On Thu, Dec 01, 2022 at 05:04:02PM +0000, Qing Zhao wrote: > > > > On Dec 1, 2022, at 11:42 AM, Kees Cook <keesc...@chromium.org> wrote: > > > > On Wed, Nov 30, 2022 at 02:25:56PM +0000, Qing Zhao wrote: > >> '-Wstrict-flex-arrays' > >> Warn about inproper usages of flexible array members according to > >> the LEVEL of the 'strict_flex_array (LEVEL)' attribute attached to > >> the trailing array field of a structure if it's available, > >> otherwise according to the LEVEL of the option > >> '-fstrict-flex-arrays=LEVEL'. > >> > >> This option is effective only when LEVEL is bigger than 0. > >> Otherwise, it will be ignored with a warning. > >> > >> when LEVEL=1, warnings will be issued for a trailing array > >> reference of a structure that have 2 or more elements if the > >> trailing array is referenced as a flexible array member. > >> > >> when LEVEL=2, in addition to LEVEL=1, additional warnings will be > >> issued for a trailing one-element array reference of a structure if > >> the array is referenced as a flexible array member. > >> > >> when LEVEL=3, in addition to LEVEL=2, additional warnings will be > >> issued for a trailing zero-length array reference of a structure if > >> the array is referenced as a flexible array member. > >> > >> At the same time, -Warray-bounds is updated: > > > > Why is there both -Wstrict-flex-arrays and -Warray-bounds? I thought > > only the latter was going to exist? > > Yes, It’s very easy to merge these two warnings into one: > > -Warray-bounds, when combined with -fstrict-flex-arrays, in addition to > report all the out-of-bounds warnings, it also report > the misuse of flexible array members according to the LEVEL of > -fstrict-flex-arrays > > The major question is, do we need one separate warning option to report the > misuse of flexible array member only? > If so, then we need to add a new one.
I guess it is up to you, but I think it just makes things needlessly complex. I think having 1 option for behavior (-ftrict-flex-arrays), and 1 option for warnings (-Warray-bounds) is sufficient. I think adding -Wstrict-flex-arrays is confusing. -- Kees Cook
