python binding installation fails under cygwin

[jtmoon79]

Compiling the python binding under cygwin fails.
This may be a problem with zeromq linking to libraries. However, pyzmq brings out the problem.

$ uname -a
    CYGWIN_NT-6.1 TMOON-DEV2 1.7.9(0.237/5/3) 2011-03-29 10:10 i686 Cygwin
$ mkdir /tmp/tmp1
$ cd /tmp/tmp1
$ wget 'http://download.zeromq.org/zeromq-2.1.7.zip'
$ unzip zeromq-2.1.7.zip
$ cd zeromq-2.1.7
$ ./configure
$ make 
    ... succeeds...
$ make install
    
    ... notable output...
    libtool: install: ranlib /usr/local/lib/libzmq.a
    ----------------------------------------------------------------------
    Libraries have been installed in:
       /usr/local/lib
    
    If you ever happen to want to link against installed libraries
    in a given directory, LIBDIR, you must either use libtool, and
    specify the full pathname of the library, or use the `-LLIBDIR'
    flag during linking and do at least one of the following:
       - add LIBDIR to the `PATH' environment variable
         during execution
       - add LIBDIR to the `LD_RUN_PATH' environment variable
         during linking
       - use the `-LLIBDIR' linker flag
    
    See any operating system documentation about shared libraries for
    more information, such as the ld(1) and ld.so(8) manual pages.
    ----------------------------------------------------------------------
    ... succeeds ...
$ cd ../
$ wget --no-check-certificate 'https://github.com/downloads/zeromq/pyzmq/pyzmq-2.1.7.zip'
$ unzip pyzmq-2.1.7.zip
$ cd pyzmq-2.1.7
$ which python && python --version
    /usr/bin/python
    Python 2.6.5
$ python setup.py configure --zmq=/usr/local
    running configure
    ******************************************
    Configure: Autodetecting ZMQ settings...
        Custom ZMQ dir:       /usr/local
    cc -I/usr/local/include -Izmq/utils -Izmq/core -Izmq/devices -c detect/vers.c -o detect/vers.o
    cc detect/vers.o -L/usr/local/lib -Wl,-R/usr/local/lib -lzmq -o detect/vers.exe
    /usr/local/lib/libzmq.a(libzmq_la-zmq.o): In function `zmq_init':
    /tmp/tmp1/zeromq-2.1.7/src/zmq.cpp:280: undefined reference to `std::nothrow'
    /tmp/tmp1/zeromq-2.1.7/src/zmq.cpp:280: undefined reference to `std::nothrow'
    /usr/local/lib/libzmq.a(libzmq_la-zmq.o):zmq.cpp:(.eh_frame+0x12): undefined reference to `___gxx_personality_v0'
    /usr/local/lib/libzmq.a(libzmq_la-ctx.o): In function `_ZNSt17_Rb_tree_iteratorISt4pairIKSsN3zmq10endpoint_tEEEppEv':
    /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/stl_tree.h:182: undefined reference to `std::_Rb_tree_increment(std::_Rb_tree_node_base*)'
    /usr/lib/gcc/i686-pc-cygwin/4.3.4/include/c++/bits/stl_tree.h:182: undefined reference to `std::_Rb_tree_increment(std::_Rb_tree_node_base*)'
    /usr/local/lib/libzmq.a(libzmq_la-ctx.o): In function `_ZNSt8_Rb_treeISsSt4pairIKSsN3zmq10endpoint_tEESt10_Select1stIS4_ESt4lessISsESaIS4_EE5eraseESt17_Rb_tree_iteratorIS4_E':
    ...error continue for a long time...

The undefined references are to many different libraries. I may re-post this error at zeromq.

-J_Tom_Moon_79

[jtmoon79]

also reported at https://zeromq.jira.com/browse/LIBZMQ-219
this appears to be a duplicate of #99

[minrk]

I should note that the configure step that failed hasn't done anything Python related yet, it's just trying to build and run the simplest pure-C program to print the libzmq version. See here for the contents of the program that's failing to link.

I think libzmq is not built properly if such a simple program doesn't work.

[sustrik]

It looks like the program is not linked with libstdc++ which it should be.

[minrk]

@sustrik Is this a problem with the libzmq build itself, or should programs linking against libzmq have to explicitly include libstdc++?

This appears unique to cygwin.

[sustrik]

The problem is with C programs linking with libzmq. C doesn't link in C++ runtime (libstdc++) automatically, so you have to link it by hand (-lstdc++). No idea what the actual problem here is, but the errors point to not having C++ runtime available.

[minrk]

Okay, so this is only an issue when libzmq is a static library, as the dynamic library links libstc++ explicitly. Apparently nobody uses pyzmq with static libzmq, or this would have come up sooner.

I removed my dynamic library, and after specifying that just the detect program be linked to libstdc++, the rest of pyzmq still built and ran fine. That would suggest that l don't need to add stdc++ to libraries for each individual Python extension, rather just the little test program, but I don't know if that's quite accurate.

@jtmoon I have done this in my stdc++ branch (here), so if you can test it, that would be great. If you get past detect, and then see the same errors when you actually try to use pyzmq, I will add stdc++ to the libraries to link on the actual extensions.

[jtmoon79]

@minrk FAILED with a different error. Instead of a long list of reference errors there was 4 reference errors to _uuid functions.

$ wget --no-check-certificate https://download.github.com/minrk-pyzmq-e7b1562.zip
$ unzip minrk-pyzmq-e7b1562.zip
$ cd minrk-pyzmq-e7b1562/
$ python setup.py configure --zmq=/usr/local
running configure
******************************************
Configure: Autodetecting ZMQ settings...
Custom ZMQ dir: /usr/local
cc -I/usr/local/include -Izmq/utils -Izmq/core -Izmq/devices -c detect/vers.c -o detect/vers.o
cc detect/vers.o -L/usr/local/lib -Wl,-R/usr/local/lib -lzmq -lstdc++ -o detect/vers.exe
/usr/local/lib/libzmq.a(libzmq_la-uuid.o): In function 'uuid_t':
/tmp/tmp1/zeromq-2.1.7/src/uuid.cpp:80: undefined reference to '_uuid_generate'
/tmp/tmp1/zeromq-2.1.7/src/uuid.cpp:81: undefined reference to '_uuid_unparse'
/tmp/tmp1/zeromq-2.1.7/src/uuid.cpp:80: undefined reference to '_uuid_generate'
/tmp/tmp1/zeromq-2.1.7/src/uuid.cpp:81: undefined reference to '_uuid_unparse'
collect2: ld returned 1 exit status
Fatal:
Failed to link ZMQ test program. Please check to make sure:
* You have a C compiler installed
* A development version of Python is installed (including header files)
* A development version of ZMQ >= 2.1.0 is installed (including header files)
* If ZMQ is not in a default location, supply the argument --zmq=
* If you did recently install ZMQ to a default location,
try rebuilding the ld cache with 'sudo ldconfig'
or specify zmq's location with '--zmq=/usr/local'

******************************************


-J_Tom_Moon_79

[minrk]

@jtmoon79, right - there are other libraries that it needs besides stdc++ when it's static, silly me for testing on OSX. It will need uuid and pthread as well, presumably.

There seems to be a general problem with using static libraries, so it shouldn't be a cygwin-specific fix (though cygwin does appear to be the only place that people are trying to use a static libzmq with pyzmq).

@sustrik - is there a good way to detect ahead of time whether a library will be linked as static or dynamic?

[sustrik]

When you link with static libzmq.a, all the dependencies are static as well. If you link with dynamic libzmq.so the dependencies are dynamic as well.

[minrk]

Yes, but what I need is a way to find out whether libzmq is static before linking against it, because I need to pass different arguments to the linker if it is. Essentially I want a command that returns the answer to the question: 'if I pass -lfoo to gcc, what file will it use for libfoo?'

[minrk]

@jtmoon79 Just out of curiosity, are you deliberately choosing statlic libzmq, or did the zeromq installer not build the dynamic libraries?

[jtmoon79]

@minrk The libzmq installed using the default configuration from package zeromq-2.1.7.zip (see the original posted reproduction steps above). So however zeromq-2.1.7 normally builds and installs under cygwin, that's what happened. If you need, I can post more output captured from the build and installation of libmzq.

[minrk]

@sustrik - do you know why libzmq doesn't build dynamic libraries by default on Cygwin unlike everywhere else?