CA1065: Ignore System.Diagnostics.UnreachableException

src/NetAnalyzers/Core/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/DoNotRaiseExceptionsInUnexpectedLocations.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System;
 using System.Collections.Generic;
@@ -67,6 +67,7 @@ public override void Initialize(AnalysisContext context)
             {
                 Compilation compilation = compilationStartContext.Compilation;
                 INamedTypeSymbol? exceptionType = compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemException);
+                INamedTypeSymbol? unreachableExceptionType = compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemDiagnosticsUnreachableException);
                 if (exceptionType == null)
                 {
                     return;
@@ -101,7 +102,9 @@ public override void Initialize(AnalysisContext context)
                         }
 
                         // Get ThrowOperation's ExceptionType
-                        if (throwOperation.GetThrownExceptionType() is INamedTypeSymbol thrownExceptionType && thrownExceptionType.DerivesFrom(exceptionType))
+                        if (throwOperation.GetThrownExceptionType() is INamedTypeSymbol thrownExceptionType &&
+                            thrownExceptionType.DerivesFrom(exceptionType) &&
+                            !SymbolEqualityComparer.Default.Equals(thrownExceptionType, unreachableExceptionType))
                         {
                             // If no exceptions are allowed or if the thrown exceptions is not an allowed one..
                             if (methodCategory.AllowedExceptions.IsEmpty || !methodCategory.AllowedExceptions.Any(n => thrownExceptionType.IsAssignableTo(n, compilation)))

src/NetAnalyzers/UnitTests/Microsoft.CodeQuality.Analyzers/ApiDesignGuidelines/DoNotRaiseExceptionsInUnexpectedLocationsTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the MIT license.  See License.txt in the project root for license information.
 
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
@@ -744,6 +744,46 @@ End Class
             return VerifyVB.VerifyAnalyzerAsync(code);
         }
 
+        [Fact, WorkItem(6001, "https://github.com/dotnet/roslyn-analyzers/issues/6001")]
+        public Task UnreachableException_NoDiagnostic()
+        {
+            const string code = """
+                                public class ShouldNotViolate
+                                {
+                                    static ShouldNotViolate()
+                                    {
+                                        throw new System.Diagnostics.UnreachableException();
+                                    }
+                                }
+                                """;
+
+            return new VerifyCS.Test
+            {
+                TestCode = code,
+                FixedCode = code,
+                ReferenceAssemblies = ReferenceAssemblies.Net.Net70
+            }.RunAsync();
+        }
+
+        [Fact, WorkItem(6001, "https://github.com/dotnet/roslyn-analyzers/issues/6001")]
+        public Task VB_UnreachableException_NoDiagnostic()
+        {
+            const string code = """
+                                Public Class ShouldNotViolate
+                                    Shared Sub New()
+                                        Throw New System.Diagnostics.UnreachableException()
+                                    End Sub
+                                End Class
+                                """;
+
+            return new VerifyVB.Test
+            {
+                TestCode = code,
+                FixedCode = code,
+                ReferenceAssemblies = ReferenceAssemblies.Net.Net70
+            }.RunAsync();
+        }
+
         #endregion
 
         #region Operator tests

src/Utilities/Compiler/WellKnownTypeNames.cs

@@ -227,6 +227,7 @@ internal static class WellKnownTypeNames
         public const string SystemDiagnosticsProcessStartInfo = "System.Diagnostics.ProcessStartInfo";
         public const string SystemDiagnosticsTraceListener = "System.Diagnostics.TraceListener";
         public const string SystemDiagnosticsTracingEventSource = "System.Diagnostics.Tracing.EventSource";
+        public const string SystemDiagnosticsUnreachableException = "System.Diagnostics.UnreachableException";
         public const string SystemDirectoryDirectoryEntry = "System.DirectoryServices.DirectoryEntry";
         public const string SystemDirectoryServicesActiveDirectoryADSearcher = "System.DirectoryServices.ActiveDirectory.ADSearcher";
         public const string SystemDirectoryServicesDirectorySearcher = "System.DirectoryServices.DirectorySearcher";