Warren Young wrote:
I maintain MySQL++ (http://tangentsoft.net/mysql++/), a C++ API for
MySQL. It builds fine under Cygwin when we create a static library, but
linking fails due to undefined symbols when we ask for a shared object.
The symptom is the libtool error "libtool: link: warning: undefined
symbols not allowed in i686-pc-cygwin shared libraries" when creating
the shared object itself. I found some messages in the archive saying
that this can be fixed by using the link flag -no-undefined, but that
didn't help.
Now, libtool just warns here, doesn't return an error code. No .so file
is created in the .libs directory. Also, a mere 8-byte .a file is
created. (It contains "!<arch>\n")
After this point in the MySQL++ build process, several example programs
are built. When linking the first one, we get a spate of errors. I
think this is secondary damage, because it tries to link to that .a
file, but it's basically empty. Naturally g++ can't find any of the
symbol definitions it needs to link the program.
If you need to play with this to understand what I mean, download the
v2.0 beta 2 source from the URL above...it's LGPL.
How do I convince libtool to create the bloody .so file?
Use the Cygwin autotools (libtool-1.5.18, automake-1.9, autoconf-2.5x)
*and* add the flag -no-undefined to libmysqlpp_la_LDFLAGS? And you
also need to use a shared libmysqlclient library.
Older versions of libtool as included with the tarball don't work.
Comments on the tarball:
/usr/bin/install -c -m 644 'coldata.h' '/usr/include/coldata.h'
/usr/bin/install -c -m 644 'compare.h' '/usr/include/compare.h'
/usr/bin/install -c -m 644 'connection.h' '/usr/include/connection.h'
[...]
/usr/bin/install -c -m 644 'vallist.h' '/usr/include/vallist.h'
You should put the headers into a separate directory, e.g.
/usr/include/mysql++.
Besides that all is fine:
$ ls -lRCGF ../.inst
../.inst:
usr/
../.inst/usr:
bin/ include/ lib/
../.inst/usr/bin:
cygmysqlpp-2.dll*
../.inst/usr/include:
coldata.h defs.h mysql++.h row.h
compare.h exceptions.h noexceptions.h sql_string.h
connection.h field_names.h null.h stream2string.h
const_string.h field_types.h platform.h string_util.h
convert.h fields.h qparms.h tiny_int.h
custom-macros.h lockable.h query.h type_info.h
custom.h manip.h resiter.h vallist.h
datetime.h myset.h result.h
../.inst/usr/lib:
libmysqlpp.dll.a* libmysqlpp.la*
The permissions of the .a and .dll.a files are wrong, I wonder if
libtool will ever get this right ;)
Send you a patchfile with PM.
Gerrit
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