Allow hidden visibility default on gcc/clang

[mvieth]

Can be enabled/disabled with the CMake option PCL_SYMBOL_VISIBILITY_HIDDEN. The main benefits are reduced library size and reduced risk of certain bugs. Some sources also claim that it can increase execution speed under certain conditions, but so far I did not test whether this is the case for PCL. This is feature is still somewhat experimental (although I did a lot of testing), so for anyone reading this who got a linker error when this is enabled: please open an issue, it may be that PCL_EXPORTS is missing somewhere.

Range image

For gcc, I could only get it to work with the whole RangeImage class marked as PCL_EXPORTS (i.e. __attribute__ ((visibility ("default")))), otherwise I get the linking error undefined reference to vtable RangeImage. For MSVC on the other hand, marking the whole class as PCL_EXPORTS (i.e. __declspec(dllexport)) seems to be problematic because when including range_image.h in another PCL module, RangeImage is also marked as dllexport so the compiler seems to expect a definition of the static members (lookup tables) in that module as well. In the future, it might be a good idea to move away from the static class member lookup tables, and perhaps use static local variables instead like in RGB2sRGB_LUT).

Supervoxel clustering

Moved the specializations of getPoint to supervoxel_clustering.h, using traits::HasColor. This was necessary to resolve some interdependencies between SupervoxelClustering, OctreePointCloudAdjacencyContainer, and `OctreePointCloudAdjacency

Further changes

• removed PCL_EXPORTS on TransformationEstimationSVD again. I added it in a previous PR but noticed now that it was not necessary and caused warnings on MSVC.

Library size

in kilobytes	MinSizeRel, hidden symbols	MinSizeRel, hidden symbols off	Release, hidden symbols	Release, hidden symbols off
common	726	839	825	879
features	43023	49729	51947	57824
filters	8708	10326	10013	11194
io_ply	324	412	401	467
io	2454	3272	2985	3587
kdtree	1199	1565	1453	1754
keypoints	1674	2032	2040	2337
ml	125	146	188	196
octree	2593	2818	3252	3371
outofcore	81	85	97	101
people	22	22	29	29
recognition	5455	6821	6642	7592
registration	2108	2793	2428	2829
sample_consensus	13392	14776	16101	17036
search	2059	2501	2463	2850
segmentation	12893	16671	15067	18132
stereo	241	258	302	306
surface	6304	7174	8178	8747
tracking	3903	4578	4814	5378
visualization	1294	1648	1601	1865

Built with GCC 13.2. All CMake options except CMAKE_BUILD_TYPE and PCL_SYMBOL_VISIBILITY_HIDDEN are the default ones

[larshg]

This would close #1913 FYI.

[Osyotr]

Range image

You should move the key function (in this case virtual destructor) into a CPP file. https://gcc.gnu.org/wiki/VerboseDiagnostics#missing_vtable

[mvieth]

Range image

You should move the key function (in this case virtual destructor) into a CPP file. https://gcc.gnu.org/wiki/VerboseDiagnostics#missing_vtable

Thanks for the suggestion, that seems to work. Then let's go with that solution since it does not require an if-else based on the compiler.