On Wed, Feb 05, 2025 at 03:51:35PM +1030, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > So, in order to avoid ending up with a flexible-array member in the > middle of other structs, we use the `struct_group_tagged()` helper > to create a new tagged `struct tty_buffer_hdr`. This structure > groups together all the members of the flexible `struct tty_buffer` > except the flexible array. > > As a result, the array is effectively separated from the rest of the > members without modifying the memory layout of the flexible structure. > We then change the type of the middle struct member currently causing > trouble from `struct tty_buffer` to `struct tty_buffer_hdr`. > > We also want to ensure that when new members need to be added to the > flexible structure, they are always included within the newly created > tagged struct. For this, we use `static_assert()`. This ensures that the > memory layout for both the flexible structure and the new tagged struct > is the same after any changes. > > This approach avoids having to implement `struct tty_buffer_hdr` as a > completely separate structure, thus preventing having to maintain two > independent but basically identical structures, closing the door to > potential bugs in the future. Why not just have a separate structure and embed that in the places it is used? No duplication should be needed or am I missing something? I don't mind that, it would make this all much simpler and more obvious over time, and the tty layer needs all the "simplification" it can get :) thanks, greg k-h
