Bug #14788: librados (C++) linker error (undefined reference) - Ceph - Ceph

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Bug #14788

closed

librados (C++) linker error (undefined reference)

Added by Jesse Williamson about 8 years ago. Updated over 7 years ago.

Status:

Resolved

Priority:

Normal

Assignee:

Kefu Chai

Category:

Target version:

% Done:

Source:

Community (dev)

Tags:

Backport:

infernalis

Regression:

Yes

Severity:

3 - minor

Reviewed:

Affected Versions:

ceph-qa-suite:

Pull request ID:

Crash signature (v1):

Crash signature (v2):

Description

When compiling a patched librados C++ example (or other C++ programs-- see included patchfile), pointing to the headers in the git repository causes linker errors
against librados (note that the stock Makefile uses only the system-wide headers and libraries, so here we're manually pointing at
the local build):

g++ -g -c hello_world.cc -o hello_world.o -std=c++0x -I../../src/include
g++ -I../../src/include -g hello_world.o -o librados_hello_world -Wl,-rpath,../../../ceph/src/.libs -L../../../ceph/src/.libs/ -lrados
hello_world.o: In function `ceph::buffer::list::iterator_impl<false>::iterator_impl(ceph::buffer::list*, unsigned int)':
/home/jwilliamson/work/ceph/ceph/examples/librados/../../src/include/rados/buffer.h:289: undefined reference to `ceph::buffer::list::iterator_impl<false>::advance(int)'

Using the system-wide headers results in successful linkage:
g++ -g -c hello_world.cc -o hello_world.o -std=c++0x
g++ -g hello_world.o -o librados_hello_world -Wl,-rpath,../../../ceph/src/.libs -L../../../ceph/src/.libs/ -lrados

Files

0001-examples-librados-hello_world.cc-missing-semicolon.patch (950 Bytes) 0001-examples-librados-hello_world.cc-missing-semicolon.patch

Jesse Williamson, 02/17/2016 02:57 PM

Related issues 2 (0 open — 2 closed)

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Updated by Joao Eduardo Luis about 8 years ago

Source changed from other to Community (dev)

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Updated by Kefu Chai about 8 years ago

Status changed from New to 12
Assignee set to Kefu Chai

so it sounds like a regression after introducing the buffer::list::const_iterator.

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Updated by Brad Hubbard about 8 years ago

What version is this?

That missing semicolon was fixed last year.

I can't reproduce this behaviour on master, can you Jesse?

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Updated by Kefu Chai about 8 years ago

Related to Bug #13429: bufferlist::iterator no longer ABI compatible added

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Updated by Kefu Chai about 8 years ago

Status changed from 12 to New

this reminds me of #13429.

turns out i was compiling with the header in my source repo, while linking against the packaged librados in system.

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Updated by Kefu Chai about 8 years ago

if that's the case which Jesse ran into. it's because the new buffer.h is referencing the symbols of buffer::list::iterator_impl<false>::*. so, if the client code is compiled using the new header file, the resulting object code will need the (weak) symbols of buffer::list::iterator_impl<false>::*.

but if the client code is compiled using the old header file, it will linked just fine with the new library.

the buffer::list::iterator_impl template class was introduced when adding list::const_iterator, in hope to consolidate the shared bits of list::const_iterator and list::iterator. but it introduced some ABI incompatibilities. #13429 addressed some of them by re-exposing the methods offered by list::iterator in hammer using their old symbol names (signatures). but it does not remove the dependency to the buffer::list::iterator_impl symbols.

i will try to add __attribute__ ((visibility ("hidden"))) to the template to hide its symbol to see how it works.

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