Create a new channel as a copy of main.
Rename main to:
Delete main? This cannot be undone.
// RUN: %clang_cc1 %s -fblocks -triple x86_64-apple-darwin -emit-llvm -o - | FileCheck %s struct A { ~A(); }; void f() { __block A a; } // CHECK: call void @_ZN1AD1Ev