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Re: [C PATCH] Fix -Wunused-function (PR debug/66869)
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: "Joseph S. Myers" <joseph at codesourcery dot com>, Marek Polacek <polacek at redhat dot com>, Jason Merrill <jason at redhat dot com>, Jan Hubicka <hubicka at ucw dot cz>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 27 Jan 2016 11:17:18 +0100
- Subject: Re: [C PATCH] Fix -Wunused-function (PR debug/66869)
- Authentication-results: sourceware.org; auth=none
- References: <20160125203829 dot GP3017 at tucnak dot redhat dot com> <CAFiYyc12VJd=HcmH6YsnwVWinfzBnMzq-WyujU85eg05LCUReg at mail dot gmail dot com> <20160126161813 dot GB3017 at tucnak dot redhat dot com>
On Tue, Jan 26, 2016 at 5:18 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Tue, Jan 26, 2016 at 04:21:08PM +0100, Richard Biener wrote:
>> > --- gcc/c/c-decl.c.jj 2016-01-21 00:41:47.000000000 +0100
>> > +++ gcc/c/c-decl.c 2016-01-25 16:36:31.973504082 +0100
>> > @@ -10741,11 +10741,19 @@ c_write_global_declarations_1 (tree glob
>> > if (TREE_CODE (decl) == FUNCTION_DECL
>> > && DECL_INITIAL (decl) == 0
>> > && DECL_EXTERNAL (decl)
>> > - && !TREE_PUBLIC (decl)
>> > - && C_DECL_USED (decl))
>> > + && !TREE_PUBLIC (decl))
>> > {
>> > - pedwarn (input_location, 0, "%q+F used but never defined", decl);
>> > - TREE_NO_WARNING (decl) = 1;
>> > + if (C_DECL_USED (decl))
>> > + {
>> > + pedwarn (input_location, 0, "%q+F used but never defined", decl);
>> > + TREE_NO_WARNING (decl) = 1;
>> > + }
>> > + /* For -Wunused-function push the unused statics into cgraph,
>> > + so that check_global_declaration emits the warning. */
>> > + else if (warn_unused_function
>> > + && ! DECL_ARTIFICIAL (decl)
>> > + && ! TREE_NO_WARNING (decl))
>> > + cgraph_node::get_create (decl);
>>
>> Err, so why not warn here directly?
>
> You mean check if it has a cgraph node (i.e. get instead of get_create) and
> if it doesn't, warn? What I'm worried in that case is that it might have a
> cgraph node created later on for whatever reason and that we'll get double
> warning (from here and from cgraphunit.c (check_global_declaration)).
> I can try it though.
No, simply warn and set TREE_NO_WARNING so cgraph doesn't warn again.
Richard.
> Jakub