On 2011-12-31 14:00:04 -0600, Jonathan Nieder wrote:
> Vincent Lefevre wrote:
>
> > At runtime? Do you mean that one needs to change the library path
> > also for running the generated executable?
>
> Yes, gcc-snapshot includes a snapshot of libgcc (and libstdc++,
> libgcj, libobjc, etc). So checking those libraries' behavior involves
> modifying the library path at runtime.
OK, I thought that the static version was used in such a case, but
I've now seen that the gcc doc (under -static-libgcc) says that it
is not always possible (in particular for C++ and Java).
Alternatively, couldn't /usr/lib/gcc-snapshot/lib be added to the
run path instead of having to use LD_LIBRARY_PATH? For instance,
having
export LD_RUN_PATH=/usr/lib/gcc-snapshot/lib
in the gcc-snapshot wrapper seems to work (I've done tests with mksh).
Without this run path setting:
$ ldd mksh
linux-vdso.so.1 => (0x00007fff829ff000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f159516a000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1
(0x00007f1594f54000)
/lib64/ld-linux-x86-64.so.2 (0x00007f159550d000)
With this setting:
$ ldd mksh
linux-vdso.so.1 => (0x00007fff69fff000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f85a6818000)
libgcc_s.so.1 => /usr/lib/gcc-snapshot/lib/libgcc_s.so.1
(0x00007f85a6603000)
/lib64/ld-linux-x86-64.so.2 (0x00007f85a6bbb000)
without modifying LD_LIBRARY_PATH.
> From time to time the ABI can be bumped, which means the dependencies
> of generated executables need not always be satisfied by the ordinary
> copies of those libraries in /lib.
I also suppose that there may be incompatilibities if the software
compiled with gcc-snapshot is linked against libraries compiled with
normal GCC versions (if they both use libgcc).
> > The README.Debian file
> > doesn't say anything like that. According to the README.Debian
> > file, the wrapper is just what we need.
>
> Good catch, thanks. Can you suggest an improved wording?
Let's first see what you think about the run path...
--
Vincent Lefèvre <vinc...@vinc17.net> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / Arénaire project (LIP, ENS-Lyon)
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