Use C# 14's field keyword in more places (#117817)

Author: stephentoub

src/libraries/Common/src/System/CodeDom/CodeObject.cs

@@ -16,10 +16,8 @@ public class CodeObject
     internal class CodeObject
 #endif
     {
-        private IDictionary? _userData;
-
         public CodeObject() { }
 
-        public IDictionary UserData => _userData ??= new ListDictionary();
+        public IDictionary UserData => field ??= new ListDictionary();
     }
 }

src/libraries/Common/src/System/Data/Common/AdapterUtil.cs

@@ -19,11 +19,8 @@ internal static partial class ADP
     {
         // NOTE: Initializing a Task in SQL CLR requires the "UNSAFE" permission set (https://learn.microsoft.com/dotnet/framework/performance/sql-server-programming-and-host-protection-attributes)
         // Therefore we are lazily initializing these Tasks to avoid forcing customers to use the "UNSAFE" set when they are actually using no Async features
-        private static Task<bool>? _trueTask;
-        internal static Task<bool> TrueTask => _trueTask ??= Task.FromResult(true);
-
-        private static Task<bool>? _falseTask;
-        internal static Task<bool> FalseTask => _falseTask ??= Task.FromResult(false);
+        internal static Task<bool> TrueTask => field ??= Task.FromResult(true);
+        internal static Task<bool> FalseTask => field ??= Task.FromResult(false);
 
         internal const CompareOptions DefaultCompareOptions = CompareOptions.IgnoreKanaType | CompareOptions.IgnoreWidth | CompareOptions.IgnoreCase;
         internal const int DefaultConnectionTimeout = DbConnectionStringDefaults.ConnectTimeout;

src/libraries/Common/src/System/Security/Cryptography/Oids.Shared.cs

@@ -8,74 +8,41 @@ namespace System.Security.Cryptography
 {
     internal static partial class Oids
     {
-        private static Oid? s_rsaOid;
-        private static Oid? s_ecPublicKeyOid;
-        private static Oid? s_tripleDesCbcOid;
-        private static Oid? s_aes256CbcOid;
-        private static Oid? s_secp256R1Oid;
-        private static Oid? s_secp384R1Oid;
-        private static Oid? s_secp521R1Oid;
-        private static Oid? s_sha256Oid;
-        private static Oid? s_pkcs7DataOid;
-        private static Oid? s_contentTypeOid;
-        private static Oid? s_documentDescriptionOid;
-        private static Oid? s_documentNameOid;
-        private static Oid? s_localKeyIdOid;
-        private static Oid? s_messageDigestOid;
-        private static Oid? s_signingTimeOid;
-        private static Oid? s_pkcs9ExtensionRequestOid;
-        private static Oid? s_basicConstraints2Oid;
-        private static Oid? s_enhancedKeyUsageOid;
-        private static Oid? s_keyUsageOid;
-        private static Oid? s_subjectAltNameOid;
-        private static Oid? s_subjectKeyIdentifierOid;
-        private static Oid? s_authorityKeyIdentifierOid;
-        private static Oid? s_authorityInformationAccessOid;
-        private static Oid? s_crlNumberOid;
-        private static Oid? s_crlDistributionPointOid;
-        private static Oid? s_commonNameOid;
-        private static Oid? s_countryOrRegionOid;
-        private static Oid? s_localityNameOid;
-        private static Oid? s_stateOrProvinceNameOid;
-        private static Oid? s_organizationOid;
-        private static Oid? s_organizationalUnitOid;
-        private static Oid? s_emailAddressOid;
-
-        internal static Oid RsaOid => s_rsaOid ??= InitializeOid(Rsa);
-        internal static Oid EcPublicKeyOid => s_ecPublicKeyOid ??= InitializeOid(EcPublicKey);
-        internal static Oid TripleDesCbcOid => s_tripleDesCbcOid ??= InitializeOid(TripleDesCbc);
-        internal static Oid Aes256CbcOid => s_aes256CbcOid ??= InitializeOid(Aes256Cbc);
-        internal static Oid secp256r1Oid => s_secp256R1Oid ??= new Oid(secp256r1, nameof(ECCurve.NamedCurves.nistP256));
-        internal static Oid secp384r1Oid => s_secp384R1Oid ??= new Oid(secp384r1, nameof(ECCurve.NamedCurves.nistP384));
-        internal static Oid secp521r1Oid => s_secp521R1Oid ??= new Oid(secp521r1, nameof(ECCurve.NamedCurves.nistP521));
-        internal static Oid Sha256Oid => s_sha256Oid ??= InitializeOid(Sha256);
-
-        internal static Oid Pkcs7DataOid => s_pkcs7DataOid ??= InitializeOid(Pkcs7Data);
-        internal static Oid ContentTypeOid => s_contentTypeOid ??= InitializeOid(ContentType);
-        internal static Oid DocumentDescriptionOid => s_documentDescriptionOid ??= InitializeOid(DocumentDescription);
-        internal static Oid DocumentNameOid => s_documentNameOid ??= InitializeOid(DocumentName);
-        internal static Oid LocalKeyIdOid => s_localKeyIdOid ??= InitializeOid(LocalKeyId);
-        internal static Oid MessageDigestOid => s_messageDigestOid ??= InitializeOid(MessageDigest);
-        internal static Oid SigningTimeOid => s_signingTimeOid ??= InitializeOid(SigningTime);
-        internal static Oid Pkcs9ExtensionRequestOid => s_pkcs9ExtensionRequestOid ??= InitializeOid(Pkcs9ExtensionRequest);
-
-        internal static Oid BasicConstraints2Oid => s_basicConstraints2Oid ??= InitializeOid(BasicConstraints2);
-        internal static Oid EnhancedKeyUsageOid => s_enhancedKeyUsageOid ??= InitializeOid(EnhancedKeyUsage);
-        internal static Oid KeyUsageOid => s_keyUsageOid ??= InitializeOid(KeyUsage);
-        internal static Oid AuthorityKeyIdentifierOid => s_authorityKeyIdentifierOid ??= InitializeOid(AuthorityKeyIdentifier);
-        internal static Oid SubjectKeyIdentifierOid => s_subjectKeyIdentifierOid ??= InitializeOid(SubjectKeyIdentifier);
-        internal static Oid SubjectAltNameOid => s_subjectAltNameOid ??= InitializeOid(SubjectAltName);
-        internal static Oid AuthorityInformationAccessOid => s_authorityInformationAccessOid ??= InitializeOid(AuthorityInformationAccess);
-        internal static Oid CrlNumberOid => s_crlNumberOid ??= InitializeOid(CrlNumber);
-        internal static Oid CrlDistributionPointsOid => s_crlDistributionPointOid ??= InitializeOid(CrlDistributionPoints);
-
-        internal static Oid CommonNameOid => s_commonNameOid ??= InitializeOid(CommonName);
-        internal static Oid CountryOrRegionNameOid => s_countryOrRegionOid ??= InitializeOid(CountryOrRegionName);
-        internal static Oid LocalityNameOid => s_localityNameOid ??= InitializeOid(LocalityName);
-        internal static Oid StateOrProvinceNameOid => s_stateOrProvinceNameOid ??= InitializeOid(StateOrProvinceName);
-        internal static Oid OrganizationOid => s_organizationOid ??= InitializeOid(Organization);
-        internal static Oid OrganizationalUnitOid => s_organizationalUnitOid ??= InitializeOid(OrganizationalUnit);
-        internal static Oid EmailAddressOid => s_emailAddressOid ??= InitializeOid(EmailAddress);
+        internal static Oid RsaOid => field ??= InitializeOid(Rsa);
+        internal static Oid EcPublicKeyOid => field ??= InitializeOid(EcPublicKey);
+        internal static Oid TripleDesCbcOid => field ??= InitializeOid(TripleDesCbc);
+        internal static Oid Aes256CbcOid => field ??= InitializeOid(Aes256Cbc);
+        internal static Oid secp256r1Oid => field ??= new Oid(secp256r1, nameof(ECCurve.NamedCurves.nistP256));
+        internal static Oid secp384r1Oid => field ??= new Oid(secp384r1, nameof(ECCurve.NamedCurves.nistP384));
+        internal static Oid secp521r1Oid => field ??= new Oid(secp521r1, nameof(ECCurve.NamedCurves.nistP521));
+        internal static Oid Sha256Oid => field ??= InitializeOid(Sha256);
+
+        internal static Oid Pkcs7DataOid => field ??= InitializeOid(Pkcs7Data);
+        internal static Oid ContentTypeOid => field ??= InitializeOid(ContentType);
+        internal static Oid DocumentDescriptionOid => field ??= InitializeOid(DocumentDescription);
+        internal static Oid DocumentNameOid => field ??= InitializeOid(DocumentName);
+        internal static Oid LocalKeyIdOid => field ??= InitializeOid(LocalKeyId);
+        internal static Oid MessageDigestOid => field ??= InitializeOid(MessageDigest);
+        internal static Oid SigningTimeOid => field ??= InitializeOid(SigningTime);
+        internal static Oid Pkcs9ExtensionRequestOid => field ??= InitializeOid(Pkcs9ExtensionRequest);
+
+        internal static Oid BasicConstraints2Oid => field ??= InitializeOid(BasicConstraints2);
+        internal static Oid EnhancedKeyUsageOid => field ??= InitializeOid(EnhancedKeyUsage);
+        internal static Oid KeyUsageOid => field ??= InitializeOid(KeyUsage);
+        internal static Oid AuthorityKeyIdentifierOid => field ??= InitializeOid(AuthorityKeyIdentifier);
+        internal static Oid SubjectKeyIdentifierOid => field ??= InitializeOid(SubjectKeyIdentifier);
+        internal static Oid SubjectAltNameOid => field ??= InitializeOid(SubjectAltName);
+        internal static Oid AuthorityInformationAccessOid => field ??= InitializeOid(AuthorityInformationAccess);
+        internal static Oid CrlNumberOid => field ??= InitializeOid(CrlNumber);
+        internal static Oid CrlDistributionPointsOid => field ??= InitializeOid(CrlDistributionPoints);
+
+        internal static Oid CommonNameOid => field ??= InitializeOid(CommonName);
+        internal static Oid CountryOrRegionNameOid => field ??= InitializeOid(CountryOrRegionName);
+        internal static Oid LocalityNameOid => field ??= InitializeOid(LocalityName);
+        internal static Oid StateOrProvinceNameOid => field ??= InitializeOid(StateOrProvinceName);
+        internal static Oid OrganizationOid => field ??= InitializeOid(Organization);
+        internal static Oid OrganizationalUnitOid => field ??= InitializeOid(OrganizationalUnit);
+        internal static Oid EmailAddressOid => field ??= InitializeOid(EmailAddress);
 
         private static Oid InitializeOid(string oidValue)
         {

src/libraries/Common/tests/TestUtilities/System/IO/FileCleanupTestBase.cs

@@ -100,8 +100,7 @@ protected virtual void Dispose(bool disposing)
         protected string GetRandomLinkPath([CallerMemberName] string memberName = null, [CallerLineNumber] int lineNumber = 0) => Path.Combine(TestDirectoryActualCasing, GetRandomLinkName(memberName, lineNumber));
         protected string GetRandomDirPath([CallerMemberName] string memberName = null, [CallerLineNumber] int lineNumber = 0)  => Path.Combine(TestDirectoryActualCasing, GetRandomDirName(memberName, lineNumber));
 
-        private string _testDirectoryActualCasing;
-        private string TestDirectoryActualCasing => _testDirectoryActualCasing ??= GetTestDirectoryActualCasing();
+        private string TestDirectoryActualCasing => field ??= GetTestDirectoryActualCasing();
 
         /// <summary>Gets a test file full path that is associated with the call site.</summary>
         /// <param name="index">An optional index value to use as a suffix on the file name.  Typically a loop index.</param>

src/libraries/Microsoft.Extensions.Http/src/DefaultHttpMessageHandlerBuilder.cs

@@ -13,7 +13,6 @@ namespace Microsoft.Extensions.Http
 {
     internal sealed class DefaultHttpMessageHandlerBuilder : HttpMessageHandlerBuilder
     {
-        private HttpMessageHandler? _primaryHandler;
         private string? _name;
 
         public DefaultHttpMessageHandlerBuilder(IServiceProvider services)
@@ -34,8 +33,8 @@ public override string? Name
 
         public override HttpMessageHandler PrimaryHandler
         {
-            get => _primaryHandler ??= CreatePrimaryHandler();
-            set => _primaryHandler = value;
+            get => field ??= CreatePrimaryHandler();
+            set => field = value;
         }
 
         public override IList<DelegatingHandler> AdditionalHandlers { get; } = new List<DelegatingHandler>();

src/libraries/Microsoft.Extensions.Http/src/Logging/LoggingHttpMessageHandlerBuilderFilter.cs

@@ -15,8 +15,7 @@ internal sealed class LoggingHttpMessageHandlerBuilderFilter : IHttpMessageHandl
     {
         // we want to prevent a circular depencency between ILoggerFactory and IHttpMessageHandlerBuilderFilter, in case
         // any of ILoggerProvider instances use IHttpClientFactory to send logs to an external server
-        private ILoggerFactory? _loggerFactory;
-        private ILoggerFactory LoggerFactory => _loggerFactory ??= _serviceProvider.GetRequiredService<ILoggerFactory>();
+        private ILoggerFactory LoggerFactory => field ??= _serviceProvider.GetRequiredService<ILoggerFactory>();
         private readonly IServiceProvider _serviceProvider;
         private readonly IOptionsMonitor<HttpClientFactoryOptions> _optionsMonitor;
 

src/libraries/Microsoft.Extensions.Logging.EventLog/src/EventLogSettings.cs

@@ -10,8 +10,6 @@ namespace Microsoft.Extensions.Logging.EventLog
     /// </summary>
     public class EventLogSettings
     {
-        private IEventLog? _eventLog;
-
         /// <summary>
         /// Gets or sets the name of the event log. If <see langword="null" /> or not specified, "Application" is the default.
         /// </summary>
@@ -34,10 +32,10 @@ public class EventLogSettings
 
         internal IEventLog EventLog
         {
-            get => _eventLog ??= CreateDefaultEventLog();
+            get => field ??= CreateDefaultEventLog();
 
             // For unit testing purposes only.
-            set => _eventLog = value;
+            set => field = value;
         }
 
         private WindowsEventLog CreateDefaultEventLog()

src/libraries/System.CodeDom/src/System/CodeDom/CodeArrayIndexerExpression.cs

@@ -5,8 +5,6 @@ namespace System.CodeDom
 {
     public class CodeArrayIndexerExpression : CodeExpression
     {
-        private CodeExpressionCollection _indices;
-
         public CodeArrayIndexerExpression() { }
 
         public CodeArrayIndexerExpression(CodeExpression targetObject, params CodeExpression[] indices)
@@ -17,6 +15,6 @@ public CodeArrayIndexerExpression(CodeExpression targetObject, params CodeExpres
 
         public CodeExpression TargetObject { get; set; }
 
-        public CodeExpressionCollection Indices => _indices ??= new CodeExpressionCollection();
+        public CodeExpressionCollection Indices => field ??= new CodeExpressionCollection();
     }
 }

src/libraries/System.CodeDom/src/System/CodeDom/CodeCastExpression.cs

@@ -5,8 +5,6 @@ namespace System.CodeDom
 {
     public class CodeCastExpression : CodeExpression
     {
-        private CodeTypeReference _targetType;
-
         public CodeCastExpression() { }
 
         public CodeCastExpression(CodeTypeReference targetType, CodeExpression expression)
@@ -29,8 +27,8 @@ public CodeCastExpression(Type targetType, CodeExpression expression)
 
         public CodeTypeReference TargetType
         {
-            get => _targetType ??= new CodeTypeReference("");
-            set => _targetType = value;
+            get => field ??= new CodeTypeReference("");
+            set => field = value;
         }
 
         public CodeExpression Expression { get; set; }

src/libraries/System.CodeDom/src/System/CodeDom/CodeCatchClause.cs

@@ -5,7 +5,6 @@ namespace System.CodeDom
 {
     public class CodeCatchClause
     {
-        private CodeStatementCollection _statements;
         private CodeTypeReference _catchExceptionType;
         private string _localName;
 
@@ -41,6 +40,6 @@ public CodeTypeReference CatchExceptionType
             set => _catchExceptionType = value;
         }
 
-        public CodeStatementCollection Statements => _statements ??= new CodeStatementCollection();
+        public CodeStatementCollection Statements => field ??= new CodeStatementCollection();
     }
 }