Share DiagnosticStrings add mechanism to generate a DiagnosticDescriptor given a DiagnosticId (#2170)

* Add DiagnosticId enum
Add GetDiagnosticDescriptor

* Check that the diagnostic id is in the range of the supported linker warnings

* Lint

* Share DiagnosticString

* Noisy whitespace

* Warnings go up to 6000 inclusive

* PR feedback

* Get diagnostic string
Update test

* Lint

* PR feedback

21 files changed, 310 insertions, 212 deletions

diff --git a/illink.sln b/illink.sln
index 947101370..f8752fdc6 100644
--- a/illink.sln
+++ b/illink.sln
@@ -36,6 +36,11 @@ EndProject
 Project("{D954291E-2A0B-460D-934E-DC6B0785DB48}") = "ILLink.Shared", "src\ILLink.Shared\ILLink.Shared.shproj", "{92F5E753-2179-46DC-BDCE-736858C18DC7}"
 EndProject
 Global
+	GlobalSection(SharedMSBuildProjectFiles) = preSolution
+		src\ILLink.Shared\ILLink.Shared.projitems*{92f5e753-2179-46dc-bdce-736858c18dc7}*SharedItemsImports = 13
+		src\ILLink.Shared\ILLink.Shared.projitems*{dd28e2b1-057b-4b4d-a04d-b2ebd9e76e46}*SharedItemsImports = 5
+		src\ILLink.Shared\ILLink.Shared.projitems*{f1a44a78-34ee-408b-8285-9a26f0e7d4f2}*SharedItemsImports = 5
+	EndGlobalSection
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
 		Debug|x64 = Debug|x64
diff --git a/src/ILLink.CodeFix/BaseAttributeCodeFixProvider.cs b/src/ILLink.CodeFix/BaseAttributeCodeFixProvider.cs
index 491c02e74..a5431142b 100644
--- a/src/ILLink.CodeFix/BaseAttributeCodeFixProvider.cs
+++ b/src/ILLink.CodeFix/BaseAttributeCodeFixProvider.cs
@@ -69,9 +69,9 @@ namespace ILLink.CodeFix
 			CancellationToken cancellationToken)
 		{
 			var semanticModel = await document.GetSemanticModelAsync (cancellationToken).ConfigureAwait (false);
-			if (semanticModel is null) {
+			if (semanticModel is null)
 				return document;
-			}
+
 			var newAttribute = generator
 				.Attribute (generator.TypeExpression (AttributeSymbol), attrArgs)
 				.WithAdditionalAnnotations (
diff --git a/src/ILLink.CodeFix/RequiresAssemblyFilesCodeFixProvider.cs b/src/ILLink.CodeFix/RequiresAssemblyFilesCodeFixProvider.cs
index b172b7e51..a4a65999d 100644
--- a/src/ILLink.CodeFix/RequiresAssemblyFilesCodeFixProvider.cs
+++ b/src/ILLink.CodeFix/RequiresAssemblyFilesCodeFixProvider.cs
@@ -5,9 +5,11 @@
 using System;
 using System.Collections.Immutable;
 using System.Composition;
+using System.Linq;
 using System.Threading.Tasks;
 using ILLink.CodeFixProvider;
 using ILLink.RoslynAnalyzer;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp;
@@ -18,8 +20,12 @@ namespace ILLink.CodeFix
 	[ExportCodeFixProvider (LanguageNames.CSharp, Name = nameof (RequiresAssemblyFilesCodeFixProvider)), Shared]
 	public class RequiresAssemblyFilesCodeFixProvider : BaseAttributeCodeFixProvider
 	{
-		public sealed override ImmutableArray<string> FixableDiagnosticIds
-			=> ImmutableArray.Create (RequiresAssemblyFilesAnalyzer.IL3000, RequiresAssemblyFilesAnalyzer.IL3001, RequiresAssemblyFilesAnalyzer.IL3002);
+		public ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create (
+			DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.AvoidAssemblyLocationInSingleFile),
+			DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.AvoidAssemblyGetFilesInSingleFile),
+			DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.RequiresAssemblyFiles));
+
+		public sealed override ImmutableArray<string> FixableDiagnosticIds => SupportedDiagnostics.Select (dd => dd.Id).ToImmutableArray ();
 
 		private protected override LocalizableString CodeFixTitle => new LocalizableResourceString (nameof (Resources.RequiresAssemblyFilesCodeFixTitle), Resources.ResourceManager, typeof (Resources));
 
diff --git a/src/ILLink.CodeFix/RequiresUnreferencedCodeCodeFixProvider.cs b/src/ILLink.CodeFix/RequiresUnreferencedCodeCodeFixProvider.cs
index 5f2a60605..ba24b1ca2 100644
--- a/src/ILLink.CodeFix/RequiresUnreferencedCodeCodeFixProvider.cs
+++ b/src/ILLink.CodeFix/RequiresUnreferencedCodeCodeFixProvider.cs
@@ -5,9 +5,11 @@
 using System;
 using System.Collections.Immutable;
 using System.Composition;
+using System.Linq;
 using System.Threading.Tasks;
 using ILLink.CodeFixProvider;
 using ILLink.RoslynAnalyzer;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp;
@@ -18,8 +20,9 @@ namespace ILLink.CodeFix
 	[ExportCodeFixProvider (LanguageNames.CSharp, Name = nameof (RequiresUnreferencedCodeCodeFixProvider)), Shared]
 	public class RequiresUnreferencedCodeCodeFixProvider : BaseAttributeCodeFixProvider
 	{
-		public sealed override ImmutableArray<string> FixableDiagnosticIds
-			=> ImmutableArray.Create (RequiresUnreferencedCodeAnalyzer.IL2026);
+		public ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create (DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.RequiresUnreferencedCode));
+
+		public sealed override ImmutableArray<string> FixableDiagnosticIds => SupportedDiagnostics.Select (dd => dd.Id).ToImmutableArray ();
 
 		private protected override LocalizableString CodeFixTitle => new LocalizableResourceString (nameof (Resources.RequiresUnreferencedCodeCodeFixTitle), Resources.ResourceManager, typeof (Resources));
 
diff --git a/src/ILLink.CodeFix/UnconditionalSuppressMessageCodeFixProvider.cs b/src/ILLink.CodeFix/UnconditionalSuppressMessageCodeFixProvider.cs
index 1a7f57dd6..2cdd032e4 100644
--- a/src/ILLink.CodeFix/UnconditionalSuppressMessageCodeFixProvider.cs
+++ b/src/ILLink.CodeFix/UnconditionalSuppressMessageCodeFixProvider.cs
@@ -5,9 +5,10 @@
 using System.Collections.Immutable;
 using System.Composition;
 using System.Globalization;
+using System.Linq;
 using System.Threading.Tasks;
 using ILLink.CodeFixProvider;
-using ILLink.RoslynAnalyzer;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp;
@@ -22,7 +23,11 @@ namespace ILLink.CodeFix
 		public const string FullyQualifiedUnconditionalSuppressMessageAttribute = "System.Diagnostics.CodeAnalysis." + UnconditionalSuppressMessageAttribute;
 
 		public sealed override ImmutableArray<string> FixableDiagnosticIds
-			=> ImmutableArray.Create (RequiresUnreferencedCodeAnalyzer.IL2026, RequiresAssemblyFilesAnalyzer.IL3000, RequiresAssemblyFilesAnalyzer.IL3001, RequiresAssemblyFilesAnalyzer.IL3002);
+			=> (new DiagnosticId[] {
+				DiagnosticId.RequiresUnreferencedCode,
+				DiagnosticId.AvoidAssemblyLocationInSingleFile,
+				DiagnosticId.AvoidAssemblyGetFilesInSingleFile,
+				DiagnosticId.RequiresAssemblyFiles }).Select (d => d.AsString ()).ToImmutableArray ();
 
 		private protected override LocalizableString CodeFixTitle => new LocalizableResourceString (nameof (Resources.UconditionalSuppressMessageCodeFixTitle), Resources.ResourceManager, typeof (Resources));
 
diff --git a/src/ILLink.RoslynAnalyzer/DiagnosticDescriptors.cs b/src/ILLink.RoslynAnalyzer/DiagnosticDescriptors.cs
new file mode 100644
index 000000000..4b955a058
--- /dev/null
+++ b/src/ILLink.RoslynAnalyzer/DiagnosticDescriptors.cs
@@ -0,0 +1,68 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using ILLink.Shared;
+using Microsoft.CodeAnalysis;
+
+namespace ILLink.RoslynAnalyzer
+{
+	public static class DiagnosticDescriptors
+	{
+		public static DiagnosticDescriptor GetDiagnosticDescriptor (DiagnosticId diagnosticId)
+		{
+			var diagnosticString = new DiagnosticString (diagnosticId);
+			return new DiagnosticDescriptor (diagnosticId.AsString (),
+				diagnosticString.GetTitleFormat (),
+				diagnosticString.GetMessageFormat (),
+				GetDiagnosticCategory (diagnosticId),
+				DiagnosticSeverity.Warning,
+				true);
+		}
+
+		public static DiagnosticDescriptor GetDiagnosticDescriptor (DiagnosticId diagnosticId,
+			LocalizableResourceString? lrsTitle = null,
+			LocalizableResourceString? lrsMessage = null,
+			string? diagnosticCategory = null,
+			DiagnosticSeverity diagnosticSeverity = DiagnosticSeverity.Warning,
+			bool isEnabledByDefault = true,
+			string? helpLinkUri = null)
+		{
+			if (lrsTitle == null || lrsMessage == null) {
+				var diagnosticString = new DiagnosticString (diagnosticId);
+				return new DiagnosticDescriptor (diagnosticId.AsString (),
+					diagnosticString.GetTitleFormat (),
+					diagnosticString.GetMessageFormat (),
+					diagnosticCategory ?? GetDiagnosticCategory (diagnosticId),
+					diagnosticSeverity,
+					isEnabledByDefault,
+					helpLinkUri);
+			}
+
+			return new DiagnosticDescriptor (diagnosticId.AsString (),
+				lrsTitle!,
+				lrsMessage!,
+				diagnosticCategory ?? GetDiagnosticCategory (diagnosticId),
+				diagnosticSeverity,
+				isEnabledByDefault,
+				helpLinkUri);
+		}
+
+		static string GetDiagnosticCategory (DiagnosticId diagnosticId)
+		{
+			switch ((int) diagnosticId) {
+			case > 2000 and < 3000:
+				return DiagnosticCategory.Trimming;
+
+			case >= 3000 and <= 6000:
+				return DiagnosticCategory.SingleFile;
+
+			default:
+				break;
+			}
+
+			throw new ArgumentException ($"The provided diagnostic id '{diagnosticId}' does not fall into the range of supported warning codes 2001 to 6000 (inclusive).");
+		}
+	}
+}
diff --git a/src/ILLink.RoslynAnalyzer/RequiresAssemblyFilesAnalyzer.cs b/src/ILLink.RoslynAnalyzer/RequiresAssemblyFilesAnalyzer.cs
index dbce10d38..3207cc237 100644
--- a/src/ILLink.RoslynAnalyzer/RequiresAssemblyFilesAnalyzer.cs
+++ b/src/ILLink.RoslynAnalyzer/RequiresAssemblyFilesAnalyzer.cs
@@ -4,7 +4,6 @@
 
 using System;
 using System.Collections.Immutable;
-using System.Linq;
 using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Diagnostics;
@@ -14,58 +13,21 @@ namespace ILLink.RoslynAnalyzer
 	[DiagnosticAnalyzer (LanguageNames.CSharp)]
 	public sealed class RequiresAssemblyFilesAnalyzer : RequiresAnalyzerBase
 	{
-		public const string IL3000 = nameof (IL3000);
-		public const string IL3001 = nameof (IL3001);
-		public const string IL3002 = nameof (IL3002);
-		public const string IL3003 = nameof (IL3003);
-
 		private const string RequiresAssemblyFilesAttribute = nameof (RequiresAssemblyFilesAttribute);
 		public const string RequiresAssemblyFilesAttributeFullyQualifiedName = "System.Diagnostics.CodeAnalysis." + RequiresAssemblyFilesAttribute;
 
-		static readonly DiagnosticDescriptor s_locationRule = new DiagnosticDescriptor (
-			IL3000,
-			new LocalizableResourceString (nameof (SharedStrings.AvoidAssemblyLocationInSingleFileTitle),
-				SharedStrings.ResourceManager, typeof (SharedStrings)),
-			new LocalizableResourceString (nameof (SharedStrings.AvoidAssemblyLocationInSingleFileMessage),
-				SharedStrings.ResourceManager, typeof (SharedStrings)),
-			DiagnosticCategory.SingleFile,
-			DiagnosticSeverity.Warning,
-			isEnabledByDefault: true,
+		static readonly DiagnosticDescriptor s_locationRule = DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.AvoidAssemblyLocationInSingleFile,
 			helpLinkUri: "https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/il3000");
 
-		static readonly DiagnosticDescriptor s_getFilesRule = new DiagnosticDescriptor (
-			IL3001,
-			new LocalizableResourceString (nameof (SharedStrings.AvoidAssemblyGetFilesInSingleFileTitle),
-				SharedStrings.ResourceManager, typeof (SharedStrings)),
-			new LocalizableResourceString (nameof (SharedStrings.AvoidAssemblyGetFilesInSingleFileMessage),
-				SharedStrings.ResourceManager, typeof (SharedStrings)),
-			DiagnosticCategory.SingleFile,
-			DiagnosticSeverity.Warning,
-			isEnabledByDefault: true,
+		static readonly DiagnosticDescriptor s_getFilesRule = DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.AvoidAssemblyGetFilesInSingleFile,
 			helpLinkUri: "https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/il3001");
 
-		static readonly DiagnosticDescriptor s_requiresAssemblyFilesRule = new DiagnosticDescriptor (
-			IL3002,
-			new LocalizableResourceString (nameof (SharedStrings.RequiresAssemblyFilesTitle),
-				SharedStrings.ResourceManager, typeof (SharedStrings)),
-			new LocalizableResourceString (nameof (SharedStrings.RequiresAssemblyFilesMessage),
-				SharedStrings.ResourceManager, typeof (SharedStrings)),
-			DiagnosticCategory.SingleFile,
-			DiagnosticSeverity.Warning,
-			isEnabledByDefault: true,
+		static readonly DiagnosticDescriptor s_requiresAssemblyFilesRule = DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.RequiresAssemblyFiles,
 			helpLinkUri: "https://docs.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/il3002");
 
-		static readonly DiagnosticDescriptor s_requiresAttributeMismatch = new DiagnosticDescriptor (
-			IL3003,
-			new LocalizableResourceString (nameof (SharedStrings.RequiresAttributeMismatchTitle),
-			SharedStrings.ResourceManager, typeof (SharedStrings)),
-			new LocalizableResourceString (nameof (SharedStrings.RequiresAttributeMismatchMessage),
-			SharedStrings.ResourceManager, typeof (SharedStrings)),
-			DiagnosticCategory.Trimming,
-			DiagnosticSeverity.Warning,
-			isEnabledByDefault: true);
+		static readonly DiagnosticDescriptor s_requiresAssembyFilesAttributeMismatch = DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.RequiresAssembyFilesAttributeMismatch);
 
-		public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create (s_locationRule, s_getFilesRule, s_requiresAssemblyFilesRule, s_requiresAttributeMismatch);
+		public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create (s_locationRule, s_getFilesRule, s_requiresAssemblyFilesRule, s_requiresAssembyFilesAttributeMismatch);
 
 		private protected override string RequiresAttributeName => RequiresAssemblyFilesAttribute;
 
@@ -75,16 +37,18 @@ namespace ILLink.RoslynAnalyzer
 
 		private protected override DiagnosticDescriptor RequiresDiagnosticRule => s_requiresAssemblyFilesRule;
 
-		private protected override DiagnosticDescriptor RequiresAttributeMismatch => s_requiresAttributeMismatch;
+		private protected override DiagnosticDescriptor RequiresAttributeMismatch => s_requiresAssembyFilesAttributeMismatch;
 
 		protected override bool IsAnalyzerEnabled (AnalyzerOptions options, Compilation compilation)
 		{
 			var isSingleFileAnalyzerEnabled = options.GetMSBuildPropertyValue (MSBuildPropertyOptionNames.EnableSingleFileAnalyzer, compilation);
 			if (!string.Equals (isSingleFileAnalyzerEnabled?.Trim (), "true", StringComparison.OrdinalIgnoreCase))
 				return false;
+
 			var includesAllContent = options.GetMSBuildPropertyValue (MSBuildPropertyOptionNames.IncludeAllContentForSelfExtract, compilation);
 			if (string.Equals (includesAllContent?.Trim (), "true", StringComparison.OrdinalIgnoreCase))
 				return false;
+
 			return true;
 		}
 
@@ -94,10 +58,10 @@ namespace ILLink.RoslynAnalyzer
 
 			var assemblyType = compilation.GetTypeByMetadataName ("System.Reflection.Assembly");
 			if (assemblyType != null) {
-				// properties
+				// Properties
 				ImmutableArrayOperations.AddIfNotNull (dangerousPatternsBuilder, ImmutableArrayOperations.TryGetSingleSymbol<IPropertySymbol> (assemblyType.GetMembers ("Location")));
 
-				// methods
+				// Methods
 				dangerousPatternsBuilder.AddRange (assemblyType.GetMembers ("GetFile").OfType<IMethodSymbol> ());
 				dangerousPatternsBuilder.AddRange (assemblyType.GetMembers ("GetFiles").OfType<IMethodSymbol> ());
 			}
@@ -120,6 +84,7 @@ namespace ILLink.RoslynAnalyzer
 				operationContext.ReportDiagnostic (Diagnostic.Create (s_locationRule, operationContext.Operation.Syntax.GetLocation (), member.GetDisplayName ()));
 				return true;
 			}
+
 			return false;
 		}
 
diff --git a/src/ILLink.RoslynAnalyzer/RequiresUnreferencedCodeAnalyzer.cs b/src/ILLink.RoslynAnalyzer/RequiresUnreferencedCodeAnalyzer.cs
index 3e6cbc493..53c91a8b8 100644
--- a/src/ILLink.RoslynAnalyzer/RequiresUnreferencedCodeAnalyzer.cs
+++ b/src/ILLink.RoslynAnalyzer/RequiresUnreferencedCodeAnalyzer.cs
@@ -13,32 +13,13 @@ namespace ILLink.RoslynAnalyzer
 	[DiagnosticAnalyzer (LanguageNames.CSharp)]
 	public sealed class RequiresUnreferencedCodeAnalyzer : RequiresAnalyzerBase
 	{
-		public const string IL2026 = nameof (IL2026);
-		public const string IL2046 = nameof (IL2046);
 		const string RequiresUnreferencedCodeAttribute = nameof (RequiresUnreferencedCodeAttribute);
 		public const string FullyQualifiedRequiresUnreferencedCodeAttribute = "System.Diagnostics.CodeAnalysis." + RequiresUnreferencedCodeAttribute;
 
-		static readonly DiagnosticDescriptor s_requiresUnreferencedCodeRule = new DiagnosticDescriptor (
-			IL2026,
-			new LocalizableResourceString (nameof (SharedStrings.RequiresUnreferencedCodeTitle),
-			SharedStrings.ResourceManager, typeof (SharedStrings)),
-			new LocalizableResourceString (nameof (SharedStrings.RequiresUnreferencedCodeMessage),
-			SharedStrings.ResourceManager, typeof (SharedStrings)),
-			DiagnosticCategory.Trimming,
-			DiagnosticSeverity.Warning,
-			isEnabledByDefault: true);
+		static readonly DiagnosticDescriptor s_requiresUnreferencedCodeRule = DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.RequiresUnreferencedCode);
+		static readonly DiagnosticDescriptor s_requiresUnreferencedCodeAttributeMismatch = DiagnosticDescriptors.GetDiagnosticDescriptor (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch);
 
-		static readonly DiagnosticDescriptor s_requiresAttributeMismatch = new DiagnosticDescriptor (
-			IL2046,
-			new LocalizableResourceString (nameof (SharedStrings.RequiresAttributeMismatchTitle),
-			SharedStrings.ResourceManager, typeof (SharedStrings)),
-			new LocalizableResourceString (nameof (SharedStrings.RequiresAttributeMismatchMessage),
-			SharedStrings.ResourceManager, typeof (SharedStrings)),
-			DiagnosticCategory.Trimming,
-			DiagnosticSeverity.Warning,
-			isEnabledByDefault: true);
-
-		public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create (s_requiresUnreferencedCodeRule, s_requiresAttributeMismatch);
+		public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create (s_requiresUnreferencedCodeRule, s_requiresUnreferencedCodeAttributeMismatch);
 
 		private protected override string RequiresAttributeName => RequiresUnreferencedCodeAttribute;
 
@@ -48,7 +29,7 @@ namespace ILLink.RoslynAnalyzer
 
 		private protected override DiagnosticDescriptor RequiresDiagnosticRule => s_requiresUnreferencedCodeRule;
 
-		private protected override DiagnosticDescriptor RequiresAttributeMismatch => s_requiresAttributeMismatch;
+		private protected override DiagnosticDescriptor RequiresAttributeMismatch => s_requiresUnreferencedCodeAttributeMismatch;
 
 		protected override bool IsAnalyzerEnabled (AnalyzerOptions options, Compilation compilation)
 		{
diff --git a/src/ILLink.RoslynAnalyzer/DiagnosticCategory.cs b/src/ILLink.Shared/DiagnosticCategory.cs
index 28cf0f031..1bbf868d9 100644
--- a/src/ILLink.RoslynAnalyzer/DiagnosticCategory.cs
+++ b/src/ILLink.Shared/DiagnosticCategory.cs
@@ -2,7 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-namespace ILLink.RoslynAnalyzer
+namespace ILLink.Shared
 {
 	internal static class DiagnosticCategory
 	{
diff --git a/src/ILLink.Shared/DiagnosticId.cs b/src/ILLink.Shared/DiagnosticId.cs
new file mode 100644
index 000000000..0dd728ed3
--- /dev/null
+++ b/src/ILLink.Shared/DiagnosticId.cs
@@ -0,0 +1,20 @@
+namespace ILLink.Shared
+{
+	public enum DiagnosticId
+	{
+		// Linker diagnostic ids.
+		RequiresUnreferencedCode = 2026,
+		RequiresUnreferencedCodeAttributeMismatch = 2046,
+
+		// Single-file diagnostic ids.
+		AvoidAssemblyLocationInSingleFile = 3000,
+		AvoidAssemblyGetFilesInSingleFile = 3001,
+		RequiresAssemblyFiles = 3002,
+		RequiresAssembyFilesAttributeMismatch = 3003
+	}
+
+	public static class DiagnosticIdExtensions
+	{
+		public static string AsString (this DiagnosticId diagnosticId) => $"IL{(int) diagnosticId}";
+	}
+}
diff --git a/src/ILLink.Shared/DiagnosticString.cs b/src/ILLink.Shared/DiagnosticString.cs
new file mode 100644
index 000000000..dbd530207
--- /dev/null
+++ b/src/ILLink.Shared/DiagnosticString.cs
@@ -0,0 +1,25 @@
+namespace ILLink.Shared
+{
+	public readonly struct DiagnosticString
+	{
+		readonly string _titleFormat;
+		readonly string _messageFormat;
+
+		public DiagnosticString (DiagnosticId diagnosticId)
+		{
+			var resourceManager = SharedStrings.ResourceManager;
+			_titleFormat = resourceManager.GetString ($"{diagnosticId}Title");
+			_messageFormat = resourceManager.GetString ($"{diagnosticId}Message");
+		}
+
+		public string GetMessage (params string[] args) =>
+			string.Format (_messageFormat, args);
+
+		public string GetMessageFormat () => _messageFormat;
+
+		public string GetTitle (params string[] args) =>
+			string.Format (_titleFormat, args);
+
+		public string GetTitleFormat () => _titleFormat;
+	}
+}
diff --git a/src/ILLink.Shared/ILLink.Shared.projitems b/src/ILLink.Shared/ILLink.Shared.projitems
index 227b6f712..8b672c98b 100644
--- a/src/ILLink.Shared/ILLink.Shared.projitems
+++ b/src/ILLink.Shared/ILLink.Shared.projitems
@@ -9,6 +9,9 @@
     <Import_RootNamespace>ILLink.Shared</Import_RootNamespace>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="$(MSBuildThisFileDirectory)DiagnosticCategory.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)DiagnosticId.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)DiagnosticString.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MessageFormat.cs" />
   </ItemGroup>
   <ItemGroup>
diff --git a/src/ILLink.Shared/MessageFormat.cs b/src/ILLink.Shared/MessageFormat.cs
index 96bd7a782..e8ae020f7 100644
--- a/src/ILLink.Shared/MessageFormat.cs
+++ b/src/ILLink.Shared/MessageFormat.cs
@@ -6,21 +6,21 @@ namespace ILLink.Shared
 	{
 		public static string FormatRequiresAttributeMessageArg (string? message)
 		{
-			string arg1 = "";
 			if (!string.IsNullOrEmpty (message))
-				arg1 = $" {message}{(message!.TrimEnd ().EndsWith (".") ? "" : ".")}";
-			return arg1;
+				return $" {message}{(message!.TrimEnd ().EndsWith (".") ? "" : ".")}";
+
+			return string.Empty;
 		}
 
 		public static string FormatRequiresAttributeUrlArg (string? url)
 		{
-			string arg2 = "";
 			if (!string.IsNullOrEmpty (url))
-				arg2 = " " + url;
-			return arg2;
+				return $" {url}";
+
+			return string.Empty;
 		}
 
-		public static string FormatRequiresAttributeMismatch (bool memberHasAttribute, bool isInterface, string var0, string var1, string var2)
+		public static string FormatRequiresAttributeMismatch (bool memberHasAttribute, bool isInterface, params object[] args)
 		{
 			string format = (memberHasAttribute, isInterface) switch {
 				(false, true) => SharedStrings.InterfaceRequiresMismatchMessage,
@@ -28,7 +28,8 @@ namespace ILLink.Shared
 				(false, false) => SharedStrings.BaseRequiresMismatchMessage,
 				(true, false) => SharedStrings.DerivedRequiresMismatchMessage
 			};
-			return string.Format (format, var0, var1, var2);
+
+			return string.Format (format, args);
 		}
 	}
 }
\ No newline at end of file
diff --git a/src/ILLink.Shared/SharedStrings.resx b/src/ILLink.Shared/SharedStrings.resx
index a662c41cd..d5015e17d 100644
--- a/src/ILLink.Shared/SharedStrings.resx
+++ b/src/ILLink.Shared/SharedStrings.resx
@@ -141,11 +141,11 @@
   <data name="RequiresAssemblyFilesMessage" xml:space="preserve">
     <value>Using member '{0}' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.{1}{2}</value>
   </data>
-  <data name="RequiresAttributeMismatchMessage" xml:space="preserve">
-    <value>{0}. Attributes must match across all interface implementations or overrides.</value>
+  <data name="RequiresUnreferencedCodeAttributeMismatchMessage" xml:space="preserve">
+    <value>{0}. 'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides.</value>
   </data>
-  <data name="RequiresAttributeMismatchTitle" xml:space="preserve">
-    <value>RequiresAttribute must match across all interface implementations or overrides.</value>
+  <data name="RequiresUnreferencedCodeAttributeMismatchTitle" xml:space="preserve">
+    <value>'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides.</value>
   </data>
   <data name="BaseRequiresMismatchMessage" xml:space="preserve">
     <value>Base member '{2}' with '{0}' has a derived member '{1}' without '{0}'</value>
diff --git a/src/linker/Linker.Steps/ValidateVirtualMethodAnnotationsStep.cs b/src/linker/Linker.Steps/ValidateVirtualMethodAnnotationsStep.cs
index a26964587..c3787a12e 100644
--- a/src/linker/Linker.Steps/ValidateVirtualMethodAnnotationsStep.cs
+++ b/src/linker/Linker.Steps/ValidateVirtualMethodAnnotationsStep.cs
@@ -43,8 +43,10 @@ namespace Mono.Linker.Steps
 			var annotations = Context.Annotations;
 			bool methodHasAttribute = annotations.HasLinkerAttribute<RequiresUnreferencedCodeAttribute> (method);
 			if (methodHasAttribute != annotations.HasLinkerAttribute<RequiresUnreferencedCodeAttribute> (baseMethod)) {
-				string message = MessageFormat.FormatRequiresAttributeMismatch (methodHasAttribute, baseMethod.DeclaringType.IsInterface, nameof (RequiresUnreferencedCodeAttribute), method.GetDisplayName (), baseMethod.GetDisplayName ());
-				Context.LogWarning (string.Format (SharedStrings.RequiresAttributeMismatchMessage, message), 2046, method, subcategory: MessageSubCategory.TrimAnalysis);
+				string message = MessageFormat.FormatRequiresAttributeMismatch (methodHasAttribute,
+					baseMethod.DeclaringType.IsInterface, nameof (RequiresUnreferencedCodeAttribute), method.GetDisplayName (), baseMethod.GetDisplayName ());
+				Context.LogWarning (new DiagnosticString (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).GetMessage (message),
+					2046, method, subcategory: MessageSubCategory.TrimAnalysis);
 			}
 		}
 	}
diff --git a/test/ILLink.RoslynAnalyzer.Tests/RequiresAssemblyFilesAnalyzerTests.cs b/test/ILLink.RoslynAnalyzer.Tests/RequiresAssemblyFilesAnalyzerTests.cs
index cf09be77e..5d9801dd2 100644
--- a/test/ILLink.RoslynAnalyzer.Tests/RequiresAssemblyFilesAnalyzerTests.cs
+++ b/test/ILLink.RoslynAnalyzer.Tests/RequiresAssemblyFilesAnalyzerTests.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.Testing;
@@ -73,7 +74,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestRequiresAssemblyFieldsOnEvent,
 				// (12,17): warning IL3002: Using member 'C.E' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (12, 17, 12, 18).WithArguments ("C.E", "", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (12, 17, 12, 18).WithArguments ("C.E", "", ""));
 		}
 
 		[Fact]
@@ -96,7 +97,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestRequiresAssemblyFilesOnMethod,
 				// (13,3): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (13, 3, 13, 7).WithArguments ("C.M1()", "", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (13, 3, 13, 7).WithArguments ("C.M1()", "", ""));
 		}
 
 		[Fact]
@@ -119,9 +120,9 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestRequiresAssemblyFilesOnProperty,
 				// (11,3): warning IL3002: Using member 'C.P' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (12, 3, 12, 4).WithArguments ("C.P", "", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (12, 3, 12, 4).WithArguments ("C.P", "", ""),
 				// (13,12): warning IL3002: Using member 'C.P' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (13, 35, 13, 36).WithArguments ("C.P", "", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (13, 35, 13, 36).WithArguments ("C.P", "", ""));
 		}
 
 		[Fact]
@@ -155,7 +156,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestRequiresAssemblyFilesOnMethodInsideProperty,
 				// (24,3): warning IL3002: Using member 'C.P' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (24, 3, 24, 4).WithArguments ("C.P", "", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (24, 3, 24, 4).WithArguments ("C.P", "", ""));
 		}
 
 		[Fact]
@@ -178,7 +179,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestRequiresAssemblyFilesWithMessageAndUrl,
 				// (13,3): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. Message from attribute. https://helpurl
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (13, 3, 13, 7).WithArguments ("C.M1()", " Message from attribute.", " https://helpurl"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (13, 3, 13, 7).WithArguments ("C.M1()", " Message from attribute.", " https://helpurl"));
 		}
 
 		[Fact]
@@ -201,7 +202,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestRequiresAssemblyFilesWithMessageAndUrl,
 				// (13,3): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. https://helpurl
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (13, 3, 13, 7).WithArguments ("C.M1()", "", " https://helpurl"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (13, 3, 13, 7).WithArguments ("C.M1()", "", " https://helpurl"));
 		}
 
 		[Fact]
@@ -244,7 +245,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (TestNoDiagnosticIsProducedIfCallerIsAnnotated,
 				// (8,3): warning IL3002: Using member 'C.M2()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. Warn from M2.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (8, 3, 8, 7).WithArguments ("C.M2()", " Warn from M2.", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (8, 3, 8, 7).WithArguments ("C.M2()", " Warn from M2.", ""));
 		}
 
 		[Fact]
@@ -259,7 +260,7 @@ class C
 
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (5,26): warning IL3000: 'System.Reflection.Assembly.Location' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (5, 26, 5, 66).WithArguments ("System.Reflection.Assembly.Location"));
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (5, 26, 5, 66).WithArguments ("System.Reflection.Assembly.Location"));
 		}
 
 		[Fact]
@@ -280,7 +281,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (8,13): warning IL3000: 'System.Reflection.Assembly.Location' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.Assembly.Location")
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.Assembly.Location")
 			);
 		}
 
@@ -300,9 +301,9 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (8,13): warning IL3001: Assemblies embedded in a single-file app cannot have additional files in the manifest.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3001).WithSpan (8, 13, 8, 41).WithArguments ("System.Reflection.Assembly.GetFile(string)"),
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyGetFilesInSingleFile).WithSpan (8, 13, 8, 41).WithArguments ("System.Reflection.Assembly.GetFile(string)"),
 				// (9,13): warning IL3001: Assemblies embedded in a single-file app cannot have additional files in the manifest.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3001).WithSpan (9, 13, 9, 25).WithArguments ("System.Reflection.Assembly.GetFiles()")
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyGetFilesInSingleFile).WithSpan (9, 13, 9, 25).WithArguments ("System.Reflection.Assembly.GetFiles()")
 				);
 		}
 
@@ -322,11 +323,11 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (8,13): warning IL3002: Using member 'System.Reflection.AssemblyName.CodeBase.get' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. The code will return an empty string for assemblies embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.AssemblyName.CodeBase.get", " The code will return an empty string for assemblies embedded in a single-file app.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.AssemblyName.CodeBase.get", " The code will return an empty string for assemblies embedded in a single-file app.", ""),
 				// (8,13): warning IL3000: 'System.Reflection.AssemblyName.CodeBase' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.AssemblyName.CodeBase"),
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.AssemblyName.CodeBase"),
 				// (9,13): warning IL3000: 'System.Reflection.AssemblyName.EscapedCodeBase' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (9, 13, 9, 30).WithArguments ("System.Reflection.AssemblyName.EscapedCodeBase")
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (9, 13, 9, 30).WithArguments ("System.Reflection.AssemblyName.EscapedCodeBase")
 				);
 		}
 
@@ -348,9 +349,9 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (8,13): warning IL3000: 'System.Reflection.Assembly.Location' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.Assembly.Location"),
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (8, 13, 8, 23).WithArguments ("System.Reflection.Assembly.Location"),
 				// (9,13): warning IL3001: Assemblies embedded in a single-file app cannot have additional files in the manifest.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3001).WithSpan (9, 13, 9, 25).WithArguments ("System.Reflection.Assembly.GetFiles()")
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyGetFilesInSingleFile).WithSpan (9, 13, 9, 25).WithArguments ("System.Reflection.Assembly.GetFiles()")
 				);
 		}
 
@@ -413,7 +414,7 @@ class C
 
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (6,50): warning IL3002: Using member 'C.InitC()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""));
 		}
 
 		[Fact]
@@ -435,9 +436,9 @@ class C
 
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (10,20): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (10, 20, 10, 22).WithArguments ("C.M1()", "", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (10, 20, 10, 22).WithArguments ("C.M1()", "", ""),
 				// (11,26): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (11, 26, 11, 30).WithArguments ("C.M1()", "", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (11, 26, 11, 30).WithArguments ("C.M1()", "", ""));
 		}
 
 		[Fact]
@@ -500,13 +501,13 @@ public class E
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(7,17): warning IL3002: Using method 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when trimming application code. message.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (7, 17, 7, 21).WithArguments ("C.M1()", " message.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (7, 17, 7, 21).WithArguments ("C.M1()", " message.", ""),
 				// /0/Test0.cs(11,27): warning IL3002: Using method 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when trimming application code. message.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (11, 27, 11, 33).WithArguments ("C.M1()", " message.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (11, 27, 11, 33).WithArguments ("C.M1()", " message.", ""),
 				// /0/Test0.cs(14,31): warning IL3002: Using method 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when trimming application code. message.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (14, 31, 14, 37).WithArguments ("C.M1()", " message.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (14, 31, 14, 37).WithArguments ("C.M1()", " message.", ""),
 				// /0/Test0.cs(21,31): warning IL3002: Using method 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when trimming application code. message.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (21, 31, 21, 37).WithArguments ("C.M1()", " message.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (21, 31, 21, 37).WithArguments ("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -547,9 +548,9 @@ public class C
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(7,27): warning IL3000: 'System.Reflection.Assembly.Location' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (7, 27, 7, 44).WithArguments ("System.Reflection.Assembly.Location", "", ""),
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (7, 27, 7, 44).WithArguments ("System.Reflection.Assembly.Location", "", ""),
 				// /0/Test0.cs(9,13): warning IL3001: 'System.Reflection.Assembly.GetFiles()' will throw for assemblies embedded in a single-file app
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3001).WithSpan (9, 13, 9, 32).WithArguments("System.Reflection.Assembly.GetFiles()", "", ""),
+				VerifyCS.Diagnostic (DiagnosticId.AvoidAssemblyGetFilesInSingleFile).WithSpan (9, 13, 9, 32).WithArguments("System.Reflection.Assembly.GetFiles()", "", ""),
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -585,7 +586,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(10,15): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. message.
-					VerifyCS.Diagnostic(RequiresAssemblyFilesAnalyzer.IL3002).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresAssemblyFiles).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -627,11 +628,11 @@ class C
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(6,50): warning IL3002: Using member 'C.InitC()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""),
 				},
 				fixedExpected: new[] {
 				// /0/Test0.cs(6,50): warning IL3002: Using member 'C.InitC()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""),
 				});
 		}
 
@@ -675,7 +676,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(12,28): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. message.
-					VerifyCS.Diagnostic(RequiresAssemblyFilesAnalyzer.IL3002).WithSpan(12, 28, 12, 32).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresAssemblyFiles).WithSpan(12, 28, 12, 32).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> (),
 				numberOfIterations: 2);
@@ -712,7 +713,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(10,15): warning IL3002: Using member 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. message.
-					VerifyCS.Diagnostic(RequiresAssemblyFilesAnalyzer.IL3002).WithSpan(10, 20, 10, 24).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresAssemblyFiles).WithSpan(10, 20, 10, 24).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -762,7 +763,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(14,21): warning IL3002: Using method 'C.M1()' which has 'RequiresAssemblyFilesAttribute' can break functionality when trimming application code. message.
-					VerifyCS.Diagnostic(RequiresAssemblyFilesAnalyzer.IL3002).WithSpan(14, 21, 14, 25).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresAssemblyFiles).WithSpan(14, 21, 14, 25).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -787,7 +788,7 @@ class StaticCtor
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (13,7): warning IL3002: Using member 'StaticCtor.StaticCtor()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. Message for --TestStaticCtor--.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (13, 7, 13, 24).WithArguments ("StaticCtor.StaticCtor()", " Message for --TestStaticCtor--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (13, 7, 13, 24).WithArguments ("StaticCtor.StaticCtor()", " Message for --TestStaticCtor--.", "")
 				);
 		}
 
@@ -816,7 +817,7 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (18,11): warning IL3002: Using member 'StaticCtorTriggeredByFieldAccess.StaticCtorTriggeredByFieldAccess()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.. Message for --StaticCtorTriggeredByFieldAccess.Cctor--.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (18, 11, 18, 49).WithArguments ("StaticCtorTriggeredByFieldAccess.StaticCtorTriggeredByFieldAccess()", " Message for --StaticCtorTriggeredByFieldAccess.Cctor--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (18, 11, 18, 49).WithArguments ("StaticCtorTriggeredByFieldAccess.StaticCtorTriggeredByFieldAccess()", " Message for --StaticCtorTriggeredByFieldAccess.Cctor--.", "")
 				);
 		}
 
@@ -848,9 +849,9 @@ class C
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (21,3): warning IL3002: Using member 'StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. Message for --StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking--.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (21, 3, 21, 69).WithArguments ("StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking()", " Message for --StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking--.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (21, 3, 21, 69).WithArguments ("StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking()", " Message for --StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking--.", ""),
 				// (21,3): warning IL3002: Using member 'StaticCtorTriggeredByMethodCall.StaticCtorTriggeredByMethodCall()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app. Message for --StaticCtorTriggeredByMethodCall.Cctor--.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (21, 3, 21, 41).WithArguments ("StaticCtorTriggeredByMethodCall.StaticCtorTriggeredByMethodCall()", " Message for --StaticCtorTriggeredByMethodCall.Cctor--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (21, 3, 21, 41).WithArguments ("StaticCtorTriggeredByMethodCall.StaticCtorTriggeredByMethodCall()", " Message for --StaticCtorTriggeredByMethodCall.Cctor--.", "")
 				);
 		}
 
@@ -891,11 +892,11 @@ class BaseClass
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (7,23): warning IL3003: Member 'DerivedClass.VirtualMethod()' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualMethod()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (7, 23, 7, 36).WithArguments ("Member 'DerivedClass.VirtualMethod()' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualMethod()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (7, 23, 7, 36).WithArguments ("Member 'DerivedClass.VirtualMethod()' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualMethod()' without 'RequiresAssemblyFilesAttribute'"),
 				// (15,3): warning IL3003: Member 'DerivedClass.VirtualPropertyWithAnnotationInAccesor.get' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualPropertyWithAnnotationInAccesor.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (15, 3, 15, 6).WithArguments ("Member 'DerivedClass.VirtualPropertyWithAnnotationInAccesor.get' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualPropertyWithAnnotationInAccesor.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (15, 3, 15, 6).WithArguments ("Member 'DerivedClass.VirtualPropertyWithAnnotationInAccesor.get' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualPropertyWithAnnotationInAccesor.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (20,25): warning IL3003: Member 'DerivedClass.VirtualPropertyWithAnnotationInProperty' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualPropertyWithAnnotationInProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (20, 25, 20, 64).WithArguments ("Member 'DerivedClass.VirtualPropertyWithAnnotationInProperty' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualPropertyWithAnnotationInProperty' without 'RequiresAssemblyFilesAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (20, 25, 20, 64).WithArguments ("Member 'DerivedClass.VirtualPropertyWithAnnotationInProperty' with 'RequiresAssemblyFilesAttribute' overrides base member 'BaseClass.VirtualPropertyWithAnnotationInProperty' without 'RequiresAssemblyFilesAttribute'"));
 		}
 
 		[Fact]
@@ -934,11 +935,11 @@ class BaseClass
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (6,23): warning IL3003: Base member 'BaseClass.VirtualMethod()' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualMethod()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (6, 23, 6, 36).WithArguments ("Base member 'BaseClass.VirtualMethod()' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualMethod()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (6, 23, 6, 36).WithArguments ("Base member 'BaseClass.VirtualMethod()' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualMethod()' without 'RequiresAssemblyFilesAttribute'"),
 				// (13,3): warning IL3003: Base member 'BaseClass.VirtualPropertyWithAnnotationInAccesor.get' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualPropertyWithAnnotationInAccesor.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (13, 3, 13, 6).WithArguments ("Base member 'BaseClass.VirtualPropertyWithAnnotationInAccesor.get' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualPropertyWithAnnotationInAccesor.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (13, 3, 13, 6).WithArguments ("Base member 'BaseClass.VirtualPropertyWithAnnotationInAccesor.get' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualPropertyWithAnnotationInAccesor.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (17,25): warning IL3003: Base member 'BaseClass.VirtualPropertyWithAnnotationInProperty' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualPropertyWithAnnotationInProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (17, 25, 17, 64).WithArguments ("Base member 'BaseClass.VirtualPropertyWithAnnotationInProperty' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualPropertyWithAnnotationInProperty' without 'RequiresAssemblyFilesAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (17, 25, 17, 64).WithArguments ("Base member 'BaseClass.VirtualPropertyWithAnnotationInProperty' with 'RequiresAssemblyFilesAttribute' has a derived member 'DerivedClass.VirtualPropertyWithAnnotationInProperty' without 'RequiresAssemblyFilesAttribute'"));
 		}
 
 		[Fact]
@@ -1020,17 +1021,17 @@ interface IRAF
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (7,14): warning IL3003: Member 'Implementation.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (7, 14, 7, 20).WithArguments ("Member 'Implementation.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (7, 14, 7, 20).WithArguments ("Member 'Implementation.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (13,3): warning IL3003: Member 'Implementation.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (19,13): warning IL3003: Member 'Implementation.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (19, 13, 19, 24).WithArguments ("Member 'Implementation.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (19, 13, 19, 24).WithArguments ("Member 'Implementation.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'"),
 				// (48,12): warning IL3003: Member 'ExplicitImplementation.IRAF.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (48, 12, 48, 18).WithArguments ("Member 'ExplicitImplementation.IRAF.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (48, 12, 48, 18).WithArguments ("Member 'ExplicitImplementation.IRAF.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (54,3): warning IL3003: Member 'ExplicitImplementation.IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (54, 3, 54, 6).WithArguments ("Member 'ExplicitImplementation.IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (54, 3, 54, 6).WithArguments ("Member 'ExplicitImplementation.IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (60,11): warning IL3003: Member 'ExplicitImplementation.IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (60, 11, 60, 22).WithArguments ("Member 'ExplicitImplementation.IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (60, 11, 60, 22).WithArguments ("Member 'ExplicitImplementation.IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
 		}
 
 		[Fact]
@@ -1087,17 +1088,17 @@ interface IRAF
 }";
 			return VerifyRequiresAssemblyFilesAnalyzer (src,
 				// (6,14): warning IL3003: Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (6, 14, 6, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (6, 14, 6, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (11,3): warning IL3003: Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (11, 3, 11, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (11, 3, 11, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (16,13): warning IL3003: Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (16, 13, 16, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (16, 13, 16, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"),
 				// (25,14): warning IL3003: Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (25, 14, 25, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (25, 14, 25, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (30,3): warning IL3003: Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (30, 3, 30, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (30, 3, 30, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (35,13): warning IL3003: Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (35, 13, 35, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (35, 13, 35, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
 		}
 
 		[Fact]
@@ -1158,17 +1159,17 @@ class AnotherImplementation : IRAF
 
 			await VerifyRequiresAssemblyFilesAnalyzer (src, additionalReferences: new[] { compilation },
 				// (4,14): warning IL3003: Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (4, 14, 4, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (4, 14, 4, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (9,3): warning IL3003: Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (9, 3, 9, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (9, 3, 9, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (14,13): warning IL3003: Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (14, 13, 14, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (14, 13, 14, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'Implementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"),
 				// (23,14): warning IL3003: Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (23, 14, 23, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (23, 14, 23, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (28,3): warning IL3003: Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (28, 3, 28, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (28, 3, 28, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (33,13): warning IL3003: Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (33, 13, 33, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (33, 13, 33, 24).WithArguments ("Interface member 'IRAF.NumProperty' with 'RequiresAssemblyFilesAttribute' has an implementation member 'AnotherImplementation.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
 		}
 
 		[Fact]
@@ -1230,11 +1231,11 @@ class AnotherImplementation : IRAF
 
 			await VerifyRequiresAssemblyFilesAnalyzer (src, additionalReferences: new[] { compilation },
 				// (7,14): warning IL3003: Member 'Implementation.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (7, 14, 7, 20).WithArguments ("Member 'Implementation.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (7, 14, 7, 20).WithArguments ("Member 'Implementation.Method()' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.Method()' without 'RequiresAssemblyFilesAttribute'"),
 				// (13,3): warning IL3003: Member 'Implementation.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.StringProperty.get' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresAssemblyFilesAttribute'"),
 				// (19,13): warning IL3003: Member 'Implementation.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3003).WithSpan (19, 13, 19, 24).WithArguments ("Member 'Implementation.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresAssembyFilesAttributeMismatch).WithSpan (19, 13, 19, 24).WithArguments ("Member 'Implementation.NumProperty' with 'RequiresAssemblyFilesAttribute' implements interface member 'IRAF.NumProperty' without 'RequiresAssemblyFilesAttribute'"));
 		}
 	}
 }
diff --git a/test/ILLink.RoslynAnalyzer.Tests/RequiresUnreferencedCodeAnalyzerTests.cs b/test/ILLink.RoslynAnalyzer.Tests/RequiresUnreferencedCodeAnalyzerTests.cs
index b38749841..4f26b6bb1 100644
--- a/test/ILLink.RoslynAnalyzer.Tests/RequiresUnreferencedCodeAnalyzerTests.cs
+++ b/test/ILLink.RoslynAnalyzer.Tests/RequiresUnreferencedCodeAnalyzerTests.cs
@@ -5,6 +5,8 @@
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
+using ILLink.RoslynAnalyzer;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.Testing;
 using Microsoft.CodeAnalysis.Text;
@@ -65,7 +67,7 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (TestRequiresWithMessageOnlyOnMethod,
 				// (8,17): warning IL2026: Using method 'C.M1()' which has `RequiresUnreferencedCodeAttribute` can break functionality when trimming application code. message.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (8, 17, 8, 21).WithArguments ("C.M1()", " message.", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (8, 17, 8, 21).WithArguments ("C.M1()", " message.", ""));
 		}
 
 		[Fact]
@@ -133,13 +135,13 @@ public class E
 
 			await VerifyRequiresUnreferencedCodeCodeFix (test, fixtest, new[] {
 	// /0/Test0.cs(9,17): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-	VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (9, 17, 9, 21).WithArguments ("C.M1()", " message.", ""),
+	VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (9, 17, 9, 21).WithArguments ("C.M1()", " message.", ""),
 	// /0/Test0.cs(13,27): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-	VerifyCS.Diagnostic(RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(13, 27, 13, 33).WithArguments("C.M1()", " message.", ""),
+	VerifyCS.Diagnostic(DiagnosticId.RequiresUnreferencedCode).WithSpan(13, 27, 13, 33).WithArguments("C.M1()", " message.", ""),
 	// /0/Test0.cs(17,31): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-	VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (17, 31, 17, 37).WithArguments ("C.M1()", " message.", ""),
+	VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (17, 31, 17, 37).WithArguments ("C.M1()", " message.", ""),
 	// /0/Test0.cs(24,31): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-	VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (24, 31, 24, 37).WithArguments ("C.M1()", " message.", "")
+	VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (24, 31, 24, 37).WithArguments ("C.M1()", " message.", "")
 			}, new[] {
 	// /0/Test0.cs(27,10): error CS7036: There is no argument given that corresponds to the required formal parameter 'message' of 'RequiresUnreferencedCodeAttribute.RequiresUnreferencedCodeAttribute(string)'
 	DiagnosticResult.CompilerError("CS7036").WithSpan(27, 10, 27, 36).WithArguments("message", "System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute.RequiresUnreferencedCodeAttribute(string)"),
@@ -185,7 +187,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(12,22): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCS.Diagnostic(RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(12, 22, 12, 26).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresUnreferencedCode).WithSpan(12, 22, 12, 26).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -230,7 +232,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(12,28): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCS.Diagnostic(RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(12, 28, 12, 32).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresUnreferencedCode).WithSpan(12, 28, 12, 32).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> (),
 				// The default iterations for the codefix is the number of diagnostics (1 in this case)
@@ -271,7 +273,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(10,19): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCS.Diagnostic(RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(10, 19, 10, 23).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresUnreferencedCode).WithSpan(10, 19, 10, 23).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: new[] {
 					// /0/Test0.cs(10,6): error CS7036: There is no argument given that corresponds to the required formal parameter 'message' of 'RequiresUnreferencedCodeAttribute.RequiresUnreferencedCodeAttribute(string)'
@@ -310,11 +312,11 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(10,15): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCS.Diagnostic(RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresUnreferencedCode).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: new[] {
 					// /0/Test0.cs(10,15): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCS.Diagnostic(RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
+					VerifyCS.Diagnostic(DiagnosticId.RequiresUnreferencedCode).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
 				});
 		}
 
@@ -337,7 +339,7 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (MessageAndUrlOnMethod,
 				// (8,3): warning IL2026: Using method 'C.RequiresWithMessageAndUrl()' which has `RequiresUnreferencedCodeAttribute` can break functionality when trimming application code. Message for --RequiresWithMessageAndUrl--. https://helpurl
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (8, 3, 8, 31).WithArguments ("C.RequiresWithMessageAndUrl()", " Message for --RequiresWithMessageAndUrl--.", " https://helpurl")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (8, 3, 8, 31).WithArguments ("C.RequiresWithMessageAndUrl()", " Message for --RequiresWithMessageAndUrl--.", " https://helpurl")
 				);
 		}
 
@@ -367,8 +369,8 @@ class C
 }";
 
 			return VerifyRequiresUnreferencedCodeAnalyzer (source,
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (18, 3, 18, 34).WithArguments ("C.MessageWithoutTrailingPeriod()", " Warning message.", string.Empty),
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (19, 3, 19, 31).WithArguments ("C.MessageWithTrailingPeriod()", " Warning message.", string.Empty));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (18, 3, 18, 34).WithArguments ("C.MessageWithoutTrailingPeriod()", " Warning message.", string.Empty),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (19, 3, 19, 31).WithArguments ("C.MessageWithTrailingPeriod()", " Warning message.", string.Empty));
 		}
 
 		[Fact]
@@ -391,7 +393,7 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (PropertyRequires,
 				// (8,7): warning IL2026: Using method 'C.PropertyRequires.get' which has `RequiresUnreferencedCodeAttribute` can break functionality when trimming application code. Message for --getter PropertyRequires--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (8, 7, 8, 23).WithArguments ("C.PropertyRequires.get", " Message for --getter PropertyRequires--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (8, 7, 8, 23).WithArguments ("C.PropertyRequires.get", " Message for --getter PropertyRequires--.", "")
 				);
 		}
 
@@ -415,7 +417,7 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (PropertyRequires,
 				// (8,3): warning IL2026: Using method 'C.PropertyRequires.set' which has `RequiresUnreferencedCodeAttribute` can break functionality when trimming application code. Message for --setter PropertyRequires--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (8, 3, 8, 19).WithArguments ("C.PropertyRequires.set", " Message for --setter PropertyRequires--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (8, 3, 8, 19).WithArguments ("C.PropertyRequires.set", " Message for --setter PropertyRequires--.", "")
 				);
 		}
 
@@ -439,7 +441,7 @@ class StaticCtor
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (13,7): warning IL2026: Using method 'StaticCtor.StaticCtor()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message for --TestStaticCtor--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (13, 7, 13, 24).WithArguments ("StaticCtor.StaticCtor()", " Message for --TestStaticCtor--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (13, 7, 13, 24).WithArguments ("StaticCtor.StaticCtor()", " Message for --TestStaticCtor--.", "")
 				);
 		}
 
@@ -468,7 +470,7 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (18,11): warning IL2026: Using method 'StaticCtorTriggeredByFieldAccess.StaticCtorTriggeredByFieldAccess()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message for --StaticCtorTriggeredByFieldAccess.Cctor--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (18, 11, 18, 49).WithArguments ("StaticCtorTriggeredByFieldAccess.StaticCtorTriggeredByFieldAccess()", " Message for --StaticCtorTriggeredByFieldAccess.Cctor--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (18, 11, 18, 49).WithArguments ("StaticCtorTriggeredByFieldAccess.StaticCtorTriggeredByFieldAccess()", " Message for --StaticCtorTriggeredByFieldAccess.Cctor--.", "")
 				);
 		}
 
@@ -500,9 +502,9 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (21,3): warning IL2026: Using method 'StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message for --StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (21, 3, 21, 69).WithArguments ("StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking()", " Message for --StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking--.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (21, 3, 21, 69).WithArguments ("StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking()", " Message for --StaticCtorTriggeredByMethodCall.TriggerStaticCtorMarking--.", ""),
 				// (21,3): warning IL2026: Using method 'StaticCtorTriggeredByMethodCall.StaticCtorTriggeredByMethodCall()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message for --StaticCtorTriggeredByMethodCall.Cctor--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (21, 3, 21, 41).WithArguments ("StaticCtorTriggeredByMethodCall.StaticCtorTriggeredByMethodCall()", " Message for --StaticCtorTriggeredByMethodCall.Cctor--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (21, 3, 21, 41).WithArguments ("StaticCtorTriggeredByMethodCall.StaticCtorTriggeredByMethodCall()", " Message for --StaticCtorTriggeredByMethodCall.Cctor--.", "")
 				);
 		}
 
@@ -529,7 +531,7 @@ class C
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (TypeIsBeforeFieldInit,
 				// (8,29): warning IL2026: Using method 'C.TypeIsBeforeFieldInit.AnnotatedMethod()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message from --TypeIsBeforeFieldInit.AnnotatedMethod--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (8, 29, 8, 47).WithArguments ("C.TypeIsBeforeFieldInit.AnnotatedMethod()", " Message from --TypeIsBeforeFieldInit.AnnotatedMethod--.", "")
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (8, 29, 8, 47).WithArguments ("C.TypeIsBeforeFieldInit.AnnotatedMethod()", " Message from --TypeIsBeforeFieldInit.AnnotatedMethod--.", "")
 				);
 		}
 
@@ -553,7 +555,7 @@ class C
 
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (6,50): warning IL2026: Using method 'C.InitC()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message from --C.InitC--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", " Message from --C.InitC--.", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", " Message from --C.InitC--.", ""));
 		}
 
 		[Fact]
@@ -575,9 +577,9 @@ class C
 
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (10,20): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message from --C.M1--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (10, 20, 10, 22).WithArguments ("C.M1()", " Message from --C.M1--.", ""),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (10, 20, 10, 22).WithArguments ("C.M1()", " Message from --C.M1--.", ""),
 				// (11,26): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. Message from --C.M1--.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (11, 26, 11, 30).WithArguments ("C.M1()", " Message from --C.M1--.", ""));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (11, 26, 11, 30).WithArguments ("C.M1()", " Message from --C.M1--.", ""));
 		}
 
 		[Fact]
@@ -612,9 +614,9 @@ class BaseClass
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (7,23): warning IL2046: Member 'DerivedClass.VirtualMethod()' with 'RequiresUnreferencedCodeAttribute' overrides base member 'BaseClass.VirtualMethod()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (7, 23, 7, 36).WithArguments ("Member 'DerivedClass.VirtualMethod()' with 'RequiresUnreferencedCodeAttribute' overrides base member 'BaseClass.VirtualMethod()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (7, 23, 7, 36).WithArguments ("Member 'DerivedClass.VirtualMethod()' with 'RequiresUnreferencedCodeAttribute' overrides base member 'BaseClass.VirtualMethod()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (15,3): warning IL2046: Member 'DerivedClass.VirtualProperty.get' with 'RequiresUnreferencedCodeAttribute' overrides base member 'BaseClass.VirtualProperty.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (15, 3, 15, 6).WithArguments ("Member 'DerivedClass.VirtualProperty.get' with 'RequiresUnreferencedCodeAttribute' overrides base member 'BaseClass.VirtualProperty.get' without 'RequiresUnreferencedCodeAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (15, 3, 15, 6).WithArguments ("Member 'DerivedClass.VirtualProperty.get' with 'RequiresUnreferencedCodeAttribute' overrides base member 'BaseClass.VirtualProperty.get' without 'RequiresUnreferencedCodeAttribute'"));
 		}
 
 		[Fact]
@@ -648,9 +650,9 @@ class BaseClass
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (13,3): warning IL2046: Base member 'BaseClass.VirtualProperty.get' with 'RequiresUnreferencedCodeAttribute' has a derived member 'DerivedClass.VirtualProperty.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (13, 3, 13, 6).WithArguments ("Base member 'BaseClass.VirtualProperty.get' with 'RequiresUnreferencedCodeAttribute' has a derived member 'DerivedClass.VirtualProperty.get' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (13, 3, 13, 6).WithArguments ("Base member 'BaseClass.VirtualProperty.get' with 'RequiresUnreferencedCodeAttribute' has a derived member 'DerivedClass.VirtualProperty.get' without 'RequiresUnreferencedCodeAttribute'"),
 				// (6,23): warning IL2046: Base member 'BaseClass.VirtualMethod()' with 'RequiresUnreferencedCodeAttribute' has a derived member 'DerivedClass.VirtualMethod()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (6, 23, 6, 36).WithArguments ("Base member 'BaseClass.VirtualMethod()' with 'RequiresUnreferencedCodeAttribute' has a derived member 'DerivedClass.VirtualMethod()' without 'RequiresUnreferencedCodeAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (6, 23, 6, 36).WithArguments ("Base member 'BaseClass.VirtualMethod()' with 'RequiresUnreferencedCodeAttribute' has a derived member 'DerivedClass.VirtualMethod()' without 'RequiresUnreferencedCodeAttribute'"));
 		}
 
 		[Fact]
@@ -706,13 +708,13 @@ interface IRUC
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (7,14): warning IL2046: Member 'Implementation.RUC()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.RUC()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (7, 14, 7, 17).WithArguments ("Member 'Implementation.RUC()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (7, 14, 7, 17).WithArguments ("Member 'Implementation.RUC()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (13,3): warning IL2046: Member 'Implementation.Property.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.Property.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.Property.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.Property.get' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.Property.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.Property.get' without 'RequiresUnreferencedCodeAttribute'"),
 				// (33,12): warning IL2046: Member 'ExplicitImplementation.IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.RUC()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (33, 12, 33, 15).WithArguments ("Member 'ExplicitImplementation.IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (33, 12, 33, 15).WithArguments ("Member 'ExplicitImplementation.IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (39,3): warning IL2046: Member 'ExplicitImplementation.IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.Property.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (39, 3, 39, 6).WithArguments ("Member 'ExplicitImplementation.IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.Property.get' without 'RequiresUnreferencedCodeAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (39, 3, 39, 6).WithArguments ("Member 'ExplicitImplementation.IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRUC.Property.get' without 'RequiresUnreferencedCodeAttribute'"));
 		}
 
 		[Fact]
@@ -753,13 +755,13 @@ interface IRUC
 }";
 			return VerifyRequiresUnreferencedCodeAnalyzer (src,
 				// (6,14): warning IL2046: Interface member 'IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.RUC()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (6, 14, 6, 17).WithArguments ("Interface member 'IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (6, 14, 6, 17).WithArguments ("Interface member 'IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (11,3): warning IL2046: Interface member 'IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.Property.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (11, 3, 11, 6).WithArguments ("Interface member 'IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.Property.get' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (11, 3, 11, 6).WithArguments ("Interface member 'IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.Property.get' without 'RequiresUnreferencedCodeAttribute'"),
 				// (18,14): warning IL2046: Interface member 'IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.RUC()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (18, 14, 18, 17).WithArguments ("Interface member 'IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (18, 14, 18, 17).WithArguments ("Interface member 'IRUC.RUC()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.RUC()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (23,3): warning IL2046: Interface member 'IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.Property.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (23, 3, 23, 6).WithArguments ("Interface member 'IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.Property.get' without 'RequiresUnreferencedCodeAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (23, 3, 23, 6).WithArguments ("Interface member 'IRUC.Property.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.Property.get' without 'RequiresUnreferencedCodeAttribute'"));
 		}
 
 		[Fact]
@@ -804,13 +806,13 @@ class AnotherImplementation : IRAF
 
 			await VerifyRequiresUnreferencedCodeAnalyzer (src, additionalReferences: new[] { compilation },
 				// (4,14): warning IL2046: Interface member 'IRAF.Method()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.Method()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (4, 14, 4, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.Method()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (4, 14, 4, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.Method()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (16,14): warning IL2046: Interface member 'IRAF.Method()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (16, 14, 16, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (16, 14, 16, 20).WithArguments ("Interface member 'IRAF.Method()' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.Method()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (9,3): warning IL2046: Interface member 'IRAF.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (9, 3, 9, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (9, 3, 9, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'Implementation.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'"),
 				// (21,3): warning IL2046: Interface member 'IRAF.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (21, 3, 21, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (21, 3, 21, 6).WithArguments ("Interface member 'IRAF.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' has an implementation member 'AnotherImplementation.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'"));
 		}
 
 		[Fact]
@@ -856,9 +858,9 @@ class AnotherImplementation : IRAF
 
 			await VerifyRequiresUnreferencedCodeAnalyzer (src, additionalReferences: new[] { compilation },
 				// (7,14): warning IL2046: Member 'Implementation.Method()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRAF.Method()' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (7, 14, 7, 20).WithArguments ("Member 'Implementation.Method()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRAF.Method()' without 'RequiresUnreferencedCodeAttribute'"),
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (7, 14, 7, 20).WithArguments ("Member 'Implementation.Method()' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRAF.Method()' without 'RequiresUnreferencedCodeAttribute'"),
 				// (13,3): warning IL2046: Member 'Implementation.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'. Attributes must match across all interface implementations or overrides.
-				VerifyCS.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2046).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'"));
+				VerifyCS.Diagnostic (DiagnosticId.RequiresUnreferencedCodeAttributeMismatch).WithSpan (13, 3, 13, 6).WithArguments ("Member 'Implementation.StringProperty.get' with 'RequiresUnreferencedCodeAttribute' implements interface member 'IRAF.StringProperty.get' without 'RequiresUnreferencedCodeAttribute'"));
 		}
 	}
 }
diff --git a/test/ILLink.RoslynAnalyzer.Tests/UnconditionalSuppressMessageCodeFixTests.cs b/test/ILLink.RoslynAnalyzer.Tests/UnconditionalSuppressMessageCodeFixTests.cs
index 05fe2ba10..7d4aa24a6 100644
--- a/test/ILLink.RoslynAnalyzer.Tests/UnconditionalSuppressMessageCodeFixTests.cs
+++ b/test/ILLink.RoslynAnalyzer.Tests/UnconditionalSuppressMessageCodeFixTests.cs
@@ -6,6 +6,7 @@ using System;
 using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 using ILLink.CodeFix;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.Diagnostics;
 using Microsoft.CodeAnalysis.Testing;
@@ -88,7 +89,7 @@ public class C
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(7,17): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-				VerifyCSUSMwithRUC.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan (7, 17, 7, 21).WithArguments ("C.M1()", " message.", ""),
+				VerifyCSUSMwithRUC.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan (7, 17, 7, 21).WithArguments ("C.M1()", " message.", ""),
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -118,7 +119,7 @@ public class C
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(7,17): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-				VerifyCSUSMwithRAF.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (7, 17, 7, 21).WithArguments ("C.M1()", " message.", "")
+				VerifyCSUSMwithRAF.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (7, 17, 7, 21).WithArguments ("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -159,9 +160,9 @@ public class C
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(7,27): warning IL3000: 'System.Reflection.Assembly.Location' always returns an empty string for assemblies embedded in a single-file app. If the path to the app directory is needed, consider calling 'System.AppContext.BaseDirectory'.
-				VerifyCSUSMwithRAF.Diagnostic(RequiresAssemblyFilesAnalyzer.IL3000).WithSpan (7, 27, 7, 44).WithArguments ("System.Reflection.Assembly.Location", "", ""),
+				VerifyCSUSMwithRAF.Diagnostic(DiagnosticId.AvoidAssemblyLocationInSingleFile).WithSpan (7, 27, 7, 44).WithArguments ("System.Reflection.Assembly.Location", "", ""),
 				// /0/Test0.cs(9,13): warning IL3001: 'System.Reflection.Assembly.GetFiles()' will throw for assemblies embedded in a single-file app
-				VerifyCSUSMwithRAF.Diagnostic(RequiresAssemblyFilesAnalyzer.IL3001).WithSpan (9, 13, 9, 32).WithArguments("System.Reflection.Assembly.GetFiles()", "", ""),
+				VerifyCSUSMwithRAF.Diagnostic(DiagnosticId.AvoidAssemblyGetFilesInSingleFile).WithSpan (9, 13, 9, 32).WithArguments("System.Reflection.Assembly.GetFiles()", "", ""),
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -197,7 +198,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(10,15): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCSUSMwithRUC.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
+					VerifyCSUSMwithRUC.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan(10, 15, 10, 19).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -239,7 +240,7 @@ class C
 				fixtest,
 				baselineExpected: new[] {
 				// /0/Test0.cs(6,50): warning IL3002: Using member 'C.InitC()' which has 'RequiresAssemblyFilesAttribute' can break functionality when embedded in a single-file app.
-				VerifyCSUSMwithRAF.Diagnostic (RequiresAssemblyFilesAnalyzer.IL3002).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""),
+				VerifyCSUSMwithRAF.Diagnostic (DiagnosticId.RequiresAssemblyFiles).WithSpan (6, 50, 6, 55).WithArguments ("C.InitC()", "", ""),
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -283,7 +284,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(12,28): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCSUSMwithRUC.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(12, 28, 12, 32).WithArguments("C.M1()", " message.", "")
+					VerifyCSUSMwithRUC.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan(12, 28, 12, 32).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -319,7 +320,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(10,15): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCSUSMwithRUC.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(10, 20, 10, 24).WithArguments("C.M1()", " message.", "")
+					VerifyCSUSMwithRUC.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan(10, 20, 10, 24).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
@@ -369,7 +370,7 @@ public class C
 				fix,
 				baselineExpected: new[] {
 					// /0/Test0.cs(14,21): warning IL2026: Using method 'C.M1()' which has 'RequiresUnreferencedCodeAttribute' can break functionality when trimming application code. message.
-					VerifyCSUSMwithRUC.Diagnostic (RequiresUnreferencedCodeAnalyzer.IL2026).WithSpan(14, 21, 14, 25).WithArguments("C.M1()", " message.", "")
+					VerifyCSUSMwithRUC.Diagnostic (DiagnosticId.RequiresUnreferencedCode).WithSpan(14, 21, 14, 25).WithArguments("C.M1()", " message.", "")
 				},
 				fixedExpected: Array.Empty<DiagnosticResult> ());
 		}
diff --git a/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpAnalyzerVerifier`1.cs b/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpAnalyzerVerifier`1.cs
index bedb7541e..a5777675b 100644
--- a/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpAnalyzerVerifier`1.cs
+++ b/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpAnalyzerVerifier`1.cs
@@ -8,6 +8,7 @@ using System.Reflection;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Testing;
@@ -234,7 +235,8 @@ namespace ILLink.RoslynAnalyzer.Tests
 				var applicableAnalyzer = analyzers.FirstOrDefault (a => a.SupportedDiagnostics.Any (dd => dd.Id == diagnosticsId));
 				if (applicableAnalyzer != null) {
 					var analyzerType = applicableAnalyzer.GetType ();
-					var rule = diagnostics[i].HasLocation && applicableAnalyzer.SupportedDiagnostics.Length == 1 ? string.Empty : $"{analyzerType.Name}.{diagnosticsId}";
+					var rule = diagnostics[i].HasLocation &&
+						applicableAnalyzer.SupportedDiagnostics.Length == 1 ? string.Empty : GetDiagnosticIdArgumentString (diagnosticsId);
 
 					if (!diagnostics[i].HasLocation) {
 						builder.Append ($"new DiagnosticResult({rule})");
@@ -308,13 +310,13 @@ namespace ILLink.RoslynAnalyzer.Tests
 				var applicableAnalyzer = analyzers.FirstOrDefault (a => a.SupportedDiagnostics.Any (dd => dd.Id == diagnosticsId));
 				if (applicableAnalyzer != null) {
 					var analyzerType = applicableAnalyzer.GetType ();
-					var rule = location != Location.None && location.IsInSource && applicableAnalyzer.SupportedDiagnostics.Length == 1 ? string.Empty : $"{analyzerType.Name}.{diagnosticsId}";
+					var rule = location != Location.None && location.IsInSource &&
+						applicableAnalyzer.SupportedDiagnostics.Length == 1 ? string.Empty : GetDiagnosticIdArgumentString (diagnosticsId);
 
 					if (location == Location.None || !location.IsInSource) {
 						builder.Append ($"new DiagnosticResult({rule})");
 					} else {
-						var resultMethodName = location.SourceTree!.FilePath.EndsWith (".cs") ? "VerifyCS.Diagnostic" : "VerifyVB.Diagnostic";
-						builder.Append ($"{resultMethodName}({rule})");
+						builder.Append ($"VerifyCS.Diagnostic({rule})");
 					}
 				} else {
 					builder.Append (
@@ -604,7 +606,7 @@ namespace ILLink.RoslynAnalyzer.Tests
 				return string.Equals (expected.Message, actual.GetMessage ());
 			}
 		}
-
+		private static string GetDiagnosticIdArgumentString (string diagnosticId) => $"DiagnosticId.{(DiagnosticId) Int32.Parse (diagnosticId.Substring (2))}";
 
 		internal readonly struct MatchQuality : IComparable<MatchQuality>, IEquatable<MatchQuality>
 		{
diff --git a/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpCodeFixVerifier`2.cs b/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpCodeFixVerifier`2.cs
index 52fd90eff..9f68969a2 100644
--- a/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpCodeFixVerifier`2.cs
+++ b/test/ILLink.RoslynAnalyzer.Tests/Verifiers/CSharpCodeFixVerifier`2.cs
@@ -5,6 +5,7 @@
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
+using ILLink.Shared;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CodeFixes;
 using Microsoft.CodeAnalysis.CSharp.Testing;
@@ -47,6 +48,9 @@ namespace ILLink.RoslynAnalyzer.Tests
 		public static DiagnosticResult Diagnostic (string diagnosticId)
 			=> CSharpAnalyzerVerifier<TAnalyzer>.Diagnostic (diagnosticId);
 
+		public static DiagnosticResult Diagnostic (DiagnosticId diagnosticId)
+			=> CSharpAnalyzerVerifier<TAnalyzer>.Diagnostic (DiagnosticDescriptors.GetDiagnosticDescriptor (diagnosticId));
+
 		/// <inheritdoc cref="AnalyzerVerifier{TAnalyzer, TTest}.Diagnostic(DiagnosticDescriptor)"/>
 		public static DiagnosticResult Diagnostic (DiagnosticDescriptor descriptor)
 			=> CSharpAnalyzerVerifier<TAnalyzer>.Diagnostic (descriptor);
diff --git a/test/Mono.Linker.Tests.Cases/DataFlow/VirtualMethodHierarchyDataflowAnnotationValidation.cs b/test/Mono.Linker.Tests.Cases/DataFlow/VirtualMethodHierarchyDataflowAnnotationValidation.cs
index 25107c005..4e59e09b4 100644
--- a/test/Mono.Linker.Tests.Cases/DataFlow/VirtualMethodHierarchyDataflowAnnotationValidation.cs
+++ b/test/Mono.Linker.Tests.Cases/DataFlow/VirtualMethodHierarchyDataflowAnnotationValidation.cs
@@ -271,9 +271,13 @@ namespace Mono.Linker.Tests.Cases.DataFlow
 
 
 			// === RequiresUnreferencedCode ===
-			[ExpectedWarning ("IL2046", "DerivedClass.RequiresUnreferencedCodeBaseWithDerivedWithout()", "BaseClass.RequiresUnreferencedCodeBaseWithDerivedWithout()")]
+			[ExpectedWarning ("IL2046", "DerivedClass.RequiresUnreferencedCodeBaseWithDerivedWithout()",
+				"BaseClass.RequiresUnreferencedCodeBaseWithDerivedWithout()",
+				"'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides")]
 			public override void RequiresUnreferencedCodeBaseWithDerivedWithout () { }
-			[ExpectedWarning ("IL2046", "DerivedClass.RequiresUnreferencedCodeBaseWithoutDerivedWith_()", "BaseClass.RequiresUnreferencedCodeBaseWithoutDerivedWith_()")]
+			[ExpectedWarning ("IL2046", "DerivedClass.RequiresUnreferencedCodeBaseWithoutDerivedWith_()",
+				"BaseClass.RequiresUnreferencedCodeBaseWithoutDerivedWith_()",
+				"'RequiresUnreferencedCodeAttribute' annotations must match across all interface implementations or overrides")]
 			[RequiresUnreferencedCode ("")]
 			public override void RequiresUnreferencedCodeBaseWithoutDerivedWith_ () { }
 			[LogDoesNotContain ("DerivedClass.RequiresUnreferencedCodeBaseWithDerivedWith_")]