Sometimes. But sometimes you have a set of functions that are called through function pointers that need the same signature, and one or more of them ignore some of the arguments. These days I’d spell that __attribute__((unused)); but it’s a perfectly reasonable case.

    #if otherbuild
        dosomething(param);
     #endif

the above type of thing happens once in a while. nos the paramater is needed but the normal build doesn't use it

Fwiw, unused-cast-to-void is a case that GCC and Clang ignore when using -Wno-old-style-cast, which is what most projects prohibiting C-style casts are going to be using (or whatever the equivalent their compiler provides).

C++17 has the [[maybe_unused]] attribute.