Fixes unused parameter warnings in the null VFD

[derobins]

No description provided.

[derobins]

fwiw, we should abandon the H5_ATTR_UNUSED scheme and replace it with (void) casts, which are less ridiculous and more portable. Then we can get rid of craziness like H5_ATTR_NDEBUG_UNUSED and H5_ATTR_PARALLEL_UNUSED and related.

[gnuoyd]

On Tue, Nov 09, 2021 at 03:01:19PM -0800, Dana Robinson wrote: fwiw, we should abandon the H5_ATTR_UNUSED scheme and replace it with (void) casts, which are less ridiculous and more portable. Then we can get rid of craziness like H5_ATTR_NDEBUG_UNUSED and H5_ATTR_PARALLEL_UNUSED and related.

Generally I think that the attributes should be used sparingly, and I definitely do not like the way that these attributes are spelled. I'd like to lower the case, drop the _attr, and invert the double-negative of _NDEBUG_UNUSED: h5_unused h5_debug_used h5_parallel_unused. I appreciate the granularity of the existing attributes, though. Seems like (void) casts cannot express "used by debug code." Dave

[soumagne]

Also agree with Dave, I think attributes are useful and we should keep them, casting to void is not good imo. We should just simplify them. FWIW you should have a look there: https://github.com/torvalds/linux/blob/master/include/linux/compiler_attributes.h

[derobins]

I'll take a look at those that link and think about this some more. We can discuss at the next engineering meeting. I just want to avoid the macro combinatorial explosion as we started addressing warnings in the non-debug, parallel, etc. cases.

[derobins]

In this case, though, we're not including H5private.h so the macros are not available. Using (void) casts in this instance might be the right choice even if we improve the "attribute unused" macro system for use in the library/tools/tests.

[gnuoyd]

This change is fine for code that's external to the library.