[Bug c++/58362] New: Wrong column number for unused parameter

[Bug c++/58362] New: Wrong column number for unused parameter

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

            Bug ID: 58362
           Summary: Wrong column number for unused parameter
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glisse at gcc dot gnu.org

void f (long s) { }

y.cc:1:6: warning: unused parameter 's' [-Wunused-parameter]
 void f (long s) { }
      ^

Note the column information, which should point to s instead.
I tried the following:

--- function.c    (revision 202365)
+++ function.c    (working copy)
@@ -4997,21 +4997,22 @@ use_return_register (void)
 void
 do_warn_unused_parameter (tree fn)
 {
   tree decl;

   for (decl = DECL_ARGUMENTS (fn);
        decl; decl = DECL_CHAIN (decl))
     if (!TREE_USED (decl) && TREE_CODE (decl) == PARM_DECL
     && DECL_NAME (decl) && !DECL_ARTIFICIAL (decl)
     && !TREE_NO_WARNING (decl))
-      warning (OPT_Wunused_parameter, "unused parameter %q+D", decl);
+      warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wunused_parameter,
+          "unused parameter %q+D", decl);
 }

 /* Generate RTL for the end of the current function.  */

 void
 expand_function_end (void)
 {
   rtx clobber_after;

   /* If arg_pointer_save_area was referenced only from a nested

And I checked in gdb, the first argument of warning_at has the right column
information, but it is ignored :-(

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Maybe it's just me, but I don't understand what -ignored- means in this
context, could you please explain?

[Bug c++/58362] Wrong column number for unused parameter

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

--- Comment #2 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Paolo Carlini from comment #1)
> Maybe it's just me, but I don't understand what -ignored- means in this
> context, could you please explain?

It means that the diagnostic machinery takes the column information from
somewhere else (I didn't really understand where) instead of using the one from
the loc parameter.

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Oh I see, but that should be rather easy to track down.

[Bug c++/58362] Wrong column number for unused parameter

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |manu at gcc dot gnu.org

--- Comment #5 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Paolo Carlini from comment #4)
> The damage happens at error.c:3435. Should we just use "%qD", no '+' ?

Yes. And this is the reason I am against the magic +/# for location info.
Unless you know (and keep remembering) the diagnostic machinery very well, the
+ doesn't mean anything and it is easy to miss, whereas
"warning_at(DECL_SOURCE_LOCATION(decl)" seems pretty self-evident to me.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idX340

--- Comment #16 from Jeffrey A. Law <law at redhat dot com> ---
Jan's patch papers over the problem of incorrect initialization of "found".  I
expect to be able to run through the formalities necessary to install the fix
tonight.

Reverting until I take care of things tonight is the better option.

[Bug c++/58362] Wrong column number for unused parameter

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Paolo Carlini from comment #4)
> The damage happens at error.c:3435.

Yes, location_of replaces the declaration of the argument with that of the
function :-(

> Should we just use "%qD", no '+' ?

I don't think I ever understood what '+' meant, or found the relevant doc. But
the comment in front of location_of seems to agree with your solution. And
indeed it works.

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-09-08
     Ever confirmed|0                           |1

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Testing of C++ succeeded. I will test C too and in case will submit. I guess
Honza can approve the patch.

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at ucw dot cz

--- Comment #8 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Honza can you review gcc/function.c changes?

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

--- Comment #9 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I sent the simple patch and apparently people would rather prefer fixing
location_of to not do t = DECL_CONTEXT (t) for PARM_DECLs, likewise the C
front-end of course, in such a way that '+' works and we don't have to pass the
DECL_SOURCE_LOCATION. I can't work on this right now.

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

--- Comment #10 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Nope, sorry, the C front-end is already fine, thus I guess we really want to
change location_of in the C++ front-end.

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|hubicka at ucw dot cz              |
           Assignee|unassigned at gcc dot gnu.org      |paolo.carlini at oracle dot com
   Target Milestone|---                         |4.9.0

--- Comment #11 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Ok, that's doable.

[Bug c++/58362] Wrong column number for unused parameter

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58362

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #13 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed for 4.9.0.