dynamic shared library that includes both C++ and C sources

Keith Bostic bostic@abyssinian.sleepycat.com
Mon Oct 4 06:08:00 GMT 1999

I'm having trouble with gcc and a dynamic shared library that
includes both C++ and C sources.

I'm using gcc with gld 2.8.1 on BSD/OS 4.0, but I've
seen the same problem on both FreeBSD 3.2-STABLE and SUSE Linux

Here are the steps:

1. Build a dynamic shared library that contains both C++ and
   C sources.  (The C++ modules are a thin API on top of the
   C sources -- they call the C modules, but C modules never
   call or reference symbols in the C++ modules.)

2. Build a C-source program and use gcc to link against the
   library.  Errors appear, such as:

abyssinian:build_local {312} cc -g -I. -Wall -W t.c .libs/libdb-3.0.so
t.c: In function `main':
.libs/libdb-3.0.so: undefined reference to `ostream::operator<<(char const *)'
.libs/libdb-3.0.so: undefined reference to `terminate(void)'

3. Confirm that those symbols don't appear in any C modules:

abyssinian:build_local {313} nm -o *.lo | egrep terminate
cxx_app.lo:         U terminate__Fv
cxx_except.lo:         U terminate__Fv
cxx_lock.lo:         U terminate__Fv
cxx_log.lo:         U terminate__Fv
cxx_mpool.lo:         U terminate__Fv
cxx_table.lo:         U terminate__Fv
cxx_txn.lo:         U terminate__Fv

4. Note, you can build the source file correctly if you use C++:

abyssinian:build_local {315} g++ -g -I. -Wall -W t.c .libs/libdb-3.0.so


Does anybody understand what the problem is, here?

Are there any suggested workarounds?  Is it a bad idea to include
both C++ and C modules in the same library?

I would appreciate getting any replies by email.

Thank you!

Keith Bostic
Sleepycat Software Inc.		db@sleepycat.com
394 E. Riding Dr.		+1-978-287-4781
Carlisle, MA 01741-1601		http://www.sleepycat.com

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