Re: LIBRARY_PATH not used before /usr/lib anymore in gcc 4.2 and later?

[Andrew Haley <aph at redhat dot com>]

Frederik wrote:
> I've got different versions of the boost libraries installed on my 
> system: one is installed system wide in /usr/lib64, while other versions 
> are installed in /cvos/shared/apps/boost/gcc-4.[123]/1.35.0, compiled 
> with the respective different versions of gcc.
> 
> When I want to use one of the custom built libraries, I set the CPATH, 
> LIBRARY_PATH and LD_LIBRARY_PATH variables to the respective include 
> files and libraries.
> 
> For the gcc 4.1 one, this works correctly:
> $ g++ -o test test.cpp -lboost_regex
> $ ldd test | grep boost
>         libboost_regex.so.1.35.0 => /cvos/shared/apps/boost/
> gcc-4.1/1.35.0/lib/libboost_regex.so.1.35.0 (0x00007f2352ad1000)
> 
> And without the environment vars set, it links against the one in /usr/
> lib64:
>         libboost_regex.so.2 => /usr/lib64/libboost_regex.so.2 
> (0x00007fb000918000)

What does readelf -d test say?

> However when I do exactly the same with gcc 4.2 and gcc 4.3, it always 
> links against the libboost_regex.so.2 on in /usr/lib64 and not against 
> the libboost_regex.so.1.35.0 in /cvos/shared/apps/boost/gcc-4.[23]/1.35.0/
> lib, even though the LIBRARY_PATH and LD_LIBRARY_PATH variables have this 
> directory set as first.
> 
> The versions used are gcc 4.1.2 20070626 (Red Hat 4.1.2-14), stock gcc 
> 4.2.4 and stock gcc 4.3.1.
> 
> Has this behaviour changed in gcc 4.2, or is it something RH specific 
> which makes that it works with my gcc 4.1?

This is nothing to do with gcc: it's controlled by the shared library
loader /lib/ld-linux.so, which is part of glibc.

Andrew.