Coding standard: Deprecate use of void cast to suppress unused variable warnings?

[kuhar]

FYI, there was a recent-ish thread that touched the same topic: [[maybe-unused]] vs __attribute__((unused)) vs (void) var for assert variables

Some handpicked replies:

[[maybe-unused]] vs __attribute__((unused)) vs (void) var for assert variables

I don’t think this is an area where we should try to innovate. Casting to void is a tried and true idiom for indicating that a value is unused. It’s even documented in the coding standards for folks who aren’t familiar with the idiom. I don’t see value in deviating from C just for it’s own sake, there should be some value proposition, like safety, for doing so.

[[maybe-unused]] vs __attribute__((unused)) vs (void) var for assert variables

Just MHO I don’t see an advantage to using the attribute. It is more verbose and the cast to void idiom is obvious enough. The one advantage I see of the attribute is that it is more “explicit”, but this is C++ which is full of magic and special cases (sadly). I don’t think this is better than the old C idiom.

[[maybe-unused]] vs __attribute__((unused)) vs (void) var for assert variables

The advantage of [[maybe_unused]] attribute is that it can apply to pretty much anything. I.e. you can mark functions/arguments with it, if there is some rarely used value (like for printf-like functions). But for simple unused variables, (void) is more concise idiom understood by pretty much everyone.

[[maybe-unused]] vs __attribute__((unused)) vs (void) var for assert variables

In the past, “don’t mass-convert” was generally applied to more extensive changes such as clang-formatting entire files or renaming methods/fields to conform to newer spelling recommendations. The latter sorts of changes are commonly held to interfere with other people’s work on the same files. (Although, clang-formatting a file prior to doing extensive work on that file is actually seen as a good thing, because the individual changes are expected to be clang-formatted.) In this case, however, …

[[maybe-unused]] vs __attribute__((unused)) vs (void) var for assert variables

Consistency of the codebase matters a lot to me.