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From: "joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/101265] C2X [[maybe_unused]] ignored when placed after array
 declaration
Date: Wed, 30 Jun 2021 16:54:45 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101265

--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery =
dot com> ---
On Tue, 29 Jun 2021, gcc at alanwu dot email via Gcc-bugs wrote:

>         [[maybe_unused]] int thisworks[1];

That attribute appertains to the declared entity.

>         int thisdoesnt[1] [[maybe_unused]];

Whereas that one appertains to the array type (that position after an=20
array declarator can also be used for e.g. a pointer to an array, an array=
=20
of arrays, etc., and an attribute there appertains to the specific array=20
given by that declarator - not the declared entity as a whole).

It's not clear what it would mean to declare that some particular part of=20
the type of an entity is possibly unused like that.  Appropriate places in=
=20
a declaration are either at the start as in the first example, or after=20
the identifier where an attribute specifier sequence appertains to the=20
declared entity.

In general you need to be a lot more careful about the positioning of [[]]=
=20
attributes than __attribute__.=