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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/58101] Wrong out-of-bounds warning under -Os
Date: Thu, 23 Dec 2021 06:36:57 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D58101

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Further reduced:
int a [1];

void foo (int n)
{
   if (n <=3D 1) return;
   int i =3D 1;
   a [i] =3D a [i - 1];
}

This is one of these false positives warning where we should maybe not warn=
 but
instead just change the code to be a trap.

Note in the original testcase, GCC is able to remove the loop and just chan=
ge
it to one statement. That is part of the reason for the warning even.

clang does not warn about the above because they only warn for the literal =
a[1]
case.=