[Bug c++/64352] New: [5.0 regression] No SFINAE with deleted function

[Bug c++/64352] New: [5.0 regression] No SFINAE with deleted function

[lucdanton at free dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64352

            Bug ID: 64352
           Summary: [5.0 regression] No SFINAE with deleted function
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: lucdanton at free dot fr

Created attachment 34300
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34300&action=edit
Minimal testcase

Using:
g++-trunk (GCC) 5.0.0 20141218 (experimental)

Testcase:

template<bool B> struct bool_type
{ static constexpr bool value = B; };

using true_type = bool_type<true>;
using false_type = bool_type<false>;

template<typename T> T&& declval();

template<typename...> struct void_ { using type = void; };
template<typename... I> using void_t = typename void_<I...>::type;

template<typename _Tp, typename = void>
struct _Has_addressof_free: false_type { };

template<typename _Tp>
struct _Has_addressof_free
<_Tp, void_t<decltype( operator&(declval<const _Tp&>()) )>>
: true_type { };

struct foo {};
void operator&(foo) = delete;

int main()
{
    static_assert( !_Has_addressof_free<int>::value, "" );
    // error: use of deleted function 'void operator&(foo)'
    static_assert( _Has_addressof_free<foo>::value, "" );
}

This produces the following:

$ g++-trunk -std=c++11 main.cpp 
main.cpp: In function 'int main()':
main.cpp:17:33: error: use of deleted function 'void operator&(foo)'
 <_Tp, void_t<decltype( operator&(declval<const _Tp&>()) )>>
                                 ^
main.cpp:21:6: note: declared here
 void operator&(foo) = delete;
      ^
main.cpp:27:5: error: static assertion failed: 
     static_assert( _Has_addressof_free<foo>::value, "" );
     ^

I'm not entirely sure this is a regression, e.g. libstdc++'s
testsuite/experimental/optional/observers/2.cc is very similar
but passes. I'm working on experimental/optional however and
I ended up tripping over this, and I didn't touch the
_Has_addressof_* stuff. It is copied (almost) verbatim here,
but not the declval/true_type/false_type/[__]void[_t] bits,
in case that's of any help.

Changing the deleted definition with e.g. a dummy definition
('{}') makes the program compiles as expected.

[Bug c++/64352] [5.0 regression] No SFINAE with deleted function

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64352

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2014-12-18
                 CC|                            |jason at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org
     Ever confirmed|0                           |1

[Bug c++/64352] [5.0 regression] No SFINAE with deleted function

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64352

--- Comment #1 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Thu Dec 18 22:22:42 2014
New Revision: 218877

URL: https://gcc.gnu.org/viewcvs?rev=218877&root=gcc&view=rev
Log:
    PR c++/64352
    * pt.c (tsubst_copy_and_build): Pass complain to mark_used.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/deleted9.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/pt.c

[Bug c++/64352] [5.0 regression] No SFINAE with deleted function

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64352

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |5.0

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.

[Bug c++/64352] [5.0 regression] No SFINAE with deleted function

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64352

--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Wed Jan  7 15:18:32 2015
New Revision: 219310

URL: https://gcc.gnu.org/viewcvs?rev=219310&root=gcc&view=rev
Log:
    PR c++/64352
    * pt.c (tsubst_copy_and_build): Pass complain to mark_used.

Added:
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/cpp0x/deleted9.C
Modified:
    branches/gcc-4_9-branch/gcc/cp/ChangeLog
    branches/gcc-4_9-branch/gcc/cp/pt.c