.NET 4.8 & 6.0. Nullable reference types.

Author: menees

src/Diff.Net.ruleset

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<RuleSet Name="New Rule Set" Description=" " ToolsVersion="16.0">
+<RuleSet Name="New Rule Set" Description=" " ToolsVersion="17.0">
   <Rules AnalyzerId="CodeCracker.CSharp" RuleNamespace="CodeCracker.CSharp">
     <Rule Id="CC0001" Action="None" />
     <Rule Id="CC0014" Action="None" />
@@ -17,6 +17,9 @@
     <Rule Id="MEN007" Action="Warning" />
     <Rule Id="MEN010" Action="Warning" />
   </Rules>
+  <Rules AnalyzerId="Microsoft.CodeAnalysis.NetAnalyzers" RuleNamespace="Microsoft.CodeAnalysis.NetAnalyzers">
+    <Rule Id="CA1031" Action="Warning" />
+  </Rules>
   <Rules AnalyzerId="Microsoft.CodeQuality.Analyzers" RuleNamespace="Microsoft.CodeQuality.Analyzers">
     <Rule Id="CA1062" Action="None" />
   </Rules>

src/Diff.Net/CommandLineProcessor.cs

@@ -34,9 +34,9 @@ internal static class CommandLineProcessor
 		private static string[] GetNames()
 		{
 			// Note: This method is called from a static initializer, so it shouldn't depend on other static fields.
-			List<string> result = new List<string>(2);
+			List<string> result = new(2);
 
-			CommandLine cmdLine = new CommandLine(false);
+			CommandLine cmdLine = new(false);
 			cmdLine.AddSwitch("f", string.Empty, (value, errors) => ProcessFileOption(value), CommandLineSwitchOptions.AllowMultiple);
 			cmdLine.AddSwitch("d", string.Empty, (value, errors) => ProcessDirOption(value), CommandLineSwitchOptions.AllowMultiple);
 			cmdLine.AddValueHandler((value, errors) => result.Add(TextUtility.StripQuotes(value)));

src/Diff.Net/Diff.Net.csproj

@@ -1,15 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
 
 	<PropertyGroup>
-		<TargetFrameworks>netcoreapp3.1;net45</TargetFrameworks>
 		<OutputType>WinExe</OutputType>
 		<UseWindowsForms>true</UseWindowsForms>
 		<ApplicationIcon>Images\DiffDotNet.ico</ApplicationIcon>
 		<ApplicationManifest>app.manifest</ApplicationManifest>
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="Menees.Diffs.Windows.Forms" Version="4.9.10" />
+		<PackageReference Include="Menees.Diffs.Windows.Forms" Version="5.0.0" />
 	</ItemGroup>
 
 	<ItemGroup>

src/Diff.Net/DirDiffDialog.cs

@@ -153,7 +153,7 @@ private void Edit_TextChanged(object sender, EventArgs e)
 
 		private void GetDirectory(TextBox edit, string title)
 		{
-			string selectedFolder = WindowsUtility.SelectFolder(this, title, edit.Text);
+			string? selectedFolder = WindowsUtility.SelectFolder(this, title, edit.Text);
 			if (!string.IsNullOrEmpty(selectedFolder))
 			{
 				edit.Text = selectedFolder;

src/Diff.Net/DirDiffForm.cs

@@ -17,7 +17,7 @@ internal sealed partial class DirDiffForm : ExtendedForm, IDifferenceForm
 	{
 		#region Private Data Members
 
-		private ShowDiffArgs lastDiffArgs;
+		private ShowDiffArgs? lastDiffArgs;
 
 		#endregion
 
@@ -32,11 +32,11 @@ public DirDiffForm()
 
 		#region Public Properties
 
-		public string ToolTipText
+		public string? ToolTipText
 		{
 			get
 			{
-				string result = null;
+				string? result = null;
 
 				if (this.lastDiffArgs != null)
 				{
@@ -53,7 +53,7 @@ public string ToolTipText
 
 		public void ShowDifferences(ShowDiffArgs e)
 		{
-			DirectoryDiff diff = new DirectoryDiff(
+			DirectoryDiff diff = new(
 				Options.ShowOnlyInA,
 				Options.ShowOnlyInB,
 				Options.ShowDifferent,
@@ -88,7 +88,7 @@ private void DiffCtrl_RecompareNeeded(object sender, EventArgs e)
 		{
 			if (this.lastDiffArgs != null)
 			{
-				using (WaitCursor wc = new WaitCursor(this))
+				using (WaitCursor wc = new(this))
 				{
 					this.ShowDifferences(this.lastDiffArgs);
 				}

src/Diff.Net/FileDiffDialog.cs

@@ -139,7 +139,7 @@ private void GetFileName(TextBox edit, string title)
 				// Try to make sure GetDirectoryName won't blow up.
 				if (fileName.IndexOfAny(Path.GetInvalidPathChars()) < 0)
 				{
-					string directoryName = Path.GetDirectoryName(fileName);
+					string? directoryName = Path.GetDirectoryName(fileName);
 					if (!string.IsNullOrEmpty(directoryName))
 					{
 						this.OpenDlg.InitialDirectory = directoryName;