generalize AmOptional003 to switch expressions (close #44)

Author: BarionLP

Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <SupportedFrameworks>net10.0</SupportedFrameworks>
     <DotNetVersion>net10.0</DotNetVersion>
-    <PackVersion>0.4.1</PackVersion>
+    <PackVersion>0.4.2</PackVersion>
     <Nullable>enable</Nullable>
   </PropertyGroup>
 </Project>

analyzer/Ametrin.Optional.Analyzer.csproj

@@ -25,7 +25,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.0.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.3.0" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

analyzer/AmetrinOptionalAnalyzer.cs

@@ -20,7 +20,7 @@ public static readonly DiagnosticDescriptor UnnecessaryRequire
         = new(id: "AmOptional002", title: "Unnecessary Require call", messageFormat: "type already is {0}", category: "Usage", DiagnosticSeverity.Warning, isEnabledByDefault: true);
 
     public static readonly DiagnosticDescriptor WrongConditionalType
-        = new(id: "AmOptional003", title: "Wrong conditional return type", messageFormat: "default means {0} instead of {1}", category: "Usage", DiagnosticSeverity.Info, isEnabledByDefault: true);
+        = new(id: "AmOptional003", title: "Potentially wrong return type", messageFormat: "default means {0} instead of {1}", category: "Usage", DiagnosticSeverity.Info, isEnabledByDefault: true);
 
     public static readonly DiagnosticDescriptor ImpossibleAs
         = new(id: "AmOptional004", title: "Impossible As call", messageFormat: "Cannot safely up-cast {0} to {1}. Use Require<T>.", category: "Usage", DiagnosticSeverity.Error, isEnabledByDefault: true);
@@ -195,18 +195,28 @@ public override void Initialize(AnalysisContext context)
 
             if (conversion.Type is not INamedTypeSymbol target || !IsOptionalType(target)) return;
 
-            if (conversion.Operand is not IConditionalOperation condition || IsOptionalType(condition.Type!)) return;
-
-            if (IsDefaultLiteral(condition.WhenTrue))
+            if (conversion.Operand is IConditionalOperation condition && !IsOptionalType(condition.Type!))
             {
-                context.ReportDiagnostic(Diagnostic.Create(WrongConditionalType, condition.WhenTrue.Syntax.GetLocation(), condition.Type!.ToDisplayString(), conversion.Type.ToDisplayString()));
-            }
+                if (IsDefaultLiteral(condition.WhenTrue))
+                {
+                    context.ReportDiagnostic(Diagnostic.Create(WrongConditionalType, condition.WhenTrue.Syntax.GetLocation(), condition.Type!.ToDisplayString(), conversion.Type.ToDisplayString()));
+                }
 
-            if (condition.WhenFalse is not null && IsDefaultLiteral(condition.WhenFalse))
+                if (condition.WhenFalse is not null && IsDefaultLiteral(condition.WhenFalse))
+                {
+                    context.ReportDiagnostic(Diagnostic.Create(WrongConditionalType, condition.WhenFalse.Syntax.GetLocation(), condition.Type!.ToDisplayString(), conversion.Type.ToDisplayString()));
+                }
+            }
+            else if (conversion.Operand is ISwitchExpressionOperation switchExpression && !IsOptionalType(switchExpression.Type!))
             {
-                context.ReportDiagnostic(Diagnostic.Create(WrongConditionalType, condition.WhenFalse.Syntax.GetLocation(), condition.Type!.ToDisplayString(), conversion.Type.ToDisplayString()));
+                foreach (var arm in switchExpression.Arms)
+                {
+                    if (IsDefaultLiteral(arm.Value))
+                    {
+                        context.ReportDiagnostic(Diagnostic.Create(WrongConditionalType, arm.Value.Syntax.GetLocation(), switchExpression.Type!.ToDisplayString(), conversion.Type.ToDisplayString()));
+                    }
+                }
             }
-
         }, OperationKind.Conversion);
 
         context.RegisterOperationAction(static context =>

generator/Ametrin.Optional.Generator.csproj

@@ -14,7 +14,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.0.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.3.0" />
   </ItemGroup>
 
 </Project>