Retarget analysers from .NETStandard 2.1 to 2.0

Directory.Build.targets

@@ -138,6 +138,10 @@
     <PackageReference Update="coverlet.collector" Version="6.0.0" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Update="Microsoft.Bcl.Memory" Version="9.0.0-preview.7.24405.7" />
+  </ItemGroup>
+
   <PropertyGroup>
     <CodeAnalysisSettingsLocation>$(MSBuildThisFileDirectory)</CodeAnalysisSettingsLocation>
     <CodeAnalysisRuleSet>$(CodeAnalysisSettingsLocation)LeanCode.CodeAnalysis.ruleset</CodeAnalysisRuleSet>

src/Tools/LeanCode.CodeAnalysis/Analyzers/EnsureCommandValidatorsFollowNamingConvention.cs

@@ -39,7 +39,7 @@ private static void AnalyzeSymbol(SyntaxNodeAnalysisContext context)
 
         if (TryGetCommandValidator(type, out var commandValidator))
         {
-            var expectedName = GetCommandValidatorExpectedName(commandValidator);
+            var expectedName = GetCommandValidatorExpectedName(commandValidator!);
 
             if (type.Name != expectedName)
             {
@@ -61,10 +61,7 @@ internal static string GetCommandValidatorExpectedName(INamedTypeSymbol commandV
         );
     }
 
-    private static bool TryGetCommandValidator(
-        INamedTypeSymbol type,
-        [NotNullWhen(true)] out INamedTypeSymbol? commandValidator
-    )
+    private static bool TryGetCommandValidator(INamedTypeSymbol type, out INamedTypeSymbol? commandValidator)
     {
         var validator = GetImplementedValidator(type);
 

src/Tools/LeanCode.CodeAnalysis/Analyzers/SuggestCommandsHaveValidators.cs

@@ -45,14 +45,14 @@ private static void AnalyzeSymbol(SyntaxNodeAnalysisContext context)
 
         var tree = type.DeclaringSyntaxReferences.First().SyntaxTree;
 
-        if (!CommandIsValidated(commandType, tree, context.SemanticModel))
+        if (!CommandIsValidated(commandType!, tree, context.SemanticModel))
         {
-            var diagnostic = Diagnostic.Create(Rule, type.Locations[0], commandType.Name);
+            var diagnostic = Diagnostic.Create(Rule, type.Locations[0], commandType!.Name);
             context.ReportDiagnostic(diagnostic);
         }
     }
 
-    private static bool IsCommandHandler(INamedTypeSymbol type, [NotNullWhen(true)] out INamedTypeSymbol? commandType)
+    private static bool IsCommandHandler(INamedTypeSymbol type, out INamedTypeSymbol? commandType)
     {
         var handler = type.AllInterfaces.FirstOrDefault(i => i.GetFullNamespaceName() == HandlerTypeName);
 

src/Tools/LeanCode.CodeAnalysis/LeanCode.CodeAnalysis.csproj

@@ -6,11 +6,13 @@
     <NoPackageAnalysis>true</NoPackageAnalysis>
 
     <!-- It needs to target .NETStandard, otherwise it won't work in Omnisharp. See next comment for details. -->
-    <TargetFramework>netstandard2.1</TargetFramework>
+    <!-- It also needs to be .NETStandard 2.0, because msbuild in Visual Studio does not support 2.1. -->
+    <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.Bcl.Memory" />
   </ItemGroup>
 
   <ItemGroup>

src/Tools/LeanCode.CodeAnalysis/NetStandard21Compatibility/MissingFileMethods.cs

@@ -0,0 +1,47 @@
+// Based on https://github.com/dotnet/runtime/blob/5535e31a712343a63f5d7d796cd874e563e5ac14/src/libraries/System.Private.CoreLib/src/System/IO/File.cs
+// as linked by docs on 02.09.2024
+
+global using File = LeanCode.CodeAnalysis.NetStandard21Compatibility.MissingFileMethods;
+using System.Text;
+
+namespace LeanCode.CodeAnalysis.NetStandard21Compatibility;
+
+public static class MissingFileMethods
+{
+    private static readonly Encoding UTF8NoBOM = new UTF8Encoding(
+        encoderShouldEmitUTF8Identifier: false,
+        throwOnInvalidBytes: true
+    );
+
+    public static void Delete(string path) => System.IO.File.Delete(path);
+
+    public static Task WriteAllTextAsync(
+        string path,
+        string? contents,
+        CancellationToken cancellationToken = default
+    ) => WriteAllTextAsync(path, contents, UTF8NoBOM, cancellationToken);
+
+    public static async Task WriteAllTextAsync(
+        string path,
+        string? contents,
+        Encoding encoding,
+        CancellationToken cancellationToken = default
+    )
+    {
+        if (string.IsNullOrWhiteSpace(path))
+        {
+            throw new ArgumentException("Path is invalid");
+        }
+
+        using var stream = System.IO.File.OpenWrite(path);
+
+        var preamble = encoding.GetPreamble();
+        await stream.WriteAsync(preamble, 0, preamble.Length, cancellationToken);
+
+        if (contents is not null)
+        {
+            var encoded = encoding.GetBytes(contents);
+            await stream.WriteAsync(encoded, 0, encoded.Length, cancellationToken);
+        }
+    }
+}

src/Tools/LeanCode.CodeAnalysis/NetStandard21Compatibility/MissingStringMethods.cs

@@ -0,0 +1,10 @@
+// Based on https://github.com/dotnet/runtime/blob/5535e31a712343a63f5d7d796cd874e563e5ac14/src/libraries/System.Private.CoreLib/src/System/String.Searching.cs#L26C13-L26C56
+// as linked by docs on 02.09.2024
+
+namespace System;
+
+public static class MissingStringMethods
+{
+    public static bool Contains(this string s, string value, StringComparison comparisonType) =>
+        s.IndexOf(value, comparisonType) >= 0;
+}