Re: Symbols in .so even when using fvisibility=hidden

[Robert Wohlrab <robert dot wohlrab at gmx dot de>]

Ian Lance Taylor wrote:
> Robert Wohlrab <robert.wohlrab@gmx.de> writes:
> > I have the problem that I have a shared object which is mostly c with a
> > relative small part C++. It is compiled with -fvisibility=hidden and only
> > some small parts are exported. I noticed today that non-exported C++
> > symbols were also exported. This is quite mysterious because they are 5
> > functions from templates (looks related to std::vector with allocator
> > stuff to me). The shared object is generated by source files from
> > mupen64plus-core (can be found on bitbucket) using `make -C
> > projects/unix/ all`.
> >
> > Is there any way to disable that symbols? The vector is not used outside
> > that shared object and the interface of the shared object should be as
> > clean as possible. I tried already with -fvisibility-inlines-hidden but
> > without success.
> 
> In general this should not happen.  Can you provide a small standalone
> test case which shows the problem?

I am not sure what the problem really is - so it is a little bit hard to make 
a test case. I tried to create one by stripping of some files and functions. 
It also includes a debian directory because I used dpkg-gensymbols to check 
for exported symbols. debian/libtest0.symbols says that no function is 
exported (I wrote it because it is what the source says - it is not 
autogenerated), but dpkg-gensymbols will then report that 5 other functions 
were exported by libtest.so.0.

The Makefile says that visibility is hidden and the test.cpp doesn't say that 
anything should be exported.

As far as I know dpkg-gensymbols uses `objdump -T` do generate a list of 
exported functions. See debian/control for a list of symbols it reports. In my 
tests I just `tar xvf test_0.tar.gz && cd test-0 && debuild`

I tested it using binutils-gold and normal binutils, but that doesn't seem to 
change anything.
-- 
Robert Wohlrab

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