Link problems

Link problems

[Jarmo]

Hi,

I am developping application called MathPlanner. It is created with gcc 2.96 
and is working ok. Same days ago I installed gcc 3.0.4 from my linux 
distribution disk. MathPlanner compiles with no errors or warnings. But it is 
unable to link.   It does not find symbols from shared library libqt-mt.

lot of these  "undefined reference to QObject::"  

Do I have to rebuild every depending library with gcc 3.0.4 or what is wrong ?


Best regards,
Jarmo

Re: Link problems

[bjorn rohde jensen]

Hi Jarmo,

 You can not in general crosslink object code generated by
different compilers. You should use one and only one
compiler to create an application. One does usually not
have to rebuild the system C libraries, but C++ libs etc
definitely should be.
 The unresolved symbols are probably due to different
name mangling schemes employed by gcc-2.96, which is not
actually an official gcc release, and gcc-3.0.4. This is
done to protect users from linking incompatible object
files to create applications with spectacularly odd behaviour,
such as random core dumps despite code correctness and so on.

Yours sincerely,

Bjorn

Re: Link problems

[Oscar Fuentes]

bjorn rohde jensen <bjensen@fastmail.fm> writes:

> Hi Jarmo,
> 
>  You can not in general crosslink object code generated by
> different compilers. You should use one and only one
> compiler to create an application. One does usually not
> have to rebuild the system C libraries, but C++ libs etc
> definitely should be.
>  The unresolved symbols are probably due to different
> name mangling schemes employed by gcc-2.96, which is not
> actually an official gcc release, and gcc-3.0.4. This is
> done to protect users from linking incompatible object
> files to create applications with spectacularly odd behaviour,
> such as random core dumps despite code correctness and so on.

Actually, that incompatibility among gcc 2.9x and gcc 3.x comes from
the introduction of a new "standard" C++ ABI on the gcc 3.x
series. One of the main goals of the new ABI is to allow the
interchange of object code among different C++ compilers which use
said ABI.

-- 
Oscar

Re: Link problems

[bjorn rohde jensen]

Hi Oscar,

 Well, i did say generally. Object file compatibility
does fall outside the C++ specs to my limited knowledge,
it is a gcc extension. One has to be carefull about this
sort of thing though, try searching gcc.gnu.org for info
on the ABI, things are far from compatible at the moment.

Yours sincerely,

Bjorn