[Bug c++/29131] New: Bad name lookup for templates

[Bug c++/29131] New: Bad name lookup for templates

[andrew dot stubbs at st dot com]

The following C++ code should not compile:

template<class T>
int t(T i)
{
  return f (i);  // error: f not visible here
}

int
f (int i)
{
  return i;
}

int
main()
{
  return t(1);
}

The C++ standard clause 14.6.3 states that names should be looked up from the
point they are used. I.e. functions defined after that point are not visible.
This is true for regular functions, but GCC does not get this right for
template functions.


-- 
           Summary: Bad name lookup for templates
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: andrew dot stubbs at st dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-09-18 17:28 -------
(In reply to comment #0)
> The C++ standard clause 14.6.3 states that names should be looked up from the
> point they are used. I.e. functions defined after that point are not visible.
> This is true for regular functions, but GCC does not get this right for
> template functions.

No you missed something but I don't have the standard in front of me.
14.6.3 is talking about something different.  Anyways this is unqualified
function call that is dependent on a template arguments.

I think 14.6.3 is really talking about what PR 2922 is about and not this one.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-09-19 03:47 -------
Actually wait, what is happening here is ADL is happening for fundemantal types
which is a question of a Defect report, I forgot which one now.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-09-19 03:49 -------
Actually you missed 14.6.4.2.  This really has nothing to do with 14.6.3.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2006-09-19 03:51 -------
Also "f (i)" is a dependent expression because of 14.6.2/1 as i is (obviously)
dependent so 14.6.3 does not apply.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2006-09-19 04:06 -------
So GCC does not implement 14.6.4.2/1, part 1:
- For the part of look using unqualified name lookup (3.4.1), only function
declareations with external linkage from the template context are found.

And since ADL on fundalment types not exist, that is the only part that happens
so this is invalid code based on that and nothing else.

Next time becareful when trying to figuring out why something is invalid code
because it is easy to get it wrong and then have a someone else having to look
at the standard to prove you wrong.  In fact the following is valid code
because of ADL (since template instantiation conext is also included for ADL):
template<class T>
int t(T i)
{
  return f (i);  // error: f not visible here
}

struct a{};

int
f (a i)
{
  return 0;
}

int
main()
{
  a b;
  return t(b);
}


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-09-19 04:06:38
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #6 from pinskia at gcc dot gnu dot org  2006-09-19 04:30 -------
This is DR 225 really.
http://www.open-std.org/JTC1/SC22/WG21/docs/cwg_active.html#225
Which means there is a question if this is really invalid code after all.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |SUSPENDED
            Summary|Bad name lookup for         |[DR 225] Bad name lookup for
                   |templates                   |templates


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #7 from pinskia at gcc dot gnu dot org  2009-12-05 00:13 -------
*** Bug 42281 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jezz at hkfree dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates

[pinskia at gcc dot gnu dot org]

------- Comment #8 from pinskia at gcc dot gnu dot org  2009-12-08 22:02 -------
*** Bug 34886 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rvovsd at mail dot ru


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates due to foundemtal types namespace for ADL.

[paolo dot carlini at oracle dot com]

------- Comment #9 from paolo dot carlini at oracle dot com  2010-02-05 12:52 -------
*** Bug 31816 has been marked as a duplicate of this bug. ***


-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nicolas dot burrus at ensta
                   |                            |dot fr


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates due to foundemtal types namespace for ADL.

[pinskia at gcc dot gnu dot org]

------- Comment #10 from pinskia at gcc dot gnu dot org  2010-03-04 20:28 -------
*** Bug 43261 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |boostcpp at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[pinskia at gcc dot gnu dot org]

------- Comment #11 from pinskia at gcc dot gnu dot org  2010-03-24 16:45 -------
*** Bug 43506 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |yao_yin at 163 dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[pinskia at gcc dot gnu dot org]

------- Comment #12 from pinskia at gcc dot gnu dot org  2010-03-29 20:53 -------
*** Bug 43506 has been marked as a duplicate of this bug. ***


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[pinskia at gcc dot gnu dot org]

------- Comment #13 from pinskia at gcc dot gnu dot org  2010-07-29 15:19 -------
*** Bug 45132 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |g_sauthoff at web dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[nplatis at freemail dot gr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

--- Comment #25 from Nikos Platis <nplatis at freemail dot gr> 2012-04-26 21:02:36 UTC ---
The situation in the actual glm is more like the following. We also put t() and
f() in namespace glm as well, se we get the following code, which produces the
error:

namespace glm {
  namespace detail {
    struct dvec3{};
  }
  typedef detail::dvec3 vec3;
}

namespace glm {
    template<class T>
    int t(T i)
    {
    return f (i);
    }

    int f (glm::vec3 i)
    {
      return 0;
    }
}

int main()
{
  glm::vec3 b;
  return glm::t(b);
}

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[marc.glisse at normalesup dot org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Marc Glisse <marc.glisse at normalesup dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |marc.glisse at normalesup
                   |                            |dot org

--- Comment #24 from Marc Glisse <marc.glisse at normalesup dot org> 2012-04-26 19:14:45 UTC ---
(In reply to comment #22)
> I am sorry if my knowledge on this issue is limited, but if I put t() and f()
> in namespace glm (re. the code in comment #20), should this compile? (That is
> what you comment #19 implies). Actually it does not.

So you are talking about this? Notice how vec3 isn't actually in glm.
Interactions between namespaces and name lookup can be difficult.

namespace glm {
  namespace detail {
    struct vec3{};
  }
  using detail::vec3;
}

template<class T>
int t(T i)
{
  return f (i);
}

namespace glm {
  int
    f (glm::vec3 i)
    {
      return 0;
    }
}

int main()
{
  glm::vec3 b;
  return t(b);
}

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

--- Comment #23 from Jason Merrill <jason at gcc dot gnu.org> 2012-04-26 15:51:35 UTC ---
(In reply to comment #22)
> I am sorry if my knowledge on this issue is limited, but if I put t() and f()
> in namespace glm (re. the code in comment #20), should this compile? (That is
> what you comment #19 implies). Actually it does not.

That's surprising, but I would need a self-contained testcase to comment
further.

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[nplatis at freemail dot gr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

--- Comment #22 from Nikos Platis <nplatis at freemail dot gr> 2012-04-26 14:33:45 UTC ---
I am sorry if my knowledge on this issue is limited, but if I put t() and f()
in namespace glm (re. the code in comment #20), should this compile? (That is
what you comment #19 implies). Actually it does not.

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

--- Comment #21 from Jason Merrill <jason at gcc dot gnu.org> 2012-04-26 14:09:14 UTC ---
(In reply to comment #20)
> glm::vec3 does not seem like a fundamental type.

It isn't, but its associated namespace is glm, and your f isn't in glm.

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[nplatis at freemail dot gr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Nikos Platis <nplatis at freemail dot gr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nplatis at freemail dot gr

--- Comment #20 from Nikos Platis <nplatis at freemail dot gr> 2012-04-25 17:33:24 UTC ---
I am having a problem using code similar to the one in comment #5, but using
glm::vec3, from the glm library (http://glm.g-truc.net/), as the type used to
instanciate the template.

Then I get an error message that "‘f’ was not declared in this scope, and no
declarations were found by argument-dependent lookup at the point of
instantiation"

glm::vec3 does not seem like a fundamental type.


#include "glm/glm.hpp"

template<class T>
int t(T i)
{
  return f (i);
}

int
f (glm::vec3 i)
{
  return 0;
}

int
main()
{
  glm::vec3 b;
  return t(b);
}

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |phresnel at gmail dot com

--- Comment #19 from Jason Merrill <jason at gcc dot gnu.org> 2011-09-26 17:07:22 UTC ---
*** Bug 41995 has been marked as a duplicate of this bug. ***

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.7.0

--- Comment #18 from Jason Merrill <jason at gcc dot gnu.org> 2011-05-20 18:56:23 UTC ---
Fixed for 4.7.

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

--- Comment #17 from Jason Merrill <jason at gcc dot gnu.org> 2011-05-20 18:01:27 UTC ---
Author: jason
Date: Fri May 20 18:01:22 2011
New Revision: 173965

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=173965
Log:
    PR c++/24163
    PR c++/29131
gcc/cp/
    * pt.c (tsubst_copy_and_build) [CALL_EXPR]: Avoid repeating
    unqualified lookup.
    * semantics.c (perform_koenig_lookup): Add complain parm.
    * cp-tree.h: Adjust.
    * parser.c (cp_parser_postfix_expression): Adjust.
    (cp_parser_perform_range_for_lookup): Adjust.
libstdc++-v3/
    * include/ext/pb_ds/assoc_container.hpp: Explicitly qualify calls to
    functions from dependent bases.
    * include/ext/pb_ds/detail/rb_tree_map_/erase_fn_imps.hpp: Likewise.
    * include/ext/pb_ds/detail/rb_tree_map_/
    split_join_fn_imps.hpp: Likewise.
    * include/ext/pb_ds/detail/splay_tree_/erase_fn_imps.hpp: Likewise.
    * include/ext/pb_ds/detail/splay_tree_/insert_fn_imps.hpp: Likewise.
    * include/ext/pb_ds/detail/splay_tree_/splay_fn_imps.hpp: Likewise.
    * include/ext/pb_ds/detail/splay_tree_/
    split_join_fn_imps.hpp: Likewise.
    * include/ext/pb_ds/detail/tree_policy/
    order_statistics_imp.hpp: Likewise.
    * include/ext/pb_ds/detail/trie_policy/
    prefix_search_node_update_imp.hpp: Likewise.
    * include/ext/rc_string_base.h: Likewise.
    * include/ext/rope: Likewise.
    * include/ext/ropeimpl.h: Likewise.
    * testsuite/util/exception/safety.h: Likewise.
    * testsuite/util/native_type/native_priority_queue.hpp: Likewise.
    * testsuite/util/testsuite_io.h: Likewise.
    * include/std/functional: Declare mem_fn earlier.
    * include/tr1/functional: Likewise.
    * include/tr1/exp_integral.tcc: Declare __expint_E1 earlier.

Added:
    trunk/gcc/testsuite/g++.dg/template/koenig9.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/cp-tree.h
    trunk/gcc/cp/parser.c
    trunk/gcc/cp/pt.c
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/opt/pr47615.C
    trunk/gcc/testsuite/g++.dg/overload/defarg1.C
    trunk/gcc/testsuite/g++.dg/tc1/dr213.C
    trunk/gcc/testsuite/g++.dg/torture/pr34850.C
    trunk/gcc/testsuite/g++.dg/torture/pr39362.C
    trunk/gcc/testsuite/g++.old-deja/g++.brendan/crash56.C
    trunk/gcc/testsuite/g++.old-deja/g++.pt/memtemp47.C
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/ext/pb_ds/assoc_container.hpp
    trunk/libstdc++-v3/include/ext/pb_ds/detail/rb_tree_map_/erase_fn_imps.hpp
   
trunk/libstdc++-v3/include/ext/pb_ds/detail/rb_tree_map_/split_join_fn_imps.hpp
    trunk/libstdc++-v3/include/ext/pb_ds/detail/splay_tree_/erase_fn_imps.hpp
    trunk/libstdc++-v3/include/ext/pb_ds/detail/splay_tree_/insert_fn_imps.hpp
    trunk/libstdc++-v3/include/ext/pb_ds/detail/splay_tree_/splay_fn_imps.hpp
   
trunk/libstdc++-v3/include/ext/pb_ds/detail/splay_tree_/split_join_fn_imps.hpp
   
trunk/libstdc++-v3/include/ext/pb_ds/detail/tree_policy/order_statistics_imp.hpp
   
trunk/libstdc++-v3/include/ext/pb_ds/detail/trie_policy/prefix_search_node_update_imp.hpp
    trunk/libstdc++-v3/include/ext/rc_string_base.h
    trunk/libstdc++-v3/include/ext/rope
    trunk/libstdc++-v3/include/ext/ropeimpl.h
    trunk/libstdc++-v3/include/std/functional
    trunk/libstdc++-v3/include/tr1/exp_integral.tcc
    trunk/libstdc++-v3/include/tr1/functional
    trunk/libstdc++-v3/testsuite/util/exception/safety.h
    trunk/libstdc++-v3/testsuite/util/native_type/native_priority_queue.hpp
    trunk/libstdc++-v3/testsuite/util/testsuite_io.h

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dave@boost-consulting.com

--- Comment #16 from Jason Merrill <jason at gcc dot gnu.org> 2011-05-20 15:56:21 UTC ---
*** Bug 36883 has been marked as a duplicate of this bug. ***

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |ASSIGNED
                 CC|                            |jason at gcc dot gnu.org
         AssignedTo|unassigned at gcc dot       |jason at gcc dot gnu.org
                   |gnu.org                     |

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

--- Comment #15 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-05-05 00:58:04 UTC ---
http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_closed.html#225 is now NAD
(I think that should un-suspend several PRs)

[Bug c++/29131] [DR 225] Bad name lookup for templates due to fundamental types namespace for ADL.

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29131

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |slyfox at inbox dot ru

--- Comment #14 from Andrew Pinski <pinskia at gcc dot gnu.org> 2010-10-18 20:27:20 UTC ---
*** Bug 46075 has been marked as a duplicate of this bug. ***