[PING^3] [C/C++] PR c/4076 -Wunused doesn't warn about static function only called by itself

["Manuel López-Ibáñez" <lopezibanez at gmail dot com>]

I ping my original patch:
http://gcc.gnu.org/ml/gcc-patches/2007-03/msg00171.html
because it worked fine for its intended purpose. The only case for
which it seems it doesn't work is for functions inside of anonymous
namespaces. However, those are not considered static functions anyway
and -Wunused-function only warns for static functions. So no matter
what my patch does, they are not going to be used. Also, moving the
condition into mark_used causes a weird ICE.

An alternative would be to fix the issue in the C front-end and open a
new PR exclusively for the C++ front-end.

Cheers,

Manuel.

On 24/03/07, Manuel López-Ibáñez <lopezibanez@gmail.com> wrote:
> On 19/03/07, Nathan Sidwell <nathan@codesourcery.com> wrote:
> > Manuel López-Ibáñez wrote:
> >
> > > I can copy the condition. Much better, I can put it inside mark_used
> > > so we don't have to duplicate it everywhere.
> >
> > that seems a much better approach :)
> >
>
> Bad news. It produces ICE in:
> libstdc++-v3/src/pool_allocator.cc:112: internal compiler error: in
> build_call_a, at cp/call.c:325
>
>  if (TREE_CODE (function) == ADDR_EXPR
>       && TREE_CODE (TREE_OPERAND (function, 0)) == FUNCTION_DECL)
>     {
>       decl = TREE_OPERAND (function, 0);
>       if (!TREE_USED (decl))
>         {
>           /* We invoke build_call directly for several library
>              functions.  These may have been declared normally if
>              we're building libgcc, so we can't just check
>              DECL_ARTIFICIAL.  */
>           gcc_assert (DECL_ARTIFICIAL (decl)
>                       || !strncmp (IDENTIFIER_POINTER (DECL_NAME (decl)),
>                                    "__", 2));
>           mark_used (decl);
>         }
>     }
>
> DECL_ARTIFICIAL is false and IDENTIFIER_POINTER (DECL_NAME (decl)) is
> "_M_allocate_chunk"
>
> Any ideas?
>
>
> > > It seems that check_global_declarations, which is the one that emits
> > > the Wunused-function warnings, is not called for functions in an
> > > anonymous namespace. I tried finding where the decision is made
> > > without any success. Any ideas?
> >
> > sorry, nothing comes to mind.  It is an orthogonal issue though, IMHO.
> >
>
> So what is the point in making my patch to worry about functions in
> anonymous namespaces if anyway they are not equivalent to static with
> respect to TREE_USED ? That is, no matter what my patch does, the
> warning is not going to be emitted.
>
> Cheers,
> Manuel.