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From: "qinzhao at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/101836] __builtin_object_size(P->M, 1) where M is an
 array and the last member of a struct fails
Date: Mon, 27 Jun 2022 14:01:42 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101836

--- Comment #32 from qinzhao at gcc dot gnu.org ---
(In reply to James Y Knight from comment #31)
> It doesn't make sense to have a mode in which `int array[0]` is accepted =
but
> is not a flex array.
>=20
> Either that should be a compilation error (as the standard specifies), or=
 it
> should be a flex array. Accepting it as an extension but having it do the
> wrong thing is not useful or helpful.
>=20
> Note that Clang has a dedicated warning flag for zero-length arrays:
> -Wzero-length-array, so anyone who wants to prohibit them may use
> -Werror=3Dzero-length-array. It would be helpful for GCC could follow suit
> there.

there is a Bugzilla that has been filed for GCC to request the same warning=
 for
GCC:
https://gcc.gnu.org/bugzilla//show_bug.cgi?id=3D94428

-Wzero-length-array


As suggested by Siddhesh in comment#23, -Wstrict-flex-arrays might be neces=
sary
to be added too, and=20
-Wzero-length-array will be an alias to=20
-Wstrict-flex-arrays=3D3=