Added new color traits in point_types.hpp

[ueqri]

A follow up work of #4706 (comment) #4706 (comment).

New color traits:

• has_Lab
• has_HSV
• has_rgb
• has_any_color

Add deprecated comments for has_color.

[ueqri]

I'm not very sure about the 1.15 as the deprecated version here. If needed, I'd be glad to change it. 😊

pcl/common/include/pcl/impl/point_types.hpp

Lines 2437 to 2442 in 1ebd7f5

	/** Deprecated: Metafunction to check if a given point type has either rgb or rgba field. */
	template <typename PointT>
	struct PCL_DEPRECATED(1, 15, "Please use has_rgb instead.")
	has_color : has_any_field<PointT, boost::mpl::vector<pcl::fields::rgb,
	pcl::fields::rgba> >
	{ };

For CI build on Ubuntu 18.04, the PCL_WARNINGS_ARE_ERRORS is open by default, and there is no exclusive rules like -Wno-error=deprecated-declarations in CMAKE_CXX_FLAGS. So the errors occurs in CI checks.

pcl/.ci/azure-pipelines/azure-pipelines.yaml

Lines 48 to 53 in 6cc233a

	18.04 GCC: # oldest LTS
	CONTAINER: env1804
	CC: gcc
	CXX: g++
	BUILD_GPU: ON
	CMAKE_ARGS: '-DPCL_WARNINGS_ARE_ERRORS=ON'

This PR has been built and tested successfully in local env18.04 container with -Wno-error=deprecated-declarations flag. 😀

[kunaltyagi]

Should we change the existing use of has_color and friends to has_rgb?

For the deprecation, perhaps putting the struct in a namespace and deprecating only the using has_color = details::has_color; might do the trick

[ueqri]

Thanks for your kind review!

Should we change the existing use of has_color and friends to has_rgb?

I'd be glad to change the existing use of has_color has_color_v HasColor HasNoColor to has_rgb families.

For the deprecation, perhaps putting the struct in a namespace and deprecating only the using has_color = details::has_color; might do the trick

I'd move the struct to namespace detail and deprecate the using has_color = details::has_color;. Thanks for your advice! 😀

UPDATE: Still not very sure about how to implement the deprecating only the using has_color = details::has_color;. I just deprecated the struct in namespace detail in 8dd75c4 commit. I'd be grateful if you could give me more hints about this.

[kunaltyagi]

LGTM, minor clarification needed

[ueqri]

Since has_color family is the same as has_rgb currently, I was wondering if we could remove the test codes of has_color family in test/common/test_type_traits.cpp of this PR branch. In this way, we could avoid lots of unnecessary deprecated warnings during PCL sources build.