The D language has an alternative comment notation to those found in C(++) and
Java.  It is denoted by /+ ... +/.

Doxygen doesn't recognise this feature of D at present, leading to commented-out
entities being documented nonetheless and garbage comments within function
signatures.

An important aspect of /+ ... +/ comments is that, unlike /* ... */ comments,
they can be nested.


Steps to reproduce:
1. Copy and paste these lines into a D source file:

    void uncommentedOutFunction() {}

    /+
    void commentedOutFunction() {}
    +/

    void functionWithCommentedOutParameter(int noComment/+, char[] comment+/) {}

2. Run Doxygen.


Actual results:
Comment markers are not recognised, so documentation comes out like this:

    Functions
    void  _uncommentedOutFunction_ ()
    void  _commentedOutFunction_ ()
    void  _functionWithCommentedOutParameter_ (int noComment/+, char[] comment+/)
    ----
    Function Documentation

    void commentedOutFunction( )

    void functionWithCommentedOutParameter( int noComment/+ ,
                                            char[]comment+/
                                          )

    void uncommentedOutFunction( )


Expected results:
Stripped away the comments, leaving this

    Functions
    void  _uncommentedOutFunction_ ()
    void  _functionWithCommentedOutParameter_ (int noComment)
    ----
    Function Documentation

    void functionWithCommentedOutParameter( int noComment )

    void uncommentedOutFunction( )


An open issue is whether Doxygen should support documentation comments done like
this.  There are two options: either strip away all /+ ... +/ comments, or
support documentation comments like this /+! ... +/.  (Further, is it worth
supporting JavaDoc-like /++ ... +/ and/or /+* ... +/ as well?)  Take your pick.

For the time being (pending bug 301895) at least, C preprocessor directives
occurring within /+ ... +/ should still be processed.