Fix a typo in the synopsis comment. NFC. Thanks to K-ballo for the catch
llvm-svn: 324851
diff --git a/libcxx/include/utility b/libcxx/include/utility
index 535e3cb..f11d580 100644
--- a/libcxx/include/utility
+++ b/libcxx/include/utility
@@ -52,7 +52,7 @@
>::type
move_if_noexcept(T& x) noexcept; // constexpr in C++14
-template <class T> constexpr add_const<T>_t& as_const(T& t) noexcept; // C++17
+template <class T> constexpr add_const_t<T>& as_const(T& t) noexcept; // C++17
template <class T> void as_const(const T&&) = delete; // C++17
template <class T> typename add_rvalue_reference<T>::type declval() noexcept;