[Bug c++/50828] New: class template parameter not printed for member function template in candidate list

[Bug c++/50828] New: class template parameter not printed for member function template in candidate list

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

             Bug #: 50828
           Summary: class template parameter not printed for member
                    function template in candidate list
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: redi@gcc.gnu.org


template<typename T>
  struct A {
    template<typename U>
      void f() { }
  };

int main() {
  A<void> a;
  a.f(0);
}

With -fpretty-templates this gives:

f.C: In function ‘int main()’:
f.C:9:8: error: no matching function for call to ‘A<void>::f(int)’
f.C:9:8: note: candidate is:
f.C:4:12: note: template<class U> void A::f() [with U = U, T = void]

T is shown in the argument list, but not the signature. It should be:

f.C:4:12: note: template<class U> void A<T>::f() [with U = U, T = void]
                                        ^^^

For a non-template member function the class template parameter is shown
correctly.

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-22 13:29:19 UTC ---
I noticed this while analysing PR 42356, the missing template argument makes it
much harder to see why name lookup results are ambiguous

template<typename T>
  struct A {
    template<typename U>
      void f() { }
  };

struct B : A<int>, A<void> { };

int main() {
  B a;
  a.f();
}

f.C: In function ‘int main()’:
f.C:11:5: error: request for member ‘f’ is ambiguous
f.C:4:12: error: candidates are: template<class U> void A::f() [with U = U, T =
void]
f.C:4:12: error:                 template<class U> void A::f() [with U = U, T =
int]

Because T isn't shown in the signature it's not immediately obvious that name
lookup found A<void>::f and A<int>::f in different base classes.

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-22 21:39:49 UTC ---
Seems due to the below, ie, no decoration for a primary. Remains to be seen if
in other contexts (in this case the call chain is dump_template_decl ->
dump_function_decl -> dump_type -> dump_aggr_type -> dump_template_parms) we
actually do *not* want decorations, otherwise seems easy to change.

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

/* Dump the template parameters from the template info INFO under control of
   FLAGS. PRIMARY indicates whether this is a primary template decl, or
   specialization (partial or complete). For partial specializations we show
   the specialized parameter values. For a primary template we show no
   decoration.  */

static void
dump_template_parms (tree info, int primary, int flags)
{
  tree args = info ? TI_ARGS (info) : NULL_TREE;

  if (primary && flags & TFF_TEMPLATE_NAME)
    return;

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-22 22:01:12 UTC ---
Changing it would be consistent with the output for non-template member
functions of class templates:

template<typename T>
  struct A {
    void f() { }
  };

int main() {
  A<void> a;
  a.f(0);
}

t.C: In function ‘int main()’:
t.C:8:8: error: no matching function for call to ‘A<void>::f(int)’
t.C:8:8: note: candidate is:
t.C:3:10: note: void A<T>::f() [with T = void]
t.C:3:10: note:   candidate expects 0 arguments, 1 provided

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-22 23:39:06 UTC ---
Indeed.

The difference between the two is in flags (primary is true for both of
course): due to the '| TFF_TEMPLATE_NAME' # error.c:1214 in dump_template_decl.
The fact is, toward the end of dump_template_decl there are quite a few of '|
TFF_TEMPLATE_NAME' and before trying removing one we should make sense of the
others.

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-10-23
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com
     Ever Confirmed|0                           |1

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-10-23 19:13:51 UTC ---
Looking into it.

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

--- Comment #6 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-09-24 16:56:52 UTC ---
Author: paolo
Date: Mon Sep 24 16:56:41 2012
New Revision: 191673

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=191673
Log:
2012-09-24  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/50828
    * error.c (dump_function_decl): Strip TFF_TEMPLATE_NAME from flags
    at the outset.

Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/error.c

[Bug c++/50828] class template parameter not printed for member function template in candidate list

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50828

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.8.0

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-09-24 16:58:40 UTC ---
Fixed.