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From: "rverschelde at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/104789] [12 Regression] New
 -Wstringop-overflow false positive since r12-5863-g9354a7d70caef1c9
Date: Mon, 07 Mar 2022 12:39:08 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104789

--- Comment #6 from R=C3=A9mi Verschelde <rverschelde at gmail dot com> ---
Indeed if the warning was reworded to make it clear that it's a risk and no=
t a
certainty would solve this.

Both the reduced test case and the original code are both risky: `component=
s`
is an `uint32_t` that is set to either 1 or 3, so in the context of that co=
de
`header_bytes` would never exceed 8.

But if this was changed to anything higher than 3 then yes, there would be a
buffer overflow. If this is what this warning aims to warn about (the risk =
of
buffer overflow and not the certainty of one), then there's probably no fal=
se
positive.

Adding:
```
if (components > 3) {
        return 0;
}
```
to the reduced testcase does prevent the warning.

On the other hand, the same kind of check doesn't seem to solve the warning=
 in
the original Godot case, so you're right about the reduced testcase being t=
oo
reduced. I'll dig further and see if I can make a better testcase, or
understand why a check on `components` (or even `header_bytes > 7`) isn't
sufficient in Godot.=