C++: Linking to two versions of opencv. How can I tell the linker to pick a specific verion

Question

Description

I have the following problem:

I am developing the library libmy_code.so
I need to link against a closed source library libclosed_source.so over which I have no control
libclosed_source.so is statically linked against opencv 3.2.0
libclosed_source.so has exported all symbols (also those from opencv 3.2.0 which I do not want)
My library libmy_code.so also needs the newer version opencv 3.4.11
I use CMake as the build system

See the following diagram

 +-------------+ +--->|libmy_code.so+<-------+ | +-------------+ | | | Statically linked | |dynamically linked | | | | | | | | | +-------+-----------+ | |libclosed_source.so| | +-------------------+ | ^ | | Statically linked | | +---+---------+ +-----+------+ |OpenCV 3.4.11| |Opencv 3.2.0| +-------------+ +------------+

Problem

My library libmy_code.so uses cv::resize. The CMake build system correctly locates cv::resize in the headers of OpenCV 3.4.11 (I use find_package(OpenCV) and point it to the opencv 3.4.11 install).
However the linker links cv::resize to libclosed_source.so (which contains the Opencv3.2.0 version of cv::resize statically).
My build system runs in a docker container which definitely does not have opencv 3.2.0.
The closest question I have found is this

How can I tell the linker not to linker opencv functions libmy_code.so to libclosed_source.so but directly to Opencv 3.4.11 ??

If you're using CMake you can use HINTS to direct it to pick a specific location when importing a library - see stackoverflow.com/questions/12075371/… — Den-Jason
– Den-Jason, Commented Nov 18, 2020 at 10:59
Similar problem solved, see stackoverflow.com/questions/21783761/… — Milind Deore
– Milind Deore, Commented Nov 18, 2020 at 11:07
@Den-Jason I only have OpenCV 3.4.11 in the build container. OpenCV 3.2 enters in by being statically linked to libclosed_source.so. Will HINTS still work?? — Gerald Mwangi
– Gerald Mwangi, Commented Nov 18, 2020 at 11:12
Does this answer your question? How do I link different versions of the same library in g++? — Adrian Mole
– Adrian Mole, Commented Nov 18, 2020 at 11:33

Gerald Mwangi · Accepted Answer · 2021-07-02 11:42:09Z

Solution

My solution to the problem is to load libclosed_source.so dynamically per dlopen with RTLD_DEEPBIND|RTLD_LOCAL into libmy_code.so. This way libmy_code.so can use opencv 3.4.11 and libclosed_source.so can still use opencv 3.2.0.

The executable that was linked against libmy_code.so had to be compiled with -fPIC to prevent problems with libstdc++, more to that in Weird interaction of RTLD_DEEPBIND, Position independent Code (PIC) and C++ STL (std::cout)

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C++: Linking to two versions of opencv. How can I tell the linker to pick a specific verion

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