[Bug c++/58954] New: accessing a private member function in decltype of a friend class causes access control error

[Bug c++/58954] New: accessing a private member function in decltype of a friend class causes access control error

[myspam456 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

            Bug ID: 58954
           Summary: accessing a private member function in decltype of a
                    friend class causes access control error
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: myspam456 at gmail dot com

When trying to use decltype on a member function which has a late specified
return type calling a private member function of a friend class I receive the
below error.  My understanding is that the "friend struct base<derived>;" in
derived should cause this error to not occur which is the case with clang.  

Adding "foo_argument<derived>" does cause the error to disappear.  

I apologize for the length of the example, but I've had difficulty reproducing
it with fewer lines of code.

main.cpp: In instantiation of ‘struct foo_argument<derived>’:
main.cpp:43:47:   required from here
main.cpp:9:50: error: no matching function for call to
‘foo_argument<derived>::test(<unresolved overloaded function type>)’
     using type = decltype(test(&T::template foo<>));
                                                  ^
main.cpp:9:50: note: candidate is:
main.cpp:7:16: note: template<class Ret, class C, class Arg> static Arg
foo_argument<T>::test(Ret (C::*)(Arg)) [with Ret = Ret; C = C; Arg = Arg; T =
derived]
     static Arg test(Ret (C::*)(Arg));
                ^
main.cpp:7:16: note:   template argument deduction/substitution failed:
main.cpp:35:9: error: ‘int derived::foo_impl(int)’ is private
     int foo_impl(int i)
         ^
main.cpp:9:50: error: within this context
     using type = decltype(test(&T::template foo<>));

The below example can be seen at:
http://coliru.stacked-crooked.com/a/3ffd6557434a3ab9

#include <utility>

template<class T>
struct foo_argument
{
    template<class Ret, class C, class Arg>
    static Arg test(Ret (C::*)(Arg));

    using type = decltype(test(&T::template foo<>));
};

template<class T, class D>
struct dependent { typedef T type; };

template<class T, class D>
using Dependent = typename dependent<T, D>::type;

template<class T>
struct base
{
    friend struct foo_argument<T>;

    template<class Ignore = void>
    auto foo(int i) -> decltype(std::declval<Dependent<T&,
Ignore>>().foo_impl(i))
    {
        return static_cast<T&>(*this).foo_impl(i);
    }
};

struct derived : base<derived>
{
    friend struct base<derived>;
    //friend struct foo_argument<derived>;
  private:
    int foo_impl(int i)
    {
        return 123 + i;
    }
};

int main()
{
    using foo_arg_type = foo_argument<derived>::type;
}
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Subject: [Bug tree-optimization/58955] New: wrong code at -O3 on x86_64-linux-gnu
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idX955

            Bug ID: 58955
           Summary: wrong code at -O3 on x86_64-linux-gnu
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

The current gcc trunk miscompiles the following testcase on x86_64-linux-gnu at
-O3 (in both 32-bit and 64-bit modes).

This is a regression from 4.8.x.

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure
--enable-languages=c,c++,objc,obj-c++,fortran,lto --disable-werror
--enable-checking=none --with-gmp=/usr/local/gcc-trunk
--with-mpfr=/usr/local/gcc-trunk --with-mpc=/usr/local/gcc-trunk
--with-cloog=/usr/local/gcc-trunk --prefix=/usr/local/gcc-trunk
Thread model: posix
gcc version 4.9.0 20131031 (experimental) [trunk revision 204248] (GCC)
$
$ gcc-trunk -O2 small.c; a.out
1
$ gcc-4.8 -O3 small.c; a.out
1
$ gcc-trunk -O3 small.c; a.out
0
$

------------------------------------


int printf (const char *, ...);

int a, b, c, d[4] = { 0, 0, 0, 1 };

int
main ()
{
  for (; a < 4; a++)
    {
      int e = d[a];
      for (c = 1; c < 1; c++);
      b = e;
      d[a] = 0;
    }
  printf ("%d\n", b);
  return 0;
}

[Bug c++/58954] accessing a private member function in decltype of a friend class causes access control error

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler@googlemail.
                   |                            |com

--- Comment #1 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
This seems to be a regression, the example was accepted in gcc 4.7.3.

The following is a first attempt to reduce the complexity of the example, in
particular by removing any library dependencies and any possible interaction
with alias templates and alias typedefs, furthermore the additional friend
declaration in template base is neither needed nor should it be relevant for
this issue, therefore has been removed:

//---------------
template<class T>
T&& declval();

template<class T>
struct foo_argument
{
  template<class Ret, class C, class Arg>
  static Arg test(Ret (C::*)(Arg));

  typedef decltype(test(&T::template foo<>)) type;
};

template<class T, class>
struct dependent { typedef T type; };

template<class T>
struct base
{
  template<class Ignore = void>
  auto foo(int i) -> decltype(declval<
    typename dependent<T&, Ignore>::type
  >().foo_impl(i));
};

struct derived : base<derived>
{
  friend struct base<derived>;
private:
  int foo_impl(int i);
};

int main()
{
  foo_argument<derived>::type var = 0;
  return var;
}
//---------------
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Subject: [Bug fortran/57893] Crash for allocatable character string during compilation.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW893

--- Comment #2 from Paul Thomas <pault at gcc dot gnu.org> ---
Author: pault
Date: Fri Nov  1 06:56:41 2013
New Revision: 204286

URL: http://gcc.gnu.org/viewcvs?rev 4286&root=gcc&view=rev
Log:
2013-11-01  Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/57893
    * gfortran.dg/unlimited_polymorphic_13.f90 : Break up select
    type block.

Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/gfortran.dg/unlimited_polymorphic_13.f90

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-01
                 CC|myspam456 at gmail dot com         |
            Summary|accessing a private member  |[4.8/4.9 Regression]
                   |function in decltype of a   |accessing a private member
                   |friend class causes access  |function in decltype of a
                   |control error               |friend class causes access
                   |                            |control error
     Ever confirmed|0                           |1

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Thanks Daniel.

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.8.3

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

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

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

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri Dec 13 03:58:48 2013
New Revision: 205952

URL: http://gcc.gnu.org/viewcvs?rev=205952&root=gcc&view=rev
Log:
    PR c++/58954
    * pt.c (resolve_overloaded_unification): Use instantiate_template.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/access02.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/pt.c

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri Dec 13 03:59:10 2013
New Revision: 205954

URL: http://gcc.gnu.org/viewcvs?rev=205954&root=gcc&view=rev
Log:
    PR c++/58954
    * pt.c (resolve_overloaded_unification): Discard access checks.

Added:
    branches/gcc-4_8-branch/gcc/testsuite/g++.dg/cpp0x/access02.C
Modified:
    branches/gcc-4_8-branch/gcc/cp/ChangeLog
    branches/gcc-4_8-branch/gcc/cp/pt.c

[Bug c++/58954] [4.8/4.9 Regression] accessing a private member function in decltype of a friend class causes access control error

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58954

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

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

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 4.8.3/4.9.