols:=Nothing,
 optionsCallback:=Sub(Options) EnableOption(Options, ImplementIEquatableId),
 ignoreTrivia:=False)

src/ExpressionEvaluator/Core/Source/ResultProvider/Formatter.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-#pragma warning disable RS0007 // Avoid zero-length array allocations.
+#pragma warning disable CA1825 // Avoid zero-length array allocations.
 
 using System;
 using System.Collections.ObjectModel;

src/ExpressionEvaluator/Core/Source/ResultProvider/Helpers/ArrayBuilder.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-#pragma warning disable RS0007 // Avoid zero-length array allocations.
+#pragma warning disable CA1825 // Avoid zero-length array allocations.
 
 using System.Collections.Generic;
 using System.Collections.ObjectModel;

src/ExpressionEvaluator/Core/Source/ResultProvider/ResultProvider.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
-#pragma warning disable RS0007 // Avoid zero-length array allocations.
+#pragma warning disable CA1825 // Avoid zero-length array allocations.
 
 using System;
 using System.Collections.ObjectModel;

src/ExpressionEvaluator/Core/Source/ResultProvider/ResultProvider.shproj

@@ -8,7 +8,6 @@
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.Common.Default.props" />
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.Common.props" />
-  <PropertyGroup />
   <Import Project="ResultProvider.projitems" Label="Shared" />
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.CSharp.targets" />
 </Project>
\ No newline at end of file

src/ExpressionEvaluator/Core/Test/ResultProvider/ResultProviderTestUtilities.csproj

@@ -12,6 +12,7 @@
     <AssemblyName>Roslyn.ExpressionEvaluator.ResultProvider.Test.Utilities</AssemblyName>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <TargetFrameworkVersion>v4.6</TargetFrameworkVersion>
+  	<NoWarn>$(NoWarn);CA1825</NoWarn> <!-- Disable CA1825 (Avoid unnecessary zero-length array allocations. Use Array.Empty<X>() instead) as Array.Empty not available in one of the targets for this shared project -->
   </PropertyGroup>
   <ItemGroup Label="File References">
     <Reference Include="Microsoft.CSharp" />

src/Features/CSharp/Portable/Completion/CompletionProviders/CrefCompletionProvider.cs

@@ -399,7 +399,7 @@ private CompletionItemRules GetRules(string displayText)
             }
         }
 
-        private static readonly string InsertionTextProperty = "insertionText";
+        private const string InsertionTextProperty = "insertionText";
 
         protected override Task<TextChange?> GetTextChangeAsync(CompletionItem selectedItem, char? ch, CancellationToken cancellationToken)
         {

src/Features/CSharp/Portable/MakeMethodSynchronous/CSharpMakeMethodSynchronousCodeFixProvider.cs

@@ -10,7 +10,8 @@
 
 namespace Microsoft.CodeAnalysis.CSharp.MakeMethodSynchronous
 {
-    [ExportCodeFixProvider(LanguageNames.CSharp), Shared]
+    [ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.MakeMethodSynchronous), Shared]
+    [ExtensionOrder(After = PredefinedCodeFixProviderNames.AddImport)]
     internal class CSharpMakeMethodSynchronousCodeFixProvider : AbstractMakeMethodSynchronousCodeFixProvider
     {
         private const string CS1998 = nameof(CS1998); // This async method lacks 'await' operators and will run synchronously.

src/Features/Core/Portable/AddImport/References/SymbolReference.cs

@@ -98,7 +98,7 @@ public override int GetHashCode()
                     document, node, placeSystemNamespaceFirst, hasExistingImport, cancellationToken).ConfigureAwait(false);
 
                 return GetFixData(
-                    document, textChanges.ToImmutableArray(), description,
+                    document, textChanges, description,
                     GetTags(document), GetPriority(document));
             }
 

src/Features/Core/Portable/CodeFixes/PredefinedCodeFixProviderNames.cs

@@ -32,6 +32,7 @@ internal static class PredefinedCodeFixProviderNames
         public const string ImplementAbstractClass = nameof(ImplementAbstractClass);
         public const string ImplementInterface = nameof(ImplementInterface);
         public const string InsertMissingCast = nameof(InsertMissingCast);
+        public const string MakeMethodSynchronous = nameof(MakeMethodSynchronous);
         public const string MoveToTopOfFile = nameof(MoveToTopOfFile);
         public const string PopulateSwitch = nameof(PopulateSwitch);
         public const string QualifyMemberAccess = nameof(QualifyMemberAccess);

src/Features/Core/Portable/CodeFixes/Suppression/AbstractSuppressionCodeFixProvider.cs

@@ -19,8 +19,8 @@ namespace Microsoft.CodeAnalysis.CodeFixes.Suppression
     internal abstract partial class AbstractSuppressionCodeFixProvider : ISuppressionFixProvider
     {
         public const string SuppressMessageAttributeName = "System.Diagnostics.CodeAnalysis.SuppressMessage";
-        private static readonly string s_globalSuppressionsFileName = "GlobalSuppressions";
-        private static readonly string s_suppressionsFileCommentTemplate =
+        private const string s_globalSuppressionsFileName = "GlobalSuppressions";
+        private const string s_suppressionsFileCommentTemplate =
 @"
 {0} This file is used by Code Analysis to maintain SuppressMessage 
 {0} attributes that are applied to this project.

src/Features/Core/Portable/DocumentHighlighting/IRemoteDocumentHighlights.cs

@@ -19,7 +19,7 @@ internal struct SerializableDocumentHighlights
         public ImmutableArray<HighlightSpan> HighlightSpans;
 
         public DocumentHighlights Rehydrate(Solution solution)
-            => new DocumentHighlights(solution.GetDocument(DocumentId), HighlightSpans.ToImmutableArray());
+            => new DocumentHighlights(solution.GetDocument(DocumentId), HighlightSpans);
 
         public static SerializableDocumentHighlights Dehydrate(DocumentHighlights highlights)
             => new SerializableDocumentHighlights

src/Features/Core/Portable/FeaturesResources.Designer.cs

@@ -1891,7 +1891,7 @@ internal class FeaturesResources {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Make method synchronous..
+        ///   Looks up a localized string similar to Make method synchronous.
         /// </summary>
         internal static string Make_method_synchronous {
             get {

src/Features/Core/Portable/FeaturesResources.resx

@@ -886,7 +886,7 @@ Do you want to continue?</value>
     <value>Unable to load Analyzer assembly {0}: {1}</value>
   </data>
   <data name="Make_method_synchronous" xml:space="preserve">
-    <value>Make method synchronous.</value>
+    <value>Make method synchronous</value>
   </data>
   <data name="Add_this_or_Me_qualification" xml:space="preserve">
     <value>Add 'this' or 'Me' qualification.</value>

src/Features/Core/Portable/MetadataAsSource/AbstractMetadataAsSourceService.DocCommentFormatter.cs

@@ -12,12 +12,12 @@ internal partial class AbstractMetadataAsSourceService
     {
         internal class DocCommentFormatter
         {
-            private static readonly int s_indentSize = 2;
-            private static readonly int s_wrapLength = 80;
+            private const int s_indentSize = 2;
+            private const int s_wrapLength = 80;
 
             private static readonly string s_summaryHeader = FeaturesResources.Summary_colon;
             private static readonly string s_paramHeader = FeaturesResources.Parameters_colon;
-            private static readonly string s_labelFormat = "{0}:";
+            private const string s_labelFormat = "{0}:";
             private static readonly string s_typeParameterHeader = FeaturesResources.Type_parameters_colon;
             private static readonly string s_returnsHeader = FeaturesResources.Returns_colon;
             private static readonly string s_exceptionsHeader = FeaturesResources.Exceptions_colon;

src/Features/Core/Portable/Remote/RemoteArguments.cs

@@ -43,7 +43,7 @@ internal INavigateToSearchResult Rehydrate(Solution solution)
         {
             return new NavigateToSearchResult(
                 AdditionalInformation, Kind, MatchKind, IsCaseSensitive,
-                Name, NameMatchSpans.ToImmutableArray(),
+                Name, NameMatchSpans,
                 SecondarySort, Summary, NavigableItem.Rehydrate(solution));
         }
 
@@ -113,7 +113,7 @@ public INavigableItem Rehydrate(Solution solution)
                 ? ImmutableArray<INavigableItem>.Empty
                 : ChildItems.SelectAsArray(c => c.Rehydrate(solution));
             return new NavigableItem(
-                Glyph, DisplayTaggedParts.ToImmutableArray(),
+                Glyph, DisplayTaggedParts,
                 DisplayFileLocation, IsImplicitlyDeclared,
                 solution.GetDocument(Document),
                 SourceSpan,

src/Features/VisualBasic/Portable/MakeMethodSynchronous/VisualBasicMakeMethodSynchronousCodeFixProvider.vb

@@ -7,7 +7,8 @@ Imports Microsoft.CodeAnalysis.MakeMethodSynchronous
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 
 Namespace Microsoft.CodeAnalysis.VisualBasic.MakeMethodSynchronous
-    <ExportCodeFixProvider(LanguageNames.VisualBasic), [Shared]>
+    <ExportCodeFixProvider(LanguageNames.VisualBasic, Name:=PredefinedCodeFixProviderNames.MakeMethodSynchronous), [Shared]>
+    <ExtensionOrder(After:=PredefinedCodeFixProviderNames.AddImport)>
     Friend Class VisualBasicMakeMethodSynchronousCodeFixProvider
         Inherits AbstractMakeMethodSynchronousCodeFixProvider
 

src/Scripting/CoreTestUtilities/ObjectFormatterTests.Fixtures.cs

@@ -16,7 +16,7 @@ public class Nested<T>
         {
             public readonly int A = 1;
             public readonly int B = 2;
-            public static readonly int S = 3;
+            public const int S = 3;
         }
     }
 

src/Test/Perf/Utilities/VsPerfTest.cs

@@ -7,7 +7,7 @@ namespace Roslyn.Test.Performance.Utilities
 {
     public abstract class VsPerfTest : PerfTest
     {
-        private static readonly string _rootSuffix = "RoslynPerf";
+        private const string _rootSuffix = "RoslynPerf";
 
         private readonly ILogger _logger;
         private readonly string _testTemplateName;

src/Tools/BuildBoss/StructuredLoggerCheckerUtil.cs

@@ -24,10 +24,10 @@ namespace BuildBoss
     internal sealed class StructuredLoggerCheckerUtil : ICheckerUtil
     {
         internal static readonly StringComparer FilePathComparer = StringComparer.OrdinalIgnoreCase;
-        private static readonly string s_copyingFileFrom = "Copying file from \"";
-        private static readonly string s_creatingHardLink = "Creating hard link to copy \"";
-        private static readonly string s_didNotCopy = "Did not copy from file \"";
-        private static readonly string s_to = "\" to \"";
+        private const string s_copyingFileFrom = "Copying file from \"";
+        private const string s_creatingHardLink = "Creating hard link to copy \"";
+        private const string s_didNotCopy = "Did not copy from file \"";
+        private const string s_to = "\" to \"";
 
         private readonly XDocument _document;
         private readonly Dictionary<string, List<string>> _copyMap = new Dictionary<string, List<string>>(FilePathComparer);

src/VisualStudio/CSharp/Impl/Options/Formatting/NewLinesViewModel.cs

@@ -44,7 +44,7 @@ class C {
 //]
 }";
 
-        private static readonly string s_tryCatchFinallyPreview = @"using System;
+        private const string s_tryCatchFinallyPreview = @"using System;
 class C {
     void Foo() {
 //[
@@ -58,7 +58,7 @@ class C {
     }
 }";
 
-        private static readonly string s_ifElsePreview = @"class C {
+        private const string s_ifElsePreview = @"class C {
     void Foo() {
 //[
         if (false) {
@@ -69,7 +69,7 @@ class C {
     }
 }";
 
-        private static readonly string s_forBlockPreview = @"class C {
+        private const string s_forBlockPreview = @"class C {
     void Foo() {
 //[
         for (int i; i < 10; i++){
@@ -78,7 +78,7 @@ class C {
     }
 }";
 
-        private static readonly string s_lambdaPreview = @"using System;
+        private const string s_lambdaPreview = @"using System;
 class C {
     void Foo() {
 //[
@@ -88,7 +88,7 @@ class C {
 //]
     }
 }";
-        private static readonly string s_anonymousMethodPreview = @"using System;
+        private const string s_anonymousMethodPreview = @"using System;
 
 delegate int D(int x);
 
@@ -102,7 +102,7 @@ class C {
     }
 }";
 
-        private static readonly string s_anonymousTypePreview = @"using System;
+        private const string s_anonymousTypePreview = @"using System;
 class C {
     void Foo() {
 //[
@@ -112,7 +112,7 @@ class C {
 //]
     }
 }";
-        private static readonly string s_InitializerPreviewTrue = @"using System;
+        private const string s_InitializerPreviewTrue = @"using System;
 using System.Collections.Generic;
 
 class C {
@@ -140,7 +140,7 @@ class B {
     public int A { get; set; }
     public int B { get; set; }
 }";
-        private static readonly string s_InitializerPreviewFalse = @"using System;
+        private const string s_InitializerPreviewFalse = @"using System;
 using System.Collections.Generic;
 
 class C {
@@ -165,7 +165,7 @@ class B {
     public int A { get; set; }
     public int B { get; set; }
 }";
-        private static readonly string s_objectInitializerPreview = @"using System;
+        private const string s_objectInitializerPreview = @"using System;
 class C {
     void Foo() {
 //[
@@ -180,7 +180,7 @@ class B {
     public int A { get; set; }
     public int B { get; set; }
 }";
-        private static readonly string s_queryExpressionPreview = @"using System;
+        private const string s_queryExpressionPreview = @"using System;
 using System.Linq;
 using System.Collections.Generic;
 class C {

src/VisualStudio/CSharp/Impl/Options/Formatting/SpacingViewModel.cs

@@ -13,7 +13,7 @@ namespace Microsoft.VisualStudio.LanguageServices.CSharp.Options.Formatting
     /// </summary>
     internal class SpacingViewModel : AbstractOptionPreviewViewModel
     {
-        private static readonly string s_methodPreview = @"
+        private const string s_methodPreview = @"
 class C {
 //[
     void Foo(){
@@ -29,14 +29,14 @@ class C {
     }
 }";
 
-        private static readonly string s_bracketPreview = @"class C {
+        private const string s_bracketPreview = @"class C {
     void Foo(){
 //[
         int[] x = new int[10];
 //]
     }
 }";
-        private static readonly string s_forDelimiterPreview = @"class C{
+        private const string s_forDelimiterPreview = @"class C{
     void Foo(int x, object y) {
 //[
         for (int i; i < x; i++) {
@@ -45,7 +45,7 @@ class C {
     }
 }";
 
-        private static readonly string s_delimiterPreview = @"class C{
+        private const string s_delimiterPreview = @"class C{
     void Foo(int x, object y) {
 //[
             this.Foo(x, y);
@@ -53,7 +53,7 @@ class C {
     }
 }";
 
-        private static readonly string s_castPreview = @"class C{
+        private const string s_castPreview = @"class C{
     void Foo(object x) {
 //[
         int y = (int)x;
@@ -61,7 +61,7 @@ class C {
     }
 }";
 
-        private static readonly string s_expressionPreview = @"class C{
+        private const string s_expressionPreview = @"class C{
     void Foo(int x, object y) {
 //[
         var x = 3;
@@ -71,7 +71,7 @@ class C {
     }
 }";
 
-        private static readonly string s_expressionSpacingPreview = @"
+        private const string s_expressionSpacingPreview = @"
 class c {
     int Foo(int x, int y) {
 //[
@@ -79,7 +79,7 @@ class c {
 //]
     }
 }";
-        private static readonly string s_declarationSpacingPreview = @"class MyClass {
+        private const string s_declarationSpacingPreview = @"class MyClass {
 //[
     int         index = 0;
     string      text = ""Start"";
@@ -90,7 +90,7 @@ class c {
                 }
 //]
 }";
-        private static readonly string s_baseColonPreview = @"//[
+        private const string s_baseColonPreview = @"//[
 interface I {
 }
 

src/VisualStudio/CSharp/Impl/Options/Formatting/StyleViewModel.cs

@@ -21,7 +21,7 @@ internal class StyleViewModel : AbstractOptionPreviewViewModel
     {
         #region "Preview Text"
 
-        private static readonly string s_fieldDeclarationPreviewTrue = @"
+        private const string s_fieldDeclarationPreviewTrue = @"
 class C{
     int capacity;
     void Method()
@@ -32,7 +32,7 @@ void Method()
     }
 }";
 
-        private static readonly string s_fieldDeclarationPreviewFalse = @"
+        private const string s_fieldDeclarationPreviewFalse = @"
 class C{
     int capacity;
     void Method()
@@ -43,7 +43,7 @@ void Method()
     }
 }";
 
-        private static readonly string s_propertyDeclarationPreviewTrue = @"
+        private const string s_propertyDeclarationPreviewTrue = @"
 class C{
     public int Id { get; set; }
     void Method()
@@ -54,7 +54,7 @@ void Method()
     }
 }";
 
-        private static readonly string s_propertyDeclarationPreviewFalse = @"
+        private const string s_propertyDeclarationPreviewFalse = @"
 class C{
     public int Id { get; set; }
     void Method()
@@ -65,7 +65,7 @@ void Method()
     }
 }";
 
-        private static readonly string s_eventDeclarationPreviewTrue = @"
+        private const string s_eventDeclarationPreviewTrue = @"
 using System;
 class C{
     event EventHandler Elapsed;
@@ -77,7 +77,7 @@ void Handler(object sender, EventArgs args)
     }
 }";
 
-        private static readonly string s_eventDeclarationPreviewFalse = @"
+        private const string s_eventDeclarationPreviewFalse = @"
 using System;
 class C{
     event EventHandler Elapsed;
@@ -89,7 +89,7 @@ void Handler(object sender, EventArgs args)
     }
 }";
 
-        private static readonly string s_methodDeclarationPreviewTrue = @"
+        private const string s_methodDeclarationPreviewTrue = @"
 using System;
 class C{
     void Display()
@@ -100,7 +100,7 @@ void Display()
     }
 }";
 
-        private static readonly string s_methodDeclarationPreviewFalse = @"
+        private const string s_methodDeclarationPreviewFalse = @"
 using System;
 class C{
     void Display()
@@ -111,7 +111,7 @@ void Display()
     }
 }";
 
-        private static readonly string s_intrinsicPreviewDeclarationTrue = @"
+        private const string s_intrinsicPreviewDeclarationTrue = @"
 class Program
 {
 //[
@@ -123,7 +123,7 @@ static void M(int argument)
 //]
 }";
 
-        private static readonly string s_intrinsicPreviewDeclarationFalse = @"
+        private const string s_intrinsicPreviewDeclarationFalse = @"
 using System;
 class Program
 {
@@ -136,7 +136,7 @@ static void M(Int32 argument)
 //]
 }";
 
-        private static readonly string s_intrinsicPreviewMemberAccessTrue = @"
+        private const string s_intrinsicPreviewMemberAccessTrue = @"
 class Program
 {
 //[
@@ -147,7 +147,7 @@ static void M()
 //]
 }";
 
-        private static readonly string s_intrinsicPreviewMemberAccessFalse = @"
+        private const string s_intrinsicPreviewMemberAccessFalse = @"
 using System;
 class Program
 {
@@ -489,7 +489,7 @@ public int GetAge()
 }}
 ";
 
-        private static readonly string s_preferExpressionBodyForMethods = @"
+        private const string s_preferExpressionBodyForMethods = @"
 using System;
 
 //[
@@ -502,7 +502,7 @@ class Customer
 //]
 ";
 
-        private static readonly string s_preferBlockBodyForMethods = @"
+        private const string s_preferBlockBodyForMethods = @"
 using System;
 
 //[
@@ -518,7 +518,7 @@ public int GetAge()
 //]
 ";
 
-        private static readonly string s_preferExpressionBodyForConstructors = @"
+        private const string s_preferExpressionBodyForConstructors = @"
 using System;
 
 //[
@@ -531,7 +531,7 @@ class Customer
 //]
 ";
 
-        private static readonly string s_preferBlockBodyForConstructors = @"
+        private const string s_preferBlockBodyForConstructors = @"
 using System;
 
 //[
@@ -547,7 +547,7 @@ public Customer(int age)
 //]
 ";
 
-        private static readonly string s_preferExpressionBodyForOperators = @"
+        private const string s_preferExpressionBodyForOperators = @"
 using System;
 
 struct ComplexNumber
@@ -559,7 +559,7 @@ struct ComplexNumber
 }
 ";
 
-        private static readonly string s_preferBlockBodyForOperators = @"
+        private const string s_preferBlockBodyForOperators = @"
 using System;
 
 struct ComplexNumber
@@ -573,7 +573,7 @@ struct ComplexNumber
 }
 ";
 
-        private static readonly string s_preferExpressionBodyForProperties = @"
+        private const string s_preferExpressionBodyForProperties = @"
 using System;
 
 //[
@@ -585,7 +585,7 @@ class Customer
 //]
 ";
 
-        private static readonly string s_preferBlockBodyForProperties = @"
+        private const string s_preferBlockBodyForProperties = @"
 using System;
 
 //[
@@ -597,7 +597,7 @@ class Customer
 //]
 ";
 
-        private static readonly string s_preferExpressionBodyForAccessors = @"
+        private const string s_preferExpressionBodyForAccessors = @"
 using System;
 
 //[
@@ -613,7 +613,7 @@ public int Age
 //]
 ";
 
-        private static readonly string s_preferBlockBodyForAccessors = @"
+        private const string s_preferBlockBodyForAccessors = @"
 using System;
 
 //[
@@ -629,7 +629,7 @@ public int Age
 //]
 ";
 
-        private static readonly string s_preferExpressionBodyForIndexers= @"
+        private const string s_preferExpressionBodyForIndexers = @"
 using System;
 
 //[
@@ -641,7 +641,7 @@ class List<T>
 //]
 ";
 
-        private static readonly string s_preferBlockBodyForIndexers = @"
+        private const string s_preferBlockBodyForIndexers = @"
 using System;
 
 //[

src/VisualStudio/CSharp/Impl/Options/Formatting/WrappingViewModel.cs

@@ -13,7 +13,7 @@ namespace Microsoft.VisualStudio.LanguageServices.CSharp.Options.Formatting
     /// </summary>
     internal class WrappingViewModel : AbstractOptionPreviewViewModel
     {
-        private static readonly string s_blockPreview = @"
+        private const string s_blockPreview = @"
 class C
 {
 //[
@@ -21,7 +21,7 @@ class C
 //]    
 }";
 
-        private static readonly string s_declarationPreview = @"
+        private const string s_declarationPreview = @"
 class C{
     void foo()
     {

src/VisualStudio/CSharp/Repl/CSharpInteractiveCommands.cs

@@ -9,7 +9,7 @@ internal static class CSharpInteractiveCommands
         public const int InteractiveToolWindow = 0x0001;
         public const int ResetInteractiveFromProject = 0x0002;
 
-        public static readonly string InteractiveCommandSetIdString = "1492DB0A-85A2-4E43-BF0D-CE55B89A8CC6";
+        public const string InteractiveCommandSetIdString = "1492DB0A-85A2-4E43-BF0D-CE55B89A8CC6";
         public static readonly Guid InteractiveCommandSetId = new Guid(InteractiveCommandSetIdString);
     }
 }

src/VisualStudio/Core/Def/ID.InteractiveCommands.cs

@@ -14,10 +14,10 @@ internal static class InteractiveCommands
             // TODO: Remove pending https://github.com/dotnet/roslyn/issues/8927 .
             public const int ExecuteInInteractiveWindow = 0x0010C;
 
-            public static readonly string CSharpInteractiveCommandSetIdString = "1492DB0A-85A2-4E43-BF0D-CE55B89A8CC6";
+            public const string CSharpInteractiveCommandSetIdString = "1492DB0A-85A2-4E43-BF0D-CE55B89A8CC6";
             public static readonly Guid CSharpInteractiveCommandSetId = new Guid(CSharpInteractiveCommandSetIdString);
 
-            public static readonly string VisualBasicInteractiveCommandSetIdString = "93DF185E-D75B-4FDB-9D47-E90F111971C5";
+            public const string VisualBasicInteractiveCommandSetIdString = "93DF185E-D75B-4FDB-9D47-E90F111971C5";
             public static readonly Guid VisualBasicInteractiveCommandSetId = new Guid(VisualBasicInteractiveCommandSetIdString);
         }
     }

src/VisualStudio/Core/Def/Implementation/Library/ObjectBrowser/Helpers.cs

@@ -62,7 +62,7 @@ public static uint ObjectListKindToListType(ObjectListKind kind)
             return 0;
         }
 
-        public static readonly _LIB_LISTFLAGS ClassView = _LIB_LISTFLAGS.LLF_TRUENESTING;
+        public const _LIB_LISTFLAGS ClassView = _LIB_LISTFLAGS.LLF_TRUENESTING;
 
         public static bool IsClassView(uint flags)
         {

src/VisualStudio/Core/Def/Implementation/ProjectSystem/InvisibleEditor.cs

@@ -153,9 +153,13 @@ public void Dispose()
             }
         }
 
+#pragma warning disable CA1821 // Remove empty Finalizers
+#if DEBUG
         ~InvisibleEditor()
         {
             Debug.Assert(Environment.HasShutdownStarted, GetType().Name + " was leaked without Dispose being called.");
         }
+#endif
+#pragma warning restore CA1821 // Remove empty Finalizers
     }
 }

src/VisualStudio/Core/Def/Implementation/Workspace/GlobalUndoServiceFactory.WorkspaceGlobalUndoTransaction.cs

@@ -117,11 +117,15 @@ public void Dispose()
                 }
             }
 
+#pragma warning disable CA1821 // Remove empty Finalizers
+#if DEBUG
             ~WorkspaceUndoTransaction()
             {
                 // make sure we closed it correctly
                 Contract.Requires(!_transactionAlive);
             }
+#endif
+#pragma warning restore CA1821 // Remove empty Finalizers
         }
     }
 }

src/VisualStudio/VisualBasic/Repl/VisualBasicInteractiveCommands.vb

@@ -7,7 +7,7 @@ Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic.Interactive
         Public Const InteractiveToolWindow = &H1
         Public Const ResetInteractiveFromProject = &H2
 
-        Public ReadOnly InteractiveCommandSetIdString As String = "93DF185E-D75B-4FDB-9D47-E90F111971C5"
+        Public Const InteractiveCommandSetIdString As String = "93DF185E-D75B-4FDB-9D47-E90F111971C5"
         Public ReadOnly InteractiveCommandSetId As Guid = New Guid(InteractiveCommandSetIdString)
     End Module
 End Namespace

src/Workspaces/CSharp/Portable/CSharpWorkspace.csproj

@@ -98,6 +98,7 @@
     <Compile Include="CodeStyle\TypeStyle\TypeStyleHelper.cs" />
     <Compile Include="Composition\CSharpWorkspaceFeatures.cs" />
     <Compile Include="Extensions\BaseMethodDeclarationSyntaxExtensions.cs" />
+    <Compile Include="Extensions\UsingDirectiveSyntaxExtensions.cs" />
     <Compile Include="Formatting\CSharpFormattingService.cs" />
     <Compile Include="FindSymbols\CSharpDeclaredSymbolInfoFactoryService.cs" />
     <Compile Include="Simplification\Reducers\CSharpDefaultExpressionReducer.Rewriter.cs" />

src/Workspaces/CSharp/Portable/Extensions/CompilationUnitSyntaxExtensions.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using System.Threading;
 using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.AddImports;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.CSharp.Utilities;
@@ -119,57 +120,15 @@ private static TextSpan GetUsingsSpan(CompilationUnitSyntax root, NamespaceDecla
                 return root;
             }
 
-            var comparer = placeSystemNamespaceFirst
-                ? UsingsAndExternAliasesDirectiveComparer.SystemFirstInstance
-                : UsingsAndExternAliasesDirectiveComparer.NormalInstance;
-
             var usings = AddUsingDirectives(root, usingDirectives);
 
             // Keep usings sorted if they were originally sorted.
-            if (root.Usings.IsSorted(comparer))
-            {
-                usings.Sort(comparer);
-            }
+            usings.SortUsingDirectives(root.Usings, placeSystemNamespaceFirst);
 
             if (root.Externs.Count == 0)
             {
-                if (root.Usings.Count == 0)
-                {
-                    // We don't have any existing usings. Move any trivia on the first token 
-                    // of the file to the first using.
-                    // 
-                    // Don't do this for doc comments, as they belong to the first element
-                    // already in the file (like a class) and we don't want it to move to
-                    // the using.
-                    var firstToken = root.GetFirstToken();
-
-                    // Remove the leading directives from the first token.
-                    var newFirstToken = firstToken.WithLeadingTrivia(
-                        firstToken.LeadingTrivia.Where(t => IsDocCommentOrElastic(t)));
-
-                    root = root.ReplaceToken(firstToken, newFirstToken);
-
-                    // Move the leading trivia from the first token to the first using.
-                    var newFirstUsing = usings[0].WithLeadingTrivia(
-                        firstToken.LeadingTrivia.Where(t => !IsDocCommentOrElastic(t)));
-                    usings[0] = newFirstUsing;
-                }
-                else
-                {
-                    var originalFirstUsing = root.Usings[0];
-                    if (usings[0] != originalFirstUsing)
-                    {
-                        // We added a new first-using.  Take the trivia on the existing first using
-                        // And move it to the new using.
-                        var originalFirstUsingCurrentIndex = usings.IndexOf(originalFirstUsing);
-
-                        var newFirstUsing = usings[0].WithLeadingTrivia(originalFirstUsing.GetLeadingTrivia())
-                                                     .WithAppendedTrailingTrivia(SyntaxFactory.ElasticCarriageReturnLineFeed);
-
-                        usings[0] = newFirstUsing;
-                        usings[originalFirstUsingCurrentIndex] = originalFirstUsing.WithoutLeadingTrivia();
-                    }
-                }
+                root = AddImportHelpers.MoveTrivia(
+                    CSharpSyntaxFactsService.Instance, root, root.Usings, usings);
             }
 
             return root.WithUsings(
@@ -215,6 +174,7 @@ private static bool IsDocCommentOrElastic(SyntaxTrivia t)
             {
                 usings.InsertRange(startOfLastDirective, usingDirectives);
             }
+
             return usings;
         }
     }

src/Workspaces/CSharp/Portable/Extensions/NamespaceDeclarationSyntaxExtensions.cs

@@ -2,15 +2,7 @@
 
 using System.Collections.Generic;
 using System.Linq;
-using System.Threading;
-using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.CSharp;
-using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using Microsoft.CodeAnalysis.CSharp.Utilities;
-using Microsoft.CodeAnalysis.Shared.Extensions;
-using Microsoft.CodeAnalysis.Text;
-using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.CSharp.Extensions
 {
@@ -27,24 +19,15 @@ internal static class NamespaceDeclarationSyntaxExtensions
                 return namespaceDeclaration;
             }
 
-            var specialCaseSystem = placeSystemNamespaceFirst;
-            var comparer = specialCaseSystem
-                ? UsingsAndExternAliasesDirectiveComparer.SystemFirstInstance
-                : UsingsAndExternAliasesDirectiveComparer.NormalInstance;
+            var newUsings = new List<UsingDirectiveSyntax>();
+            newUsings.AddRange(namespaceDeclaration.Usings);
+            newUsings.AddRange(usingDirectives);
 
-            var usings = new List<UsingDirectiveSyntax>();
-            usings.AddRange(namespaceDeclaration.Usings);
-            usings.AddRange(usingDirectives);
-
-            if (namespaceDeclaration.Usings.IsSorted(comparer))
-            {
-                usings.Sort(comparer);
-            }
-
-            usings = usings.Select(u => u.WithAdditionalAnnotations(annotations)).ToList();
-            var newNamespace = namespaceDeclaration.WithUsings(usings.ToSyntaxList());
+            newUsings.SortUsingDirectives(namespaceDeclaration.Usings, placeSystemNamespaceFirst);
+            newUsings = newUsings.Select(u => u.WithAdditionalAnnotations(annotations)).ToList();
 
+            var newNamespace = namespaceDeclaration.WithUsings(newUsings.ToSyntaxList());
             return newNamespace;
         }
     }
-}
+}
\ No newline at end of file

src/Workspaces/CSharp/Portable/Extensions/UsingDirectiveSyntaxExtensions.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.CSharp.Utilities;
+using Roslyn.Utilities;
+
+namespace Microsoft.CodeAnalysis.CSharp.Extensions
+{
+    internal static class UsingDirectiveSyntaxExtensions
+    {
+        public static void SortUsingDirectives(
+            this List<UsingDirectiveSyntax> usingDirectives,
+            SyntaxList<UsingDirectiveSyntax> existingDirectives,
+            bool placeSystemNamespaceFirst)
+        {
+            var systemFirstInstance = UsingsAndExternAliasesDirectiveComparer.SystemFirstInstance;
+            var normalInstance = UsingsAndExternAliasesDirectiveComparer.NormalInstance;
+
+            var specialCaseSystem = placeSystemNamespaceFirst;
+            var comparers = specialCaseSystem
+                ? (systemFirstInstance, normalInstance)
+                : (normalInstance, systemFirstInstance);
+
+            // First, see if the usings were sorted according to the user's preference.  If so,
+            // keep the same sorting after we add the using.  However, if the usings weren't sorted
+            // according to their preference, then see if they're sorted in the other way.  If so
+            // preserve that sorting as well.  That way if the user is working with a file that 
+            // was written on a machine with a different default, the usings will stay in a 
+            // reasonable order.
+            if (existingDirectives.IsSorted(comparers.Item1))
+            {
+                usingDirectives.Sort(comparers.Item1);
+            }
+            else if (existingDirectives.IsSorted(comparers.Item2))
+            {
+                usingDirectives.Sort(comparers.Item2);
+            }
+        }
+    }
+}
\ No newline at end of file

src/Workspaces/CSharp/Portable/LanguageServices/CSharpSyntaxFactsService.cs

@@ -32,6 +32,9 @@ private CSharpSyntaxFactsService()
 
         public StringComparer StringComparer { get; } = StringComparer.Ordinal;
 
+        public SyntaxTrivia ElasticCarriageReturnLineFeed
+            => SyntaxFactory.ElasticCarriageReturnLineFeed;
+
         protected override IDocumentationCommentService DocumentationCommentService
             => CSharpDocumentationCommentService.Instance;
 
@@ -1350,6 +1353,9 @@ public bool IsRegularComment(SyntaxTrivia trivia)
         public bool IsDocumentationComment(SyntaxTrivia trivia)
             => trivia.IsDocComment();
 
+        public bool IsElastic(SyntaxTrivia trivia)
+            => trivia.IsElastic();
+
         public bool IsDocumentationCommentExteriorTrivia(SyntaxTrivia trivia)
             => trivia.Kind() == SyntaxKind.DocumentationCommentExteriorTrivia;
 

src/Workspaces/CSharp/Portable/Simplification/CSharpSimplificationService.cs

@@ -168,7 +168,7 @@ protected override bool CanNodeBeSimplifiedWithoutSpeculation(SyntaxNode node)
             return false;
         }
 
-        private static readonly string s_CS8019_UnusedUsingDirective = "CS8019";
+        private const string s_CS8019_UnusedUsingDirective = "CS8019";
 
         protected override void GetUnusedNamespaceImports(SemanticModel model, HashSet<SyntaxNode> namespaceImports, CancellationToken cancellationToken)
         {

src/Workspaces/Core/Portable/AddImports/AddImportHelpers.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.CodeAnalysis.LanguageServices;
+using Microsoft.CodeAnalysis.Shared.Extensions;
+
+namespace Microsoft.CodeAnalysis.AddImports
+{
+    internal static class AddImportHelpers
+    {
+        public static TRootSyntax MoveTrivia<TRootSyntax, TImportDirectiveSyntax>(
+            ISyntaxFactsService syntaxFacts,
+            TRootSyntax root,
+            SyntaxList<TImportDirectiveSyntax> existingImports,
+            List<TImportDirectiveSyntax> newImports)
+            where TRootSyntax : SyntaxNode
+            where TImportDirectiveSyntax : SyntaxNode
+        {
+            if (existingImports.Count == 0)
+            {
+                // We don't have any existing usings. Move any trivia on the first token 
+                // of the file to the first using.
+                // 
+                // Don't do this for doc comments, as they belong to the first element
+                // already in the file (like a class) and we don't want it to move to
+                // the using.
+                var firstToken = root.GetFirstToken();
+
+                // Remove the leading directives from the first token.
+                var newFirstToken = firstToken.WithLeadingTrivia(
+                    firstToken.LeadingTrivia.Where(t => IsDocCommentOrElastic(syntaxFacts, t)));
+
+                root = root.ReplaceToken(firstToken, newFirstToken);
+
+                // Move the leading trivia from the first token to the first using.
+                var newFirstUsing = newImports[0].WithLeadingTrivia(
+                    firstToken.LeadingTrivia.Where(t => !IsDocCommentOrElastic(syntaxFacts, t)));
+                newImports[0] = newFirstUsing;
+            }
+            else
+            {
+                var originalFirstUsing = existingImports[0];
+                if (newImports[0] != originalFirstUsing)
+                {
+                    // We added a new first-using.  Take the trivia on the existing first using
+                    // And move it to the new using.
+                    var originalFirstUsingCurrentIndex = newImports.IndexOf(originalFirstUsing);
+
+                    newImports[0] = newImports[0].WithLeadingTrivia(originalFirstUsing.GetLeadingTrivia());
+
+                    if (!syntaxFacts.IsEndOfLineTrivia(newImports[0].GetTrailingTrivia().LastOrDefault()))
+                    {
+                        newImports[0] = newImports[0].WithAppendedTrailingTrivia(syntaxFacts.ElasticCarriageReturnLineFeed);
+                    }
+
+                    newImports[originalFirstUsingCurrentIndex] = originalFirstUsing.WithoutLeadingTrivia();
+                }
+            }
+
+            return root;
+        }
+
+        private static bool IsDocCommentOrElastic(ISyntaxFactsService syntaxFacts, SyntaxTrivia t)
+            => syntaxFacts.IsDocumentationComment(t) || syntaxFacts.IsElastic(t);
+    }
+}
\ No newline at end of file

src/Workspaces/Core/Portable/CodeCleanup/AbstractCodeCleanerService.cs

@@ -648,7 +648,7 @@ private class SpanMarker
 
             public SyntaxAnnotation Annotation { get; }
 
-            public static readonly string AnnotationId = "SpanMarker";
+            public const string AnnotationId = "SpanMarker";
 
             private SpanMarker(SpanMarkerType type, SpanMarkerType oppositeMarkerType, SyntaxAnnotation annotation)
             {

src/Workspaces/Core/Portable/CodeFixes/FixAllOccurrences/FixAllLogger.cs

@@ -15,25 +15,25 @@ namespace Microsoft.CodeAnalysis.CodeFixes
     internal static class FixAllLogger
     {
         // Fix all context logging.
-        private static readonly string s_codeFixProvider = "CodeFixProvider";
-        private static readonly string s_codeActionEquivalenceKey = "CodeActionEquivalenceKey";
-        private static readonly string s_fixAllScope = "FixAllScope";
-        private static readonly string s_languageName = "LanguageName";
-        private static readonly string s_documentCount = "DocumentCount";
+        private const string s_codeFixProvider = "CodeFixProvider";
+        private const string s_codeActionEquivalenceKey = "CodeActionEquivalenceKey";
+        private const string s_fixAllScope = "FixAllScope";
+        private const string s_languageName = "LanguageName";
+        private const string s_documentCount = "DocumentCount";
 
         // Fix all computation result logging.
-        private static readonly string s_result = "Result";
-        private static readonly string s_completed = "Completed";
-        private static readonly string s_timedOut = "TimedOut";
-        private static readonly string s_cancelled = "Cancelled";
-        private static readonly string s_allChangesApplied = "AllChangesApplied";
-        private static readonly string s_subsetOfChangesApplied = "SubsetOfChangesApplied";
+        private const string s_result = "Result";
+        private const string s_completed = "Completed";
+        private const string s_timedOut = "TimedOut";
+        private const string s_cancelled = "Cancelled";
+        private const string s_allChangesApplied = "AllChangesApplied";
+        private const string s_subsetOfChangesApplied = "SubsetOfChangesApplied";
 
         // Diagnostics and fixes logging.
-        private static readonly string s_documentsWithDiagnosticsToFix = "DocumentsWithDiagnosticsToFix";
-        private static readonly string s_projectsWithDiagnosticsToFix = "ProjectsWithDiagnosticsToFix";
-        private static readonly string s_totalDiagnosticsToFix = "TotalDiagnosticsToFix";
-        private static readonly string s_totalFixesToMerge = "TotalFixesToMerge";
+        private const string s_documentsWithDiagnosticsToFix = "DocumentsWithDiagnosticsToFix";
+        private const string s_projectsWithDiagnosticsToFix = "ProjectsWithDiagnosticsToFix";
+        private const string s_totalDiagnosticsToFix = "TotalDiagnosticsToFix";
+        private const string s_totalFixesToMerge = "TotalFixesToMerge";
 
         public static void LogState(FixAllState fixAllState, bool isInternalCodeFixProvider)
         {

src/Workspaces/Core/Portable/LanguageServices/SyntaxFactsService/ISyntaxFactsService.cs

@@ -14,6 +14,8 @@ internal interface ISyntaxFactsService : ILanguageService
         bool IsCaseSensitive { get; }
         StringComparer StringComparer { get; }
 
+        SyntaxTrivia ElasticCarriageReturnLineFeed { get; }
+
         bool SupportsIndexingInitializer(ParseOptions options);
         bool SupportsThrowExpression(ParseOptions options);
 
@@ -48,6 +50,7 @@ internal interface ISyntaxFactsService : ILanguageService
 
         bool IsRegularComment(SyntaxTrivia trivia);
         bool IsDocumentationComment(SyntaxTrivia trivia);
+        bool IsElastic(SyntaxTrivia trivia);
 
         bool IsDocumentationComment(SyntaxNode node);
         bool IsNumericLiteralExpression(SyntaxNode node);
@@ -304,4 +307,4 @@ internal enum DisplayNameOptions
         IncludeType = 1 << 3,
         IncludeTypeParameters = 1 << 4
     }
-}
+}
\ No newline at end of file

src/Workspaces/Core/Portable/NamingStyles/Serialization/NamingStylePreferences.cs

@@ -16,7 +16,7 @@ namespace Microsoft.CodeAnalysis.Diagnostics.Analyzers.NamingStyles
     /// </summary>
     internal class NamingStylePreferences : IEquatable<NamingStylePreferences>
     {
-        private readonly static int s_serializationVersion = 4;
+        private const int s_serializationVersion = 4;
 
         public readonly ImmutableArray<SymbolSpecification> SymbolSpecifications;
         public readonly ImmutableArray<NamingStyle> NamingStyles;

src/Workspaces/Core/Portable/Rename/ConflictEngine/ConflictResolver.cs

@@ -31,7 +31,7 @@ internal static partial class ConflictResolver
             propertyStyle: SymbolDisplayPropertyStyle.NameOnly,
             miscellaneousOptions: SymbolDisplayMiscellaneousOptions.EscapeKeywordIdentifiers);
 
-        private static readonly string s_metadataNameSeparators = " .,:<`>()\r\n";
+        private const string s_metadataNameSeparators = " .,:<`>()\r\n";
 
         /// <summary>
         /// Performs the renaming of the symbol in the solution, identifies renaming conflicts and automatically resolves them where possible.

src/Workspaces/Core/Portable/Workspaces.csproj

@@ -205,6 +205,7 @@
     <Compile Include="..\..\..\Compilers\Core\Portable\Syntax\SyntaxTreeExtensions.cs">
       <Link>InternalUtilities\SyntaxTreeExtensions.cs</Link>
     </Compile>
+    <Compile Include="AddImports\AddImportHelpers.cs" />
     <Compile Include="Classification\AbstractClassificationService.cs" />
     <Compile Include="Classification\IClassificationService.cs" />
     <Compile Include="ExtensionManager\IInfoBarService.cs" />

src/Workspaces/VisualBasic/Portable/Extensions/CompilationUnitSyntaxExtensions.vb

@@ -3,6 +3,7 @@
 Imports System.Runtime.CompilerServices
 Imports System.Threading
 Imports Microsoft.CodeAnalysis
+Imports Microsoft.CodeAnalysis.AddImports
 Imports Microsoft.CodeAnalysis.Text
 Imports Microsoft.CodeAnalysis.VisualBasic.Syntax
 Imports Microsoft.CodeAnalysis.VisualBasic.Utilities
@@ -45,44 +46,39 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Extensions
                 Return root
             End If
 
-            Dim comparer = If(placeSystemNamespaceFirst,
-                              ImportsStatementComparer.SystemFirstInstance,
-                              ImportsStatementComparer.NormalInstance)
+            Dim systemFirstInstance = ImportsStatementComparer.SystemFirstInstance
+            Dim normalInstance = ImportsStatementComparer.NormalInstance
+
+            Dim comparers = If(placeSystemNamespaceFirst,
+                               (systemFirstInstance, normalInstance),
+                               (normalInstance, systemFirstInstance))
 
             Dim [imports] = AddImportsStatements(root, importsStatements)
 
-            ' If the user likes to have their Imports statements unsorted, allow them to
-            If root.Imports.IsSorted(comparer) Then
-                [imports].Sort(comparer)
+            ' First, see if the imports were sorted according to the user's preference.  If so,
+            ' keep the same sorting after we add the import.  However, if the imports weren't sorted
+            ' according to their preference, then see if they're sorted in the other way.  If so
+            ' preserve that sorting as well.  That way if the user is working with a file that 
+            ' was written on a machine with a different default, the imports will stay in a 
+            ' reasonable order.
+            If root.Imports.IsSorted(comparers.Item1) Then
+                [imports].Sort(comparers.Item1)
+            ElseIf root.Imports.IsSorted(comparers.Item2) Then
+                [imports].Sort(comparers.Item2)
             End If
 
-            ' If any using we added was moved to the first location, then take the trivia from
-            ' the start of the first token And add it to the using we added.  This way things
-            ' Like #define's and #r's will stay above the using.
-            If root.Imports.Count = 0 OrElse [imports](0) IsNot root.Imports(0) Then
-                Dim firstToken = root.GetFirstToken
-
-                ' Move the leading directives from the first directive to the New using.
-                Dim firstImport = [imports](0).WithLeadingTrivia(firstToken.LeadingTrivia.Where(Function(t) Not t.IsKind(SyntaxKind.DocumentationCommentTrivia) AndAlso Not t.IsElastic))
-
-                ' Remove the leading directives from the first token.
-                Dim newFirstToken = firstToken.WithLeadingTrivia(firstToken.LeadingTrivia.Where(Function(t) t.IsKind(SyntaxKind.DocumentationCommentTrivia) OrElse t.IsElastic))
-
-                ' Remove the leading trivia from the first token from the tree.
-                root = root.ReplaceToken(firstToken, newFirstToken)
+            root = AddImportHelpers.MoveTrivia(
+                VisualBasicSyntaxFactsService.Instance, root, root.Imports, [imports])
 
-                ' Create the New list of imports
-                Dim finalImports = New List(Of ImportsStatementSyntax)
-                finalImports.Add(firstImport)
-                finalImports.AddRange(root.Imports)
-                finalImports.AddRange(importsStatements.Except({[imports](0)}))
-                finalImports.Sort(comparer)
-                [imports] = finalImports
-            End If
+            Return root.WithImports(
+                [imports].Select(Function(u) u.WithAdditionalAnnotations(annotations)).ToSyntaxList())
+        End Function
 
-            Return root.WithImports([imports].ToSyntaxList).WithAdditionalAnnotations(annotations)
+        Private Function IsDocCommentOrElastic(t As SyntaxTrivia) As Boolean
+            Return t.Kind() = SyntaxKind.DocumentationCommentTrivia OrElse t.IsElastic()
         End Function
 
+
         Private Function AddImportsStatements(root As CompilationUnitSyntax, importsStatements As IList(Of ImportsStatementSyntax)) As List(Of ImportsStatementSyntax)
             ' We need to try and not place the using inside of a directive if possible.
             Dim [imports] = New List(Of ImportsStatementSyntax)

src/Workspaces/VisualBasic/Portable/LanguageServices/VisualBasicSyntaxFactsService.vb

@@ -5,7 +5,6 @@ Imports System.Composition
 Imports System.Text
 Imports System.Threading
 Imports Microsoft.CodeAnalysis
-Imports Microsoft.CodeAnalysis.Collections
 Imports Microsoft.CodeAnalysis.Host
 Imports Microsoft.CodeAnalysis.Host.Mef
 Imports Microsoft.CodeAnalysis.LanguageServices
@@ -46,6 +45,12 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             End Get
         End Property
 
+        Public ReadOnly Property ElasticCarriageReturnLineFeed As SyntaxTrivia Implements ISyntaxFactsService.ElasticCarriageReturnLineFeed
+            Get
+                Return SyntaxFactory.ElasticCarriageReturnLineFeed
+            End Get
+        End Property
+
         Protected Overrides ReadOnly Property DocumentationCommentService As IDocumentationCommentService
             Get
                 Return VisualBasicDocumentationCommentService.Instance
@@ -1502,6 +1507,10 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
             Return trivia.Kind = SyntaxKind.DocumentationCommentTrivia
         End Function
 
+        Public Function IsElastic(trivia As SyntaxTrivia) As Boolean Implements ISyntaxFactsService.IsElastic
+            Return trivia.IsElastic()
+        End Function
+
         Public Function IsOnTypeHeader(root As SyntaxNode, position As Integer) As Boolean Implements ISyntaxFactsService.IsOnTypeHeader
             Dim statement = root.FindToken(position).GetAncestor(Of TypeStatementSyntax)
             If statement Is Nothing Then

src/Workspaces/VisualBasic/Portable/Simplification/VisualBasicSimplificationService.vb

@@ -165,8 +165,8 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Simplification
                 TypeOf node.Parent Is FieldDeclarationSyntax
         End Function
 
-        Private Shared ReadOnly s_BC50000_UnusedImportsClause As String = "BC50000"
-        Private Shared ReadOnly s_BC50001_UnusedImportsStatement As String = "BC50001"
+        Private Const s_BC50000_UnusedImportsClause As String = "BC50000"
+        Private Const s_BC50001_UnusedImportsStatement As String = "BC50001"
 
         Protected Overrides Sub GetUnusedNamespaceImports(model As SemanticModel, namespaceImports As HashSet(Of SyntaxNode), cancellationToken As CancellationToken)
             Dim root = model.SyntaxTree.GetRoot()