Error when detecting libunistring

[beuc]

Hi,

I'm currently experimenting with cross-compiling Guile 2 for Android.
https://lists.gnu.org/archive/html/guile-user/2014-06/msg00011.html


I met a weird issue: when configuring guile I get this test:
../configure --host=arm-linux-androideabi 
--prefix=/usr/src/ndk-shared/sysroot/usr --without-threads
[...]
configure:15799: checking for libunistring
configure:15821: arm-linux-androideabi-gcc -o conftest -g -O2 
-I/usr/src/ndk-shared/sysroot/usr/include  conftest.c 
/usr/src/ndk-shared/sysroot/usr/lib/libunistring.so -Wl,-rpath 
-Wl,/usr/src/ndk-shared/sysroot/usr/lib  >&5
/usr/src/ndk-shared/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld:
 /usr/src/ndk-shared/sysroot/usr/lib/libunistring.so: error: undefined 
reference to 'frexp'
collect2: ld returned 1 exit status


However, trying to reproduce with a simple project, I get:
# http://www.beuc.net/misc/testunistring.tar.gz
../configure --host=arm-linux-androideabi
[...]
configure:7108: checking for libunistring
configure:7130: arm-linux-androideabi-gcc -o conftest -g -O2   conftest.c  
-lunistring >&5
configure:7130: $? = 0
configure:7140: result: yes


I can't figure out why the guile test ends-up with linking the .so
explicitely, while my test project uses '-lunistring'.
Any leads?

Also, if using the .so directly is needed for some reason, do we need
to add '-lm' somewhere in gnulib's libunistring test?

Cheers!
Sylvain