From 405c6150017022eaf970b44dcaa8c013542e1522 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 22 Nov 2025 04:20:46 +0000
Subject: [PATCH 1/2] Initial plan


From ea5298d98d7cb53710ff532b840bae6a9e5fd572 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 22 Nov 2025 04:25:59 +0000
Subject: [PATCH 2/2] Use IOperation to detect both explicit and implicit
 integer-to-enum conversions

Co-authored-by: agocke <515774+agocke@users.noreply.github.com>
---
 src/StaticCs/EnumClosedConversionAnalyzer.cs | 29 ++++++++++++--------
 test/test/ClosedTests.cs                     |  6 ++--
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/src/StaticCs/EnumClosedConversionAnalyzer.cs b/src/StaticCs/EnumClosedConversionAnalyzer.cs
index 5edda05..6fd4332 100644
--- a/src/StaticCs/EnumClosedConversionAnalyzer.cs
+++ b/src/StaticCs/EnumClosedConversionAnalyzer.cs
@@ -1,9 +1,8 @@
 
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.CSharp;
-using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Operations;
 
 namespace StaticCs;
 
@@ -24,22 +23,30 @@ public override void Initialize(AnalysisContext ctx)
     {
         ctx.EnableConcurrentExecution();
         ctx.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.ReportDiagnostics);
-        ctx.RegisterSyntaxNodeAction(ctx =>
+        ctx.RegisterOperationAction(ctx =>
         {
-            var castSyntax = (CastExpressionSyntax)ctx.Node;
-            var model = ctx.SemanticModel;
-            var targetTypeInfo = model.GetTypeInfo(castSyntax.Type);
-
-            if (targetTypeInfo.Type is { TypeKind: TypeKind.Enum } type)
+            var conversion = (IConversionOperation)ctx.Operation;
+            
+            // Check if the conversion is from an integer type to an enum type
+            if (conversion.Type is { TypeKind: TypeKind.Enum } targetType &&
+                conversion.Operand.Type?.SpecialType is 
+                    SpecialType.System_SByte or
+                    SpecialType.System_Byte or
+                    SpecialType.System_Int16 or
+                    SpecialType.System_UInt16 or
+                    SpecialType.System_Int32 or
+                    SpecialType.System_UInt32 or
+                    SpecialType.System_Int64 or
+                    SpecialType.System_UInt64)
             {
-                foreach (var attr in type.GetAttributes())
+                foreach (var attr in targetType.GetAttributes())
                 {
                     if (attr.AttributeClass?.ToDisplayString() == "StaticCs.ClosedAttribute")
                     {
-                        ctx.ReportDiagnostic(Diagnostic.Create(s_descriptor, castSyntax.GetLocation(), type));
+                        ctx.ReportDiagnostic(Diagnostic.Create(s_descriptor, conversion.Syntax.GetLocation(), targetType));
                     }
                 }
             }
-        }, SyntaxKind.CastExpression);
+        }, OperationKind.Conversion);
     }
 }
\ No newline at end of file
diff --git a/test/test/ClosedTests.cs b/test/test/ClosedTests.cs
index bd03399..74995ec 100644
--- a/test/test/ClosedTests.cs
+++ b/test/test/ClosedTests.cs
@@ -80,7 +80,7 @@ await VerifyDiagnostics<EnumClosedConversionAnalyzer>(src,
     }
 
     [Fact]
-    public async Task ImplicitConversionToClosedLoophole()
+    public async Task ImplicitConversionToClosedError()
     {
         var src = """
 using System;
@@ -96,7 +96,9 @@ void M()
     }
 }
 """;
-        await VerifyDiagnostics<EnumClosedConversionAnalyzer>(src);
+        await VerifyDiagnostics<EnumClosedConversionAnalyzer>(src,
+            // /0/Test0.cs(9,19): error STATICCS002: Integer conversions to [Closed] enum Rgb are disallowed
+            ClosedEnumConversion.WithSpan(9, 19, 9, 20).WithArguments("Rgb"));
     }
 
     [Fact]