Records: support for fields.

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

@@ -4,6 +4,15 @@
 	{
 	}
 
+	public record Fields
+	{
+		public int A;
+		public double B = 1.0;
+		public object C;
+		public dynamic D;
+		public string S = "abc";
+	}
+
 	public record Properties
 	{
 		public int A { 

ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs

@@ -1179,24 +1179,28 @@ namespace ICSharpCode.Decompiler.CSharp
 						typeDecl.Members.Add(nestedType);
 					}
 				}
-				foreach (var field in typeDef.Fields)
+				// With C# 9 records, the relative order of fields and properties matters:
+				IEnumerable<IMember> fieldsAndProperties = recordDecompiler?.FieldsAndProperties
+					?? typeDef.Fields.Concat<IMember>(typeDef.Properties);
+				foreach (var fieldOrProperty in fieldsAndProperties)
 				{
-					if (!field.MetadataToken.IsNil && !MemberIsHidden(module.PEFile, field.MetadataToken, settings))
+					if (fieldOrProperty.MetadataToken.IsNil || MemberIsHidden(module.PEFile, fieldOrProperty.MetadataToken, settings))
+					{
+						continue;
+					}
+					if (fieldOrProperty is IField field)
 					{
 						if (typeDef.Kind == TypeKind.Enum && !field.IsConst)
 							continue;
 						var memberDecl = DoDecompile(field, decompileRun, decompilationContext.WithCurrentMember(field));
 						typeDecl.Members.Add(memberDecl);
 					}
-				}
-				foreach (var property in typeDef.Properties)
-				{
-					if (recordDecompiler?.PropertyIsGenerated(property) == true)
-					{
-						continue;
-					}
-					if (!property.MetadataToken.IsNil && !MemberIsHidden(module.PEFile, property.MetadataToken, settings))
+					else if (fieldOrProperty is IProperty property)
 					{
+						if (recordDecompiler?.PropertyIsGenerated(property) == true)
+						{
+							continue;
+						}
 						var propDecl = DoDecompile(property, decompileRun, decompilationContext.WithCurrentMember(property));
 						typeDecl.Members.Add(propDecl);
 					}

ICSharpCode.Decompiler/CSharp/RecordDecompiler.cs

@@ -152,13 +152,17 @@ namespace ICSharpCode.Decompiler.CSharp
 			// need to detect the correct interleaving.
 			// We could try to detect this from the PrintMembers body, but let's initially
 			// restrict ourselves to the common case where the record only uses properties.
-			if (recordTypeDef.Fields.All(backingFieldToAutoProperty.ContainsKey))
-			{
-				return recordTypeDef.Properties.ToList<IMember>();
-			}
-			return null;
+			return recordTypeDef.Properties.Concat<IMember>(
+				recordTypeDef.Fields.Where(f => !backingFieldToAutoProperty.ContainsKey(f))
+			).ToList();
 		}
 
+		/// <summary>
+		/// Gets the fields and properties of the record type, interleaved as necessary to
+		/// maintain Equals/ToString/etc. semantics.
+		/// </summary>
+		public IEnumerable<IMember> FieldsAndProperties => orderedMembers;
+
 		bool IsRecordType(IType type)
 		{
 			return type.GetDefinition() == recordTypeDef
@@ -422,6 +426,13 @@ namespace ICSharpCode.Decompiler.CSharp
 					if (!getterCall.Arguments[0].MatchLdThis())
 						return false;
 				}
+				else if (val.MatchLdFld(out var target, out var field) || val.MatchLdFlda(out target, out field))
+				{
+					if (!target.MatchLdThis())
+						return false;
+					if (!field.MemberDefinition.Equals(member))
+						return false;
+				}
 				else
 				{
 					return false;