From e392b74caad5d93946653d4656f1b354fa0ef713 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Feb 11 2017 13:25:42 +0000
Subject: Vendor import of libc++ release_40 branch r294803:

https://llvm.org/svn/llvm-project/libcxx/branches/release_40@294803

---

diff --git a/docs/conf.py b/docs/conf.py
index dee0367..743d0f7 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -47,9 +47,9 @@ copyright = u'2011-2017, LLVM Project'
 # built documents.
 #
 # The short X.Y version.
-version = '4.0'
+version = '4'
 # The full version, including alpha/beta/rc tags.
-release = '4.0'
+release = '4'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/include/optional b/include/optional
index c002cc7..8f47986 100644
--- a/include/optional
+++ b/include/optional
@@ -160,14 +160,12 @@ namespace std  // purposefully not using versioning namespace
 {
 
 class _LIBCPP_EXCEPTION_ABI bad_optional_access
-    : public logic_error
+    : public exception
 {
 public:
-    _LIBCPP_INLINE_VISIBILITY
-    bad_optional_access() : logic_error("bad optional access") {}
-
     // Get the key function ~bad_optional_access() into the dylib
     virtual ~bad_optional_access() _NOEXCEPT;
+    virtual const char* what() const _NOEXCEPT;
 };
 
 }  // std
diff --git a/include/variant b/include/variant
index f623cdd..bbd4bf4 100644
--- a/include/variant
+++ b/include/variant
@@ -574,7 +574,7 @@ private:
     constexpr decltype(auto) operator()(_Alts&&... __alts) const {
       __std_visit_exhaustive_visitor_check<
           _Visitor,
-          decltype(_VSTD::forward<_Alts>(__alts).__value)...>();
+          decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
       return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
                                 _VSTD::forward<_Alts>(__alts).__value...);
     }
diff --git a/src/optional.cpp b/src/optional.cpp
index f2fbfdf..2877d17 100644
--- a/src/optional.cpp
+++ b/src/optional.cpp
@@ -15,6 +15,10 @@ namespace std
 
 bad_optional_access::~bad_optional_access() _NOEXCEPT = default;
 
+const char* bad_optional_access::what() const _NOEXCEPT {
+  return "bad_optional_access";
+  }
+
 } // std
 
 _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
diff --git a/test/std/utilities/optional/optional.bad_optional_access/derive.pass.cpp b/test/std/utilities/optional/optional.bad_optional_access/derive.pass.cpp
index 85e36d2..d96f70b 100644
--- a/test/std/utilities/optional/optional.bad_optional_access/derive.pass.cpp
+++ b/test/std/utilities/optional/optional.bad_optional_access/derive.pass.cpp
@@ -11,7 +11,7 @@
 
 // <optional>
 
-// class bad_optional_access : public logic_error
+// class bad_optional_access : public exception
 
 #include <optional>
 #include <type_traits>
@@ -20,6 +20,6 @@ int main()
 {
     using std::bad_optional_access;
 
-    static_assert(std::is_base_of<std::logic_error, bad_optional_access>::value, "");
-    static_assert(std::is_convertible<bad_optional_access*, std::logic_error*>::value, "");
+    static_assert(std::is_base_of<std::exception, bad_optional_access>::value, "");
+    static_assert(std::is_convertible<bad_optional_access*, std::exception*>::value, "");
 }
diff --git a/test/std/utilities/variant/variant.visit/visit.pass.cpp b/test/std/utilities/variant/variant.visit/visit.pass.cpp
index 46d2258..408a65c 100644
--- a/test/std/utilities/variant/variant.visit/visit.pass.cpp
+++ b/test/std/utilities/variant/variant.visit/visit.pass.cpp
@@ -283,9 +283,20 @@ void test_exceptions() {
 #endif
 }
 
+// See http://llvm.org/PR31916
+void test_caller_accepts_nonconst() {
+  struct A {};
+  struct Visitor {
+    void operator()(A&) {}
+  };
+  std::variant<A> v;
+  std::visit(Visitor{}, v);
+}
+
 int main() {
   test_call_operator_forwarding();
   test_argument_forwarding();
   test_constexpr();
   test_exceptions();
+  test_caller_accepts_nonconst();
 }