add experimental analyzer

src/UniTask.Analyzer/Properties/launchSettings.json

@@ -0,0 +1,8 @@
+{
+  "profiles": {
+    "UniTask.Analyzer": {
+      "commandName": "DebugRoslynComponent",
+      "targetProject": "..\\UniTask.NetCoreSandbox\\UniTask.NetCoreSandbox.csproj"
+    }
+  }
+}

src/UniTask.Analyzer/UniTask.Analyzer.csproj

@@ -0,0 +1,29 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <OutputType>library</OutputType>
+        <TargetFramework>netstandard2.0</TargetFramework>
+        <LangVersion>latest</LangVersion>
+        <Nullable>enable</Nullable>
+        <IsRoslynComponent>true</IsRoslynComponent>
+        <TargetsForTfmSpecificContentInPackage>$(TargetsForTfmSpecificContentInPackage);PackBuildOutputs</TargetsForTfmSpecificContentInPackage>
+        <IncludeBuildOutput>false</IncludeBuildOutput>
+        <IncludeSymbols>false</IncludeSymbols>
+        <SuppressDependenciesWhenPacking>true</SuppressDependenciesWhenPacking>
+        <DevelopmentDependency>true</DevelopmentDependency>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.2">
+            <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
+            <PrivateAssets>all</PrivateAssets>
+        </PackageReference>
+        <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0" />
+    </ItemGroup>
+
+    <Target Name="PackBuildOutputs" DependsOnTargets="SatelliteDllsProjectOutputGroup;DebugSymbolsProjectOutputGroup">
+        <ItemGroup>
+            <TfmSpecificPackageFile Include="$(TargetDir)\*.dll" PackagePath="analyzers\dotnet\cs" />
+            <TfmSpecificPackageFile Include="@(SatelliteDllsProjectOutputGroupOutput->'%(FinalOutputPath)')" PackagePath="analyzers\dotnet\cs\%(SatelliteDllsProjectOutputGroupOutput.Culture)\" />
+        </ItemGroup>
+    </Target>
+</Project>

src/UniTask.Analyzer/UniTaskAnalyzer.cs

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+#pragma warning disable RS2008
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
+using System.Collections.Immutable;
+using System.Threading;
+
+namespace UniTask.Analyzer
+{
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public class UniTaskAnalyzer : DiagnosticAnalyzer
+    {
+        private static readonly DiagnosticDescriptor Rule = new DiagnosticDescriptor(
+            id: "UNITASK001",
+            title: "UniTaskAnalyzer001: Must pass CancellationToken",
+            messageFormat: "Must pass CancellationToken",
+            category: "Usage",
+            defaultSeverity: DiagnosticSeverity.Error,
+            isEnabledByDefault: true,
+            description: "Pass CancellationToken or CancellationToken.None.");
+
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get { return ImmutableArray.Create(Rule); } }
+
+        public override void Initialize(AnalysisContext context)
+        {
+            context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+            context.EnableConcurrentExecution();
+
+            context.RegisterOperationAction(AnalyzeSymbol, OperationKind.Invocation);
+        }
+
+        private static void AnalyzeSymbol(OperationAnalysisContext context)
+        {
+            var token = context.Compilation.GetTypeByMetadataName(typeof(CancellationToken).FullName);
+            if (token == null) return;
+
+            if (context.Operation is IInvocationOperation invocation)
+            {
+                foreach (var arg in invocation.Arguments)
+                {
+                    if (arg.ArgumentKind == ArgumentKind.DefaultValue)
+                    {
+                        if (SymbolEqualityComparer.Default.Equals(arg.Parameter.Type, token))
+                        {
+                            var diagnostic = Diagnostic.Create(Rule, arg.Syntax.GetLocation());
+                            context.ReportDiagnostic(diagnostic);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}