[Bug c++/58724] New: doc: use of attributes for namespace is not clear

[Bug c++/58724] New: doc: use of attributes for namespace is not clear

[akim.demaille at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

            Bug ID: 58724
           Summary: doc: use of attributes for namespace is not clear
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: akim.demaille at gmail dot com

Hi friends,

I could not find an example of a use of the attributes for namespaces.  It is
mentioned in the text body, but there is no example of the syntax (it appears
for the documentation of "visibility" in
http://gcc.gnu.org/onlinedocs/gcc-4.8.1/gcc/Function-Attributes.html#Function-Attributes).
 Also, it does not appear in the node dedicated to C++ attributes
(http://gcc.gnu.org/onlinedocs/gcc-4.8.1/gcc/C_002b_002b-Attributes.html#C_002b_002b-Attributes).

Also, it might be worth noting (in the doc) that the __attribute__ syntax is
supported, but not [[...]].  I have no idea if this is meant.  4.8 issues a
weird error message, 4.9 ices.

$ cat foo.cc
namespace foo __attribute__((visibility("default"))) {}
namespace bar [[gnu::visibility("default")]] {}
$ g++-mp-4.8 -std=c++1y foo.cc -c
foo.cc:2:46: warning: '#'tree_list' not supported by dump_decl#<declaration
error>' attribute directive ignored [-Wattributes]
 namespace bar [[gnu::visibility("default")]] {}
                                              ^
$ g++-mp-4.9 -std=c++1y foo.cc -c
foo.cc:2:46: internal compiler error: tree check: expected identifier_node,
have tree_list in private_is_attribute_p, at tree.c:5558
 namespace bar [[gnu::visibility("default")]] {}
                                              ^

foo.cc:2:46: internal compiler error: Abort trap: 6
g++-mp-4.9: internal compiler error: Abort trap: 6 (program cc1plus)
zsh: abort      g++-mp-4.9 -std=c++1y foo.cc -c
$ g++-mp-4.9 --version                                          13
g++-mp-4.9 (MacPorts gcc49 4.9-20130915_0) 4.9.0 20130915 (experimental)
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Bug c++/58724] doc: use of attributes for namespace is not clear

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-10-14
     Ever confirmed|0                           |1

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
In mainline (I don't think this can be fixed in 4.8.x), it seems to me that the
below may be all there is to the issue (for more about TREE_PURPOSE vs
get_attribute_name, see PR58600).

Can you test it on your code?

////////////////

Index: name-lookup.c
===================================================================
--- name-lookup.c       (revision 203517)
+++ name-lookup.c       (working copy)
@@ -3571,7 +3571,7 @@

   for (d = attributes; d; d = TREE_CHAIN (d))
     {
-      tree name = TREE_PURPOSE (d);
+      tree name = get_attribute_name (d);
       tree args = TREE_VALUE (d);

       if (is_attribute_p ("visibility", name))

[Bug c++/58724] doc: use of attributes for namespace is not clear

[akim.demaille at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

--- Comment #2 from Akim Demaille <akim.demaille at gmail dot com> ---
Hi Paolo,

Sorry, I don't have a checked out version of the GCC.  I'll
try to make one tomorrow.

Please, note that I was also mentioning the fact that the documentation
is not sufficiently clear, IMHO.

[Bug c++/58724] doc: use of attributes for namespace is not clear

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Well, an ICE which can be easily avoided seems a separate issue to me. By the
way, the same patchlet should work in the release branch too.

[Bug c++/58724] doc: use of attributes for namespace is not clear

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

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

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

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Let's add Dodji.

[Bug c++/58724] ICE with attribute [[gnu::visibility("default")]] on namespace

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|doc: use of attributes for  |ICE with attribute
                   |namespace is not clear      |[[gnu::visibility("default"
                   |                            |)]] on namespace
           Severity|minor                       |normal

[Bug c++/58724] ICE with attribute [[gnu::visibility("default")]] on namespace

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

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

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

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Mine. I'm also adding a small example to the docs.

[Bug c++/58724] ICE with attribute [[gnu::visibility("default")]] on namespace

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Pending patch here: http://gcc.gnu.org/ml/gcc-patches/2013-10/msg01166.html

[Bug c++/58724] ICE with attribute [[gnu::visibility("default")]] on namespace

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

--- Comment #7 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> ---
Author: paolo
Date: Tue Nov  5 15:22:36 2013
New Revision: 204401

URL: http://gcc.gnu.org/viewcvs?rev=204401&root=gcc&view=rev
Log:
2013-11-05  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/58724
    * doc/extend.texi [visibility ("visibility_type")]: Add example
    about visibility attribute on namespace declaration.

/cp
2013-11-05  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/58724
    * name-lookup.c (handle_namespace_attrs): Use get_attribute_name.

/testsuite
2013-11-05  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/58724
    * g++.dg/cpp0x/gen-attrs-56.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/gen-attrs-56.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/name-lookup.c
    trunk/gcc/doc/extend.texi
    trunk/gcc/testsuite/ChangeLog

[Bug c++/58724] ICE with attribute [[gnu::visibility("default")]] on namespace

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58724

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

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

--- Comment #8 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed.