On Thu, Oct 19, 2023 at 08:49:00PM +0000, Qing Zhao wrote: > > On Sep 25, 2023, at 2:24 PM, Tobias Burnus <tob...@codesourcery.com> wrote: > > Secondly, if this is deprecated, shouldn't then the warning enabled by, > > e.g., -Wall or made > > otherwise more prominent? (-std=?) - Currently, one either has to find the > > new flag or use > > -pedantic. > > Yes, agreed, However, I think that it might be better to delay this to next > GCC release by giving users plenty time to fix all the > -Wflex-array-member-not-at-end warnings. As I know, linux kernel exposed a > lot of warnings when adding -Wflex-array-member-not-at-end, and kernel people > are trying to fix all these warnings in the source base.
Yeah, for the code bases that use flexible arrays (C99 or GNU Extension), there are cases where they're used as intentional implicit unions, and the refactoring to make them unambiguous is non-trivial. I think it may need to be some time before -Wflex-array-member-not-at-end ends up in -Wall. I gave some examples of this code pattern (and potential solutions) here: https://lore.kernel.org/lkml/202310161249.43FB42A6@keescook -- Kees Cook
