On Wed, Aug 31, 2022 at 08:16:49PM +0000, Qing Zhao wrote: > > > On Aug 31, 2022, at 4:09 PM, Joseph Myers <jos...@codesourcery.com> wrote: > > > > On Wed, 31 Aug 2022, Qing Zhao wrote: > > > >>>> When -std=gnu89 + -fstrict-flex-array=3 (ONLY C99 flexible array member > >>>> [] is treated as a valid flexible array) present together, > >>> > >>> That seems reasonable enough without a warning. If people want a warning > >>> for flexible array members in older language modes, they can use > >>> -pedantic; I don't think we need to warn for any particular > >>> -fstrict-flex-array modes there. > >> > >> So, you mean, > >> > >> 1. GCC with -std=gnu89 support all [0], [1], and [] as Flexible array > >> member; > >> 2. Therefore. -std=gnu89 + -fstrict-flex-array=3 does not need a warning; > >> > >> ? > > > > Yes. > > > >> Then, how about: > >> > >> -std=c89: > >> > >> 1. GCC with -std=c89 also support all [0], [1], and [] as Flexible array > >> member; > >> 2, therefore, -std=c89 + -fstrict-flex-array does not need a warning too. > >> > >> ? > > > > Yes. > > > > Okay, I am fine with this. > > Richard and Kees, what’s your opinion on this?
Agreed: I think it's fine not to warn about these "conflicting" flags in those cases. It looks like the C standard warnings about flexible arrays are already hidden behind -Wpedantic, so nothing else is needed, IMO. Using -fstrict-flex-arrays just enforces that warning. ;) -- Kees Cook
