[Bug libstdc++/64647] [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[Bug libstdc++/64647] [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64647

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-01-17
      Known to work|                            |4.9.2
     Ever confirmed|0                           |1

[Bug libstdc++/64647] New: [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64647

            Bug ID: 64647
           Summary: [5 Regression] [C++14] std::__max_element contains
                    code not allowed in constexpr function
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
                CC: ville.voutilainen at gmail dot com

#include <forward_list>
#include <algorithm>

int main()
{
  std::forward_list<int> v;
  std::max_element(v.begin(), v.end());
}

Compiling with -std=c++14 gives:

In file included from /home/jwakely/gcc/5/include/c++/5.0.0/algorithm:62:0,
                 from max.cc:2:
/home/jwakely/gcc/5/include/c++/5.0.0/bits/stl_algo.h: In instantiation of
‘constexpr _ForwardIterator std::__max_element(_ForwardIterator,
_ForwardIterator, _Compare) [with _ForwardIterator =
std::_Fwd_list_iterator<int>; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’:
/home/jwakely/gcc/5/include/c++/5.0.0/bits/stl_algo.h:5514:43:   required from
‘constexpr _FIter std::max_element(_FIter, _FIter) [with _FIter =
std::_Fwd_list_iterator<int>]’
max.cc:7:38:   required from here
/home/jwakely/gcc/5/include/c++/5.0.0/bits/stl_algo.h:5489:35: error: variable
‘__result’ of non-literal type ‘std::_Fwd_list_iterator<int>’ in ‘constexpr’
function
       _ForwardIterator __result = __first;
                                   ^
In file included from /home/jwakely/gcc/5/include/c++/5.0.0/forward_list:38:0,
                 from max.cc:1:
/home/jwakely/gcc/5/include/c++/5.0.0/bits/forward_list.h:120:12: note:
‘std::_Fwd_list_iterator<int>’ is not literal because:
     struct _Fwd_list_iterator
            ^
/home/jwakely/gcc/5/include/c++/5.0.0/bits/forward_list.h:120:12: note:  
‘std::_Fwd_list_iterator<int>’ is not an aggregate, does not have a trivial
default constructor, and has no constexpr constructor that is not a copy or
move constructor
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idU932

--- Comment #10 from Paul Thomas <pault at gcc dot gnu.org> ---
Author: pault
Date: Sat Jan 17 18:08:38 2015
New Revision: 219801

URL: https://gcc.gnu.org/viewcvs?rev!9801&root=gcc&view=rev
Log:
2015-01-17  Andre Vehreschild  <vehre@gmx.de>

    PR fortran/60357
    * primary.c (build_actual_constructor): Prevent warning.
    * trans-expr.c (alloc_scalar_allocatable_for_subcomponent_
    assignment): New function encapsulates treatment of allocatable
    components.
    (gfc_trans_subcomponent_assign): Needed to distinguish between
    regular assignment and initilization.
    (gfc_trans_structure_assign): Same.
    (gfc_conv_structure): Same.

    PR fortran/61275
    * gfortran.h: deferred_parameter is not needed, because
    it artificial does the trick completely.
    * primary.c (build_actual_constructor): Same.
    (gfc_convert_to_structure_constructor): Same.
    * resolve.c (resolve_fl_derived0): Same.
    * trans-expr.c (gfc_conv_component_ref): Prevent treating
    allocatable deferred length char arrays here.
    (gfc_trans_subcomponent_assign): Same as above.
    * trans-types.c (gfc_sym_type): This is done in
    gfc_get_derived_type already.

2015-01-17  Andre Vehreschild  <vehre@gmx.de>

    PR fortran/60357
    * gfortran.dg/alloc_comp_assign_13.f08: New test.

    PR fortran/61275
    * gfortran.dg/alloc_comp_assign_14.f08: New test.

    PR fortran/55932
    * gfortran.dg/alloc_comp_initializer_4.f03: New test.

Added:
    trunk/gcc/testsuite/gfortran.dg/alloc_comp_assign_13.f08
    trunk/gcc/testsuite/gfortran.dg/alloc_comp_assign_14.f08
    trunk/gcc/testsuite/gfortran.dg/alloc_comp_initializer_4.f03
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/gfortran.h
    trunk/gcc/fortran/primary.c
    trunk/gcc/fortran/resolve.c
    trunk/gcc/fortran/trans-expr.c
    trunk/gcc/fortran/trans-types.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/64647] [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64647

Ville Voutilainen <ville.voutilainen at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at redhat dot com
          Component|libstdc++                   |c++

--- Comment #1 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
This code

template<typename T>
constexpr T foo(T t)
{
  T tt = t;
  ++tt;
  return tt;
}

struct X
{
  X() { }
  X& operator++() { return *this; }
};

int main()
{
  X x;
  foo(x);
}

is accepted by clang but rejected by gcc. Moving to front-end.

[Bug c++/64647] [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64647

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
   Target Milestone|---                         |5.0

[Bug c++/64647] [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64647

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Wed Jan 21 20:15:35 2015
New Revision: 219965

URL: https://gcc.gnu.org/viewcvs?rev=219965&root=gcc&view=rev
Log:
    PR c++/64647
    * constexpr.c (ensure_literal_type_for_constexpr_object): Don't
    give a hard error in a template instantiation.

Added:
    trunk/gcc/testsuite/g++.dg/cpp1y/constexpr-local3.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/constexpr.c

[Bug c++/64647] [5 Regression] [C++14] std::__max_element contains code not allowed in constexpr function

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64647

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

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

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.