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From: "dangelog at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/101134] Bogus -Wstringop-overflow warning about
 non-existent overflow
Date: Mon, 21 Jun 2021 16:44:48 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101134

--- Comment #2 from Giuseppe D'Angelo <dangelog at gmail dot com> ---
As I said,

> Adding enough __builtin_unreachable() for that condition removes the warn=
ings, but it should not be necessary.

I disagree with the resolution, though. While I understand that GCC cannot
reason globally, the warning message itself is miselading, as it's worded i=
n a
way that makes the user think that GCC has *conclusevely* proven the existe=
nce
of a problem, while in fact GCC is wrong. Specifically, this statement:

>     <source>:75:31: warning: writing 1 byte into a region of size 0 [-Wst=
ringop-overflow=3D]

At least, I'd like a less strong wording if GCC cannot *prove* this but only
estimate it (e.g. "warning: possible string overflow (writing 1 byte...)").
Ideally, even, having two separate warnings or two separate warning levels
(overflow proved / overflow just estimated) so one can enable only one of t=
he
two if needed.=