bolt-gen: for wire messages, print out optional fields (if present)

optional fields should be printed, if they exist. so let's print them!

tools/gen/print_impl_template

@@ -33,6 +33,11 @@ void print${options.enum_name}_message(const u8 *msg)
 ## definition for printing field sets
 <%def name="print_fieldset(fields, nested, cursor, plen)">
 % for f in fields:
+    % if f.is_extension():
+	if (plen <= 0)
+		return;
+	printf("(${','.join(f.extension_names)}):");
+    % endif
     % if f.len_field_of:
 	${f.type_obj.type_name()} ${f.name} = fromwire_${f.type_obj.name}(${cursor}, ${plen});${truncate_check(nested)} <% continue %> \
     % endif	

tools/generate-bolts.py

@@ -38,7 +38,7 @@ def next_line(args, lines):
 
 # Class definitions, to keep things classy
 class Field(object):
-    def __init__(self, name, type_obj, extension=False,
+    def __init__(self, name, type_obj, extensions=[],
                  field_comments=[], optional=False):
         self.name = name
         self.type_obj = type_obj
@@ -46,7 +46,7 @@ class Field(object):
         self.len_field_of = None
         self.len_field = None
 
-        self.is_extension = extension
+        self.extension_names = extensions
         self.is_optional = optional
         self.field_comments = field_comments
 
@@ -79,7 +79,7 @@ class Field(object):
         return self.is_optional
 
     def is_extension(self):
-        return self.is_extension
+        return bool(self.extension_names)
 
     def size(self):
         if self.count:
@@ -119,15 +119,11 @@ class Field(object):
 class FieldSet(object):
     def __init__(self):
         self.fields = OrderedDict()
-        self.extension_fields = False
         self.len_fields = {}
 
     def add_data_field(self, field_name, type_obj, count=1,
-                       is_extension=[], comments=[], optional=False):
-        if is_extension:
-            self.extension_fields = True
-
-        field = Field(field_name, type_obj, extension=bool(is_extension),
+                       extensions=[], comments=[], optional=False):
+        field = Field(field_name, type_obj, extensions=extensions,
                       field_comments=comments, optional=optional)
         if bool(count):
             try:
@@ -248,9 +244,10 @@ class Type(FieldSet):
         return name, False
 
     def add_data_field(self, field_name, type_obj, count=1,
-                       is_extension=[], comments=[], optional=False):
+                       extensions=[], comments=[], optional=False):
         FieldSet.add_data_field(self, field_name, type_obj, count,
-                                is_extension, comments=comments, optional=optional)
+                                extensions=extensions,
+                                comments=comments, optional=optional)
         if type_obj.name not in self.depends_on:
             self.depends_on[type_obj.name] = type_obj
 
@@ -459,7 +456,13 @@ class Master(object):
         subtypes = self.get_ordered_subtypes()
         stuff['structs'] = subtypes + self.tlv_messages()
         stuff['tlvs'] = self.tlvs
-        stuff['messages'] = list(self.messages.values()) + list(self.extension_msgs.values())
+
+        # We leave out extension messages in the printing pages. Any extension
+        # fields will get printed under the 'original' message, if present
+        if options.print_wire:
+            stuff['messages'] = list(self.messages.values())
+        else:
+            stuff['messages'] = list(self.messages.values()) + list(self.extension_msgs.values())
         stuff['subtypes'] = subtypes
 
         print(template.render(**stuff), file=output)
@@ -550,6 +553,9 @@ def main(options, args=None, output=sys.stdout, lines=None):
                 #   we'll refer to 'optional' message fields as 'extensions')
                 #
                 if bool(tokens[5:]):  # is an extension field
+                    if optional:
+                        raise ValueError("Extension fields cannot be optional. {}:{}"
+                                         .format(ln, line))
                     extension_name = "{}_{}".format(tokens[1], tokens[5])
                     orig_msg = msg
                     msg = master.find_message(extension_name)
@@ -558,6 +564,13 @@ def main(options, args=None, output=sys.stdout, lines=None):
                         msg.enumname = msg.name
                         msg.name = extension_name
                         master.add_extension_msg(msg.name, msg)
+                    # If this is a print_wire page, add the extension fields to the
+                    # original message, so we can print them if present.
+                    if options.print_wire:
+                        orig_msg.add_data_field(tokens[2], type_obj, count=count,
+                                                extensions=tokens[5:],
+                                                comments=list(comment_set),
+                                                optional=optional)
 
                 if collapse:
                     count = 1

tools/test/test_cases

@@ -43,6 +43,7 @@ msgdata,test_msg,test_sbt_varlen_varsize,subtype_varlen_varsize,
 msgdata,test_msg,test_sbt_arrays,subtype_arrays,
 # test extension fields
 msgdata,test_msg,extension_1,test_features,,option_short_id
+msgdata,test_msg,extension_2,test_short_id,,option_one,option_two
 
 msgtype,test_tlv1,2
 msgdata,test_tlv1,test_struct,test_short_id,