On 08/02/17 13:56 +0000, Jonathan Wakely wrote:
Definitely a clang bug, see http://melpon.org/wandbox/permlink/PkbNSpvjPrLh8rovIf we remove the nested namespace we see that the friend declaration is declaring a second, unrelated function, and so we get an ambiguity: http://melpon.org/wandbox/permlink/wvmzgAzpLp5pOf86
It's https://llvm.org/bugs/show_bug.cgi?id=31852