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Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

warn-unused-variables.h
// Verify that we don't warn about variables of internal-linkage type in
// headers, as the use may be in another TU.
namespace PR15558 {
namespace {
class A {};
}

class B {
  static A a;
  static A b;
  static const int x = sizeof(b);
};
}