Frederik Himpe wrote: > On Wed, 11 Jun 2008 16:01:07 +0100, Andrew Haley wrote: > >> Frederik wrote: >>> On Wed, 11 Jun 2008 14:55:54 +0100, Andrew Haley wrote: >>> >>>> Frederik wrote: >>>>> On Wed, 11 Jun 2008 13:46:45 +0100, Andrew Haley wrote: >>>>> >>>>>> What does readelf -d test say? >>>>> $ echo $LIBRARY_PATH >>>>> /cvos/shared/apps/gcc/gcc-4.2.4//lib:/cvos/shared/apps/boost/ > gcc-4.2/1.35.0/lib >>>> I'm not sure this will have any effect. >>> Isn't the above necessary so that it searches for the libboost_regex.so >>> link in that directory, which would make it build at compile time >>> against libboost.so.1.35.0 in my case? (Well, that's what I expected, > >>>>> $ echo $LD_LIBRARY_PATH >>>>> /cvos/shared/apps/gcc/gcc-4.2.4//lib:/cvos/shared/apps/boost/ >>> gcc-4.2/1.35.0/lib:/cvos/shared/apps/sge/6.1/lib/lx26-amd64 >>> >>>> This should work, though. >>>>> $ g++ -o test test.cpp -lboost_regex >>>> Use `gcc -v' here. Let's see what that says. >> OK, here's the important part. These are the directories that the >> linker searches first: >> >> -L/cvos/shared/apps/gcc/gcc-4.2.4//lib/../lib64 \ >> -L/cvos/shared/apps/gcc/gcc-4.2.4/lib/gcc/x86_64-unknown-linux-gnu/4.2.4 >> \ >> -L/cvos/shared/apps/gcc/gcc-4.2.4/lib/gcc/x86_64-unknown-linux- > gnu/4.2.4/../../../../lib64 >> \ -L/lib/../lib64 \ >> -L/usr/lib/../lib64 \ >> -L/cvos/shared/apps/gcc/gcc-4.2.4//lib \ >> -L/cvos/shared/apps/boost/gcc-4.2/1.35.0/lib \ >> -L/cvos/shared/apps/gcc/gcc-4.2.4/lib/gcc/x86_64-unknown-linux- > gnu/4.2.4/../../.. >> \ >> >> Only if libboost_regex is not found in one of these will ld use >> `LD_LIBRARY_PATH'. > > AFAIK, you are talking here about runtime linking, Certainly not, no. It's up to you; you can either accept my advice or ignore me. However, the system is doing what I expect: it searches the -L paths first *at link time* and then uses LD_LIBRARY_PATH, also at link time. I even appended the ld documentation to my earlier mail. > while my problem is > during building already: it builds against a different soname: Yes, just as I'd expect. If you do gcc -v with gcc 4.1 you'll notice that its default library directories includes the one that contains libboost_regex.so.1 > $ objdump -x /cvos/shared/apps/boost/gcc-4.2/1.35.0/lib/libboost_regex.so > | grep SONAME > SONAME libboost_regex.so.1.35.0 > $ objdump -x /usr/lib64/libboost_regex.so | grep SONAME > SONAME libboost_regex.so.2 > > Also when using LD_LIBRARY_PATH for runtime linking, it does look first in > these directories before looking into /usr/lib64. gcc 4.1 clearly does the > same at build time with LIBRARY_PATH, but not my self compiled gcc 4.2 and > 4.3. > >> If you want to make sure that your libboost_regex is >> used, either put it in one of these directories or specify -L >> explicitly. > > That's indeed a workaround. Still I don't understand why I would need this > for gcc 4.2 and 4.3, but not for gcc 4.1. It's because you have put the Boost library in gcc 4.1's own library directory. gcc 4.1 will search that directory before any paths in environment variables. Andrew.
