Change the base class of std::bad_optional_access.  This is a (subtle) ABI change, and is in response to http://http://wg21.link/LWG2806, which I *expect* to be adopted in Kona. I am making this change now in anticipation, and will get it into 4.0, because (a) 4.0 is the first release with std::optional, and (b) I don't want to make an ABI-change later, when the user base should be significantly larger. Note that I didn't change std::experimental::bad_optional_access, because that's still specified to derive from std::logic_error.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294133 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/experimental/optional b/include/experimental/optional
index f32941b..ba06972 100644
--- a/include/experimental/optional
+++ b/include/experimental/optional
@@ -152,7 +152,7 @@
 	bad_optional_access() : std::logic_error("Bad optional Access") {}
 
 //	Get the key function ~bad_optional_access() into the dylib
-    virtual ~bad_optional_access() _NOEXCEPT;
+    virtual ~bad_optional_access();
 };
 
 _LIBCPP_END_NAMESPACE_EXPERIMENTAL
diff --git a/include/optional b/include/optional
index b13a2d5..ff3e929 100644
--- a/include/optional
+++ b/include/optional
@@ -160,14 +160,12 @@
 {
 
 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 ~bad_optional_access();
+    virtual const char* what() const _NOEXCEPT;
 };
 
 }  // std
diff --git a/src/optional.cpp b/src/optional.cpp
index f2fbfdf..baee026 100644
--- a/src/optional.cpp
+++ b/src/optional.cpp
@@ -13,12 +13,16 @@
 namespace std
 {
 
-bad_optional_access::~bad_optional_access() _NOEXCEPT = default;
+bad_optional_access::~bad_optional_access() = default;
+
+const char* bad_optional_access::what() const _NOEXCEPT {
+  return "bad_optional_access";
+  }
 
 } // std
 
 _LIBCPP_BEGIN_NAMESPACE_EXPERIMENTAL
 
-bad_optional_access::~bad_optional_access() _NOEXCEPT = default;
+bad_optional_access::~bad_optional_access() = default;
 
 _LIBCPP_END_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 @@
 {
     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, "");
 }