Re: AC_CHECK_LIB not finding my library

[Joel J. Adamson]

>>>>> "Eric" == Eric Blake <address@hidden> writes:

    > On 04/14/2010 10:50 AM, Joel J. Adamson wrote:
    >> Hello,
    >> 
    >> I have an auto-tooled library installed, and I'm building an
    >> application with it.  During the ./configure step, the test
    >> specified by
    >> 
    >> AC_CHECK_LIB([haploid], [rec_mating],,,[-lm])
    >> 
    >> fails:
    >> 
    >> checking for rec_mating in -lhaploid... no

    > Does the corresponding config.log give you more insight into what
    > was attempted, and why it might have failed?

Whoops --- I meant to check that before I wrote my message.  It seems
I'm having some problems with OpenMP:

configure:3555: checking for rec_mating in -lhaploid
configure:3590: gcc -o conftest -g -O2   conftest.c -lhaploid -lm -lm  >&5
/usr/lib/../lib/gcc/x86_64-redhat-linux/4.4.3/../../../libhaploid.so: undefined 
reference to `GOMP_parallel_end'
/usr/lib/../lib/gcc/x86_64-redhat-linux/4.4.3/../../../libhaploid.so: undefined 
reference to `omp_get_num_threads'
/usr/lib/../lib/gcc/x86_64-redhat-linux/4.4.3/../../../libhaploid.so: undefined 
reference to `GOMP_parallel_start'
/usr/lib/../lib/gcc/x86_64-redhat-linux/4.4.3/../../../libhaploid.so: undefined 
reference to `omp_get_thread_num'
collect2: ld returned 1 exit status
configure:3597: $? = 1

I reconfigured the library with

AC_CHECK_LIB([gomp], [omp_get_num_threads])

recompiled and then reinstalled the library.  I added the same check to
configure.ac for the application and everything works now.

Thanks for the insanely quick response: can this go in the FAQ?  I've
seen a few people talking about it on the web[1][2][3], and they didn't come up
with this solution (they nor I were smart enough to look in
config.log).

Thanks,

Joel


Footnotes: 
[1]  http://blog.flameeyes.eu/2008/04/29/i-consider-ac_check_lib-harmful

[2]  http://www.keyongtech.com/4420100-ac_check_lib


[3]  http://forums.freebsd.org/showthread.php?t=9706

-- 
Joel J. Adamson
Servedio Lab
University of North Carolina at Chapel Hill

FSF Member #8164
http://www.unc.edu/~adamsonj

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