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

1 files changed, 44 insertions, 0 deletions

diff --git a/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_assign.fail.cpp b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_assign.fail.cpp
new file mode 100644
index 00000000000..18193e000ed
--- /dev/null
+++ b/libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/variadic_assign.fail.cpp
@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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
+// UNSUPPORTED: c++98, c++03
+
+// <mutex>
+
+// template <class ...Mutex> class lock_guard;
+
+// lock_guard& operator=(lock_guard const&) = delete;
+
+#define _LIBCPP_ABI_VARIADIC_LOCK_GUARD
+#include <mutex>
+
+int main()
+{
+    using M = std::mutex;
+    M m0, m1, m2;
+    M om0, om1, om2;
+    {
+        using LG = std::lock_guard<>;
+        LG lg1, lg2;
+        lg1 = lg2; // expected-error{{overload resolution selected deleted operator '='}}
+    }
+    {
+        using LG = std::lock_guard<M, M>;
+        LG lg1(m0, m1);
+        LG lg2(om0, om1);
+        lg1 = lg2; // expected-error{{overload resolution selected deleted operator '='}}
+    }
+    {
+        using LG = std::lock_guard<M, M, M>;
+        LG lg1(m0, m1, m2);
+        LG lg2(om0, om1, om2);
+        lg1 = lg2; // expected-error{{overload resolution selected deleted operator '='}}
+    }
+}