Re: test-getgroups.c:stringop-overflow warning on newer GCC

[Paul Eggert]

On 1/1/21 6:30 PM, Bernhard Voelker wrote:
> As I see the same on Fedora, the issue seems to be upstream, doesn't it?

I see the problem on Fedora 33 as well. It doesn't appear to be a GCC 
bug. unistd.h's declaration expands to this:

extern int getgroups (int __size, __gid_t __list[]) __attribute__ 
((__nothrow__, __leaf__)) __attribute__ ((__access__ (__write_only__, 2, 
1)));

and the "__write_only__, 2, 1" means that getgroup's 1st argument 
specifies the number of items in the 2nd-argument array, which means if 
the 1st argument is -1 the call is invalid. This checking is enabled by 
-Wstringop-overflow=2 which is the GCC default in 10.2.1.

I am using gcc (GCC) 10.2.1 20201125 (Red Hat 10.2.1-9).