Non-deterministic System.DateTime usage Roslyn Analyzer (#284)

Microsoft.DurableTask.sln

@@ -67,7 +67,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Benchmarks", "test\Benchmar
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Analyzers", "src\Analyzers\Analyzers.csproj", "{998E9D97-BD36-4A9D-81FC-5DAC1CE40083}"
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Analyzers.Test", "test\Analyzers.Test\Analyzers.Test.csproj", "{541FCCCE-1059-4691-B027-F761CD80DE92}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Analyzers.Tests", "test\Analyzers.Tests\Analyzers.Tests.csproj", "{541FCCCE-1059-4691-B027-F761CD80DE92}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

src/Analyzers/AnalyzerReleases.Shipped.md

@@ -0,0 +1,3 @@
+; Shipped analyzer releases
+; https://github.com/dotnet/roslyn-analyzers/blob/main/src/Microsoft.CodeAnalysis.Analyzers/ReleaseTrackingAnalyzers.Help.md
+

src/Analyzers/AnalyzerReleases.Unshipped.md

@@ -0,0 +1,8 @@
+; Unshipped analyzer release
+; https://github.com/dotnet/roslyn-analyzers/blob/main/src/Microsoft.CodeAnalysis.Analyzers/ReleaseTrackingAnalyzers.Help.md
+
+### New Rules
+
+Rule ID | Category | Severity | Notes
+--------|----------|----------|-------
+DURABLE0001 | Orchestration | Warning | DateTimeOrchestrationAnalyzer

src/Analyzers/Analyzers.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <IsRoslynComponent>true</IsRoslynComponent>
+    <EnableStyleCop>true</EnableStyleCop>
 
     <!-- Do not include the generator as a lib dependency -->
     <IncludeBuildOutput>false</IncludeBuildOutput>
@@ -29,6 +30,7 @@
   <ItemGroup>
     <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.9.2" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.ResxSourceGenerator" Version="3.11.0-beta1.24165.2" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

src/Analyzers/AnalyzersCategories.cs

@@ -0,0 +1,15 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+namespace Microsoft.DurableTask.Analyzers;
+
+/// <summary>
+/// Provides a set of well-known categories that are used by the analyzers diagnostics.
+/// </summary>
+static class AnalyzersCategories
+{
+    /// <summary>
+    /// The category for the orchestration related analyzers.
+    /// </summary>
+    public const string Orchestration = "Orchestration";
+}

src/Analyzers/KnownTypeSymbols.cs

@@ -0,0 +1,58 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.DurableTask.Analyzers;
+
+/// <summary>
+/// Provides a set of well-known types that are used by the analyzers.
+/// Inspired by KnownTypeSymbols class in
+/// <see href="https://github.com/dotnet/runtime/blob/2a846acb1a92e811427babe3ff3f047f98c5df02/src/libraries/System.Text.Json/gen/Helpers/KnownTypeSymbols.cs">System.Text.Json.SourceGeneration</see> source code.
+/// Lazy initialization is used to avoid the the initialization of all types during class construction, since not all symbols are used by all analyzers.
+/// </summary>
+sealed class KnownTypeSymbols(Compilation compilation)
+{
+    readonly Compilation compilation = compilation;
+
+    INamedTypeSymbol? functionOrchestrationAttribute;
+    INamedTypeSymbol? functionNameAttribute;
+    INamedTypeSymbol? taskOrchestratorInterface;
+    INamedTypeSymbol? taskOrchestratorBaseClass;
+    INamedTypeSymbol? durableTaskRegistry;
+
+    /// <summary>
+    /// Gets an OrchestrationTriggerAttribute type symbol.
+    /// </summary>
+    public INamedTypeSymbol? FunctionOrchestrationAttribute => this.GetOrResolveFullyQualifiedType("Microsoft.Azure.Functions.Worker.OrchestrationTriggerAttribute", ref this.functionOrchestrationAttribute);
+
+    /// <summary>
+    /// Gets a FunctionNameAttribute type symbol.
+    /// </summary>
+    public INamedTypeSymbol? FunctionNameAttribute => this.GetOrResolveFullyQualifiedType("Microsoft.Azure.Functions.Worker.FunctionAttribute", ref this.functionNameAttribute);
+
+    /// <summary>
+    /// Gets an ITaskOrchestrator type symbol.
+    /// </summary>
+    public INamedTypeSymbol? TaskOrchestratorInterface => this.GetOrResolveFullyQualifiedType("Microsoft.DurableTask.ITaskOrchestrator", ref this.taskOrchestratorInterface);
+
+    /// <summary>
+    /// Gets a TaskOrchestrator type symbol.
+    /// </summary>
+    public INamedTypeSymbol? TaskOrchestratorBaseClass => this.GetOrResolveFullyQualifiedType("Microsoft.DurableTask.TaskOrchestrator`2", ref this.taskOrchestratorBaseClass);
+
+    /// <summary>
+    /// Gets a DurableTaskRegistry type symbol.
+    /// </summary>
+    public INamedTypeSymbol? DurableTaskRegistry => this.GetOrResolveFullyQualifiedType("Microsoft.DurableTask.DurableTaskRegistry", ref this.durableTaskRegistry);
+
+    INamedTypeSymbol? GetOrResolveFullyQualifiedType(string fullyQualifiedName, ref INamedTypeSymbol? field)
+    {
+        if (field != null)
+        {
+            return field;
+        }
+
+        return field = this.compilation.GetTypeByMetadataName(fullyQualifiedName);
+    }
+}

src/Analyzers/Orchestration/DateTimeOrchestrationAnalyzer.cs

@@ -0,0 +1,87 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Collections.Concurrent;
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
+
+namespace Microsoft.DurableTask.Analyzers.Orchestration;
+
+/// <summary>
+/// Analyzer that reports a warning when a non-deterministic DateTime property is used in an orchestration method.
+/// </summary>
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class DateTimeOrchestrationAnalyzer : OrchestrationAnalyzer
+{
+    /// <summary>
+    /// Diagnostic ID supported for the analyzer.
+    /// </summary>
+    public const string DiagnosticId = "DURABLE0001";
+
+    static readonly LocalizableString Title = new LocalizableResourceString(nameof(Resources.DateTimeOrchestrationAnalyzerTitle), Resources.ResourceManager, typeof(Resources));
+    static readonly LocalizableString MessageFormat = new LocalizableResourceString(nameof(Resources.DateTimeOrchestrationAnalyzerMessageFormat), Resources.ResourceManager, typeof(Resources));
+
+    static readonly DiagnosticDescriptor Rule = new(
+        DiagnosticId,
+        Title,
+        MessageFormat,
+        AnalyzersCategories.Orchestration,
+        DiagnosticSeverity.Warning,
+        isEnabledByDefault: true);
+
+    /// <inheritdoc/>
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => [Rule];
+
+    /// <inheritdoc/>
+    protected override void RegisterAdditionalCompilationStartAction(CompilationStartAnalysisContext context, OrchestrationAnalysisResult orchestrationAnalysisResult)
+    {
+        INamedTypeSymbol systemDateTimeSymbol = context.Compilation.GetSpecialType(SpecialType.System_DateTime);
+
+        // stores the symbols (such as methods) and the DateTime references used in them
+        ConcurrentBag<(ISymbol Symbol, IPropertyReferenceOperation Operation)> dateTimeUsage = [];
+
+        // search for usages of DateTime.Now, DateTime.UtcNow, DateTime.Today and store them
+        context.RegisterOperationAction(
+            ctx =>
+        {
+            ctx.CancellationToken.ThrowIfCancellationRequested();
+
+            var operation = (IPropertyReferenceOperation)ctx.Operation;
+            IPropertySymbol property = operation.Property;
+
+            if (!property.ContainingSymbol.Equals(systemDateTimeSymbol, SymbolEqualityComparer.Default))
+            {
+                return;
+            }
+
+            if (property.Name is nameof(DateTime.Now) or nameof(DateTime.UtcNow) or nameof(DateTime.Today))
+            {
+                ISymbol method = ctx.ContainingSymbol;
+                dateTimeUsage.Add((method, operation));
+            }
+        },
+            OperationKind.PropertyReference);
+
+        // compare whether the found DateTime usages occur in methods invoked by orchestrations
+        context.RegisterCompilationEndAction(ctx =>
+        {
+            foreach ((ISymbol symbol, IPropertyReferenceOperation operation) in dateTimeUsage)
+            {
+                if (symbol is IMethodSymbol method)
+                {
+                    if (orchestrationAnalysisResult.OrchestrationsByMethod.TryGetValue(method, out ConcurrentBag<AnalyzedOrchestration> orchestrations))
+                    {
+                        string methodName = symbol.Name;
+                        string dateTimePropertyName = operation.Property.ToString();
+                        string orchestrationNames = string.Join(", ", orchestrations.Select(o => o.Name).OrderBy(n => n));
+
+                        // e.g.: "The method 'Method1' uses 'System.Date.Now' that may cause non-deterministic behavior when invoked from orchestration 'MyOrchestrator'"
+                        ctx.ReportDiagnostic(Rule, operation, methodName, dateTimePropertyName, orchestrationNames);
+                    }
+                }
+            }
+        });
+    }
+}