[Bug c++/58714] Bogus value category in ternary operator?

[Bug c++/58714] Bogus value category in ternary operator?

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Dup

*** This bug has been marked as a duplicate of bug 53000 ***

[Bug c++/58714] Bogus value category in ternary operator?

[ali.baharev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

--- Comment #2 from Ali Baharev <ali.baharev at gmail dot com> ---
OK, sorry for the dupe.

[Bug c++/58714] Bogus value category in ternary operator?

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

Marc Glisse <glisse at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |NEW
   Last reconfirmed|                            |2013-10-13
                 CC|                            |glisse at gcc dot gnu.org
         Resolution|DUPLICATE                   |---
     Ever confirmed|0                           |1

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
The quoted paragraph is implemented in gcc-4.9. However, this still fails. The
strange thing is that both of these versions work:

  static_cast<X&>(t ? a : b) = X{};
  (t ? a : b) = static_cast<X&&>(X{});

There is special code in cp_build_modify_expr to handle assignment to a
conditional, but it contains this line:

        rhs = stabilize_expr (rhs, &preeval);

which apparently loses the prvalue-ness of rhs.

I think we can consider it as a different issue from PR 53000, because
operator?: worked ok, it is the later assignment which failed. By the way, this
C++03 version:

struct X {
  private:
  X& operator=(const X&);
  X& operator=(X& );
};

void f(bool t) {
  X a, b;
  *(t ? &a : &b) = X();
  (t ? a : b) = X();
}

says:

c.cc: In function 'void f(bool)':
c.cc:3:6: error: 'X& X::operator=(const X&)' is private
   X& operator=(const X&);
      ^
c.cc:9:18: error: within this context
   *(t ? &a : &b) = X();
                  ^
c.cc:4:6: error: 'X& X::operator=(X&)' is private
   X& operator=(X& );
      ^
c.cc:10:15: error: within this context
   (t ? a : b) = X();
               ^
c.cc:4:6: error: 'X& X::operator=(X&)' is private
   X& operator=(X& );
      ^
c.cc:10:15: error: within this context
   (t ? a : b) = X();
               ^

The fact that it tries to use X::operator=(X&) seems like a bug, which could
easily be turned into wrong-code.

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

Marc Glisse <glisse at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code

--- Comment #4 from Marc Glisse <glisse at gcc dot gnu.org> ---
The C++03 wrong-code version:

struct X {
    X& operator=(const X&){}
    X& operator=(X&){__builtin_abort();}
};

int main(int argv,char**) {
  X a, b;
  ((argv > 2) ? a : b) = X();
}

I don't know if stabilize_expr is wrong, or if it is wrong to call it, I'll
leave that to someone else.

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Fri May  9 18:16:05 2014
New Revision: 210283

URL: http://gcc.gnu.org/viewcvs?rev=210283&root=gcc&view=rev
Log:
    PR c++/58714
    * tree.c (stabilize_expr): A stabilized prvalue is an xvalue.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/rv-cond1.C
    trunk/gcc/testsuite/g++.dg/expr/cond12.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/tree.c

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

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

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

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed on trunk currently.

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Thu Aug  7 18:54:27 2014
New Revision: 213724

URL: https://gcc.gnu.org/viewcvs?rev=213724&root=gcc&view=rev
Log:
    PR c++/58714
    * tree.c (stabilize_expr): A stabilized prvalue is an xvalue.

Added:
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/cpp0x/rv-cond1.C
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/expr/cond12.C
Modified:
    branches/gcc-4_9-branch/gcc/cp/ChangeLog
    branches/gcc-4_9-branch/gcc/cp/tree.c

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.9.2

--- Comment #8 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 4.9.2.

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Thu Aug  7 19:50:04 2014
New Revision: 213734

URL: https://gcc.gnu.org/viewcvs?rev=213734&root=gcc&view=rev
Log:
    PR c++/58714
    * tree.c (stabilize_expr): A stabilized prvalue is an xvalue.

Added:
    branches/gcc-4_8-branch/gcc/testsuite/g++.dg/cpp0x/rv-cond1.C
    branches/gcc-4_8-branch/gcc/testsuite/g++.dg/expr/cond12.C
Modified:
    branches/gcc-4_8-branch/gcc/cp/ChangeLog
    branches/gcc-4_8-branch/gcc/cp/tree.c

[Bug c++/58714] Bogus overload resolution for the assignment operator in assignment to a conditional

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58714

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.9.2                       |4.8.4

--- Comment #10 from Jason Merrill <jason at gcc dot gnu.org> ---
And 4.8.4.