Remove sequential values from enum members + display powers of two (- 1) as hex.

ICSharpCode.Decompiler.Tests/CustomAttributes/S_CustomAttributes.cs

@@ -26,7 +26,7 @@ namespace CustomAttributes
 		[Flags]
 		public enum EnumWithFlag
 		{
-			All = 15,
+			All = 0xF,
 			None = 0,
 			Item1 = 1,
 			Item2 = 2,

ICSharpCode.Decompiler.Tests/TestCases/Pretty/CompoundAssignmentTest.cs

@@ -34,9 +34,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 
 		public enum ShortEnum : short
 		{
-			None = 0,
-			One = 1,
-			Two = 2,
+			None,
+			One,
+			Two,
 			Four = 4
 		}
 

ICSharpCode.Decompiler.Tests/TestCases/Pretty/InitializerTests.cs

@@ -48,14 +48,14 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 
 		private enum MyEnum
 		{
-			a = 0,
-			b = 1
+			a,
+			b
 		}
 
 		private enum MyEnum2
 		{
-			c = 0,
-			d = 1
+			c,
+			d
 		}
 
 		private class Data

ICSharpCode.Decompiler.Tests/TestCases/Pretty/Switch.cs

@@ -41,9 +41,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 
 		public enum State
 		{
-			False = 0,
-			True = 1,
-			Null = 2
+			False,
+			True,
+			Null
 		}
 
 		public static State SwitchOverNullableBool(bool? value)

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -820,10 +820,20 @@ namespace ICSharpCode.Decompiler.CSharp
 			Debug.Assert(decompilationContext.CurrentMember == field);
 			var typeSystemAstBuilder = CreateAstBuilder(decompilationContext);
 			if (decompilationContext.CurrentTypeDefinition.Kind == TypeKind.Enum) {
-				var enumDec = new EnumMemberDeclaration {
-					Name = field.Name,
-					Initializer = typeSystemAstBuilder.ConvertConstantValue(decompilationContext.CurrentTypeDefinition.EnumUnderlyingType, field.ConstantValue),
-				};
+				var index = decompilationContext.CurrentTypeDefinition.Members.IndexOf(field);
+				long previousValue = -1;
+				if (index > 0) {
+					var previousMember = (IField)decompilationContext.CurrentTypeDefinition.Members[index - 1];
+					previousValue = (long)CSharpPrimitiveCast.Cast(TypeCode.Int64, previousMember.ConstantValue, false);
+				}
+				long initValue = (long)CSharpPrimitiveCast.Cast(TypeCode.Int64, field.ConstantValue, false);
+				var enumDec = new EnumMemberDeclaration { Name = field.Name };
+				if (previousValue + 1 != initValue || decompilationContext.CurrentTypeDefinition.Attributes.Any(a => a.AttributeType.FullName == "System.FlagsAttribute")) {
+					enumDec.Initializer = typeSystemAstBuilder.ConvertConstantValue(decompilationContext.CurrentTypeDefinition.EnumUnderlyingType, field.ConstantValue);
+					if (enumDec.Initializer is PrimitiveExpression primitive && initValue > 9 && ((initValue & (initValue - 1)) == 0 || (initValue & (initValue + 1)) == 0)) {
+						primitive.SetValue(initValue, $"0x{initValue:X}");
+					}
+				}
 				enumDec.Attributes.AddRange(field.Attributes.Select(a => new AttributeSection(typeSystemAstBuilder.ConvertAttribute(a))));
 				enumDec.AddAnnotation(new Semantics.MemberResolveResult(null, field));
 				return enumDec;