Add Generic Enum.TryFormat()

src/libraries/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/Semantics/Operators.cs

@@ -1046,8 +1046,8 @@ private int WhichBofsIsBetter(BinOpFullSig bofs1, BinOpFullSig bofs2, CType type
                 bt2 = WhichTypeIsBetter(bofs1.Type2(), bofs2.Type2(), type2);
             }
 
-            Debug.Assert(Enum.IsDefined(typeof(BetterType), bt1));
-            Debug.Assert(Enum.IsDefined(typeof(BetterType), bt2));
+            Debug.Assert(Enum.IsDefined(bt1));
+            Debug.Assert(Enum.IsDefined(bt2));
             int res = bt1 switch
             {
                 BetterType.Left => -1,
@@ -1550,7 +1550,7 @@ private int WhichUofsIsBetter(UnaOpFullSig uofs1, UnaOpFullSig uofs2, CType type
                 bt = WhichTypeIsBetter(uofs1.GetType(), uofs2.GetType(), typeArg);
             }
 
-            Debug.Assert(Enum.IsDefined(typeof(BetterType), bt));
+            Debug.Assert(Enum.IsDefined(bt));
             return bt switch
             {
                 BetterType.Left => -1,

src/libraries/Microsoft.Win32.Registry/src/Microsoft/Win32/RegistryKey.cs

@@ -565,7 +565,7 @@ public void SetValue(string? name, object value, RegistryValueKind valueKind)
                 throw new ArgumentException(SR.Arg_RegValStrLenBug, nameof(name));
             }
 
-            if (!Enum.IsDefined(typeof(RegistryValueKind), valueKind))
+            if (!Enum.IsDefined(valueKind))
             {
                 throw new ArgumentException(SR.Arg_RegBadKeyKind, nameof(valueKind));
             }

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.cs

@@ -480,7 +480,7 @@ public ProcessPriorityClass PriorityClass
             }
             set
             {
-                if (!Enum.IsDefined(typeof(ProcessPriorityClass), value))
+                if (!Enum.IsDefined(value))
                 {
                     throw new InvalidEnumArgumentException(nameof(value), (int)value, typeof(ProcessPriorityClass));
                 }

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/ProcessStartInfo.cs

@@ -161,7 +161,7 @@ public ProcessWindowStyle WindowStyle
             get => _windowStyle;
             set
             {
-                if (!Enum.IsDefined(typeof(ProcessWindowStyle), value))
+                if (!Enum.IsDefined(value))
                 {
                     throw new InvalidEnumArgumentException(nameof(value), (int)value, typeof(ProcessWindowStyle));
                 }

src/libraries/System.Drawing.Common/src/System/Drawing/Printing/PrinterSettings.cs

@@ -371,7 +371,7 @@ public PrintRange PrintRange
             get { return _printRange; }
             set
             {
-                if (!Enum.IsDefined(typeof(PrintRange), value))
+                if (!Enum.IsDefined(value))
                     throw new InvalidEnumArgumentException(nameof(value), unchecked((int)value), typeof(PrintRange));
 
                 _printRange = value;

src/libraries/System.Private.CoreLib/src/System/Environment.cs

@@ -112,10 +112,10 @@ public static string ExpandEnvironmentVariables(string name)
 
         public static string GetFolderPath(SpecialFolder folder, SpecialFolderOption option)
         {
-            if (!Enum.IsDefined(typeof(SpecialFolder), folder))
+            if (!Enum.IsDefined(folder))
                 throw new ArgumentOutOfRangeException(nameof(folder), folder, SR.Format(SR.Arg_EnumIllegalVal, folder));
 
-            if (option != SpecialFolderOption.None && !Enum.IsDefined(typeof(SpecialFolderOption), option))
+            if (option != SpecialFolderOption.None && !Enum.IsDefined(option))
                 throw new ArgumentOutOfRangeException(nameof(option), option, SR.Format(SR.Arg_EnumIllegalVal, option));
 
             return GetFolderPathCore(folder, option);

src/libraries/System.Private.CoreLib/src/System/MemoryExtensions.cs

@@ -3271,10 +3271,21 @@ public bool AppendFormatted<T>(T value)
                 if (value is IFormattable)
                 {
                     // If the value can format itself directly into our buffer, do so.
+
                     if (value is ISpanFormattable)
                     {
-                        int charsWritten;
-                        if (((ISpanFormattable)value).TryFormat(_destination.Slice(_pos), out charsWritten, default, _provider)) // constrained call avoiding boxing for value types
+                        if (((ISpanFormattable)value).TryFormat(_destination.Slice(_pos), out int charsWritten, default, _provider)) // constrained call avoiding boxing for value types
+                        {
+                            _pos += charsWritten;
+                            return true;
+                        }
+
+                        return Fail();
+                    }
+
+                    if (typeof(T).IsEnum)
+                    {
+                        if (Enum.TryFormatUnconstrained(value, _destination.Slice(_pos), out int charsWritten))
                         {
                             _pos += charsWritten;
                             return true;
@@ -3318,8 +3329,18 @@ public bool AppendFormatted<T>(T value, string? format)
                     // If the value can format itself directly into our buffer, do so.
                     if (value is ISpanFormattable)
                     {
-                        int charsWritten;
-                        if (((ISpanFormattable)value).TryFormat(_destination.Slice(_pos), out charsWritten, format, _provider)) // constrained call avoiding boxing for value types
+                        if (((ISpanFormattable)value).TryFormat(_destination.Slice(_pos), out int charsWritten, format, _provider)) // constrained call avoiding boxing for value types
+                        {
+                            _pos += charsWritten;
+                            return true;
+                        }
+
+                        return Fail();
+                    }
+
+                    if (typeof(T).IsEnum)
+                    {
+                        if (Enum.TryFormatUnconstrained(value, _destination.Slice(_pos), out int charsWritten, format))
                         {
                             _pos += charsWritten;
                             return true;

src/libraries/System.Private.CoreLib/src/System/Resources/NeutralResourcesLanguageAttribute.cs

@@ -21,7 +21,7 @@ public NeutralResourcesLanguageAttribute(string cultureName, UltimateResourceFal
         {
             ArgumentNullException.ThrowIfNull(cultureName);
 
-            if (!Enum.IsDefined(typeof(UltimateResourceFallbackLocation), location))
+            if (!Enum.IsDefined(location))
                 throw new ArgumentException(SR.Format(SR.Arg_InvalidNeutralResourcesLanguage_FallbackLoc, location));
 
             CultureName = cultureName;

src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs

@@ -305,6 +305,7 @@ public void AppendFormatted<T>(T value)
             if (value is IFormattable)
             {
                 // If the value can format itself directly into our buffer, do so.
+
                 if (value is ISpanFormattable)
                 {
                     int charsWritten;
@@ -317,6 +318,18 @@ public void AppendFormatted<T>(T value)
                     return;
                 }
 
+                if (typeof(T).IsEnum)
+                {
+                    int charsWritten;
+                    while (!Enum.TryFormatUnconstrained(value, _chars.Slice(_pos), out charsWritten))
+                    {
+                        Grow();
+                    }
+
+                    _pos += charsWritten;
+                    return;
+                }
+
                 s = ((IFormattable)value).ToString(format: null, _provider); // constrained call avoiding boxing for value types
             }
             else
@@ -329,6 +342,7 @@ public void AppendFormatted<T>(T value)
                 AppendStringDirect(s);
             }
         }
+
         /// <summary>Writes the specified value to the handler.</summary>
         /// <param name="value">The value to write.</param>
         /// <param name="format">The format string.</param>
@@ -365,6 +379,18 @@ public void AppendFormatted<T>(T value, string? format)
                     return;
                 }
 
+                if (typeof(T).IsEnum)
+                {
+                    int charsWritten;
+                    while (!Enum.TryFormatUnconstrained(value, _chars.Slice(_pos), out charsWritten, format))
+                    {
+                        Grow();
+                    }
+
+                    _pos += charsWritten;
+                    return;
+                }
+
                 s = ((IFormattable)value).ToString(format, _provider); // constrained call avoiding boxing for value types
             }
             else

src/libraries/System.Private.CoreLib/src/System/Text/StringBuilder.cs

@@ -2640,6 +2640,17 @@ public void AppendFormatted<T>(T value)
                             AppendFormattedWithTempSpace(value, 0, format: null);
                         }
                     }
+                    else if (typeof(T).IsEnum)
+                    {
+                        if (Enum.TryFormatUnconstrained(value, _stringBuilder.RemainingCurrentChunk, out int charsWritten))
+                        {
+                            _stringBuilder.m_ChunkLength += charsWritten;
+                        }
+                        else
+                        {
+                            AppendFormattedWithTempSpace(value, 0, format: null);
+                        }
+                    }
                     else
                     {
                         _stringBuilder.Append(((IFormattable)value).ToString(format: null, _provider)); // constrained call avoiding boxing for value types
@@ -2693,6 +2704,17 @@ public void AppendFormatted<T>(T value, string? format)
                             AppendFormattedWithTempSpace(value, 0, format);
                         }
                     }
+                    else if (typeof(T).IsEnum)
+                    {
+                        if (Enum.TryFormatUnconstrained(value, _stringBuilder.RemainingCurrentChunk, out int charsWritten, format))
+                        {
+                            _stringBuilder.m_ChunkLength += charsWritten;
+                        }
+                        else
+                        {
+                            AppendFormattedWithTempSpace(value, 0, format);
+                        }
+                    }
                     else
                     {
                         _stringBuilder.Append(((IFormattable)value).ToString(format, _provider)); // constrained call avoiding boxing for value types

src/libraries/System.Private.CoreLib/src/System/ThrowHelper.cs

@@ -692,7 +692,7 @@ internal static void ThrowForUnsupportedIntrinsicsVector256BaseType<T>()
         [MethodImpl(MethodImplOptions.NoInlining)]
         private static string GetArgumentName(ExceptionArgument argument)
         {
-            Debug.Assert(Enum.IsDefined(typeof(ExceptionArgument), argument),
+            Debug.Assert(Enum.IsDefined(argument),
                 "The enum value is not defined, please check the ExceptionArgument Enum.");
 
             return argument.ToString();
@@ -912,7 +912,7 @@ private static string GetArgumentName(ExceptionArgument argument)
         [MethodImpl(MethodImplOptions.NoInlining)]
         private static string GetResourceString(ExceptionResource resource)
         {
-            Debug.Assert(Enum.IsDefined(typeof(ExceptionResource), resource),
+            Debug.Assert(Enum.IsDefined(resource),
                 "The enum value is not defined, please check the ExceptionResource Enum.");
 
             return SR.GetResourceString(resource.ToString());

src/libraries/System.Private.Uri/src/System/UriExt.cs

@@ -17,8 +17,6 @@ private void CreateThis(string? uri, bool dontEscape, UriKind uriKind, in UriCre
         {
             DebugAssertInCtor();
 
-            // if (!Enum.IsDefined(typeof(UriKind), uriKind)) -- We currently believe that Enum.IsDefined() is too slow
-            // to be used here.
             if ((int)uriKind < (int)UriKind.RelativeOrAbsolute || (int)uriKind > (int)UriKind.Relative)
             {
                 throw new ArgumentException(SR.Format(SR.net_uri_InvalidUriKind, uriKind));
@@ -622,8 +620,6 @@ private Uri(Flags flags, UriParser? uriParser, string uri)
         //
         internal static Uri? CreateHelper(string uriString, bool dontEscape, UriKind uriKind, ref UriFormatException? e, in UriCreationOptions creationOptions = default)
         {
-            // if (!Enum.IsDefined(typeof(UriKind), uriKind)) -- We currently believe that Enum.IsDefined() is too slow
-            // to be used here.
             if ((int)uriKind < (int)UriKind.RelativeOrAbsolute || (int)uriKind > (int)UriKind.Relative)
             {
                 throw new ArgumentException(SR.Format(SR.net_uri_InvalidUriKind, uriKind));

src/libraries/System.Private.Xml/src/System/Xml/Xsl/IlGen/OptimizerPatterns.cs

@@ -242,7 +242,7 @@ public object GetArgument(OptimizerPatternArgument argNum)
         /// </summary>
         public void AddPattern(OptimizerPatternName pattern)
         {
-            Debug.Assert(Enum.IsDefined(typeof(OptimizerPatternName), pattern));
+            Debug.Assert(Enum.IsDefined(pattern));
             Debug.Assert((int)pattern < 32);
             Debug.Assert(!_isReadOnly, "This OptimizerPatterns instance is read-only.");
             _patterns |= (1 << (int)pattern);
@@ -253,7 +253,7 @@ public void AddPattern(OptimizerPatternName pattern)
         /// </summary>
         public bool MatchesPattern(OptimizerPatternName pattern)
         {
-            Debug.Assert(Enum.IsDefined(typeof(OptimizerPatternName), pattern));
+            Debug.Assert(Enum.IsDefined(pattern));
             return (_patterns & (1 << (int)pattern)) != 0;
         }
 

src/libraries/System.Runtime/ref/System.Runtime.cs

@@ -2366,6 +2366,7 @@ protected Enum() { }
         public string ToString([System.Diagnostics.CodeAnalysis.StringSyntaxAttribute("EnumFormat")] string? format) { throw null; }
         [System.ObsoleteAttribute("The provider argument is not used. Use ToString(String) instead.")]
         public string ToString([System.Diagnostics.CodeAnalysis.StringSyntaxAttribute("EnumFormat")] string? format, System.IFormatProvider? provider) { throw null; }
+        public static bool TryFormat<TEnum>(TEnum value, System.Span<char> destination, out int charsWritten, [System.Diagnostics.CodeAnalysis.StringSyntaxAttribute("EnumFormat")] System.ReadOnlySpan<char> format = default(System.ReadOnlySpan<char>)) where TEnum : struct { throw null; }
         public static bool TryParse(System.Type enumType, System.ReadOnlySpan<char> value, bool ignoreCase, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out object? result) { throw null; }
         public static bool TryParse(System.Type enumType, System.ReadOnlySpan<char> value, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out object? result) { throw null; }
         public static bool TryParse(System.Type enumType, string? value, bool ignoreCase, [System.Diagnostics.CodeAnalysis.NotNullWhenAttribute(true)] out object? result) { throw null; }