[Bug c++/63149] New: can't initialize std::vector<T> from auto-deduced type 'const std::initializer_list<T> &'

[Bug c++/63149] New: can't initialize std::vector<T> from auto-deduced type 'const std::initializer_list<T> &'

[richard-gccbugzilla at metafoo dot co.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63149

            Bug ID: 63149
           Summary: can't initialize std::vector<T> from auto-deduced type
                    'const std::initializer_list<T> &'
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: richard-gccbugzilla at metafoo dot co.uk

Reduced testcase:

namespace std {
  template<typename T> struct initializer_list {
    const T *p; unsigned long n;
    initializer_list(const T *p, unsigned long n);
  };
}
struct vector { vector(std::initializer_list<int>); };
void f(vector);
const auto &r = {1, 2, 3};
int main() { f(r); }

GCC rejects-valid here, saying: 

<stdin>:10:15: error: could not convert ‘r’ from ‘const
std::initializer_list<const int>’ to ‘vector’

Replacing

  const auto &r = {1, 2, 3};

with any of

  const std::initializer_list<int> &r = {1, 2, 3};
  auto &&r = {1, 2, 3};
  auto r = {1, 2, 3};

... makes the problem disappear, so it seems that the 'const' from the
reference is somehow getting muddled into the
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From: "richard-gccbugzilla at metafoo dot co.uk" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/63149] wrong auto deduction from braced-init-list
Date: Wed, 03 Sep 2014 01:07:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idc149

Richard Smith <richard-gccbugzilla at metafoo dot co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|can't initialize            |wrong auto deduction from
                   |std::vector<T> from         |braced-init-list
                   |auto-deduced type 'const    |
                   |std::initializer_list<T> &' |

--- Comment #1 from Richard Smith <richard-gccbugzilla at metafoo dot co.uk> ---
... deduced type. [Oops, hit 'enter' early.]

Even simpler testcase:

#include <initializer_list>
const auto r = { 1, 2, 3 };
using X = decltype(r);
using X = const std::initializer_list<int>;

fails because decltype(r) is deduced as 'const std::initializer_list<const
int>' rather than 'const std::initializer_list<int>'.

[Bug c++/63149] wrong auto deduction from braced-init-list

[ppluzhnikov at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63149

Paul Pluzhnikov <ppluzhnikov at google dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ppluzhnikov at google dot com

--- Comment #2 from Paul Pluzhnikov <ppluzhnikov at google dot com> ---
Google ref: b/17312516

[Bug c++/63149] wrong auto deduction from braced-init-list

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63149

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-12-13
                 CC|                            |ville.voutilainen at gmail dot com
     Ever confirmed|0                           |1
      Known to fail|                            |4.8.2, 4.9.1, 5.0