namespace Microsoft.CodeAnalysis
 {
      public interface ISymbol
      {
+          /// <summary>
+          /// Whether this symbol uses the updated memory safety rules and is considered <see langword="unsafe"/> under those rules.
+          /// </summary>
+          [Experimental(RoslynExperiments.PreviewLanguageFeatureApi, UrlFormat = "https://github.com/dotnet/roslyn/issues/82789")]
+          bool RequiresUnsafe { get; }
      }
 }

 namespace Microsoft.CodeAnalysis.CSharp
 {
     public sealed class CSharpCompilationOptions
     {
+        /// <summary>
+        /// Memory safety rules.
+        /// <list type="bullet">
+        /// <item><c>0</c> - legacy rules</item>
+        /// <item><c>2</c> - updated rules (support for <c>[RequiresUnsafe]</c> members)</item>
+        /// </list>
+        /// </summary>
+        [Experimental(RoslynExperiments.PreviewLanguageFeatureApi, UrlFormat = "https://github.com/dotnet/roslyn/issues/82789")]
+        public int MemorySafetyRules { get; private set; }
 
+        [Experimental(RoslynExperiments.PreviewLanguageFeatureApi, UrlFormat = "https://github.com/dotnet/roslyn/issues/82789")]
+        public CSharpCompilationOptions(
+            OutputKind outputKind,
+            bool reportSuppressedDiagnostics = false,
+            string? moduleName = null,
+            string? mainTypeName = null,
+            string? scriptClassName = null,
+            IEnumerable<string>? usings = null,
+            OptimizationLevel optimizationLevel = OptimizationLevel.Debug,
+            bool checkOverflow = false,
+            bool allowUnsafe = false,
+            string? cryptoKeyContainer = null,
+            string? cryptoKeyFile = null,
+            ImmutableArray<byte> cryptoPublicKey = default,
+            bool? delaySign = null,
+            Platform platform = Platform.AnyCpu,
+            ReportDiagnostic generalDiagnosticOption = ReportDiagnostic.Default,
+            int warningLevel = Diagnostic.DefaultWarningLevel,
+            IEnumerable<KeyValuePair<string, ReportDiagnostic>>? specificDiagnosticOptions = null,
+            bool concurrentBuild = true,
+            bool deterministic = false,
+            XmlReferenceResolver? xmlReferenceResolver = null,
+            SourceReferenceResolver? sourceReferenceResolver = null,
+            MetadataReferenceResolver? metadataReferenceResolver = null,
+            AssemblyIdentityComparer? assemblyIdentityComparer = null,
+            StrongNameProvider? strongNameProvider = null,
+            bool publicSign = false,
+            MetadataImportOptions metadataImportOptions = MetadataImportOptions.Public,
+            NullableContextOptions nullableContextOptions = NullableContextOptions.Disable,
+            int memorySafetyRules = 0);
 
-        public CSharpCompilationOptions(
-            OutputKind outputKind,
-            bool reportSuppressedDiagnostics = false,
-            string? moduleName = null,
-            string? mainTypeName = null,
-            string? scriptClassName = null,
-            IEnumerable<string>? usings = null,
-            OptimizationLevel optimizationLevel = OptimizationLevel.Debug,
-            bool checkOverflow = false,
-            bool allowUnsafe = false,
-            string? cryptoKeyContainer = null,
-            string? cryptoKeyFile = null,
-            ImmutableArray<byte> cryptoPublicKey = default,
-            bool? delaySign = null,
-            Platform platform = Platform.AnyCpu,
-            ReportDiagnostic generalDiagnosticOption = ReportDiagnostic.Default,
-            int warningLevel = Diagnostic.DefaultWarningLevel,
-            IEnumerable<KeyValuePair<string, ReportDiagnostic>>? specificDiagnosticOptions = null,
-            bool concurrentBuild = true,
-            bool deterministic = false,
-            XmlReferenceResolver? xmlReferenceResolver = null,
-            SourceReferenceResolver? sourceReferenceResolver = null,
-            MetadataReferenceResolver? metadataReferenceResolver = null,
-            AssemblyIdentityComparer? assemblyIdentityComparer = null,
-            StrongNameProvider? strongNameProvider = null,
-            bool publicSign = false,
-            MetadataImportOptions metadataImportOptions = MetadataImportOptions.Public,
-            NullableContextOptions nullableContextOptions = NullableContextOptions.Disable);
 
+        // 18.6 BACKCOMPAT OVERLOAD -- DO NOT TOUCH
+        public CSharpCompilationOptions(
+            OutputKind outputKind,
+            bool reportSuppressedDiagnostics,
+            string? moduleName,
+            string? mainTypeName,
+            string? scriptClassName,
+            IEnumerable<string>? usings,
+            OptimizationLevel optimizationLevel,
+            bool checkOverflow,
+            bool allowUnsafe,
+            string? cryptoKeyContainer,
+            string? cryptoKeyFile,
+            ImmutableArray<byte> cryptoPublicKey,
+            bool? delaySign,
+            Platform platform,
+            ReportDiagnostic generalDiagnosticOption,
+            int warningLevel,
+            IEnumerable<KeyValuePair<string, ReportDiagnostic>>? specificDiagnosticOptions,
+            bool concurrentBuild,
+            bool deterministic,
+            XmlReferenceResolver? xmlReferenceResolver,
+            SourceReferenceResolver? sourceReferenceResolver,
+            MetadataReferenceResolver? metadataReferenceResolver,
+            AssemblyIdentityComparer? assemblyIdentityComparer,
+            StrongNameProvider? strongNameProvider,
+            bool publicSign,
+            MetadataImportOptions metadataImportOptions,
+            NullableContextOptions nullableContextOptions);
 
+        [Experimental(RoslynExperiments.PreviewLanguageFeatureApi, UrlFormat = "https://github.com/dotnet/roslyn/issues/82789")]
+        public CSharpCompilationOptions WithMemorySafetyRules(int version);
     }
 }