AppleClang: -Wextra-qualification warning messages

[TP-David]

After pull request #1440, these warnings started appearing when building on Mac with AppleClang 15.0.0.15000309. A message like below appears for every usage of VSG_type_name within the vsg namespace it seems, this makes the build log unreadable.

In file included from /product/external/VulkanSceneGraph/src/vsg/core/Allocator.cpp:16:
In file included from /product/external/VulkanSceneGraph/include/vsg/io/Logger.h:15:
In file included from /product/external/VulkanSceneGraph/include/vsg/core/Inherit.h:15:
In file included from /product/external/VulkanSceneGraph/include/vsg/app/RecordTraversal.h:18:
In file included from /product/external/VulkanSceneGraph/include/vsg/maths/mat4.h:15:
In file included from /product/external/VulkanSceneGraph/include/vsg/maths/plane.h:26:
In file included from /product/external/VulkanSceneGraph/include/vsg/maths/sphere.h:26:
/product/external/VulkanSceneGraph/include/vsg/maths/vec3.h:161:5: warning: extra qualification on member 'type_name' [-Wextra-qualification]
    VSG_type_name(vsg::svec3);
    ^
/product/external/VulkanSceneGraph/include/vsg/core/type_name.h:44:47: note: expanded from macro 'VSG_type_name'
        template<> constexpr const char* vsg::type_name<T>() noexcept { return #T; } \
                                              ^
In file included from /product/external/VulkanSceneGraph/src/vsg/core/Allocator.cpp:16:
In file included from /product/external/VulkanSceneGraph/include/vsg/io/Logger.h:15:
In file included from /product/external/VulkanSceneGraph/include/vsg/core/Inherit.h:15:
In file included from /product/external/VulkanSceneGraph/include/vsg/app/RecordTraversal.h:18:
In file included from /product/external/VulkanSceneGraph/include/vsg/maths/mat4.h:15:
In file included from /product/external/VulkanSceneGraph/include/vsg/maths/plane.h:26:
In file included from /product/external/VulkanSceneGraph/include/vsg/maths/sphere.h:26:
/product/external/VulkanSceneGraph/include/vsg/maths/vec3.h:161:5: warning: extra qualification on member 'type_name' [-Wextra-qualification]
/product/external/VulkanSceneGraph/include/vsg/core/type_name.h:45:47: note: expanded from macro 'VSG_type_name'
        template<> constexpr const char* vsg::type_name<const T>() noexcept { return "const "#T; }

[robertosfield]

Ack, what a pain some compilers when they try to be "helpful". The change was to make things simpler for end users with less duplication, going back would just bring back the duplication.

A better fix would be quieten the warning. Perhaps this could be done locally just for this header with a pragama, or more globally with the CMake build options.

[TP-David]

I tried wrapping type_name.h in

#if defined(__clang__)
#    pragma clang diagnostic push
#    pragma clang diagnostic ignored "-Wextra-qualification"
#endif

#if defined(__clang__)
#    pragma clang diagnostic pop
#endif

WIth no change, I guess because the vsg::type_name is part of a #define and technically not inside the block.

[robertosfield]

Is it the use of the type_name that is the problem?

[TP-David]

It's the usage of the VSG_type_name macro, when inside a vsg namespace. I think type_name itself is fine.

[TP-David]

Created #1513