AC_DEFUN([AX_ISC_CPP14], [

CXX_SAVED=$CXX
feature=
for retry in "none" "--std=c++14" "--std=c++1y" "fail"; do
        if test "$retry" = "fail"; then
                AC_MSG_ERROR([$feature (a C++14 feature) is not supported])
        fi
        if test "$retry" != "none"; then
                AC_MSG_WARN([unsupported C++14 feature])
                AC_MSG_NOTICE([retrying by adding $retry to $CXX])
                CXX="$CXX_SAVED $retry"
                AC_MSG_CHECKING($retry support)
                AC_COMPILE_IFELSE(
                        [AC_LANG_PROGRAM(
                                [],
                                [int myincr = 1;])],
                        [AC_MSG_RESULT([yes])],
                        [AC_MSG_RESULT([no])
                         continue])
        fi

        AC_MSG_CHECKING(std::unique_ptr support)
        feature="std::unique_ptr"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <memory>],
                        [std::unique_ptr<int> a;])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(cbegin/cend support)
        feature="cbegin/cend"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <string>],
                        [const std::string& s = "abcd";
                         unsigned count = 0;
                         for (std::string::const_iterator i = s.cbegin();
                              i != s.cend(); ++i)
                                if (*i == 'b')
                                        ++count;])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(final method support)
        feature="final method"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [class Foo {
                         public:
                                virtual ~Foo() {};
                                virtual void bar() final;
                         };],[])],
                 [AC_MSG_RESULT([yes])],
                 [AC_MSG_RESULT([no])
                  continue])

        AC_MSG_CHECKING(override method support)
        feature="override method"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [class Foo {
                         public:
                                virtual ~Foo() {};
                                virtual void foobar();
                         };
                         class Bar : public Foo {
                         public:
                                virtual ~Bar() {};
                                virtual void foobar() override;
                         };],[])],
                 [AC_MSG_RESULT([yes])],
                 [AC_MSG_RESULT([no])
                  continue])

        AC_MSG_CHECKING(aggregate initialization support)
        feature="aggregate initialization"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <vector>],
                        [std::vector<int> foo = { 1, 2, 3};])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(variadic template support)
        feature="variadic template"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [template<typename ... Args>
                         struct A {
                         void foo(Args... myargs) { return; };
                         };],
                         [A<> a;
                          a.foo();])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(static_assert support)
        feature="static_assert"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [static_assert(1 + 1 == 2, "");],
                        [])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(template alias)
        feature="template alias"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [template<int i>
                         class I {
                         public: int get() { return i; };
                         };
                         using Zero = I<0>;],
                        [Zero Z;
                         return Z.get();])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(constexpr support)
        feature="constexpr"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <string>
                         typedef char const* const Tag;
                         constexpr Tag FOOBAR = "FOOBAR";],
                        [const std::string foobar(FOOBAR);
                         return static_cast<int>(foobar.length());])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(enum class support)
        feature="enum class"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [enum class FooBar {
                             FOO = 1,
                             BAR = 2
                         };],
                        [FooBar f = FooBar::FOO;
                         return (f == FooBar::FOO ? 1 : 2);])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(range-for support)
        feature="range-for support"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <vector>
                         std::vector<int> v = { 1, 2, 3, 4 };],
                        [int sum = 0;
                         for (auto i : v) {
                             sum += i;
                         }
                         return sum;])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(lambda support)
        feature="lambda"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [],
                        [auto myincr = [[]](int x) { return x + 1; };])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(thread support)
        feature="thread"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <thread>
                         #include <memory>
                         std::shared_ptr<std::thread> th;],
                        [th.reset(new std::thread([[]]() { return; }));
                         th->join();])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(mutex support)
        feature="mutex"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <mutex>
                         std::mutex mtx;],
                        [std::lock_guard<std::mutex> lock(mtx);])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(condition variable support)
        feature="condition variable"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <condition_variable>
                         std::mutex mtx;
                         std::condition_variable cv;],
                        [std::lock_guard<std::mutex> lock(mtx);
                         cv.notify_one();])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(atomic support)
        feature="atomic"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <atomic>
                         std::atomic_flag flag;],
                        [])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(chrono support)
        feature="chrono"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [#include <chrono>
                         using namespace std::chrono;],
                        [auto now = high_resolution_clock::now();])],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])

        AC_MSG_CHECKING(variable template support)
        feature="variable template"
        AC_COMPILE_IFELSE(
                [AC_LANG_PROGRAM(
                        [template<class T>
                         constexpr T pi = T(3.1415926535897932385L);],
                        [int a = pi<int>;],
                )],
                [AC_MSG_RESULT([yes])],
                [AC_MSG_RESULT([no])
                 continue])
        break
done

])dnl AX_ISC_CPP14