Eric Fiselier 48f35e074e Implement variadic lock_guard.
Summary:
This patch implements the variadic `lock_guard` paper. 

Making `lock_guard` variadic is a ABI breaking change because the specialization `lock_guard<_Mutex>` mangles differently then when it was the primary template. This change only provides variadic `lock_guard` in ABI V2 or when `_LIBCPP_ABI_VARIADIC_LOCK_GUARD` is defined.

Note that in ABI V2 `lock_guard` must always be declared as a variadic template, even in C++03, in order to keep the ABI consistent. For this reason `lock_guard` is forward declared as a variadic template in all standard dialects and therefore depends on variadic templates being provided as an extension in C++03. All supported versions of Clang and GCC provide this extension.




Reviewers: mclow.lists

Subscribers: K-ballo, mclow.lists, cfe-commits

Differential Revision: http://reviews.llvm.org/D21260

llvm-svn: 272634
2016-06-14 03:48:09 +00:00

25 lines
626 B
C++

//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: libcpp-has-no-threads
// <mutex>
// template <class Mutex> class lock_guard;
// explicit lock_guard(mutex_type& m);
#include <mutex>
int main()
{
std::mutex m;
std::lock_guard<std::mutex> lg = m; // expected-error{{no viable conversion}}
}