Recursive output of self static contained subclass of string in gdb print command

Question

everyone,

I am using OpenFOAM and it made its own Foam::string and Foam::word type like this:

(gdb) ptype Foam::word
type = class Foam::word : public Foam::string {
  public:
    static pointer typeName;
    static int debug;
    static const Foam::word null;

  private:
    void stripInvalid(void);
  public:
    word(void);
    word(const Foam::word &);
    word(pointer, bool);
    word(pointer, size_type, bool);
    word(const Foam::string &, bool);
    word(const std::__cxx11::string &, bool);
    word(Foam::Istream &);
    static bool valid(char);
    void operator=(const Foam::word &);
    void operator=(const Foam::string &);
    void operator=(const std::__cxx11::string &);
    void operator=(pointer);
}
(gdb) ptype Foam::string
type = class Foam::string : public std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > {
  public:
    static pointer typeName;
    static int debug;
    static const Foam::string null;

    string(void);
    string(const std::__cxx11::string &);
    string(pointer);
    string(pointer, size_type);
    string(char);
    string(Foam::Istream &);
    size_type count(char) const;
    bool match(const std::__cxx11::string &) const;
    Foam::string & replace(const Foam::string &, const Foam::string &, size_type);
    Foam::string & replaceAll(const Foam::string &, const Foam::string &, size_type);
    Foam::string & expand(bool);
    bool removeRepeated(char);
    Foam::string removeRepeated(char) const;
    bool removeTrailing(char);
    Foam::string removeTrailing(char) const;
    Foam::string operator()(size_type, size_type) const;
    Foam::string operator()(size_type) const;
    static bool stripInvalid<Foam::word>(Foam::string &);
    static bool stripInvalid<Foam::fileName>(Foam::string &);
    static bool valid<Foam::word>(const Foam::string &);
    static bool valid<Foam::fileName>(const Foam::string &);
}

Now, it is possible to print Foam::string::null like this:

(gdb) p Foam::string::null
$82 = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "",
    static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}}

However, when it comes to Foam::word::null, gdb will produce infinite recursive output like this:

(gdb) p Foam::word::null
$83 = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
    static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
  static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
      static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
    static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
        static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
      static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
          static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
        static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
            static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
          static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
              static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
            static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
              static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                  static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                    static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                  static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                      static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                    static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                        static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                      static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                          static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                        static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                            static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                          static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                              static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                            static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0,
                                static null = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string", static debug = 0, static null = <same as static member of an already seen type>}},
                              static typeName = 0x7ffff4e398eb "word", static debug = 0, static null = {<Foam::string> = {<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >> = "", static typeName = 0x7ffff4e38b8a "string",

My question is:

What is wrong with this kind of c++ class structure in gdb and how to print a better result.

Thanks!

Answer 1

You could try this:

set print static-members off

This should result in a more manageable output because the recursion happens through a static member. Alternatively, you could write a Python pretty-printer for the type, but that is of course much more involved.

Answer 2

I just ran into this issue with eclipse, resulting in a silent crash of the debugging session. This really blows, and 'set print static-members off' is a workaround, but not a viable solution