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Re: [google] Avoid warning when unused attribute applied to C++ member variables (issue8580044)
- From: Xinliang David Li <davidxl at google dot com>
- To: Teresa Johnson <tejohnson at google dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, reply at codereview dot appspotmail dot com
- Date: Tue, 9 Apr 2013 12:32:29 -0700
- Subject: Re: [google] Avoid warning when unused attribute applied to C++ member variables (issue8580044)
- References: <20130409180156 dot F21E0804C2 at tjsboxrox dot mtv dot corp dot google dot com>
Ok -- there are legitimate use cases for this.
David
On Tue, Apr 9, 2013 at 11:01 AM, Teresa Johnson <tejohnson@google.com> wrote:
> This patch is pending on trunk, but I would like to get this into google
> branches now as it is causing spurious warnings.
>
> Google ref b/8496800.
>
> 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
> http://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html also doesn't
> seem to preclude its use on C++ member variables.
>
> Bootstrapped and tested on x86-64-unknown-linux-gnu. Ok for google branches?
>
> 2013-04-09 Teresa Johnson <tejohnson@google.com>
>
> * c-family/c-common.c (handle_unused_attribute):
>
> Index: c-family/c-common.c
> ===================================================================
> --- c-family/c-common.c (revision 197640)
> +++ c-family/c-common.c (working copy)
> @@ -6320,6 +6320,7 @@ 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 http://codereview.appspot.com/8580044