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Re: [PATCH] Avoid warning when unused attribute applied to C++ member variables (issue8212043)

On Sun, Mar 31, 2013 at 12:10 AM, Teresa Johnson <> wrote:
> This patch allows the unused attribute to be used without warning
> on C++ class members, which are of type FIELD_DECL. This is for
> compatibility with clang, which allows the attribute to be specified on
> class members and struct fields. It looks like more work would need to
> be done to implement the actual unused variable detection and warning
> on FIELD_DECLs, but this change will at least avoid the warning on the
> code that uses the unused attribute in these cases. The documentation at
> also doesn't
> seem to preclude its use on C++ member variables.

This also allows it on field in normal C case.  As far as I understand
they are fields and not variables in the normal programming sense
which is why the document does not mention them.

Andrew Pinski

> Bootstrapped and tested on x86-64-unknown-linux-gnu. Ok for trunk?
> 2013-03-30  Teresa Johnson  <>
>         * c-family/c-common.c (handle_unused_attribute): Handle
>         FIELD_DECL for C++ class members.
> Index: c-family/c-common.c
> ===================================================================
> --- c-family/c-common.c (revision 197266)
> +++ c-family/c-common.c (working copy)
> @@ -6753,6 +6753,7 @@ handle_unused_attribute (tree *node, tree name, tr
>        if (TREE_CODE (decl) == PARM_DECL
>           || TREE_CODE (decl) == VAR_DECL
> +         || TREE_CODE (decl) == FIELD_DECL
>           || TREE_CODE (decl) == FUNCTION_DECL
>           || TREE_CODE (decl) == LABEL_DECL
>           || TREE_CODE (decl) == TYPE_DECL)
> --
> This patch is available for review at

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