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Re: gcc bug?

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On Sun, 22 May 2011 07:08:35 +0000, Jorgen Grahn wrote:

> On Sun, 2011-05-22, Balog Pal wrote:
>> "Ruben Safir" <ruben@mrbrklyn.com>
>>> I've been working with gcc 4.6 with C++ doing some templates exercises
>>>
>>> I seem to have some unexplained behavior which might be a bug, or
>>> maybe I'm ignorant.
>>
>> maybe. first run your code in valgrind and look if it points out the
>> corruption.
> 
> I get "75060 errors from 34 contexts" when I run the "del2" test, and
> they start appearing long before the crash.  Most seem to be about
> accessing freed memory. I see no reason to suspect a compiler bug. (I
> used gcc 4.4; there is no use of experimental C++0x features in the
> code.)
> 
> /Jorgen

ruben@www2:~/cplus/link_list_template_mysql> g++ -Wall -ggdb test_del2.cpp -o test_del2
ruben@www2:~/cplus/link_list_template_mysql> 

compiles cleanly

I'm seeing a behavior I never saw before, though in the template

I have this class method in the template

   template < class T >
      void List<T>::find_value(T val)
      {
	 cursor() = front();
	 while(cursor() != endd()){
	    if (*(cursor()->value()) == val)
	       return;
	    else{
	       cursor(cursor()->next());
	    }
	 }
	 if(*(endd()->value()) == val)
	    return;
	 else{
	    cursor() = 0; //park the cursor when nothing is found
	 }
      }


I'm calling it from this snippit of code



   template<typename T>
      float mean_list(chainlist::List< chainlist::List<stats::Distribution<T> >*  > *  tallies, T search_val){
	 if(tallies->endd() == 0){
	    std::cout << "Empty List" << std::endl;
	    return 0.0;
	 }
	 int sum = 0;
	 chainlist::List<stats::Distribution<T> > * dump;
	 tallies->cursor() = tallies->front();
	 while(tallies->cursor() != tallies->endd() ){
		 //tallies->cursor()->value()->find_value(search_val);
		 dump = *(tallies->cursor()->value());
		 dump->find_value(search_val);
		 sum +=  dump->cursor()->value()->population();
	 }
	 dump = *(tallies->cursor()->value());
	 dump->find_value(search_val);
	 sum +=  dump->cursor()->value()->population();
	 return sum/(tallies->size());

      }

that makes dump according to gdb a type of

(gdb) ptype dump
type = class chainlist::List<stats::Distribution<int> > 

with a public member function 
void find_value(stats::Distribution<int>);

all of which I expected.  What I don't expect is that when I call from main

 std::cout << "The standard mean for picking 7 is ==> " << stats::mean_list(tallies, 7 );

then T has to be defined as a integer, and the param 7 is being promoted and calling the Distribution object constructor.

.
Ruben

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Thread

gcc bug? Ruben Safir <ruben@mrbrklyn.com> - 2011-05-22 01:32 +0000
  Re: gcc bug? "Balog Pal" <pasa@lib.hu> - 2011-05-22 04:34 +0200
    Re: gcc bug? Ruben Safir <ruben@mrbrklyn.com> - 2011-05-22 04:13 +0000
      Re: gcc bug? Ian Collins <ian-news@hotmail.com> - 2011-05-22 16:16 +1200
    Re: gcc bug? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-22 07:08 +0000
      Re: gcc bug? Ruben Safir <ruben@mrbrklyn.com> - 2011-05-22 11:35 +0000
        Re: gcc bug? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-05-22 13:00 +0000
          Re: gcc bug? Ruben Safir <ruben@mrbrklyn.com> - 2011-05-22 14:27 +0000

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