<incomplete type> in a C++ program compiled with gcc 4.0.1

<incomplete type> in a C++ program compiled with gcc 4.0.1

[Raúl Huertas]

Hi all!

This is my first post to this mail list, and I'm not sure if it is the 
correct one. In case I'm wrong, can you please tell me wich mail list is 
the correct one?

I have this C++ program:

------------------------------------------
/*
 g++ -g -o tgdb tgdb.cc -lstdc++
*/
#include <sstream>
#include <iostream>

int main()
{
    std::stringstream a_example("I want to see this in gdb!");
    std::cout <<  a_example.str() << std::endl;
}
------------------------------------------

The program works as expected, but when I run it in GDB setting a 
breakpoint in the "cout" line, I cannot print the content of "a_example".
Here is the output of gdb:

(gdb) p a_example
$1 = <incomplete type>

(gdb) what a_example
type = stringstream

(gdb) ptype a_example
type = struct 
std::basic_stringstream<char,std::char_traits<char>,std::allocator<char> > {
    <incomplete type>
}


My gcc is:
$ g++ -v
Using built-in specs.
Target: i586-mandriva-linux-gnu
Configured with: ../configure --prefix=/usr --libexecdir=/usr/lib 
--with-slibdir=/lib --mandir=/usr/share/man --infodir=/usr/share/info 
--enable-shared --enable-threads=posix --disable-checking 
--enable-languages=c,c++,ada,f95,objc,java 
--host=i586-mandriva-linux-gnu --with-system-zlib --enable-long-long 
--enable-__cxa_atexit --enable-clocale=gnu 
--disable-libunwind-exceptions --enable-java-awt=gtk 
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre 
--enable-gtk-cairo --disable-libjava-multilib
Thread model: posix
gcc version 4.0.1 (4.0.1-5mdk for Mandriva Linux release 2006.0)

And my gdb is:
$ gdb -v
GNU gdb 6.3-5mdk (Mandriva Linux release 2006.0)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain 
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i586-mandriva-linux-gnu".

As you can see, I have used "g++ -g -o tgdb tgdb.cc -lstdc++" to compile 
the program.

Am I doing something wrong?
Why can't I see the contents of "a_example"?

Here (http://tinyurl.com/ynzagc) I have found a similar problem, but I 
really don't understand the way it is resolved.

Any ideas will be much appreciated.

Thank you very much,
Raúl.

Re: <incomplete type> in a C++ program compiled with gcc 4.0.1

[Daniel Jacobowitz]

On Fri, Nov 10, 2006 at 08:06:45PM +0100, Raúl Huertas wrote:
> This is my first post to this mail list, and I'm not sure if it is the 
> correct one. In case I'm wrong, can you please tell me wich mail list is 
> the correct one?

This one is fine.

> The program works as expected, but when I run it in GDB setting a 
> breakpoint in the "cout" line, I cannot print the content of "a_example".
> Here is the output of gdb:
> 
> (gdb) p a_example
> $1 = <incomplete type>

Unfortunately this is a GCC problem - I am not sure whether to call it
a bug or not.  This might work if you had a debugging build of
libstdc++, but debug information about some classes is only emitted
with their key methods.  You'll have to report this to the GCC
developers, probably via bugzilla.

-- 
Daniel Jacobowitz
CodeSourcery

Re: <incomplete type> in a C++ program compiled with gcc 4.0.1

[Raúl Huertas]

Daniel Jacobowitz escribió:
> (gdb) p a_example
>> $1 = <incomplete type>
>>     
>
> Unfortunately this is a GCC problem - I am not sure whether to call it
> a bug or not.  This might work if you had a debugging build of
> libstdc++, but debug information about some classes is only emitted
> with their key methods.  You'll have to report this to the GCC
> developers, probably via bugzilla.
>   
Oh, I see. Thanks a lot. ;)