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From: "msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug sanitizer/99418] sanitizer checks for accessing multidimentional VLA-array Date: Mon, 08 Mar 2021 18:23:35 +0000 [thread overview] Message-ID: <bug-99418-4-TzJbPUreKC@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-99418-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99418 Martin Sebor <msebor at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |msebor at gcc dot gnu.org --- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> --- The initialization of a reference binds it to the value of the initializer expression. In both examples the [value of the] initializer expression is undefined because it doesn't refer to an element of the array. One way to see that is in a constexpr context which rejects undefined constructs with an error (only with Clang; GCC doesn't reject invalid initialization of references there, see also pr70151): $ cat t.C && clang -S t.C constexpr int a[2] = { 1, 2 }; constexpr const int &r = a[2]; t.C:2:26: warning: array index 2 is past the end of the array (which contains 2 elements) [-Warray-bounds] constexpr const int &r = a[2]; ^ ~ t.C:1:1: note: array 'a' declared here constexpr int a[2] = { 1, 2 }; ^ t.C:2:22: error: constexpr variable 'r' must be initialized by a constant expression constexpr const int &r = a[2]; ^ ~~~~ t.C:2:22: note: dereferenced pointer past the end of subobject of 'a' is not a constant expression t.C:1:15: note: declared here constexpr int a[2] = { 1, 2 }; ^ 1 warning and 1 error generated.
next prev parent reply other threads:[~2021-03-08 18:23 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-05 19:11 [Bug sanitizer/99418] New: " vanyacpp at gmail dot com 2021-03-06 22:53 ` [Bug sanitizer/99418] " vanyacpp at gmail dot com 2021-03-07 7:44 ` vanyacpp at gmail dot com 2021-03-08 9:15 ` marxin at gcc dot gnu.org 2021-03-08 10:14 ` jakub at gcc dot gnu.org 2021-03-08 18:23 ` msebor at gcc dot gnu.org [this message] 2021-03-09 8:39 ` vanyacpp at gmail dot com 2021-03-09 8:47 ` vanyacpp at gmail dot com 2021-03-09 8:54 ` vanyacpp at gmail dot com 2021-03-09 15:48 ` [Bug sanitizer/99418] more cases where -fsanitize=bounds can check one-past-the-end accesses msebor at gcc dot gnu.org
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