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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/99578] gcc-11 -Warray-bounds or -Wstringop-overread warning
 when accessing a pointer from integer literal
Date: Sat, 13 Mar 2021 20:40:41 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99578

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |msebor at gcc dot gnu.org

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The warning is by design.  Its purpose is to detect invalid accesses at
non-zero offsets to null pointers, like in the memset call below:

  struct S { int a, b[4]; };

  void f (struct S *p)
  {
    if (p) return;
    memset (p->b, 0, 4 * sizeof p->b);
  }

For now, I recommend suppressing the warning either by #pragma GCC diagnost=
ic
or by making the pointer volatile.  In the future, providing an attribute to
annotate constant addresses with (or extending the io() attribute supported=
 by
some targets to all targets) might be another way to avoid it.=