Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

PR11000.cpp
// RUN: not %clang_cc1 -std=c++11 %s 2>&1 | FileCheck %s

// PR11000: Don't crash.
class tuple<>
{
    template <class _Alloc>
        tuple(allocator_arg_t, const _Alloc&) {}

// CHECK: 6 errors generated.