[Bug libstdc++/57043] New: converting overloaded complex function pow in C++11 is ambiguous

[Bug libstdc++/57043] New: converting overloaded complex function pow in C++11 is ambiguous

[frederic.hecht at upmc dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

             Bug #: 57043
           Summary: converting overloaded complex function pow in C++11 is
                    ambiguous
    Classification: Unclassified
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: frederic.hecht@upmc.fr


problem template the code is trivial 2 lines:
do not  compile in version 4.9, 4.8.1 4.9  with 
/usr/local/bin/g++ -v -save-temps -std=c++11 -c bugcc.cpp 

the code: 

#include <complex> 
std::complex<double>  (* powcc  )( const  std::complex<double>  &, const
std::complex<double>  &) =std::pow;

the output is 

COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.8.3' '-v' '-save-temps'
'-std=c++11' '-c' '-shared-libgcc' '-mtune=core2'
 /usr/local/libexec/gcc/x86_64-apple-darwin12.3.0/4.8.1/cc1plus -fpreprocessed
bugcc.ii -fPIC -quiet -dumpbase bugcc.cpp -mmacosx-version-min=10.8.3
-mtune=core2 -auxbase bugcc -std=c++11 -version -o bugcc.s
GNU C++ (GCC) version 4.8.1 20130404 (prerelease) (x86_64-apple-darwin12.3.0)
    compiled by GNU C version 4.8.1 20130404 (prerelease), GMP version 4.3.1,
MPFR version 2.4.1, MPC version 0.8.1
heuristiques GGC: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (GCC) version 4.8.1 20130404 (prerelease) (x86_64-apple-darwin12.3.0)
    compiled by GNU C version 4.8.1 20130404 (prerelease), GMP version 4.3.1,
MPFR version 2.4.1, MPC version 0.8.1
heuristiques GGC: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 848d439cd6121247863767d4caeedace
bugcc.cpp:2:100: erreur: converting overloaded function ‘pow’ to type ‘struct
std::complex<double> (*)(const struct std::complex<double>&, const struct
std::complex<double>&)’ is ambiguous
 std::complex<double>  (* powcc  )( const  std::complex<double>  &, const
std::complex<double>  &) =std::pow;
                                                                               
                    ^
In file included from bugcc.cpp:1:0:
/usr/local/include/c++/4.8.1/complex:1023:5: note: candidats sont:
std::complex<_Tp> std::pow(const std::complex<_Tp>&, const std::complex<_Tp>&)
[with _Tp = double]
     pow(const complex<_Tp>& __x, const complex<_Tp>& __y)
     ^
In file included from bugcc.cpp:1:0:
/usr/local/include/c++/4.8.1/complex:1871:5: note:                
std::complex<typename __gnu_cxx::__promote_2<_Tp, _Up>::__type> std::pow(const
std::complex<_Tp>&, const std::complex<_Up>&) [with _Tp = double; _Up = double;
typename __gnu_cxx::__promote_2<_Tp, _Up>::__type = double]
     pow(const std::complex<_Tp>& __x, const std::complex<_Up>& __y)
     ^
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From: "pberuto at yahoo dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/57044] New: The following code won't compile with -std=c++0x
Date: Tue, 23 Apr 2013 10:29:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW044

             Bug #: 57044
           Summary: The following code won't compile with -std=c++0x
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: pberuto@yahoo.com


The following code causes a GCC internal error Segmentation fault:

class myclass
{
public:
   template<typename T_>
   inline explicit myclass(T_ *s)
   {
      char buf[mylib::someclass::some_const]; // this line causes the fault
      // ... do something useful with buf
   }

   ...
};

// somewhere else:
nemaspace mylib
{
   class someclass
   {
   public:
      static const uint32_t some_const;
   }
}

// other info:
all GCC versions from 4.5.3 and below compile that code fine. Not tested with
other gcc versions before 4.7.2.
compile flags are CXXFLAGS="-g -O0 -pipe -std=c++0x"

Thank you.

[Bug c++/57043] converting overloaded complex function pow in C++11 is ambiguous

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-04-23
          Component|libstdc++                   |c++
      Known to work|                            |4.6.3
     Ever Confirmed|0                           |1
      Known to fail|                            |4.7.3, 4.8.0, 4.9.0

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-04-23 11:12:21 UTC ---
I think this is a front-end issue, the following compiles OK with G++ 4.6,
Clang 3.3 and ICC 13, but not G++ 4.7+ (in c++98 or c++11 mode)


template<typename D> struct complex { };

template<typename Tp>
inline complex<Tp>
pow(const complex<Tp>& x, const complex<Tp>& y)
{ return x; }

template<typename T, typename U>
struct promote_2
{
    typedef T type;
};

template<typename Tp, typename Up>
inline complex<typename promote_2<Tp, Up>::type>
pow(const complex<Tp>& x, const complex<Up>& y)
{ return x; }


complex<double> (*powcc)(const complex<double>&, const complex<double>&) = pow;

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|converting overloaded       |[4.7/4.8/4.9 Regression]
                   |complex function pow in     |converting overloaded
                   |C++11 is ambiguous          |complex function pow in
                   |                            |C++11 is ambiguous

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Marking (tentatively) as regression, then.

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

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

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

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
OK, this is puzzling.

The issue is that GCC can't tell that the first pow is more specialized than
the second; deduction happens fine, but when we substitute in Tp(1) for Tp(2)
and Up we still have complex<typename promote_2<Tp(1), Tp(1)>::type> for the
return type, which looks different from complex<Tp(1)>, so deduction fails and
we decide it isn't more specialized.

I can't figure out what interpretation of the standard clang/EDG are using to
make this work.  Are they actually instantiating promote_2?  That doesn't seem
to be it, as they also accept the following, which seems clearly unordered to
me:

template<typename D> struct complex { };

template <class T> struct promote_1 { typedef T type; };
template<typename T, typename U> struct promote_2 { typedef T type; };

template<typename Tp>
complex<typename promote_1<Tp>::type>
pow(const complex<Tp>& x, const complex<Tp>& y);

template<typename Tp, typename Up>
complex<typename promote_2<Tp, Up>::type>
pow(const complex<Tp>& x, const complex<Up>& y);

complex<double> (*powcc)(const complex<double>&, const complex<double>&) = pow;

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.4

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
So this is rightfully rejected?

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

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

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

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Discussion in the C++ committee has convinced me that G++ is wrong here.

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri Jan 31 15:20:05 2014
New Revision: 207345

URL: http://gcc.gnu.org/viewcvs?rev=207345&root=gcc&view=rev
Log:
    PR c++/57043
    * pt.c (fn_type_unification): Don't do DEDUCE_EXACT check
    during partial ordering.

Added:
    trunk/gcc/testsuite/g++.dg/template/partial15.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/pt.c

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri Jan 31 15:21:13 2014
New Revision: 207347

URL: http://gcc.gnu.org/viewcvs?rev=207347&root=gcc&view=rev
Log:
    PR c++/57043
    * pt.c (fn_type_unification): Don't do DEDUCE_EXACT check
    during partial ordering.

Added:
    branches/gcc-4_8-branch/gcc/testsuite/g++.dg/template/partial15.C
Modified:
    branches/gcc-4_8-branch/gcc/cp/ChangeLog
    branches/gcc-4_8-branch/gcc/cp/pt.c

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

--- Comment #8 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri Jan 31 15:55:46 2014
New Revision: 207355

URL: http://gcc.gnu.org/viewcvs?rev=207355&root=gcc&view=rev
Log:
    PR c++/57043
    * pt.c (fn_type_unification): Don't do DEDUCE_EXACT check
    during partial ordering.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/g++.dg/template/partial15.C
Modified:
    branches/gcc-4_7-branch/gcc/cp/ChangeLog
    branches/gcc-4_7-branch/gcc/cp/pt.c

[Bug c++/57043] [4.7/4.8/4.9 Regression] converting overloaded complex function pow in C++11 is ambiguous

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043

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

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

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.