How to match comment at the end of a line?

[ououmania]

I have been struglling for the whole day to parse comments. The basic syntax is the following:
COMMENT = { "//" ~ (!"\n" ~ ANY)* | "/" ~ (!"/" ~ ANY)* ~ "*/" }
// C/C++ field
struct_field = { type_ ~ name ~ ("=" ~ expression) ? ~ ";" ~ DUMMY_RULE? }

But I came accross two problems and don't know how to solve them:

1. Without DUMMY_RULE, the "struct_field" rule does not get the comment in its inner pairs. The comment go to the struct rule instead.
2. With DUMMY_RULE, "struct_field" captures comment on the following line too.

Is there are an easy way to avoid the two problems? Any help is appreciated.

[jbmwdzg]

@ououmania How did you define the WHITESPACE rule? if it does include the NEWLINE
then, try this
singleline_comment=@{"//" ~ (!"\n" ~ ANY)}
block_comment={ "/" ~ (!"/" ~ ANY)* ~ "*/"}
COMMENT={ block_comment | singleline_comment}