Enable nullability context for all projects (#176)

Author: atifaziz

Directory.Build.props

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <LangVersion>10</LangVersion>
-    <Nullable>warnings</Nullable>
+    <Nullable>enable</Nullable>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <!--
       > [CS8785] warning is emitted if a source generator failed to produce output

eg/SourceGenerator/Extensions.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Collections.Generic;
 using System.IO;

eg/SourceGenerator/Git/Program.cs

@@ -1,5 +1,3 @@
-#nullable enable
-
 using System;
 using System.Collections.Generic;
 using System.Linq;

src/DocoptNet.Playground/DocoptNet.Playground.csproj

@@ -2,7 +2,6 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <Nullable>disable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>

src/DocoptNet.Playground/Pages/Index.razor

@@ -81,13 +81,13 @@
 {
     bool _optionsFirst;
     bool _lastOptionsFirst;
-    string _commandLine;
-    string _lastCommandLine;
-    string _input;
-    string _lastInput;
-    string _output;
-    IDictionary<string, ArgValue> _args;
-    List<Node> _nodes;
+    string _commandLine = string.Empty;
+    string? _lastCommandLine;
+    string? _input;
+    string? _lastInput;
+    string? _output;
+    IDictionary<string, ArgValue>? _args;
+    List<Node>? _nodes;
     bool _error;
     TimeSpan? _ms;
     ElementReference _inputTextArea;
@@ -145,7 +145,7 @@ Options:
         _error = false;
         _ms = null;
 
-        if (_input.Length == 0)
+        if (_input is null or { Length: 0 })
             return;
 
         var sw = Stopwatch.StartNew();
@@ -174,15 +174,15 @@ Options:
             _output = sb.ToString();
 
             var docopt = new Docopt();
-            var argv = _commandLine.Split((char[])null, StringSplitOptions.RemoveEmptyEntries);
+            var argv = _commandLine.Split((char[]?)null, StringSplitOptions.RemoveEmptyEntries);
             _nodes = Docopt.Internal
                            .GetNodes(_input,
                                      (name, value) => new Node(name, value.Kind, 0, ArgValue.None),
                                      (name, value) => new Node(name, value.IsStringList ? ArgValueKind.StringList : ArgValueKind.String, 0, ArgValue.None),
                                      (name, _, _, _, value) => new Node(name, value.Kind, 0, ArgValue.None))
                            .GroupBy(e => e.Name, e => e, (_, g) => new Node(g.First().Name, g.First().ValueKind, g.Count(), ArgValue.None))
                            .ToList();
-            _args = Docopt.Internal.Apply(docopt, _input, argv.AsEnumerable(), help: false, version: null, optionsFirst: _optionsFirst, exit: false);
+            _args = Docopt.Internal.Apply(docopt, _input, argv.AsEnumerable(), help: false, version: null, optionsFirst: _optionsFirst, exit: false)!;
             _nodes = _nodes.Select(n => new Node(n.Name, n.ValueKind, n.Count, _args.TryGetValue(n.Name, out var v) ? v : ArgValue.None)).ToList();
             _ms = sw.Elapsed;
         }

src/DocoptNet/ApplicationResult.cs

@@ -1,8 +1,6 @@
 // Licensed under terms of MIT license (see LICENSE-MIT)
 // Copyright 2021 Atif Aziz, Dinh Doan Van Bien
 
-#nullable enable
-
 namespace DocoptNet
 {
     using System;

src/DocoptNet/ApplicationResultAccumulator.cs

@@ -1,8 +1,6 @@
 // Licensed under terms of MIT license (see LICENSE-MIT)
 // Copyright 2021 Atif Aziz, Dinh Doan Van Bien
 
-#nullable enable
-
 namespace DocoptNet
 {
     using System.Collections.Generic;

src/DocoptNet/ArgValue.cs

@@ -1,8 +1,6 @@
 // Licensed under terms of MIT license (see LICENSE-MIT)
 // Copyright 2021 Atif Aziz, Dinh Doan Van Bien
 
-#nullable enable
-
 namespace DocoptNet
 {
     using System;

src/DocoptNet/ArgsParseOptions.cs

@@ -1,8 +1,6 @@
 // Licensed under terms of MIT license (see LICENSE-MIT)
 // Copyright 2021 Atif Aziz, Dinh Doan Van Bien
 
-#nullable enable
-
 namespace DocoptNet
 {
     sealed partial class ArgsParseOptions

src/DocoptNet/CodeGeneration/CSharpSourceBuilder.cs

@@ -1,8 +1,6 @@
 // Licensed under terms of MIT license (see LICENSE-MIT)
 // Copyright 2021 Atif Aziz, Dinh Doan Van Bien
 
-#nullable enable
-
 namespace DocoptNet.CodeGeneration
 {
     using System;