Dear Matthias Klose, you wrote:
> Package: bobcat
> Version: 2.10.01-2
> Severity: normal
> User: ubuntu-de...@lists.ubuntu.com
> Usertags: origin-ubuntu natty
> User: debian-...@lists.debian.org
> Usertags: ld-as-needed
>
> with ld --as-needed fails to build with:
>
> gcc -shared -Wl,-z,def,-soname,libbobcat.so.2 -lmilter
> -L/usr/lib/libmilter -lX11 -lssl -lreadline -o
> tmp/lib/libbobcat.so.2.10.02 */os/*.o
>
> ^^^ the mistake is that shared libraries are placed before the
> object files on the command line.
>
> chmod -x libbobcat.so.2.10.02
> ln -sf libbobcat.so.2.10.02 libbobcat.so.2
> ln -sf libbobcat.so.2 libbobcat.so
> ./build lcgen
>
> and the fails later with ...
>
> g++ --std=c++0x -isystem tmp -o tmp/bin/bobcatlcgen lc/lcgen/main.cc
> lc/lcgen/o/* -lbobcat -Ltmp/lib/
> tmp/lib//libbobcat.so: undefined reference to `OpenSSL_add_all_digests'
> tmp/lib//libbobcat.so: undefined reference to `history_length'
> tmp/lib//libbobcat.so: undefined reference to `BN_init'
> tmp/lib//libbobcat.so: undefined reference to `BN_num_bits'
> tmp/lib//libbobcat.so: undefined reference to `BN_exp'
> [...]
>
> attached is what I would suspect would fix the problem but it
> doesn't. any further ideas?
I'm not sure why you're using ld --as-needed. When I add -Xlinker --as-needed
to the library construction phase lcgen indeed fails to link. When adding the
libraries defining the missing entries (e.g., -lssl) to the lcgen link command
the lcgen program links fine:
g++ --std=c++0x -isystem tmp -o tmp/bin/bobcatlcgen lc/lcgen/main.cc
lc/lcgen/o/* -lssl -lbobcat -Ltmp/lib/
I guess you will experience the same problem with other programs depending on
bobcat.
I don't know why linking against ssl is required: lcgen doesn't use the ssl
lib, and objdump processing the generated lcgen program doesn't show any ssl
references. But it does want to link against, e.g., libreadline, libX11 and
libssl, which are required by bobcat. Something to figure out.... What you
want/would expect is that bobcat's additional libraries are only needed if
there are external references to code from those libraries. Which isn't the
case with lcgen.
So, in short:
- if don't know why you want to use --as-needed, if you don't use it the
linking proceeds fine, and although the executable doesn't need symbols from
these libraries the executable links against the dynamic libs required by
bobcat.
- right now I have no other solution but to avoid --as-needed. I'll keep
your problem in mind and if/when I have a solution I'll let you know.
Thanks for bringing this problem to my attention. Once I have a solution
(other than: don't use --as-needed) I'll let you know.
--
Frank B. Brokken
Center for Information Technology, University of Groningen
(+31) 50 363 9281
Public PGP key: http://pgp.surfnet.nl
Key Fingerprint: DF32 13DE B156 7732 E65E 3B4D 7DB2 A8BE EAE4 D8AA
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