// size:
_LIBCPP_INLINE_VISIBILITY
- size_type size() const {return __matches_.size();}
+ size_type size() const _NOEXCEPT {return __matches_.size();}
_LIBCPP_INLINE_VISIBILITY
- size_type max_size() const {return __matches_.max_size();}
- _LIBCPP_INLINE_VISIBILITY
- bool empty() const {return size() == 0;}
+ size_type max_size() const _NOEXCEPT {return __matches_.max_size();}
+ _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
+ bool empty() const _NOEXCEPT {return size() == 0;}
// element access:
_LIBCPP_INLINE_VISIBILITY
--- /dev/null
+// -*- 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.
+//
+//===----------------------------------------------------------------------===//
+
+// <regex>
+
+// class match_results<BidirectionalIterator, Allocator>
+// bool empty() const;
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
+// UNSUPPORTED: clang-3.3, clang-3.4, clang-3.5, clang-3.6, clang-3.7, clang-3.8
+
+#include <regex>
+
+#include "test_macros.h"
+
+int main ()
+{
+ std::match_results<const char*> c;
+ c.empty(); // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+}