Always use hex in flags enums and in bit-wise operations.

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -830,7 +830,11 @@ namespace ICSharpCode.Decompiler.CSharp
 				}
 				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")) {
+				if (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)
+						primitive.SetValue(initValue, $"0x{initValue:X}");
+				} else if (previousValue + 1 != initValue) {
 					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}");

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -296,10 +296,6 @@ namespace ICSharpCode.Decompiler.CSharp
 				parent = conv.Parent;
 			if (value <= 9)
 				return false;
-			if (value < long.MaxValue) {
-				if (!((value & (value - 1)) == 0 || (value & (value + 1)) == 0))
-					return false;
-			}
 			switch (parent) {
 				case BinaryNumericInstruction bni:
 					if (bni.Operator == BinaryNumericOperator.BitAnd