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Conference turris::decladebug

Title:	Digital Ladebug debugger

Moderator:	TLE::LUCIA

Created:	Fri Feb 28 1992
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	969
Total number of notes:	3959

937.0. "Cannot view data members intuitively while in member function" by CXXC::MJHANS (Matthew Hanselman, DEC C/C++) Mon Apr 28 1997 16:27

    Using dxladebug 4.0-35 and DEC C++ V5.5-004
    
    Here is an example where you cannot view a class' data members, as
    ladebug will give you an "not in current scope" messsage.  Note that
    you can view the data members if you reference off the "this" pointer. 
    Also note the problem goes away if you don't have the include file
    (i.e. have the class declaration in tmp.cxx).
    
    							- Matt
    // tmp.hxx
    class C {
      char *data;
    public:
      C();
    };
    -------------------------------
    // tmp.cxx
    #include "tmp.hxx"
    
    C::C()
    {
      data = "test";
      return;
    }
    
    main()
    {
      C c;
    }
    -------------------------------
    % ladebug a.out 
    Welcome to the Ladebug Debugger Version 4.0-35
    ------------------ 
    object file name: a.out 
    Reading symbolic information ...done
    (ladebug) stop in C::C
    [#1: stop in C::C(void) ]
    (ladebug) run
    [1] stopped at [C::C(void):6 0x12000214c]
          6   data = "test";
    (ladebug) p data
    Symbol data not visible in current scope.
    Error: no value for data
    (ladebug) p this->data
    0x0
    (ladebug) quit

T.R	Title	User	Personal Name	Date	Lines
937.1		TLE::LUCIA	http://asaab.zko.dec.com/~lucia/biography.html	`Mon Apr 28 1997 16:43`	2
	This sounds remarkably like an untriggered class...
937.2		CXXC::MJHANS	Matthew Hanselman, DEC C/C++	`Mon Apr 28 1997 16:52`	31
	I reproduced the problem on V5.5, to make sure it wasn't a compiler regression. Note the output below; ladebug seems to know about everything about the class. - Matt Welcome to the Ladebug Debugger Version 4.0-35 ------------------ object file name: a.out Reading symbolic information ...done (ladebug) stop in C::C [#1: stop in C::C(void) ] (ladebug) run [1] stopped at [C::C(void):6 0x12000214c] 6 data = "test"; (ladebug) p data Symbol data not visible in current scope. Error: no value for data (ladebug) whatis C class C { char* data; C(void); } (ladebug) whatis this C* const this (ladebug) whereis C "tmp.hxx"`C "tmp.hxx"`C "tmp.hxx"`C.C "tmp.hxx"`C.C "tmp.cxx"`C
937.3	Use of 'this' is tell-tale factor	TLE::MERRITT	Steve Merritt, Ladebug Team	`Tue Apr 29 1997 09:35`	8
	From .0, if you can say 'this->foo' then the class has to have been triggered (as .2 shows). I will take a look at this bug. In regards to .1, Tim implies (and rightly so) that we are experiencing more untriggered classes than we should. This needs to be researched. -Steve
937.4	Fixed in 4.0-36	TLE::MERRITT	Steve Merritt, Ladebug Team	`Tue Apr 29 1997 10:54`	25
	I tried this out and its already been fixed. We hit this problem shortly after 4.0-35 went out. The fix for this is in 4.0-36. Welcome to the Ladebug Debugger Version 4.0-36 ------------------ object file name: tmp Reading symbolic information ...done (ladebug) stop in C::C [#1: stop in C::C(void) ] (ladebug) run [1] stopped at [C::C(void):6 0x1200022dc] 6 data = "test"; (ladebug) p data 0x1000 (ladebug) p this->data 0x1000 (ladebug) next stopped at [C::C(void):7 0x1200022e4] 7 return; (ladebug) p data 0x120001cd0="test" (ladebug) p this->data 0x120001cd0="test" (ladebug) quit