Re: Can't install gcc 3.2 alongside gcc 2.96 on Red Hat 7.3

[Jonathan Watt <jonathan dot watt at strath dot ac dot uk>]

lrtaylor@micron.com wrote:
> Jonathan,
>
> GCC supplies its own set of C++ header files along with its own C++
> library, which is why the directory is different for those headers.  The
> C++ library is fairly tightly coupled with GCC, so you probable wouldn't
> want to try to upgrade that.  An alternative would be to use STLport,
> which you might be able to use with the old compiler, but that's fraught
> with difficulties as well, so I'm not sure I would recommend that path,
> except under certain circumstances.
>
> The second comment below that you are concerned about should not concern
> you.  Basically, the C library and headers come with the system.  The
> C++ library and headers come with the compiler.  Problems you are having
> compiling C++ code will have little to nothing to do with the C library
> headers and much more to do with the C++ headers and the compiler's
> level of C++ compliance.
>
> In short, if it compiles on another system with the version of GCC that
> you are trying to install, it will very likely compile with the one you
> are trying to install.
>
> There are, however, a few caveats that you will need to be aware of.
> C++ libraries compiled with the old GCC will not be compatible with
> libraries or programs compiled with the new GCC.  This means that if
> your programs rely on C++ libraries that are installed with the system,
> you will not be able to use the ones that are installed.  Rather, you
> will have to build your own copy of them with the new compiler and place
> them in an appropriate location.  If you're just doing basic C++
> programming (that is, not relying on other C++ libraries), you shouldn't
> have any problems.
>
> (C libraries, however, are no problem.  They should generally work fine
> regardless of which compiler you built them with.)
>
> In addition, C++ program compiled with your new compiler will be
> dependent on the C++ library and other GCC libraries that come with the
> new GCC.  You will need to do one of three things in order for your
> programs to run:
>
> 1) Embed the path to the libraries into your libraries and programs that
> you build (look at the -R compiler option and -rpath linker option).
> 2) Place copies of the libraries in one of the directories that your
> system looks in by default (or add the directory to your system's
> default search path) - not recommended, by the way.
> 3) Set LD_LIBRARY_PATH to point to the location that GCC's libraries are
> installed in before running your programs.

I can't find the -R comiler and -rpath linker options. I searched the 
option summary page for gcc 3.2.3:

http://gcc.gnu.org/onlinedocs/gcc-3.2.3/gcc/Option-Summary.html

I also searched the same page for gcc 3.3.2 just in case they were new. 
I did notice the -static-libgcc option though, but I don't think I can 
use it since I need to be able to handle exceptions thrown by the 
standard C++ (and another) library.

> I would recommend either 1 or 3, and prefer 1.  And, if you plan on
> installing the programs built with the new compiler onto the system,
> you'll want to put a copy of the libraries that come with GCC into a
> directory other than your home directory.
>
> If you don't do one of those things, your program will compile fine, but
> probably won't run, because it will complain that it can't find
> libstdc++.so.5 or something like that.
>
> Basically, you can easily install and use another compiler than the
> system default, but it will take a little bit of work - or at least
> forethought - to get it to work well, depending on how you intend to use
> it and the programs or libraries that you build with it.
>
> Make sense?
>
> Cheers,
> Lyle

Thanks for taking the time to write all the above, that has cleared up 
some of the mystery of how things work.

I installed gcc 3.2.3 into my home directory /home/jwatt and tried to 
build my program. Unfortunately certain things are causing problems. 
First of all including <ostream> and <limits> doesn't seem to work 
despite files by these names existing in 
/home/jwatt/gcc/include/c++/3.2.3 and gcc -v says that, that directory 
is the first directory searched. Another issue is that I am being told 
that std::left is not declared whereas compiling with gcc 3.2 on my 
other machine it was fine.

To test that gcc would be able to find its libraries I created a small 
C++ test file called test.cpp with the following content.

#include <iostream>

int main()
{
  char buf[255];
  std::cout << "enter a value: ";
  std::cin >> buf;  // I know, just build testing
  std::cout << "you entered: " << buf << std::endl;
  return 0;
}

using 'gcc test.cpp' causes errors at the linking stage, the first being 
"undefined reference to 'std::cout'".

Has anyone any ideas as to what might be causing these problems?

Thanks again Lyle,

Jonathan