[Bug middle-end/108036] [11/12/13/14 Regression] Spurious warning for zero-sized array parameters to a function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108036 --- Comment #9 from Alejandro Colomar --- Hi Lundin! On Thu, Mar 07, 2024 at 10:18:12AM +, daniel.lundin.mail at gmail dot com wrote: > --- Comment #8 from Daniel Lundin --- > I don't believe char past_end[0] is valid C, because it is an invalid array > declaration. Unlike [] or [*] that declares an array of incomplete type. > > Since it is a function parameter, it will of course later get adjusted to a > pointer to the first element. But it still has to be a valid declaration to > begin with. Similarly, char arr[][] is invalid because it remains an > incomplete > type after adjustment (see C17 6.7.6.4 §4). Agree; ISO C seems to not allow this with their wording. (I wish it did, because it's just a matter of wording, not that they don't allow passing a pointer to past the end). But maybe the wording needed for allowing this would have other undersirable consequences, so I'm happy as long as GNU C would support this. > gcc does allow [0] as an extension since that was commonly used for purposes > of > implementing the "struct hack" back in the days before flexible array members > were standardized. > > The conclusion ought to be that gcc should let [0] through if compiled in > -std=gnu23 mode but not in -std=c23 and/or -pedantic. And agree; if support for this is added, pedantic or ISO C modes should complain about it. Have a lovely day! Alex
[Bug middle-end/108036] [11/12/13/14 Regression] Spurious warning for zero-sized array parameters to a function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108036 Daniel Lundin changed: What|Removed |Added CC||daniel.lundin.mail at gmail dot co ||m --- Comment #8 from Daniel Lundin --- I don't believe char past_end[0] is valid C, because it is an invalid array declaration. Unlike [] or [*] that declares an array of incomplete type. Since it is a function parameter, it will of course later get adjusted to a pointer to the first element. But it still has to be a valid declaration to begin with. Similarly, char arr[][] is invalid because it remains an incomplete type after adjustment (see C17 6.7.6.4 §4). gcc does allow [0] as an extension since that was commonly used for purposes of implementing the "struct hack" back in the days before flexible array members were standardized. The conclusion ought to be that gcc should let [0] through if compiled in -std=gnu23 mode but not in -std=c23 and/or -pedantic.
[Bug middle-end/108036] [11/12/13/14 Regression] Spurious warning for zero-sized array parameters to a function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108036 Jakub Jelinek changed: What|Removed |Added Target Milestone|11.4|11.5 --- Comment #7 from Jakub Jelinek --- GCC 11.4 is being released, retargeting bugs to GCC 11.5.
