Now processes auto generated backing fields (#172)

(cherry picked from commit e38b40d)

Author: josesimoes

MetadataProcessor.Shared/SkeletonGenerator/SkeletonTemplates.cs

@@ -67,7 +67,9 @@ struct Library_{{AssemblyName}}_{{Name}}{{#newline}}
 {{#if StaticFields}}{{#newline}}{{/if}}
 
 {{#each InstanceFields}}
-{{#if FieldWarning}}{{FieldWarning}}{{/if}}
+{{#if FieldWarning}}
+    {{FieldWarning}}{{#newline}}
+{{/if}}
     static const int FIELD__{{Name}} = {{ReferenceIndex}};{{#newline}}
 {{/each}}
 {{#if InstanceFields}}{{#newline}}{{/if}}

MetadataProcessor.Shared/nanoSkeletonGenerator.cs

@@ -12,6 +12,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Text;
+using System.Text.RegularExpressions;
 
 namespace nanoFramework.Tools.MetadataProcessor.Core
 {
@@ -465,27 +466,27 @@ private void GenerateAssemblyHeader()
                     fieldCount = 0;
                     foreach (var f in c.Fields.Where(f => !f.IsStatic && !f.IsLiteral))
                     {
-                        // sanity check for field name
-                        // like auto-vars and such
-                        if (f.Name.IndexOfAny(new char[] { '<', '>' }) > 0)
+                        // rename auto-properties backing field to a valid C++ identifier
+                        string fixedFieldName = string.Empty;
+                        string fieldWarning = string.Empty;
+
+                        if (Regex.IsMatch(f.Name, @"<\w+>k__BackingField"))
                         {
-                            classData.InstanceFields.Add(new InstanceField()
-                            {
-                                FieldWarning = $"*** Something wrong with field '{f.Name}'. Possibly its backing field is missing (mandatory for nanoFramework).\n"
-                            });
+                            fixedFieldName = $"{f.Name.Replace("<", "").Replace(">", "_")}";
+                            fieldWarning = $"// auto-property backing field renamed to '{fixedFieldName}'";
                         }
-                        else
+
+                        if (_tablesContext.FieldsTable.TryGetFieldReferenceId(f, false, out ushort fieldRefId))
                         {
-                            if (_tablesContext.FieldsTable.TryGetFieldReferenceId(f, false, out ushort fieldRefId))
+                            classData.InstanceFields.Add(new InstanceField()
                             {
-                                classData.InstanceFields.Add(new InstanceField()
-                                {
-                                    Name = f.Name,
-                                    ReferenceIndex = firstInstanceFieldId++
-                                });
-                            }
-                            fieldCount++;
+                                Name = string.IsNullOrEmpty(fixedFieldName) ? f.Name : fixedFieldName,
+                                ReferenceIndex = firstInstanceFieldId++,
+                                FieldWarning = fieldWarning
+                            });
                         }
+
+                        fieldCount++;
                     }
 
                     // methods