[Bug c++/57901] New: [C++11][constexpr] Cannot call-by-value such that class has non-trivial (constexpr) move constructor

[Bug c++/57901] New: [C++11][constexpr] Cannot call-by-value such that class has non-trivial (constexpr) move constructor

[bolero.murakami at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57901

            Bug ID: 57901
           Summary: [C++11][constexpr] Cannot call-by-value such that
                    class has non-trivial (constexpr) move constructor
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bolero.murakami at gmail dot com

Code:
//--------
struct Z {
    Z()         = default;
    Z(Z const&) = default;
    constexpr Z(Z&&) {} /* non-trivial (constexpr) move ctor */
};

template<typename T>
constexpr int fn0(T v) { return 0; }
template<typename T>
constexpr int fn (T v) { return fn0(v); }

constexpr auto t0 = fn0(Z()); // OK!
constexpr auto t  = fn (Z()); // error! (GCC 4.8.1, -std=c++11)
//--------

Error message:
in constexpr expansion of ‘fn<Z>(Z())’
error: ‘v’ is not a constant expression
   constexpr auto t = fn(Z());
                            ^


Class Z is literal type.
However, compilation error when it is call-by-value(more than once).

I tested this code in gcc-4.7.3, is passed.
The problem is reproduced in gcc-4.8.0, gcc-4.8.1
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idR669

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

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

--- Comment #3 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Tobias, thanks for posting the commit message.

Fixed, closing.

[Bug c++/57901] [4.8/4.9 Regression] Cannot call-by-value such that class has non-trivial (constexpr) move constructor

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57901

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-07-22
      Known to work|                            |4.7.3
            Summary|[C++11][constexpr] Cannot   |[4.8/4.9 Regression] Cannot
                   |call-by-value such that     |call-by-value such that
                   |class has non-trivial       |class has non-trivial
                   |(constexpr) move            |(constexpr) move
                   |constructor                 |constructor
     Ever confirmed|0                           |1
      Known to fail|                            |4.8.0, 4.8.1, 4.9.0

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
We may have a Dup of this.

[Bug c++/57901] [4.8/4.9 Regression] Cannot call-by-value such that class has non-trivial (constexpr) move constructor

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57901

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
   Target Milestone|---                         |4.8.2

[Bug c++/57901] [4.8/4.9 Regression] Cannot call-by-value such that class has non-trivial (constexpr) move constructor

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57901

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

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

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 4.8.2/4.9.0.