Code fixes (#955)

* Apply some code fixes

* Apply code fixes for linker project

* Apply code fixes to more projects

* Apply more code fixes

* Cleanup

* Add missing LangVersion

* Undo changes to shared file

* Undo using changes

12 files changed, 29 insertions, 48 deletions

diff --git a/test/Mono.Linker.Tests/Extensions/NiceIO.cs b/test/Mono.Linker.Tests/Extensions/NiceIO.cs
index 69b6f30f4..32cf6c7e7 100644
--- a/test/Mono.Linker.Tests/Extensions/NiceIO.cs
+++ b/test/Mono.Linker.Tests/Extensions/NiceIO.cs
@@ -316,15 +316,11 @@ namespace Mono.Linker.Tests.Extensions
 
 		static char Slash(SlashMode slashMode)
 		{
-			switch (slashMode)
-			{
-				case SlashMode.Backward:
-					return '\\';
-				case SlashMode.Forward:
-					return '/';
-				default:
-					return Path.DirectorySeparatorChar;
-			}
+			return slashMode switch {
+				SlashMode.Backward => '\\',
+				SlashMode.Forward => '/',
+				_ => Path.DirectorySeparatorChar,
+			};
 		}
 
 		public override bool Equals(Object obj)
@@ -333,8 +329,7 @@ namespace Mono.Linker.Tests.Extensions
 				return false;
 
 			// If parameter cannot be cast to Point return false.
-			var p = obj as NPath;
-			if ((Object)p == null)
+			if (!(obj is NPath p))
 				return false;
 
 			return Equals(p);
@@ -365,7 +360,7 @@ namespace Mono.Linker.Tests.Extensions
 				return true;
 
 			// If one is null, but not both, return false.
-			if (((object)a == null) || ((object)b == null))
+			if ((a is null) || (b is null))
 				return false;
 
 			// Return true if the fields match:
diff --git a/test/Mono.Linker.Tests/Mono.Linker.Tests.csproj b/test/Mono.Linker.Tests/Mono.Linker.Tests.csproj
index 236ff33ab..794710197 100644
--- a/test/Mono.Linker.Tests/Mono.Linker.Tests.csproj
+++ b/test/Mono.Linker.Tests/Mono.Linker.Tests.csproj
@@ -3,6 +3,7 @@
 
   <PropertyGroup>
     <Configurations>Debug;Release</Configurations>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(MonoBuild)' == ''">
diff --git a/test/Mono.Linker.Tests/TestCases/IndividualTests.cs b/test/Mono.Linker.Tests/TestCases/IndividualTests.cs
index 6a7ae9c56..439caf37e 100644
--- a/test/Mono.Linker.Tests/TestCases/IndividualTests.cs
+++ b/test/Mono.Linker.Tests/TestCases/IndividualTests.cs
@@ -151,8 +151,7 @@ namespace Mono.Linker.Tests.TestCases
 
 		protected Guid GetMvid (NPath assemblyPath)
 		{
-			using (var assembly = AssemblyDefinition.ReadAssembly (assemblyPath))
-			{
+			using (var assembly = AssemblyDefinition.ReadAssembly (assemblyPath)) {
 				return assembly.MainModule.Mvid;
 			}
 		}
@@ -164,8 +163,7 @@ namespace Mono.Linker.Tests.TestCases
 
 		protected LinkedTestCaseResult Run (TestCase testCase)
 		{
-			TestRunner runner;
-			return Run (testCase, out runner);
+			return Run (testCase, out _);
 		}
 		
 		protected virtual LinkedTestCaseResult Run (TestCase testCase, out TestRunner runner)
diff --git a/test/Mono.Linker.Tests/TestCases/TestDatabase.cs b/test/Mono.Linker.Tests/TestCases/TestDatabase.cs
index fbb516153..41f37400a 100644
--- a/test/Mono.Linker.Tests/TestCases/TestDatabase.cs
+++ b/test/Mono.Linker.Tests/TestCases/TestDatabase.cs
@@ -158,9 +158,7 @@ namespace Mono.Linker.Tests.TestCases
 
 		public static TestCaseCollector CreateCollector ()
 		{
-			string rootSourceDirectory;
-			string testCaseAssemblyPath;
-			GetDirectoryPaths (out rootSourceDirectory, out testCaseAssemblyPath);
+			GetDirectoryPaths (out string rootSourceDirectory, out string testCaseAssemblyPath);
 			return new TestCaseCollector (rootSourceDirectory, testCaseAssemblyPath);
 		}
 
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/AssemblyChecker.cs b/test/Mono.Linker.Tests/TestCasesRunner/AssemblyChecker.cs
index 16f4a1d1d..887456b87 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/AssemblyChecker.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/AssemblyChecker.cs
@@ -13,9 +13,9 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 		readonly AssemblyDefinition originalAssembly, linkedAssembly;
 
 		HashSet<string> linkedMembers;
-		HashSet<string> verifiedGeneratedFields = new HashSet<string> ();
-		HashSet<string> verifiedEventMethods = new HashSet<string>();
-		HashSet<string> verifiedGeneratedTypes = new HashSet<string> ();
+		readonly HashSet<string> verifiedGeneratedFields = new HashSet<string> ();
+		readonly HashSet<string> verifiedEventMethods = new HashSet<string>();
+		readonly HashSet<string> verifiedGeneratedTypes = new HashSet<string> ();
 
 		public AssemblyChecker (AssemblyDefinition original, AssemblyDefinition linked)
 		{
@@ -43,8 +43,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 
 			var membersToAssert = originalAssembly.MainModule.Types;
 			foreach (var originalMember in membersToAssert) {
-				var td = originalMember as TypeDefinition;
-				if (td != null) {
+				if (originalMember is TypeDefinition td) {
 					if (td.Name == "<Module>") {
 						linkedMembers.Remove (td.Name);
 						continue;
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/LinkerDriver.cs b/test/Mono.Linker.Tests/TestCasesRunner/LinkerDriver.cs
index 521094d8f..1589f5c6d 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/LinkerDriver.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/LinkerDriver.cs
@@ -4,7 +4,7 @@
 	public class LinkerDriver {
 		protected class TestDriver : Driver
 		{
-			LinkerCustomizations _customization;
+			readonly LinkerCustomizations _customization;
 
 			public TestDriver(Queue<string> args, LinkerCustomizations customizations) : base(args)
 			{
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/PeVerifier.cs b/test/Mono.Linker.Tests/TestCasesRunner/PeVerifier.cs
index dd3d5e37c..fe980c78d 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/PeVerifier.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/PeVerifier.cs
@@ -24,9 +24,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 
 		public virtual void Check (LinkedTestCaseResult linkResult, AssemblyDefinition original)
 		{
-			bool skipCheckEntirely;
-			HashSet<string> assembliesToSkip;
-			ProcessSkipAttributes (linkResult, original, out skipCheckEntirely, out assembliesToSkip);
+			ProcessSkipAttributes (linkResult, original, out bool skipCheckEntirely, out HashSet<string> assembliesToSkip);
 
 			if (skipCheckEntirely)
 				return;
@@ -109,8 +107,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 			if (Environment.OSVersion.Platform != PlatformID.Win32NT)
 				throw new InvalidOperationException ("This method should only be called on windows");
 
-			NPath result;
-			if (TryFindPeExecutableFromRegustrySubfolder ("NETFXSDK", out result))
+			if (TryFindPeExecutableFromRegustrySubfolder ("NETFXSDK", out NPath result))
 				return result;
 			if (TryFindPeExecutableFromRegustrySubfolder ("Windows", out result))
 				return result;
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs b/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs
index df47260d7..7abff46b1 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/ResultChecker.cs
@@ -253,7 +253,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 							case nameof (RemovedForwarderAttribute):
 								if (linkedAssembly.MainModule.ExportedTypes.Any (l => l.Name == expectedTypeName))
 									Assert.Fail ($"Forwarder `{expectedTypeName}' should have been removed");
-							
+
 								break;
 							case nameof (KeptResourceInAssemblyAttribute):
 								VerifyKeptResourceInAssembly (checkAttrInAssembly);
@@ -651,7 +651,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 				}
 			}
 
-			string DependencyToString(TestDependencyRecorder.Dependency dependency)
+			static string DependencyToString(TestDependencyRecorder.Dependency dependency)
 			{
 				return $"{dependency.Source} -> {dependency.Target} Marked: {dependency.Marked}";
 			}
@@ -687,7 +687,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 								.Select (p => "\t" + RecognizedReflectionAccessPatternToString (p)));
 
 							Assert.Fail (
-								$"Expected to find recognized reflection access pattern '{expectedSourceMethod.ToString()}: Call to {expectedReflectionMethod} accessed {expectedAccessedItem}'{Environment.NewLine}" +
+								$"Expected to find recognized reflection access pattern '{expectedSourceMethod}: Call to {expectedReflectionMethod} accessed {expectedAccessedItem}'{Environment.NewLine}" +
 								$"Potential patterns matching the source method: {Environment.NewLine}{sourceMethodCandidates}{Environment.NewLine}" +
 								$"Potential patterns matching the reflection method: {Environment.NewLine}{reflectionMethodCandidates}{Environment.NewLine}" +
 								$"If there's no matches, try to specify just a part of the source method or reflection method name and rerun the test to get potential matches.");
@@ -813,8 +813,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 
 		protected TypeDefinition GetOriginalTypeFromInAssemblyAttribute (string assemblyName, object typeOrTypeName)
 		{
-			var attributeValueAsTypeReference = typeOrTypeName as TypeReference;
-			if (attributeValueAsTypeReference != null)
+			if (typeOrTypeName is TypeReference attributeValueAsTypeReference)
 				return attributeValueAsTypeReference.Resolve ();
 
 			var assembly = ResolveOriginalsAssembly (assemblyName);
@@ -833,8 +832,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 			foreach (var typeWithRemoveInAssembly in original.AllDefinedTypes ()) {
 				foreach (var attr in typeWithRemoveInAssembly.CustomAttributes.Where (IsTypeInOtherAssemblyAssertion)) {
 					var assemblyName = (string) attr.ConstructorArguments [0].Value;
-					List<CustomAttribute> checksForAssembly;
-					if (!checks.TryGetValue (assemblyName, out checksForAssembly))
+					if (!checks.TryGetValue (assemblyName, out List<CustomAttribute> checksForAssembly))
 						checks [assemblyName] = checksForAssembly = new List<CustomAttribute> ();
 
 					checksForAssembly.Add (attr);
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/TestCaseCollector.cs b/test/Mono.Linker.Tests/TestCasesRunner/TestCaseCollector.cs
index 5c4f4dbc9..c48dd331e 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/TestCaseCollector.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/TestCaseCollector.cs
@@ -39,8 +39,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 
 			using (var caseAssemblyDefinition = AssemblyDefinition.ReadAssembly (_testCaseAssemblyPath.ToString ())) {
 				foreach (var file in sourceFiles) {
-					TestCase testCase;
-					if (CreateCase (caseAssemblyDefinition, file, out testCase))
+					if (CreateCase (caseAssemblyDefinition, file, out TestCase testCase))
 						yield return testCase;
 				}
 			}
@@ -85,10 +84,8 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 			var pathRelativeToAssembly = $"{testCaseType.FullName.Substring (testCaseType.Module.Name.Length - 3).Replace ('.', '/')}.cs";
 			var fullSourcePath = _rootDirectory.Combine (pathRelativeToAssembly).FileMustExist ();
 
-			using (var caseAssemblyDefinition = AssemblyDefinition.ReadAssembly (_testCaseAssemblyPath.ToString ()))
-			{
-				TestCase testCase;
-				if (!CreateCase (caseAssemblyDefinition, fullSourcePath, out testCase))
+			using (var caseAssemblyDefinition = AssemblyDefinition.ReadAssembly (_testCaseAssemblyPath.ToString ())) {
+				if (!CreateCase (caseAssemblyDefinition, fullSourcePath, out TestCase testCase))
 					throw new ArgumentException ($"Could not create a test case for `{testCaseType}`.  Ensure the namespace matches it's location on disk");
 
 				return testCase;
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/TestCaseMetadaProvider.cs b/test/Mono.Linker.Tests/TestCasesRunner/TestCaseMetadaProvider.cs
index 589ed2ce1..cb0d855c8 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/TestCaseMetadaProvider.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/TestCaseMetadaProvider.cs
@@ -307,8 +307,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 
 		protected virtual NPath SourceFileForAttributeArgumentValue (object value)
 		{
-			var valueAsTypeRef = value as TypeReference;
-			if (valueAsTypeRef != null) {
+			if (value is TypeReference valueAsTypeRef) {
 				// Use the parent type for locating the source file
 				var parentType = ParentMostType (valueAsTypeRef);
 				var pathRelativeToAssembly = $"{parentType.FullName.Substring (parentType.Module.Name.Length - 3).Replace ('.', '/')}.cs".ToNPath ();
diff --git a/test/Mono.Linker.Tests/TestCasesRunner/TestRunner.cs b/test/Mono.Linker.Tests/TestCasesRunner/TestRunner.cs
index 4d16a83bf..f60398db0 100644
--- a/test/Mono.Linker.Tests/TestCasesRunner/TestRunner.cs
+++ b/test/Mono.Linker.Tests/TestCasesRunner/TestRunner.cs
@@ -20,8 +20,7 @@ namespace Mono.Linker.Tests.TestCasesRunner {
 			using (var fullTestCaseAssemblyDefinition = AssemblyDefinition.ReadAssembly (testCase.OriginalTestCaseAssemblyPath.ToString ())) {
 				var metadataProvider = _factory.CreateMetadataProvider (testCase, fullTestCaseAssemblyDefinition);
 
-				string ignoreReason;
-				if (metadataProvider.IsIgnored (out ignoreReason))
+				if (metadataProvider.IsIgnored (out string ignoreReason))
 					Assert.Ignore (ignoreReason);
 
 				var sandbox = Sandbox (testCase, metadataProvider);
diff --git a/test/Mono.Linker.Tests/Tests/TypeNameParserTests.cs b/test/Mono.Linker.Tests/Tests/TypeNameParserTests.cs
index b5d124619..177e83276 100644
--- a/test/Mono.Linker.Tests/Tests/TypeNameParserTests.cs
+++ b/test/Mono.Linker.Tests/Tests/TypeNameParserTests.cs
@@ -6,7 +6,7 @@ namespace Mono.Linker.Tests {
 		[Test]
 		public void TryParseTypeAssemblyQualifiedName_Null ()
 		{
-			Assert.That (TypeNameParser.TryParseTypeAssemblyQualifiedName (null, out string typeName, out string assemblyName), Is.False);
+			Assert.That (TypeNameParser.TryParseTypeAssemblyQualifiedName (null, out _, out _), Is.False);
 		}
 		
 		[Test]