New rule: MA0133 - Use DateTimeOffset instead of DateTime to avoid an…

… implicit conversion (#506)
meziantou · Apr 25, 2023 · df707da · df707da
1 parent e679d84
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Showing 7 changed files with 72 additions and 7 deletions.
diff --git a/README.md b/README.md
@@ -148,6 +148,7 @@ If you are already using other analyzers, you can check [which rules are duplica
 |[MA0130](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0130.md)|Usage|GetType() should not be used on System.Type instances|⚠️|✔️|❌|
 |[MA0131](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0131.md)|Usage|ArgumentNullException.ThrowIfNull should not be used with non-nullable types|⚠️|✔️|❌|
 |[MA0132](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0132.md)|Design|Do not convert implicitly to DateTimeOffset|⚠️|✔️|❌|
+|[MA0133](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0133.md)|Design|Use DateTimeOffset instead of relying on the implicit conversion|ℹ️|✔️|❌|
 
 <!-- rules -->
 

diff --git a/docs/README.md b/docs/README.md
@@ -132,6 +132,7 @@
 |[MA0130](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0130.md)|Usage|GetType() should not be used on System.Type instances|<span title='Warning'>⚠️</span>|✔️|❌|
 |[MA0131](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0131.md)|Usage|ArgumentNullException.ThrowIfNull should not be used with non-nullable types|<span title='Warning'>⚠️</span>|✔️|❌|
 |[MA0132](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0132.md)|Design|Do not convert implicitly to DateTimeOffset|<span title='Warning'>⚠️</span>|✔️|❌|
+|[MA0133](https://github.com/meziantou/Meziantou.Analyzer/blob/main/docs/Rules/MA0133.md)|Design|Use DateTimeOffset instead of relying on the implicit conversion|<span title='Info'>ℹ️</span>|✔️|❌|
 
 |Id|Suppressed rule|Justification|
 |--|---------------|-------------|
@@ -534,6 +535,9 @@ dotnet_diagnostic.MA0131.severity = warning
 
 # MA0132: Do not convert implicitly to DateTimeOffset
 dotnet_diagnostic.MA0132.severity = warning
+
+# MA0133: Use DateTimeOffset instead of relying on the implicit conversion
+dotnet_diagnostic.MA0133.severity = suggestion
 ```
 
 # .editorconfig - all rules disabled
@@ -931,4 +935,7 @@ dotnet_diagnostic.MA0131.severity = none
 
 # MA0132: Do not convert implicitly to DateTimeOffset
 dotnet_diagnostic.MA0132.severity = none
+
+# MA0133: Use DateTimeOffset instead of relying on the implicit conversion
+dotnet_diagnostic.MA0133.severity = none
 ```
diff --git a/docs/Rules/MA0133.md b/docs/Rules/MA0133.md
@@ -0,0 +1,11 @@
+# MA0133 - Use DateTimeOffset instead of relying on the implicit conversion
+
+Replace `DateTime.UtcNow` or `DateTime.Now` with `DateTimeOffset.UtcNow` or `DateTimeOffset.Now` to avoid an implicit conversion.
+
+````c#
+Sample(DateTime.UtcNow); // non-compliant
+
+Sample(DateTimeOffset.UtcNow); // ok
+
+void Sample(DateTimeOffset datetime) { }
+````
diff --git a/src/Meziantou.Analyzer/RuleIdentifiers.cs b/src/Meziantou.Analyzer/RuleIdentifiers.cs
@@ -135,6 +135,7 @@ internal static class RuleIdentifiers
     public const string ObjectGetTypeOnTypeInstance = "MA0130";
     public const string ThrowIfNullWithNonNullableInstance = "MA0131";
     public const string DoNotImplicitlyConvertDateTimeToDateTimeOffset = "MA0132";
+    public const string UseDateTimeOffsetInsteadOfDateTime = "MA0133";
 
     public static string GetHelpUri(string identifier)
     {

diff --git a/src/Meziantou.Analyzer/Rules/DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer.cs b/src/Meziantou.Analyzer/Rules/DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer.cs
@@ -9,7 +9,7 @@ namespace Meziantou.Analyzer.Rules;
 [DiagnosticAnalyzer(LanguageNames.CSharp)]
 public sealed class DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer : DiagnosticAnalyzer
 {
-    private static readonly DiagnosticDescriptor s_rule = new(
+    private static readonly DiagnosticDescriptor s_ruleImplicitConversion = new(
         RuleIdentifiers.DoNotImplicitlyConvertDateTimeToDateTimeOffset,
         title: "Do not convert implicitly to DateTimeOffset",
         messageFormat: "Do not convert implicitly to DateTimeOffset",
@@ -19,7 +19,17 @@ public sealed class DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer : Dia
         description: "",
         helpLinkUri: RuleIdentifiers.GetHelpUri(RuleIdentifiers.DoNotImplicitlyConvertDateTimeToDateTimeOffset));
 
-    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(s_rule);
+    private static readonly DiagnosticDescriptor s_ruleUseDateTimeOffset = new(
+        RuleIdentifiers.UseDateTimeOffsetInsteadOfDateTime,
+        title: "Use DateTimeOffset instead of relying on the implicit conversion",
+        messageFormat: "Use DateTimeOffset instead of relying on the implicit conversion",
+        RuleCategories.Design,
+        DiagnosticSeverity.Info,
+        isEnabledByDefault: true,
+        description: "",
+        helpLinkUri: RuleIdentifiers.GetHelpUri(RuleIdentifiers.UseDateTimeOffsetInsteadOfDateTime));
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(s_ruleImplicitConversion, s_ruleUseDateTimeOffset);
 
     public override void Initialize(AnalysisContext context)
     {
@@ -46,9 +56,13 @@ private static void AnalyzeConversion(OperationAnalysisContext context, INamedTy
         {
             // DateTime.Now and DateTime.UtcNow set the DateTime.Kind, so the conversion result is well-known
             if (operation.Operand is IMemberReferenceOperation { Member.Name: "UtcNow" or "Now", Member.ContainingType.SpecialType: SpecialType.System_DateTime })
-                return;
-
-            context.ReportDiagnostic(s_rule, operation);
+            {
+                context.ReportDiagnostic(s_ruleUseDateTimeOffset, operation);
+            }
+            else
+            {
+                context.ReportDiagnostic(s_ruleImplicitConversion, operation);
+            }
         }
     }
 }
diff --git a/...ateTimeWithDateTimeOffsetAnalyzerTests.cs → ...WithDateTimeOffsetAnalyzerTests_MA0132.cs b/...ateTimeWithDateTimeOffsetAnalyzerTests.cs → ...WithDateTimeOffsetAnalyzerTests_MA0132.cs
@@ -5,13 +5,15 @@
 using Xunit;
 
 namespace Meziantou.Analyzer.Test.Rules;
-public class DoNotCompareDateTimeWithDateTimeOffsetAnalyzerTests
+
+public class DoNotCompareDateTimeWithDateTimeOffsetAnalyzerTests_MA0132
+
 {
     private static ProjectBuilder CreateProjectBuilder()
     {
         return new ProjectBuilder()
             .WithOutputKind(OutputKind.ConsoleApplication)
-            .WithAnalyzer<DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer>();
+            .WithAnalyzer<DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer>(id: "MA0132");
     }
 
     [Fact]

diff --git a/...ziantou.Analyzer.Test/Rules/DoNotCompareDateTimeWithDateTimeOffsetAnalyzerTests_MA0133.cs b/...ziantou.Analyzer.Test/Rules/DoNotCompareDateTimeWithDateTimeOffsetAnalyzerTests_MA0133.cs
@@ -0,0 +1,29 @@
+using System.Threading.Tasks;
+using Meziantou.Analyzer.Rules;
+using Microsoft.CodeAnalysis;
+using TestHelper;
+using Xunit;
+
+namespace Meziantou.Analyzer.Test.Rules;
+
+public class DoNotCompareDateTimeWithDateTimeOffsetAnalyzerTests_MA0133
+{
+    private static ProjectBuilder CreateProjectBuilder()
+    {
+        return new ProjectBuilder()
+            .WithOutputKind(OutputKind.ConsoleApplication)
+            .WithAnalyzer<DoNotImplicitlyConvertDateTimeToDateTimeOffsetAnalyzer>(id: "MA0133");
+    }
+
+    [Fact]
+    public async Task ImplicitConversion_BinaryOperation_Subtract_UtcNow()
+    {
+        await CreateProjectBuilder()
+            .WithSourceCode("""
+                using System;
+
+                _ = [|DateTime.UtcNow|] - DateTimeOffset.UtcNow;
+                """)
+            .ValidateAsync();
+    }
+}