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

[Jonathan Watt]

Claudio Bley wrote:
> 
> But, I just found out that you may just use 'make DESTDIR=path-to-rootdir
> install' as mentioned at http://gcc.gnu.org/install/finalinstall.html to
> have it install (temporarily) to a different location. 

I did read that bit, but seeing as I wasn't sure what a "temporary 
staging area" or "chroot jail" are, or how I could use them, I didn't 
try to use DESTDIR.

>>>The include directories are basically the same for both compilers except 
>>>for
>>>the libstdc++ headers. You should not have to specify any option to gcc in
>>>order to let it find its specific headers or libraries. 

Why is it different for libstdc++ headers?

>>So gcc 2.96 uses /usr/local/include too? That doesn't seem to be the 
>>case on my computer. How do the compilors tell which are their 
>>(standard) headers and libraries? A file naming convention? I'm just 
>>curious.
> 
> 
> Yes, gcc 2.96 should search /usr/local/include too because it's a standard
> system include directory. Generally, the /usr/local hierarchy is for use by
> the system administrator when installing software locally.

By 'use' I meant does it add files to this directory when installed. :) 
I guess it doesn't as I don't see any.

> Try 'cat /dev/null | gcc -v -E -':
> 
> ...]
> #include "..." search starts here:
> #include <...> search starts here:
> /usr/local/include
> /usr/lib/gcc-lib/i486-linux/3.3.3/include
> /usr/include
> [...]

What is this doing? What should it tell me? I accidentally messed up the 
build I made before I could test it (I will try again tomorrow once the 
new build is done), but from the manual I see that it should output "the 
commands executed to run the stages of compilation" and "stop after the 
preprocessing stage". I guess the trailing '-' means that there are no 
input files.

> GCC itself does not supply many headers and libraries. Instead it uses the C
> standard library of the system and other headers/libraries installed in the
> standard locations (/usr/{include,lib} and /usr/local/{include,lib}) by
> default.

Hmm. I didn't realise that. This could cause problems as my whole reason 
for wanting a more up-to-date version of gcc was that the existing one 
couldn't compile the C++ code I am working on. I kept getting error 
messages about certain aspects of the standard library not existing (it 
works using gcc 3.2 on a Mandrake 8.2 box).

Can I add a more up-to-date version of the standard C++ library to gcc 
if I install gcc under my $HOME directory? Which version normally goes 
with gcc 3.2.3? Can anyone tell me how I would get my install of gcc to 
use this library automatically?

> Have a look at http://gcc.gnu.org/install/finalinstall.html which gives a
> good overview where the various files are to be installed.
> 
> Cheers.

Thanks Claudio!

Jonathan