[Bug c++/68354] -Warray-bounds on a flexible array member in C++

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68354

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
      Known to work|                            |7.0
             Blocks|                            |69698
         Resolution|---                         |FIXED
      Known to fail|                            |5.3.0, 6.3.0

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
With GCC 7.0 and 6 the -Warray-bounds warning is gone.  With GCC 7 and 5 (but
not 6) the flexible array member is diagnosed with -Wpedantic.

The internal representation of flexible array members has also changed with
r231665: such members have a null domain, which is likely what has eliminated
the  -Warray-bounds warning.

With this, although there still are many outstanding problems with flexible
array members (see the meta-bug 69698), I think this bug can be resolved as
fixed.

$ cat y.c && gcc -O2 -S -Wall -Wextra -Wpedantic -xc++ y.c
struct S {
    int n;
    int a[];
} s;

int i;

void f ()
{
    i = s.a [0];
}
y.c:3:11: warning: ISO C++ forbids flexible array member ‘a’ [-Wpedantic]
     int a[];
           ^


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69698
[Bug 69698] [meta-bug] flexible array members