Re: [patch] c++/58051 Implement Core 1579

[Marc Glisse]

On Tue, 1 Jul 2014, Markus Trippelsdorf wrote:

This patch cause yet another LLVM build error:
[...]
Reduced:
markus@x4 llvm_build % cat CompilerInvocation.ii
template <typename T> class A
{
 T Obj;

public:
 T element_type;
 A (T *);
 template <class X> A (A<X> &&p1) { p1.Obj; }
 template <class X> A (A<X> &);
};

class B
{
public:
 B (A<int>);
};
A<int> fn1 ()
{
 A<B> a (new B (0));
 return a;
}

markus@x4 llvm_build % /var/tmp/gcc_test/usr/local/bin/g++ -c -std=c++11 
CompilerInvocation.ii
CompilerInvocation.ii: In instantiation of ‘A<T>::A(A<X>&&) [with X = B; T = 
int]’:
CompilerInvocation.ii:20:10:   required from here
CompilerInvocation.ii:3:5: error: ‘B A<B>::Obj’ is private
  T Obj;
    ^
CompilerInvocation.ii:8:38: error: within this context
  template <class X> A (A<X> &&p1) { p1.Obj; }
                                     ^

This looks invalid. As the core issue says, the return statement looks up 
a as an rvalue, so it uses that constructor for A<int>, and that uses a 
private member of a different specialization of A, which is illegal.

--
Marc Glisse