[02/11] gdb/gdbsupport/gdbserver: Require c++17

diff --git a/gdb/NEWS b/gdb/NEWS
index 81264c0cfb3..8ab2e4c593a 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,9 @@ 
 
 *** Changes since GDB 14
 
+* Building GDB and GDBserver now requires a C++17 compiler.
+  For example, GCC 9 or later.
+
 * GDB index now contains information about the main function. This speeds up
   startup when it is being used for some large binaries.
 
diff --git a/gdb/config.in b/gdb/config.in
index e17245156d8..f8926fe4404 100644
--- a/gdb/config.in
+++ b/gdb/config.in
@@ -99,8 +99,8 @@ 
 /* Define to 1 if you have the <curses.h> header file. */
 #undef HAVE_CURSES_H
 
-/* define if the compiler supports basic C++11 syntax */
-#undef HAVE_CXX11
+/* define if the compiler supports basic C++17 syntax */
+#undef HAVE_CXX17
 
 /* Define to 1 if you have the declaration of `ADDR_NO_RANDOMIZE', and to 0 if
    you don't. */
diff --git a/gdb/configure b/gdb/configure
index 408d8a50423..0878481e354 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -803,7 +803,7 @@  CCDEPMODE
 DEPDIR
 am__leading_dot
 CXX_DIALECT
-HAVE_CXX11
+HAVE_CXX17
 CXXCPP
 OTOOL64
 OTOOL
@@ -16491,9 +16491,9 @@  exec 5>>config.log
 $lt_cl_success || as_fn_exit 1
 
 
-# We require a C++11 compiler.  Check if one is available, and if
+# We require a C++17 compiler.  Check if one is available, and if
 # necessary, set CXX_DIALECT to some -std=xxx switch.
-  ax_cxx_compile_alternatives="11 0x"    ax_cxx_compile_cxx11_required=true
+  ax_cxx_compile_alternatives="17 1z"    ax_cxx_compile_cxx17_required=true
   ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -16502,9 +16502,9 @@  ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
   CXX_DIALECT=""
   ac_success=no
 
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
-$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
-if ${ax_cv_cxx_compile_cxx11+:} false; then :
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++17 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx17+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -16801,32 +16801,1362 @@  namespace cxx11
 
 
 
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L && !defined _MSC_VER
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ax_cv_cxx_compile_cxx17=yes
+else
+  ax_cv_cxx_compile_cxx17=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx17" >&5
+$as_echo "$ax_cv_cxx_compile_cxx17" >&6; }
+    if test x$ax_cv_cxx_compile_cxx17 = xyes; then
+      ac_success=yes
+    fi
+
+    if test x$ac_success = xno; then
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      switch="-std=gnu++${alternative}"
+      cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_save_CXX="$CXX"
+         CXX="$CXX $switch"
+         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+  namespace test_static_assert
+  {
+
+    template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+  }
+
+  namespace test_final_override
+  {
+
+    struct Base
+    {
+      virtual ~Base() {}
+      virtual void f() {}
+    };
+
+    struct Derived : public Base
+    {
+      virtual ~Derived() override {}
+      virtual void f() override {}
+    };
+
+  }
+
+  namespace test_double_right_angle_brackets
+  {
+
+    template < typename T >
+    struct check {};
+
+    typedef check<void> single_type;
+    typedef check<check<void>> double_type;
+    typedef check<check<check<void>>> triple_type;
+    typedef check<check<check<check<void>>>> quadruple_type;
+
+  }
+
+  namespace test_decltype
+  {
+
+    int
+    f()
+    {
+      int a = 1;
+      decltype(a) b = 2;
+      return a + b;
+    }
+
+  }
+
+  namespace test_type_deduction
+  {
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static const bool value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static const bool value = true;
+    };
+
+    template < typename T1, typename T2 >
+    auto
+    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    {
+      return a1 + a2;
+    }
+
+    int
+    test(const int c, volatile int v)
+    {
+      static_assert(is_same<int, decltype(0)>::value == true, "");
+      static_assert(is_same<int, decltype(c)>::value == false, "");
+      static_assert(is_same<int, decltype(v)>::value == false, "");
+      auto ac = c;
+      auto av = v;
+      auto sumi = ac + av + 'x';
+      auto sumf = ac + av + 1.0;
+      static_assert(is_same<int, decltype(ac)>::value == true, "");
+      static_assert(is_same<int, decltype(av)>::value == true, "");
+      static_assert(is_same<int, decltype(sumi)>::value == true, "");
+      static_assert(is_same<int, decltype(sumf)>::value == false, "");
+      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+      return (sumf > 0.0) ? sumi : add(c, v);
+    }
+
+  }
+
+  namespace test_noexcept
+  {
+
+    int f() { return 0; }
+    int g() noexcept { return 0; }
+
+    static_assert(noexcept(f()) == false, "");
+    static_assert(noexcept(g()) == true, "");
+
+  }
+
+  namespace test_constexpr
+  {
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    {
+      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+    }
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c(const CharT *const s) noexcept
+    {
+      return strlen_c_r(s, 0UL);
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("1") == 1UL, "");
+    static_assert(strlen_c("example") == 7UL, "");
+    static_assert(strlen_c("another\0example") == 7UL, "");
+
+  }
+
+  namespace test_rvalue_references
+  {
+
+    template < int N >
+    struct answer
+    {
+      static constexpr int value = N;
+    };
+
+    answer<1> f(int&)       { return answer<1>(); }
+    answer<2> f(const int&) { return answer<2>(); }
+    answer<3> f(int&&)      { return answer<3>(); }
+
+    void
+    test()
+    {
+      int i = 0;
+      const int c = 0;
+      static_assert(decltype(f(i))::value == 1, "");
+      static_assert(decltype(f(c))::value == 2, "");
+      static_assert(decltype(f(0))::value == 3, "");
+    }
+
+  }
+
+  namespace test_uniform_initialization
+  {
+
+    struct test
+    {
+      static const int zero {};
+      static const int one {1};
+    };
+
+    static_assert(test::zero == 0, "");
+    static_assert(test::one == 1, "");
+
+  }
+
+  namespace test_lambdas
+  {
+
+    void
+    test1()
+    {
+      auto lambda1 = [](){};
+      auto lambda2 = lambda1;
+      lambda1();
+      lambda2();
+    }
+
+    int
+    test2()
+    {
+      auto a = [](int i, int j){ return i + j; }(1, 2);
+      auto b = []() -> int { return '0'; }();
+      auto c = [=](){ return a + b; }();
+      auto d = [&](){ return c; }();
+      auto e = [a, &b](int x) mutable {
+        const auto identity = [](int y){ return y; };
+        for (auto i = 0; i < a; ++i)
+          a += b--;
+        return x + identity(a + b);
+      }(0);
+      return a + b + c + d + e;
+    }
+
+    int
+    test3()
+    {
+      const auto nullary = [](){ return 0; };
+      const auto unary = [](int x){ return x; };
+      using nullary_t = decltype(nullary);
+      using unary_t = decltype(unary);
+      const auto higher1st = [](nullary_t f){ return f(); };
+      const auto higher2nd = [unary](nullary_t f1){
+        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+      };
+      return higher1st(nullary) + higher2nd(nullary)(unary);
+    }
+
+  }
+
+  namespace test_variadic_templates
+  {
+
+    template <int...>
+    struct sum;
+
+    template <int N0, int... N1toN>
+    struct sum<N0, N1toN...>
+    {
+      static constexpr auto value = N0 + sum<N1toN...>::value;
+    };
+
+    template <>
+    struct sum<>
+    {
+      static constexpr auto value = 0;
+    };
+
+    static_assert(sum<>::value == 0, "");
+    static_assert(sum<1>::value == 1, "");
+    static_assert(sum<23>::value == 23, "");
+    static_assert(sum<1, 2>::value == 3, "");
+    static_assert(sum<5, 5, 11>::value == 21, "");
+    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+  }
+
+  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+  // because of this.
+  namespace test_template_alias_sfinae
+  {
+
+    struct foo {};
+
+    template<typename T>
+    using member = typename T::member_type;
+
+    template<typename T>
+    void func(...) {}
+
+    template<typename T>
+    void func(member<T>*) {}
+
+    void test();
+
+    void test() { func<foo>(0); }
+
+  }
+
+}  // namespace cxx11
+
+#endif  // __cplusplus >= 201103L
+
+
+
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L && !defined _MSC_VER
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
+
+
+
 _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
-  ax_cv_cxx_compile_cxx11=yes
+  eval $cachevar=yes
 else
-  ax_cv_cxx_compile_cxx11=no
+  eval $cachevar=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+         CXX="$ac_save_CXX"
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
-$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
-    if test x$ax_cv_cxx_compile_cxx11 = xyes; then
-      ac_success=yes
-    fi
+eval ac_res=\$$cachevar
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+      if eval test x\$$cachevar = xyes; then
+        CXX_DIALECT="$switch"
+        CXX="$CXX $switch"
+        if test -n "$CXXCPP" ; then
+          CXXCPP="$CXXCPP $switch"
+        fi
+        ac_success=yes
+        break
+      fi
+    done
+  fi
 
     if test x$ac_success = xno; then
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      switch="-std=gnu++${alternative}"
-      cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+                    for alternative in ${ax_cxx_compile_alternatives}; do
+      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+        if test x"$switch" = xMSVC; then
+                                        switch=-std:c++${alternative}
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_${switch}_MSVC" | $as_tr_sh`
+        else
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+        fi
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
 if eval \${$cachevar+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_save_CXX="$CXX"
-         CXX="$CXX $switch"
-         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+           CXX="$CXX $switch"
+           cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
@@ -17120,337 +18450,501 @@  namespace cxx11
 
 
 
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
-  eval $cachevar=yes
-else
-  eval $cachevar=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-         CXX="$ac_save_CXX"
-fi
-eval ac_res=\$$cachevar
-	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
-      if eval test x\$$cachevar = xyes; then
-        CXX_DIALECT="$switch"
-        CXX="$CXX $switch"
-        if test -n "$CXXCPP" ; then
-          CXXCPP="$CXXCPP $switch"
-        fi
-        ac_success=yes
-        break
-      fi
-    done
-  fi
 
-    if test x$ac_success = xno; then
-                    for alternative in ${ax_cxx_compile_alternatives}; do
-      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
-        if test x"$switch" = xMSVC; then
-                                        switch=-std:c++${alternative}
-          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
-        else
-          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
-        fi
-        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
-if eval \${$cachevar+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_save_CXX="$CXX"
-           CXX="$CXX $switch"
-           cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
 
 
-// If the compiler admits that it is not ready for C++11, why torture it?
+// If the compiler admits that it is not ready for C++17, why torture it?
 // Hopefully, this will speed up the test.
 
 #ifndef __cplusplus
 
 #error "This is not a C++ compiler"
 
-// MSVC always sets __cplusplus to 199711L in older versions; newer versions
-// only set it correctly if /Zc:__cplusplus is specified as well as a
-// /std:c++NN switch:
-// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
-#elif __cplusplus < 201103L && !defined _MSC_VER
+#elif __cplusplus < 201703L && !defined _MSC_VER
 
-#error "This is not a C++11 compiler"
+#error "This is not a C++17 compiler"
 
 #else
 
-namespace cxx11
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
 {
 
-  namespace test_static_assert
+  namespace test_constexpr_lambdas
   {
 
-    template <typename T>
-    struct check
-    {
-      static_assert(sizeof(int) <= sizeof(T), "not big enough");
-    };
+    constexpr int foo = [](){return 42;}();
 
   }
 
-  namespace test_final_override
+  namespace test::nested_namespace::definitions
   {
 
-    struct Base
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
     {
-      virtual ~Base() {}
-      virtual void f() {}
-    };
+      return (args * ... * 1);
+    }
 
-    struct Derived : public Base
+    template<typename... Args>
+    bool all(Args... args)
     {
-      virtual ~Derived() override {}
-      virtual void f() override {}
-    };
+      return (args && ...);
+    }
 
   }
 
-  namespace test_double_right_angle_brackets
+  namespace test_extended_static_assert
   {
 
-    template < typename T >
-    struct check {};
+    static_assert (true);
 
-    typedef check<void> single_type;
-    typedef check<check<void>> double_type;
-    typedef check<check<check<void>>> triple_type;
-    typedef check<check<check<check<void>>>> quadruple_type;
+  }
+
+  namespace test_auto_brace_init_list
+  {
 
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
   }
 
-  namespace test_decltype
+  namespace test_typename_in_template_template_parameter
   {
 
-    int
-    f()
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
     {
-      int a = 1;
-      decltype(a) b = 2;
-      return a + b;
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
     }
 
   }
 
-  namespace test_type_deduction
+  namespace test_extended_aggregate_initialization
   {
 
-    template < typename T1, typename T2 >
-    struct is_same
+    struct base1
     {
-      static const bool value = false;
+      int b1, b2 = 42;
     };
 
-    template < typename T >
-    struct is_same<T, T>
+    struct base2
     {
-      static const bool value = true;
+      base2() {
+        b3 = 42;
+      }
+      int b3;
     };
 
-    template < typename T1, typename T2 >
-    auto
-    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    struct derived : base1, base2
     {
-      return a1 + a2;
-    }
+        int d;
+    };
 
-    int
-    test(const int c, volatile int v)
-    {
-      static_assert(is_same<int, decltype(0)>::value == true, "");
-      static_assert(is_same<int, decltype(c)>::value == false, "");
-      static_assert(is_same<int, decltype(v)>::value == false, "");
-      auto ac = c;
-      auto av = v;
-      auto sumi = ac + av + 'x';
-      auto sumf = ac + av + 1.0;
-      static_assert(is_same<int, decltype(ac)>::value == true, "");
-      static_assert(is_same<int, decltype(av)>::value == true, "");
-      static_assert(is_same<int, decltype(sumi)>::value == true, "");
-      static_assert(is_same<int, decltype(sumf)>::value == false, "");
-      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
-      return (sumf > 0.0) ? sumi : add(c, v);
-    }
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
 
   }
 
-  namespace test_noexcept
+  namespace test_general_range_based_for_loop
   {
 
-    int f() { return 0; }
-    int g() noexcept { return 0; }
+    struct iter
+    {
+      int i;
 
-    static_assert(noexcept(f()) == false, "");
-    static_assert(noexcept(g()) == true, "");
+      int& operator* ()
+      {
+        return i;
+      }
 
-  }
+      const int& operator* () const
+      {
+        return i;
+      }
 
-  namespace test_constexpr
-  {
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
 
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    struct sentinel
     {
-      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
     }
 
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c(const CharT *const s) noexcept
+    bool operator!= (const iter& i, const sentinel& s)
     {
-      return strlen_c_r(s, 0UL);
+      return !(i == s);
     }
 
-    static_assert(strlen_c("") == 0UL, "");
-    static_assert(strlen_c("1") == 1UL, "");
-    static_assert(strlen_c("example") == 7UL, "");
-    static_assert(strlen_c("another\0example") == 7UL, "");
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
 
   }
 
-  namespace test_rvalue_references
+  namespace test_lambda_capture_asterisk_this_by_value
   {
 
-    template < int N >
-    struct answer
+    struct t
     {
-      static constexpr int value = N;
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
     };
 
-    answer<1> f(int&)       { return answer<1>(); }
-    answer<2> f(const int&) { return answer<2>(); }
-    answer<3> f(int&&)      { return answer<3>(); }
+  }
 
-    void
-    test()
-    {
-      int i = 0;
-      const int c = 0;
-      static_assert(decltype(f(i))::value == 1, "");
-      static_assert(decltype(f(c))::value == 2, "");
-      static_assert(decltype(f(0))::value == 3, "");
-    }
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
 
   }
 
-  namespace test_uniform_initialization
+  namespace test_constexpr_if
   {
 
-    struct test
+    template <bool cond>
+    int f ()
     {
-      static const int zero {};
-      static const int one {1};
-    };
-
-    static_assert(test::zero == 0, "");
-    static_assert(test::one == 1, "");
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
 
   }
 
-  namespace test_lambdas
+  namespace test_selection_statement_with_initializer
   {
 
-    void
-    test1()
+    int f()
     {
-      auto lambda1 = [](){};
-      auto lambda2 = lambda1;
-      lambda1();
-      lambda2();
+      return 13;
     }
 
-    int
-    test2()
+    int f2()
     {
-      auto a = [](int i, int j){ return i + j; }(1, 2);
-      auto b = []() -> int { return '0'; }();
-      auto c = [=](){ return a + b; }();
-      auto d = [&](){ return c; }();
-      auto e = [a, &b](int x) mutable {
-        const auto identity = [](int y){ return y; };
-        for (auto i = 0; i < a; ++i)
-          a += b--;
-        return x + identity(a + b);
-      }(0);
-      return a + b + c + d + e;
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
     }
 
-    int
-    test3()
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
     {
-      const auto nullary = [](){ return 0; };
-      const auto unary = [](int x){ return x; };
-      using nullary_t = decltype(nullary);
-      using unary_t = decltype(unary);
-      const auto higher1st = [](nullary_t f){ return f(); };
-      const auto higher2nd = [unary](nullary_t f1){
-        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
-      };
-      return higher1st(nullary) + higher2nd(nullary)(unary);
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
     }
 
   }
 
-  namespace test_variadic_templates
+  namespace test_non_type_auto_template_parameters
   {
 
-    template <int...>
-    struct sum;
+    template <auto n>
+    struct B
+    {};
 
-    template <int N0, int... N1toN>
-    struct sum<N0, N1toN...>
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
     {
-      static constexpr auto value = N0 + sum<N1toN...>::value;
-    };
+      return arr;
+    }
 
-    template <>
-    struct sum<>
+    auto f2() -> std::pair<int, int>&
     {
-      static constexpr auto value = 0;
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
     };
 
-    static_assert(sum<>::value == 0, "");
-    static_assert(sum<1>::value == 1, "");
-    static_assert(sum<23>::value == 23, "");
-    static_assert(sum<1, 2>::value == 3, "");
-    static_assert(sum<5, 5, 11>::value == 21, "");
-    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
 
   }
 
-  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
-  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
-  // because of this.
-  namespace test_template_alias_sfinae
+  namespace test_exception_spec_type_system
   {
 
-    struct foo {};
+    struct Good {};
+    struct Bad {};
 
-    template<typename T>
-    using member = typename T::member_type;
+    void g1() noexcept;
+    void g2();
 
     template<typename T>
-    void func(...) {}
+    Bad
+    f(T*, T*);
 
-    template<typename T>
-    void func(member<T>*) {}
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
 
-    void test();
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
 
-    void test() { func<foo>(0); }
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
 
   }
 
-}  // namespace cxx11
+}  // namespace cxx17
 
-#endif  // __cplusplus >= 201103L
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
 
 
 
@@ -17487,19 +18981,19 @@  ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
-  if test x$ax_cxx_compile_cxx11_required = xtrue; then
+  if test x$ax_cxx_compile_cxx17_required = xtrue; then
     if test x$ac_success = xno; then
-      as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+      as_fn_error $? "*** A compiler with support for C++17 language features is required." "$LINENO" 5
     fi
   fi
   if test x$ac_success = xno; then
-    HAVE_CXX11=0
-    { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
-$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+    HAVE_CXX17=0
+    { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++17 support was found" >&5
+$as_echo "$as_me: No compiler with C++17 support was found" >&6;}
   else
-    HAVE_CXX11=1
+    HAVE_CXX17=1
 
-$as_echo "#define HAVE_CXX11 1" >>confdefs.h
+$as_echo "#define HAVE_CXX17 1" >>confdefs.h
 
   fi
 
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 3912b77b27f..43e5067e6ff 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -53,9 +53,9 @@  LT_INIT
 # link tests in the configure script.
 LT_OUTPUT
 
-# We require a C++11 compiler.  Check if one is available, and if
+# We require a C++17 compiler.  Check if one is available, and if
 # necessary, set CXX_DIALECT to some -std=xxx switch.
-AX_CXX_COMPILE_STDCXX(11, , mandatory)
+AX_CXX_COMPILE_STDCXX(17, , mandatory)
 
 # Dependency checking.
 ZW_CREATE_DEPDIR
diff --git a/gdbserver/config.in b/gdbserver/config.in
index 63876afcf85..ab507aa6f6a 100644
--- a/gdbserver/config.in
+++ b/gdbserver/config.in
@@ -28,8 +28,8 @@ 
 /* Define to 1 if you have the <arpa/inet.h> header file. */
 #undef HAVE_ARPA_INET_H
 
-/* define if the compiler supports basic C++11 syntax */
-#undef HAVE_CXX11
+/* define if the compiler supports basic C++17 syntax */
+#undef HAVE_CXX17
 
 /* Define to 1 if you have the declaration of `ADDR_NO_RANDOMIZE', and to 0 if
    you don't. */
diff --git a/gdbserver/configure b/gdbserver/configure
index a49598fb682..c6b8d7803c4 100755
--- a/gdbserver/configure
+++ b/gdbserver/configure
@@ -669,7 +669,7 @@  ax_pthread_config
 SED
 ALLOCA
 CXX_DIALECT
-HAVE_CXX11
+HAVE_CXX17
 RANLIB
 AR
 INSTALL_DATA
@@ -5007,10 +5007,10 @@  ac_script='s/[\\$]/&&/g;s/;s,x,x,$//'
 program_transform_name=`$as_echo "$program_transform_name" | sed "$ac_script"`
 
 
-# We require a C++11 compiler.  Check if one is available, and if
+# We require a C++17 compiler.  Check if one is available, and if
 # necessary, set CXX_DIALECT to some -std=xxx switch.
 
-  ax_cxx_compile_alternatives="11 0x"    ax_cxx_compile_cxx11_required=true
+  ax_cxx_compile_alternatives="17 1z"    ax_cxx_compile_cxx17_required=true
   ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -5019,9 +5019,9 @@  ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
   CXX_DIALECT=""
   ac_success=no
 
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
-$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
-if ${ax_cv_cxx_compile_cxx11+:} false; then :
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++17 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx17+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -5318,32 +5318,1362 @@  namespace cxx11
 
 
 
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L && !defined _MSC_VER
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ax_cv_cxx_compile_cxx17=yes
+else
+  ax_cv_cxx_compile_cxx17=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx17" >&5
+$as_echo "$ax_cv_cxx_compile_cxx17" >&6; }
+    if test x$ax_cv_cxx_compile_cxx17 = xyes; then
+      ac_success=yes
+    fi
+
+    if test x$ac_success = xno; then
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      switch="-std=gnu++${alternative}"
+      cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_save_CXX="$CXX"
+         CXX="$CXX $switch"
+         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+  namespace test_static_assert
+  {
+
+    template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+  }
+
+  namespace test_final_override
+  {
+
+    struct Base
+    {
+      virtual ~Base() {}
+      virtual void f() {}
+    };
+
+    struct Derived : public Base
+    {
+      virtual ~Derived() override {}
+      virtual void f() override {}
+    };
+
+  }
+
+  namespace test_double_right_angle_brackets
+  {
+
+    template < typename T >
+    struct check {};
+
+    typedef check<void> single_type;
+    typedef check<check<void>> double_type;
+    typedef check<check<check<void>>> triple_type;
+    typedef check<check<check<check<void>>>> quadruple_type;
+
+  }
+
+  namespace test_decltype
+  {
+
+    int
+    f()
+    {
+      int a = 1;
+      decltype(a) b = 2;
+      return a + b;
+    }
+
+  }
+
+  namespace test_type_deduction
+  {
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static const bool value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static const bool value = true;
+    };
+
+    template < typename T1, typename T2 >
+    auto
+    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    {
+      return a1 + a2;
+    }
+
+    int
+    test(const int c, volatile int v)
+    {
+      static_assert(is_same<int, decltype(0)>::value == true, "");
+      static_assert(is_same<int, decltype(c)>::value == false, "");
+      static_assert(is_same<int, decltype(v)>::value == false, "");
+      auto ac = c;
+      auto av = v;
+      auto sumi = ac + av + 'x';
+      auto sumf = ac + av + 1.0;
+      static_assert(is_same<int, decltype(ac)>::value == true, "");
+      static_assert(is_same<int, decltype(av)>::value == true, "");
+      static_assert(is_same<int, decltype(sumi)>::value == true, "");
+      static_assert(is_same<int, decltype(sumf)>::value == false, "");
+      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+      return (sumf > 0.0) ? sumi : add(c, v);
+    }
+
+  }
+
+  namespace test_noexcept
+  {
+
+    int f() { return 0; }
+    int g() noexcept { return 0; }
+
+    static_assert(noexcept(f()) == false, "");
+    static_assert(noexcept(g()) == true, "");
+
+  }
+
+  namespace test_constexpr
+  {
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    {
+      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+    }
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c(const CharT *const s) noexcept
+    {
+      return strlen_c_r(s, 0UL);
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("1") == 1UL, "");
+    static_assert(strlen_c("example") == 7UL, "");
+    static_assert(strlen_c("another\0example") == 7UL, "");
+
+  }
+
+  namespace test_rvalue_references
+  {
+
+    template < int N >
+    struct answer
+    {
+      static constexpr int value = N;
+    };
+
+    answer<1> f(int&)       { return answer<1>(); }
+    answer<2> f(const int&) { return answer<2>(); }
+    answer<3> f(int&&)      { return answer<3>(); }
+
+    void
+    test()
+    {
+      int i = 0;
+      const int c = 0;
+      static_assert(decltype(f(i))::value == 1, "");
+      static_assert(decltype(f(c))::value == 2, "");
+      static_assert(decltype(f(0))::value == 3, "");
+    }
+
+  }
+
+  namespace test_uniform_initialization
+  {
+
+    struct test
+    {
+      static const int zero {};
+      static const int one {1};
+    };
+
+    static_assert(test::zero == 0, "");
+    static_assert(test::one == 1, "");
+
+  }
+
+  namespace test_lambdas
+  {
+
+    void
+    test1()
+    {
+      auto lambda1 = [](){};
+      auto lambda2 = lambda1;
+      lambda1();
+      lambda2();
+    }
+
+    int
+    test2()
+    {
+      auto a = [](int i, int j){ return i + j; }(1, 2);
+      auto b = []() -> int { return '0'; }();
+      auto c = [=](){ return a + b; }();
+      auto d = [&](){ return c; }();
+      auto e = [a, &b](int x) mutable {
+        const auto identity = [](int y){ return y; };
+        for (auto i = 0; i < a; ++i)
+          a += b--;
+        return x + identity(a + b);
+      }(0);
+      return a + b + c + d + e;
+    }
+
+    int
+    test3()
+    {
+      const auto nullary = [](){ return 0; };
+      const auto unary = [](int x){ return x; };
+      using nullary_t = decltype(nullary);
+      using unary_t = decltype(unary);
+      const auto higher1st = [](nullary_t f){ return f(); };
+      const auto higher2nd = [unary](nullary_t f1){
+        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+      };
+      return higher1st(nullary) + higher2nd(nullary)(unary);
+    }
+
+  }
+
+  namespace test_variadic_templates
+  {
+
+    template <int...>
+    struct sum;
+
+    template <int N0, int... N1toN>
+    struct sum<N0, N1toN...>
+    {
+      static constexpr auto value = N0 + sum<N1toN...>::value;
+    };
+
+    template <>
+    struct sum<>
+    {
+      static constexpr auto value = 0;
+    };
+
+    static_assert(sum<>::value == 0, "");
+    static_assert(sum<1>::value == 1, "");
+    static_assert(sum<23>::value == 23, "");
+    static_assert(sum<1, 2>::value == 3, "");
+    static_assert(sum<5, 5, 11>::value == 21, "");
+    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+  }
+
+  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+  // because of this.
+  namespace test_template_alias_sfinae
+  {
+
+    struct foo {};
+
+    template<typename T>
+    using member = typename T::member_type;
+
+    template<typename T>
+    void func(...) {}
+
+    template<typename T>
+    void func(member<T>*) {}
+
+    void test();
+
+    void test() { func<foo>(0); }
+
+  }
+
+}  // namespace cxx11
+
+#endif  // __cplusplus >= 201103L
+
+
+
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L && !defined _MSC_VER
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
+
+
+
 _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
-  ax_cv_cxx_compile_cxx11=yes
+  eval $cachevar=yes
 else
-  ax_cv_cxx_compile_cxx11=no
+  eval $cachevar=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+         CXX="$ac_save_CXX"
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
-$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
-    if test x$ax_cv_cxx_compile_cxx11 = xyes; then
-      ac_success=yes
-    fi
+eval ac_res=\$$cachevar
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+      if eval test x\$$cachevar = xyes; then
+        CXX_DIALECT="$switch"
+        CXX="$CXX $switch"
+        if test -n "$CXXCPP" ; then
+          CXXCPP="$CXXCPP $switch"
+        fi
+        ac_success=yes
+        break
+      fi
+    done
+  fi
 
     if test x$ac_success = xno; then
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      switch="-std=gnu++${alternative}"
-      cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+                    for alternative in ${ax_cxx_compile_alternatives}; do
+      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+        if test x"$switch" = xMSVC; then
+                                        switch=-std:c++${alternative}
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_${switch}_MSVC" | $as_tr_sh`
+        else
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+        fi
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
 if eval \${$cachevar+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_save_CXX="$CXX"
-         CXX="$CXX $switch"
-         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+           CXX="$CXX $switch"
+           cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
@@ -5637,337 +6967,501 @@  namespace cxx11
 
 
 
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
-  eval $cachevar=yes
-else
-  eval $cachevar=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-         CXX="$ac_save_CXX"
-fi
-eval ac_res=\$$cachevar
-	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
-      if eval test x\$$cachevar = xyes; then
-        CXX_DIALECT="$switch"
-        CXX="$CXX $switch"
-        if test -n "$CXXCPP" ; then
-          CXXCPP="$CXXCPP $switch"
-        fi
-        ac_success=yes
-        break
-      fi
-    done
-  fi
 
-    if test x$ac_success = xno; then
-                    for alternative in ${ax_cxx_compile_alternatives}; do
-      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
-        if test x"$switch" = xMSVC; then
-                                        switch=-std:c++${alternative}
-          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
-        else
-          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
-        fi
-        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
-if eval \${$cachevar+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_save_CXX="$CXX"
-           CXX="$CXX $switch"
-           cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
 
+}  // namespace cxx14
 
-// If the compiler admits that it is not ready for C++11, why torture it?
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
 // Hopefully, this will speed up the test.
 
 #ifndef __cplusplus
 
 #error "This is not a C++ compiler"
 
-// MSVC always sets __cplusplus to 199711L in older versions; newer versions
-// only set it correctly if /Zc:__cplusplus is specified as well as a
-// /std:c++NN switch:
-// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
-#elif __cplusplus < 201103L && !defined _MSC_VER
+#elif __cplusplus < 201703L && !defined _MSC_VER
 
-#error "This is not a C++11 compiler"
+#error "This is not a C++17 compiler"
 
 #else
 
-namespace cxx11
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
 {
 
-  namespace test_static_assert
+  namespace test_constexpr_lambdas
   {
 
-    template <typename T>
-    struct check
-    {
-      static_assert(sizeof(int) <= sizeof(T), "not big enough");
-    };
+    constexpr int foo = [](){return 42;}();
 
   }
 
-  namespace test_final_override
+  namespace test::nested_namespace::definitions
   {
 
-    struct Base
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
     {
-      virtual ~Base() {}
-      virtual void f() {}
-    };
+      return (args * ... * 1);
+    }
 
-    struct Derived : public Base
+    template<typename... Args>
+    bool all(Args... args)
     {
-      virtual ~Derived() override {}
-      virtual void f() override {}
-    };
+      return (args && ...);
+    }
 
   }
 
-  namespace test_double_right_angle_brackets
+  namespace test_extended_static_assert
   {
 
-    template < typename T >
-    struct check {};
+    static_assert (true);
 
-    typedef check<void> single_type;
-    typedef check<check<void>> double_type;
-    typedef check<check<check<void>>> triple_type;
-    typedef check<check<check<check<void>>>> quadruple_type;
+  }
+
+  namespace test_auto_brace_init_list
+  {
 
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
   }
 
-  namespace test_decltype
+  namespace test_typename_in_template_template_parameter
   {
 
-    int
-    f()
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
     {
-      int a = 1;
-      decltype(a) b = 2;
-      return a + b;
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
     }
 
   }
 
-  namespace test_type_deduction
+  namespace test_extended_aggregate_initialization
   {
 
-    template < typename T1, typename T2 >
-    struct is_same
+    struct base1
     {
-      static const bool value = false;
+      int b1, b2 = 42;
     };
 
-    template < typename T >
-    struct is_same<T, T>
+    struct base2
     {
-      static const bool value = true;
+      base2() {
+        b3 = 42;
+      }
+      int b3;
     };
 
-    template < typename T1, typename T2 >
-    auto
-    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    struct derived : base1, base2
     {
-      return a1 + a2;
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
     }
 
-    int
-    test(const int c, volatile int v)
+    bool operator!= (const iter& i, const sentinel& s)
     {
-      static_assert(is_same<int, decltype(0)>::value == true, "");
-      static_assert(is_same<int, decltype(c)>::value == false, "");
-      static_assert(is_same<int, decltype(v)>::value == false, "");
-      auto ac = c;
-      auto av = v;
-      auto sumi = ac + av + 'x';
-      auto sumf = ac + av + 1.0;
-      static_assert(is_same<int, decltype(ac)>::value == true, "");
-      static_assert(is_same<int, decltype(av)>::value == true, "");
-      static_assert(is_same<int, decltype(sumi)>::value == true, "");
-      static_assert(is_same<int, decltype(sumf)>::value == false, "");
-      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
-      return (sumf > 0.0) ? sumi : add(c, v);
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
     }
 
   }
 
-  namespace test_noexcept
+  namespace test_lambda_capture_asterisk_this_by_value
   {
 
-    int f() { return 0; }
-    int g() noexcept { return 0; }
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
 
-    static_assert(noexcept(f()) == false, "");
-    static_assert(noexcept(g()) == true, "");
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
 
   }
 
-  namespace test_constexpr
+  namespace test_constexpr_if
   {
 
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    template <bool cond>
+    int f ()
     {
-      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
     }
 
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c(const CharT *const s) noexcept
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
     {
-      return strlen_c_r(s, 0UL);
+      return 13;
     }
 
-    static_assert(strlen_c("") == 0UL, "");
-    static_assert(strlen_c("1") == 1UL, "");
-    static_assert(strlen_c("example") == 7UL, "");
-    static_assert(strlen_c("another\0example") == 7UL, "");
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
 
   }
 
-  namespace test_rvalue_references
+  namespace test_template_argument_deduction_for_class_templates
   {
 
-    template < int N >
-    struct answer
+    template <typename T1, typename T2>
+    struct pair
     {
-      static constexpr int value = N;
-    };
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
 
-    answer<1> f(int&)       { return answer<1>(); }
-    answer<2> f(const int&) { return answer<2>(); }
-    answer<3> f(int&&)      { return answer<3>(); }
+      T1 m1;
+      T2 m2;
+    };
 
-    void
-    test()
+    void f()
     {
-      int i = 0;
-      const int c = 0;
-      static_assert(decltype(f(i))::value == 1, "");
-      static_assert(decltype(f(c))::value == 2, "");
-      static_assert(decltype(f(0))::value == 3, "");
+      [[maybe_unused]] auto p = pair{13, 42u};
     }
 
   }
 
-  namespace test_uniform_initialization
+  namespace test_non_type_auto_template_parameters
   {
 
-    struct test
-    {
-      static const int zero {};
-      static const int one {1};
-    };
+    template <auto n>
+    struct B
+    {};
 
-    static_assert(test::zero == 0, "");
-    static_assert(test::one == 1, "");
+    B<5> b1;
+    B<'a'> b2;
 
   }
 
-  namespace test_lambdas
+  namespace test_structured_bindings
   {
 
-    void
-    test1()
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
     {
-      auto lambda1 = [](){};
-      auto lambda2 = lambda1;
-      lambda1();
-      lambda2();
+      return arr;
     }
 
-    int
-    test2()
+    auto f2() -> std::pair<int, int>&
     {
-      auto a = [](int i, int j){ return i + j; }(1, 2);
-      auto b = []() -> int { return '0'; }();
-      auto c = [=](){ return a + b; }();
-      auto d = [&](){ return c; }();
-      auto e = [a, &b](int x) mutable {
-        const auto identity = [](int y){ return y; };
-        for (auto i = 0; i < a; ++i)
-          a += b--;
-        return x + identity(a + b);
-      }(0);
-      return a + b + c + d + e;
+      return pr;
     }
 
-    int
-    test3()
+    struct S
     {
-      const auto nullary = [](){ return 0; };
-      const auto unary = [](int x){ return x; };
-      using nullary_t = decltype(nullary);
-      using unary_t = decltype(unary);
-      const auto higher1st = [](nullary_t f){ return f(); };
-      const auto higher2nd = [unary](nullary_t f1){
-        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
-      };
-      return higher1st(nullary) + higher2nd(nullary)(unary);
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
     }
 
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
   }
 
-  namespace test_variadic_templates
+  namespace test_exception_spec_type_system
   {
 
-    template <int...>
-    struct sum;
+    struct Good {};
+    struct Bad {};
 
-    template <int N0, int... N1toN>
-    struct sum<N0, N1toN...>
-    {
-      static constexpr auto value = N0 + sum<N1toN...>::value;
-    };
+    void g1() noexcept;
+    void g2();
 
-    template <>
-    struct sum<>
-    {
-      static constexpr auto value = 0;
-    };
+    template<typename T>
+    Bad
+    f(T*, T*);
 
-    static_assert(sum<>::value == 0, "");
-    static_assert(sum<1>::value == 1, "");
-    static_assert(sum<23>::value == 23, "");
-    static_assert(sum<1, 2>::value == 3, "");
-    static_assert(sum<5, 5, 11>::value == 21, "");
-    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
 
   }
 
-  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
-  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
-  // because of this.
-  namespace test_template_alias_sfinae
+  namespace test_inline_variables
   {
 
-    struct foo {};
-
-    template<typename T>
-    using member = typename T::member_type;
-
-    template<typename T>
-    void func(...) {}
+    template<class T> void f(T)
+    {}
 
-    template<typename T>
-    void func(member<T>*) {}
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
 
-    void test();
+    template<> inline void f<>(int)
+    {}
 
-    void test() { func<foo>(0); }
+    template<> int g<>(int)
+    {
+      return 5;
+    }
 
   }
 
-}  // namespace cxx11
+}  // namespace cxx17
 
-#endif  // __cplusplus >= 201103L
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
 
 
 
@@ -6004,19 +7498,19 @@  ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
-  if test x$ax_cxx_compile_cxx11_required = xtrue; then
+  if test x$ax_cxx_compile_cxx17_required = xtrue; then
     if test x$ac_success = xno; then
-      as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+      as_fn_error $? "*** A compiler with support for C++17 language features is required." "$LINENO" 5
     fi
   fi
   if test x$ac_success = xno; then
-    HAVE_CXX11=0
-    { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
-$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+    HAVE_CXX17=0
+    { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++17 support was found" >&5
+$as_echo "$as_me: No compiler with C++17 support was found" >&6;}
   else
-    HAVE_CXX11=1
+    HAVE_CXX17=1
 
-$as_echo "#define HAVE_CXX11 1" >>confdefs.h
+$as_echo "#define HAVE_CXX17 1" >>confdefs.h
 
   fi
 
diff --git a/gdbserver/configure.ac b/gdbserver/configure.ac
index 12bc0090d67..2609a11e6f6 100644
--- a/gdbserver/configure.ac
+++ b/gdbserver/configure.ac
@@ -46,9 +46,9 @@  AC_PROG_RANLIB
 
 AC_ARG_PROGRAM
 
-# We require a C++11 compiler.  Check if one is available, and if
+# We require a C++17 compiler.  Check if one is available, and if
 # necessary, set CXX_DIALECT to some -std=xxx switch.
-AX_CXX_COMPILE_STDCXX(11, , mandatory)
+AX_CXX_COMPILE_STDCXX(17, , mandatory)
 
 AC_HEADER_STDC
 
diff --git a/gdbsupport/Makefile.in b/gdbsupport/Makefile.in
index 07cb78fc4c7..50a5a55e19d 100644
--- a/gdbsupport/Makefile.in
+++ b/gdbsupport/Makefile.in
@@ -252,7 +252,7 @@  EXEEXT = @EXEEXT@
 GENCAT = @GENCAT@
 GMSGFMT = @GMSGFMT@
 GREP = @GREP@
-HAVE_CXX11 = @HAVE_CXX11@
+HAVE_CXX17 = @HAVE_CXX17@
 HAVE_LIBIPT = @HAVE_LIBIPT@
 HAVE_LIBXXHASH = @HAVE_LIBXXHASH@
 INCINTL = @INCINTL@
diff --git a/gdbsupport/config.in b/gdbsupport/config.in
index 2cdc1fbde61..1cef12634bd 100644
--- a/gdbsupport/config.in
+++ b/gdbsupport/config.in
@@ -28,8 +28,8 @@ 
    */
 #undef HAVE_ALLOCA_H
 
-/* define if the compiler supports basic C++11 syntax */
-#undef HAVE_CXX11
+/* define if the compiler supports basic C++17 syntax */
+#undef HAVE_CXX17
 
 /* Define to 1 if you have the declaration of `ADDR_NO_RANDOMIZE', and to 0 if
    you don't. */
diff --git a/gdbsupport/configure b/gdbsupport/configure
index 6d2a4309d7e..0ef3d25a10b 100755
--- a/gdbsupport/configure
+++ b/gdbsupport/configure
@@ -656,7 +656,7 @@  LIBINTL_DEP
 LIBINTL
 USE_NLS
 CXX_DIALECT
-HAVE_CXX11
+HAVE_CXX17
 LARGEFILE_CPPFLAGS
 EGREP
 GREP
@@ -5905,10 +5905,10 @@  fi
 
 
 
-# We require a C++11 compiler.  Check if one is available, and if
+# We require a C++17 compiler.  Check if one is available, and if
 # necessary, set CXX_DIALECT to some -std=xxx switch.
 
-  ax_cxx_compile_alternatives="11 0x"    ax_cxx_compile_cxx11_required=true
+  ax_cxx_compile_alternatives="17 1z"    ax_cxx_compile_cxx17_required=true
   ac_ext=cpp
 ac_cpp='$CXXCPP $CPPFLAGS'
 ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
@@ -5917,9 +5917,9 @@  ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
   CXX_DIALECT=""
   ac_success=no
 
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
-$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; }
-if ${ax_cv_cxx_compile_cxx11+:} false; then :
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features by default" >&5
+$as_echo_n "checking whether $CXX supports C++17 features by default... " >&6; }
+if ${ax_cv_cxx_compile_cxx17+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -6216,32 +6216,1362 @@  namespace cxx11
 
 
 
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L && !defined _MSC_VER
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
+
+
+
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ax_cv_cxx_compile_cxx17=yes
+else
+  ax_cv_cxx_compile_cxx17=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx17" >&5
+$as_echo "$ax_cv_cxx_compile_cxx17" >&6; }
+    if test x$ax_cv_cxx_compile_cxx17 = xyes; then
+      ac_success=yes
+    fi
+
+    if test x$ac_success = xno; then
+    for alternative in ${ax_cxx_compile_alternatives}; do
+      switch="-std=gnu++${alternative}"
+      cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
+if eval \${$cachevar+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_save_CXX="$CXX"
+         CXX="$CXX $switch"
+         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+// If the compiler admits that it is not ready for C++11, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
+
+#error "This is not a C++11 compiler"
+
+#else
+
+namespace cxx11
+{
+
+  namespace test_static_assert
+  {
+
+    template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+  }
+
+  namespace test_final_override
+  {
+
+    struct Base
+    {
+      virtual ~Base() {}
+      virtual void f() {}
+    };
+
+    struct Derived : public Base
+    {
+      virtual ~Derived() override {}
+      virtual void f() override {}
+    };
+
+  }
+
+  namespace test_double_right_angle_brackets
+  {
+
+    template < typename T >
+    struct check {};
+
+    typedef check<void> single_type;
+    typedef check<check<void>> double_type;
+    typedef check<check<check<void>>> triple_type;
+    typedef check<check<check<check<void>>>> quadruple_type;
+
+  }
+
+  namespace test_decltype
+  {
+
+    int
+    f()
+    {
+      int a = 1;
+      decltype(a) b = 2;
+      return a + b;
+    }
+
+  }
+
+  namespace test_type_deduction
+  {
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static const bool value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static const bool value = true;
+    };
+
+    template < typename T1, typename T2 >
+    auto
+    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    {
+      return a1 + a2;
+    }
+
+    int
+    test(const int c, volatile int v)
+    {
+      static_assert(is_same<int, decltype(0)>::value == true, "");
+      static_assert(is_same<int, decltype(c)>::value == false, "");
+      static_assert(is_same<int, decltype(v)>::value == false, "");
+      auto ac = c;
+      auto av = v;
+      auto sumi = ac + av + 'x';
+      auto sumf = ac + av + 1.0;
+      static_assert(is_same<int, decltype(ac)>::value == true, "");
+      static_assert(is_same<int, decltype(av)>::value == true, "");
+      static_assert(is_same<int, decltype(sumi)>::value == true, "");
+      static_assert(is_same<int, decltype(sumf)>::value == false, "");
+      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
+      return (sumf > 0.0) ? sumi : add(c, v);
+    }
+
+  }
+
+  namespace test_noexcept
+  {
+
+    int f() { return 0; }
+    int g() noexcept { return 0; }
+
+    static_assert(noexcept(f()) == false, "");
+    static_assert(noexcept(g()) == true, "");
+
+  }
+
+  namespace test_constexpr
+  {
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    {
+      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+    }
+
+    template < typename CharT >
+    unsigned long constexpr
+    strlen_c(const CharT *const s) noexcept
+    {
+      return strlen_c_r(s, 0UL);
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("1") == 1UL, "");
+    static_assert(strlen_c("example") == 7UL, "");
+    static_assert(strlen_c("another\0example") == 7UL, "");
+
+  }
+
+  namespace test_rvalue_references
+  {
+
+    template < int N >
+    struct answer
+    {
+      static constexpr int value = N;
+    };
+
+    answer<1> f(int&)       { return answer<1>(); }
+    answer<2> f(const int&) { return answer<2>(); }
+    answer<3> f(int&&)      { return answer<3>(); }
+
+    void
+    test()
+    {
+      int i = 0;
+      const int c = 0;
+      static_assert(decltype(f(i))::value == 1, "");
+      static_assert(decltype(f(c))::value == 2, "");
+      static_assert(decltype(f(0))::value == 3, "");
+    }
+
+  }
+
+  namespace test_uniform_initialization
+  {
+
+    struct test
+    {
+      static const int zero {};
+      static const int one {1};
+    };
+
+    static_assert(test::zero == 0, "");
+    static_assert(test::one == 1, "");
+
+  }
+
+  namespace test_lambdas
+  {
+
+    void
+    test1()
+    {
+      auto lambda1 = [](){};
+      auto lambda2 = lambda1;
+      lambda1();
+      lambda2();
+    }
+
+    int
+    test2()
+    {
+      auto a = [](int i, int j){ return i + j; }(1, 2);
+      auto b = []() -> int { return '0'; }();
+      auto c = [=](){ return a + b; }();
+      auto d = [&](){ return c; }();
+      auto e = [a, &b](int x) mutable {
+        const auto identity = [](int y){ return y; };
+        for (auto i = 0; i < a; ++i)
+          a += b--;
+        return x + identity(a + b);
+      }(0);
+      return a + b + c + d + e;
+    }
+
+    int
+    test3()
+    {
+      const auto nullary = [](){ return 0; };
+      const auto unary = [](int x){ return x; };
+      using nullary_t = decltype(nullary);
+      using unary_t = decltype(unary);
+      const auto higher1st = [](nullary_t f){ return f(); };
+      const auto higher2nd = [unary](nullary_t f1){
+        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
+      };
+      return higher1st(nullary) + higher2nd(nullary)(unary);
+    }
+
+  }
+
+  namespace test_variadic_templates
+  {
+
+    template <int...>
+    struct sum;
+
+    template <int N0, int... N1toN>
+    struct sum<N0, N1toN...>
+    {
+      static constexpr auto value = N0 + sum<N1toN...>::value;
+    };
+
+    template <>
+    struct sum<>
+    {
+      static constexpr auto value = 0;
+    };
+
+    static_assert(sum<>::value == 0, "");
+    static_assert(sum<1>::value == 1, "");
+    static_assert(sum<23>::value == 23, "");
+    static_assert(sum<1, 2>::value == 3, "");
+    static_assert(sum<5, 5, 11>::value == 21, "");
+    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+
+  }
+
+  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
+  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
+  // because of this.
+  namespace test_template_alias_sfinae
+  {
+
+    struct foo {};
+
+    template<typename T>
+    using member = typename T::member_type;
+
+    template<typename T>
+    void func(...) {}
+
+    template<typename T>
+    void func(member<T>*) {}
+
+    void test();
+
+    void test() { func<foo>(0); }
+
+  }
+
+}  // namespace cxx11
+
+#endif  // __cplusplus >= 201103L
+
+
+
+
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
+
+}  // namespace cxx14
+
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201703L && !defined _MSC_VER
+
+#error "This is not a C++17 compiler"
+
+#else
+
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
+{
+
+  namespace test_constexpr_lambdas
+  {
+
+    constexpr int foo = [](){return 42;}();
+
+  }
+
+  namespace test::nested_namespace::definitions
+  {
+
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
+    {
+      return (args * ... * 1);
+    }
+
+    template<typename... Args>
+    bool all(Args... args)
+    {
+      return (args && ...);
+    }
+
+  }
+
+  namespace test_extended_static_assert
+  {
+
+    static_assert (true);
+
+  }
+
+  namespace test_auto_brace_init_list
+  {
+
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
+  }
+
+  namespace test_typename_in_template_template_parameter
+  {
+
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
+    {
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
+    }
+
+  }
+
+  namespace test_extended_aggregate_initialization
+  {
+
+    struct base1
+    {
+      int b1, b2 = 42;
+    };
+
+    struct base2
+    {
+      base2() {
+        b3 = 42;
+      }
+      int b3;
+    };
+
+    struct derived : base1, base2
+    {
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
+    }
+
+    bool operator!= (const iter& i, const sentinel& s)
+    {
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
+    }
+
+  }
+
+  namespace test_lambda_capture_asterisk_this_by_value
+  {
+
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
+
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
+
+  }
+
+  namespace test_constexpr_if
+  {
+
+    template <bool cond>
+    int f ()
+    {
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
+    }
+
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
+    {
+      return 13;
+    }
+
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
+
+  }
+
+  namespace test_template_argument_deduction_for_class_templates
+  {
+
+    template <typename T1, typename T2>
+    struct pair
+    {
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
+
+      T1 m1;
+      T2 m2;
+    };
+
+    void f()
+    {
+      [[maybe_unused]] auto p = pair{13, 42u};
+    }
+
+  }
+
+  namespace test_non_type_auto_template_parameters
+  {
+
+    template <auto n>
+    struct B
+    {};
+
+    B<5> b1;
+    B<'a'> b2;
+
+  }
+
+  namespace test_structured_bindings
+  {
+
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
+    {
+      return arr;
+    }
+
+    auto f2() -> std::pair<int, int>&
+    {
+      return pr;
+    }
+
+    struct S
+    {
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
+    }
+
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
+  }
+
+  namespace test_exception_spec_type_system
+  {
+
+    struct Good {};
+    struct Bad {};
+
+    void g1() noexcept;
+    void g2();
+
+    template<typename T>
+    Bad
+    f(T*, T*);
+
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
+
+  }
+
+  namespace test_inline_variables
+  {
+
+    template<class T> void f(T)
+    {}
+
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
+
+    template<> inline void f<>(int)
+    {}
+
+    template<> int g<>(int)
+    {
+      return 5;
+    }
+
+  }
+
+}  // namespace cxx17
+
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
+
+
+
 _ACEOF
 if ac_fn_cxx_try_compile "$LINENO"; then :
-  ax_cv_cxx_compile_cxx11=yes
+  eval $cachevar=yes
 else
-  ax_cv_cxx_compile_cxx11=no
+  eval $cachevar=no
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+         CXX="$ac_save_CXX"
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5
-$as_echo "$ax_cv_cxx_compile_cxx11" >&6; }
-    if test x$ax_cv_cxx_compile_cxx11 = xyes; then
-      ac_success=yes
-    fi
+eval ac_res=\$$cachevar
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+      if eval test x\$$cachevar = xyes; then
+        CXX_DIALECT="$switch"
+        CXX="$CXX $switch"
+        if test -n "$CXXCPP" ; then
+          CXXCPP="$CXXCPP $switch"
+        fi
+        ac_success=yes
+        break
+      fi
+    done
+  fi
 
     if test x$ac_success = xno; then
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      switch="-std=gnu++${alternative}"
-      cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
-      { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
+                    for alternative in ${ax_cxx_compile_alternatives}; do
+      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+        if test x"$switch" = xMSVC; then
+                                        switch=-std:c++${alternative}
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_${switch}_MSVC" | $as_tr_sh`
+        else
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx17_$switch" | $as_tr_sh`
+        fi
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++17 features with $switch" >&5
+$as_echo_n "checking whether $CXX supports C++17 features with $switch... " >&6; }
 if eval \${$cachevar+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_save_CXX="$CXX"
-         CXX="$CXX $switch"
-         cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+           CXX="$CXX $switch"
+           cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 
@@ -6535,337 +7865,501 @@  namespace cxx11
 
 
 
-_ACEOF
-if ac_fn_cxx_try_compile "$LINENO"; then :
-  eval $cachevar=yes
-else
-  eval $cachevar=no
-fi
-rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
-         CXX="$ac_save_CXX"
-fi
-eval ac_res=\$$cachevar
-	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
-$as_echo "$ac_res" >&6; }
-      if eval test x\$$cachevar = xyes; then
-        CXX_DIALECT="$switch"
-        CXX="$CXX $switch"
-        if test -n "$CXXCPP" ; then
-          CXXCPP="$CXXCPP $switch"
-        fi
-        ac_success=yes
-        break
-      fi
-    done
-  fi
 
-    if test x$ac_success = xno; then
-                    for alternative in ${ax_cxx_compile_alternatives}; do
-      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
-        if test x"$switch" = xMSVC; then
-                                        switch=-std:c++${alternative}
-          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
-        else
-          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
-        fi
-        { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5
-$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; }
-if eval \${$cachevar+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  ac_save_CXX="$CXX"
-           CXX="$CXX $switch"
-           cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
+// If the compiler admits that it is not ready for C++14, why torture it?
+// Hopefully, this will speed up the test.
+
+#ifndef __cplusplus
+
+#error "This is not a C++ compiler"
+
+#elif __cplusplus < 201402L && !defined _MSC_VER
+
+#error "This is not a C++14 compiler"
+
+#else
+
+namespace cxx14
+{
+
+  namespace test_polymorphic_lambdas
+  {
+
+    int
+    test()
+    {
+      const auto lambda = [](auto&&... args){
+        const auto istiny = [](auto x){
+          return (sizeof(x) == 1UL) ? 1 : 0;
+        };
+        const int aretiny[] = { istiny(args)... };
+        return aretiny[0];
+      };
+      return lambda(1, 1L, 1.0f, '1');
+    }
+
+  }
+
+  namespace test_binary_literals
+  {
+
+    constexpr auto ivii = 0b0000000000101010;
+    static_assert(ivii == 42, "wrong value");
+
+  }
+
+  namespace test_generalized_constexpr
+  {
+
+    template < typename CharT >
+    constexpr unsigned long
+    strlen_c(const CharT *const s) noexcept
+    {
+      auto length = 0UL;
+      for (auto p = s; *p; ++p)
+        ++length;
+      return length;
+    }
+
+    static_assert(strlen_c("") == 0UL, "");
+    static_assert(strlen_c("x") == 1UL, "");
+    static_assert(strlen_c("test") == 4UL, "");
+    static_assert(strlen_c("another\0test") == 7UL, "");
+
+  }
+
+  namespace test_lambda_init_capture
+  {
+
+    int
+    test()
+    {
+      auto x = 0;
+      const auto lambda1 = [a = x](int b){ return a + b; };
+      const auto lambda2 = [a = lambda1(x)](){ return a; };
+      return lambda2();
+    }
+
+  }
+
+  namespace test_digit_separators
+  {
+
+    constexpr auto ten_million = 100'000'000;
+    static_assert(ten_million == 100000000, "");
+
+  }
+
+  namespace test_return_type_deduction
+  {
+
+    auto f(int& x) { return x; }
+    decltype(auto) g(int& x) { return x; }
+
+    template < typename T1, typename T2 >
+    struct is_same
+    {
+      static constexpr auto value = false;
+    };
+
+    template < typename T >
+    struct is_same<T, T>
+    {
+      static constexpr auto value = true;
+    };
+
+    int
+    test()
+    {
+      auto x = 0;
+      static_assert(is_same<int, decltype(f(x))>::value, "");
+      static_assert(is_same<int&, decltype(g(x))>::value, "");
+      return x;
+    }
+
+  }
 
+}  // namespace cxx14
 
-// If the compiler admits that it is not ready for C++11, why torture it?
+#endif  // __cplusplus >= 201402L
+
+
+
+
+// If the compiler admits that it is not ready for C++17, why torture it?
 // Hopefully, this will speed up the test.
 
 #ifndef __cplusplus
 
 #error "This is not a C++ compiler"
 
-// MSVC always sets __cplusplus to 199711L in older versions; newer versions
-// only set it correctly if /Zc:__cplusplus is specified as well as a
-// /std:c++NN switch:
-// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
-#elif __cplusplus < 201103L && !defined _MSC_VER
+#elif __cplusplus < 201703L && !defined _MSC_VER
 
-#error "This is not a C++11 compiler"
+#error "This is not a C++17 compiler"
 
 #else
 
-namespace cxx11
+#include <initializer_list>
+#include <utility>
+#include <type_traits>
+
+namespace cxx17
 {
 
-  namespace test_static_assert
+  namespace test_constexpr_lambdas
   {
 
-    template <typename T>
-    struct check
-    {
-      static_assert(sizeof(int) <= sizeof(T), "not big enough");
-    };
+    constexpr int foo = [](){return 42;}();
 
   }
 
-  namespace test_final_override
+  namespace test::nested_namespace::definitions
   {
 
-    struct Base
+  }
+
+  namespace test_fold_expression
+  {
+
+    template<typename... Args>
+    int multiply(Args... args)
     {
-      virtual ~Base() {}
-      virtual void f() {}
-    };
+      return (args * ... * 1);
+    }
 
-    struct Derived : public Base
+    template<typename... Args>
+    bool all(Args... args)
     {
-      virtual ~Derived() override {}
-      virtual void f() override {}
-    };
+      return (args && ...);
+    }
 
   }
 
-  namespace test_double_right_angle_brackets
+  namespace test_extended_static_assert
   {
 
-    template < typename T >
-    struct check {};
+    static_assert (true);
 
-    typedef check<void> single_type;
-    typedef check<check<void>> double_type;
-    typedef check<check<check<void>>> triple_type;
-    typedef check<check<check<check<void>>>> quadruple_type;
+  }
+
+  namespace test_auto_brace_init_list
+  {
 
+    auto foo = {5};
+    auto bar {5};
+
+    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
+    static_assert(std::is_same<int, decltype(bar)>::value);
   }
 
-  namespace test_decltype
+  namespace test_typename_in_template_template_parameter
   {
 
-    int
-    f()
+    template<template<typename> typename X> struct D;
+
+  }
+
+  namespace test_fallthrough_nodiscard_maybe_unused_attributes
+  {
+
+    int f1()
     {
-      int a = 1;
-      decltype(a) b = 2;
-      return a + b;
+      return 42;
+    }
+
+    [[nodiscard]] int f2()
+    {
+      [[maybe_unused]] auto unused = f1();
+
+      switch (f1())
+      {
+      case 17:
+        f1();
+        [[fallthrough]];
+      case 42:
+        f1();
+      }
+      return f1();
     }
 
   }
 
-  namespace test_type_deduction
+  namespace test_extended_aggregate_initialization
   {
 
-    template < typename T1, typename T2 >
-    struct is_same
+    struct base1
     {
-      static const bool value = false;
+      int b1, b2 = 42;
     };
 
-    template < typename T >
-    struct is_same<T, T>
+    struct base2
     {
-      static const bool value = true;
+      base2() {
+        b3 = 42;
+      }
+      int b3;
     };
 
-    template < typename T1, typename T2 >
-    auto
-    add(T1 a1, T2 a2) -> decltype(a1 + a2)
+    struct derived : base1, base2
     {
-      return a1 + a2;
+        int d;
+    };
+
+    derived d1 {{1, 2}, {}, 4};  // full initialization
+    derived d2 {{}, {}, 4};      // value-initialized bases
+
+  }
+
+  namespace test_general_range_based_for_loop
+  {
+
+    struct iter
+    {
+      int i;
+
+      int& operator* ()
+      {
+        return i;
+      }
+
+      const int& operator* () const
+      {
+        return i;
+      }
+
+      iter& operator++()
+      {
+        ++i;
+        return *this;
+      }
+    };
+
+    struct sentinel
+    {
+      int i;
+    };
+
+    bool operator== (const iter& i, const sentinel& s)
+    {
+      return i.i == s.i;
     }
 
-    int
-    test(const int c, volatile int v)
+    bool operator!= (const iter& i, const sentinel& s)
     {
-      static_assert(is_same<int, decltype(0)>::value == true, "");
-      static_assert(is_same<int, decltype(c)>::value == false, "");
-      static_assert(is_same<int, decltype(v)>::value == false, "");
-      auto ac = c;
-      auto av = v;
-      auto sumi = ac + av + 'x';
-      auto sumf = ac + av + 1.0;
-      static_assert(is_same<int, decltype(ac)>::value == true, "");
-      static_assert(is_same<int, decltype(av)>::value == true, "");
-      static_assert(is_same<int, decltype(sumi)>::value == true, "");
-      static_assert(is_same<int, decltype(sumf)>::value == false, "");
-      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
-      return (sumf > 0.0) ? sumi : add(c, v);
+      return !(i == s);
+    }
+
+    struct range
+    {
+      iter begin() const
+      {
+        return {0};
+      }
+
+      sentinel end() const
+      {
+        return {5};
+      }
+    };
+
+    void f()
+    {
+      range r {};
+
+      for (auto i : r)
+      {
+        [[maybe_unused]] auto v = i;
+      }
     }
 
   }
 
-  namespace test_noexcept
+  namespace test_lambda_capture_asterisk_this_by_value
   {
 
-    int f() { return 0; }
-    int g() noexcept { return 0; }
+    struct t
+    {
+      int i;
+      int foo()
+      {
+        return [*this]()
+        {
+          return i;
+        }();
+      }
+    };
 
-    static_assert(noexcept(f()) == false, "");
-    static_assert(noexcept(g()) == true, "");
+  }
+
+  namespace test_enum_class_construction
+  {
+
+    enum class byte : unsigned char
+    {};
+
+    byte foo {42};
 
   }
 
-  namespace test_constexpr
+  namespace test_constexpr_if
   {
 
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
+    template <bool cond>
+    int f ()
     {
-      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
+      if constexpr(cond)
+      {
+        return 13;
+      }
+      else
+      {
+        return 42;
+      }
     }
 
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c(const CharT *const s) noexcept
+  }
+
+  namespace test_selection_statement_with_initializer
+  {
+
+    int f()
     {
-      return strlen_c_r(s, 0UL);
+      return 13;
     }
 
-    static_assert(strlen_c("") == 0UL, "");
-    static_assert(strlen_c("1") == 1UL, "");
-    static_assert(strlen_c("example") == 7UL, "");
-    static_assert(strlen_c("another\0example") == 7UL, "");
+    int f2()
+    {
+      if (auto i = f(); i > 0)
+      {
+        return 3;
+      }
+
+      switch (auto i = f(); i + 4)
+      {
+      case 17:
+        return 2;
+
+      default:
+        return 1;
+      }
+    }
 
   }
 
-  namespace test_rvalue_references
+  namespace test_template_argument_deduction_for_class_templates
   {
 
-    template < int N >
-    struct answer
+    template <typename T1, typename T2>
+    struct pair
     {
-      static constexpr int value = N;
-    };
+      pair (T1 p1, T2 p2)
+        : m1 {p1},
+          m2 {p2}
+      {}
 
-    answer<1> f(int&)       { return answer<1>(); }
-    answer<2> f(const int&) { return answer<2>(); }
-    answer<3> f(int&&)      { return answer<3>(); }
+      T1 m1;
+      T2 m2;
+    };
 
-    void
-    test()
+    void f()
     {
-      int i = 0;
-      const int c = 0;
-      static_assert(decltype(f(i))::value == 1, "");
-      static_assert(decltype(f(c))::value == 2, "");
-      static_assert(decltype(f(0))::value == 3, "");
+      [[maybe_unused]] auto p = pair{13, 42u};
     }
 
   }
 
-  namespace test_uniform_initialization
+  namespace test_non_type_auto_template_parameters
   {
 
-    struct test
-    {
-      static const int zero {};
-      static const int one {1};
-    };
+    template <auto n>
+    struct B
+    {};
 
-    static_assert(test::zero == 0, "");
-    static_assert(test::one == 1, "");
+    B<5> b1;
+    B<'a'> b2;
 
   }
 
-  namespace test_lambdas
+  namespace test_structured_bindings
   {
 
-    void
-    test1()
+    int arr[2] = { 1, 2 };
+    std::pair<int, int> pr = { 1, 2 };
+
+    auto f1() -> int(&)[2]
     {
-      auto lambda1 = [](){};
-      auto lambda2 = lambda1;
-      lambda1();
-      lambda2();
+      return arr;
     }
 
-    int
-    test2()
+    auto f2() -> std::pair<int, int>&
     {
-      auto a = [](int i, int j){ return i + j; }(1, 2);
-      auto b = []() -> int { return '0'; }();
-      auto c = [=](){ return a + b; }();
-      auto d = [&](){ return c; }();
-      auto e = [a, &b](int x) mutable {
-        const auto identity = [](int y){ return y; };
-        for (auto i = 0; i < a; ++i)
-          a += b--;
-        return x + identity(a + b);
-      }(0);
-      return a + b + c + d + e;
+      return pr;
     }
 
-    int
-    test3()
+    struct S
     {
-      const auto nullary = [](){ return 0; };
-      const auto unary = [](int x){ return x; };
-      using nullary_t = decltype(nullary);
-      using unary_t = decltype(unary);
-      const auto higher1st = [](nullary_t f){ return f(); };
-      const auto higher2nd = [unary](nullary_t f1){
-        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
-      };
-      return higher1st(nullary) + higher2nd(nullary)(unary);
+      int x1 : 2;
+      volatile double y1;
+    };
+
+    S f3()
+    {
+      return {};
     }
 
+    auto [ x1, y1 ] = f1();
+    auto& [ xr1, yr1 ] = f1();
+    auto [ x2, y2 ] = f2();
+    auto& [ xr2, yr2 ] = f2();
+    const auto [ x3, y3 ] = f3();
+
   }
 
-  namespace test_variadic_templates
+  namespace test_exception_spec_type_system
   {
 
-    template <int...>
-    struct sum;
+    struct Good {};
+    struct Bad {};
 
-    template <int N0, int... N1toN>
-    struct sum<N0, N1toN...>
-    {
-      static constexpr auto value = N0 + sum<N1toN...>::value;
-    };
+    void g1() noexcept;
+    void g2();
 
-    template <>
-    struct sum<>
-    {
-      static constexpr auto value = 0;
-    };
+    template<typename T>
+    Bad
+    f(T*, T*);
 
-    static_assert(sum<>::value == 0, "");
-    static_assert(sum<1>::value == 1, "");
-    static_assert(sum<23>::value == 23, "");
-    static_assert(sum<1, 2>::value == 3, "");
-    static_assert(sum<5, 5, 11>::value == 21, "");
-    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
+    template<typename T1, typename T2>
+    Good
+    f(T1*, T2*);
+
+    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
 
   }
 
-  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
-  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
-  // because of this.
-  namespace test_template_alias_sfinae
+  namespace test_inline_variables
   {
 
-    struct foo {};
-
-    template<typename T>
-    using member = typename T::member_type;
-
-    template<typename T>
-    void func(...) {}
+    template<class T> void f(T)
+    {}
 
-    template<typename T>
-    void func(member<T>*) {}
+    template<class T> inline T g(T)
+    {
+      return T{};
+    }
 
-    void test();
+    template<> inline void f<>(int)
+    {}
 
-    void test() { func<foo>(0); }
+    template<> int g<>(int)
+    {
+      return 5;
+    }
 
   }
 
-}  // namespace cxx11
+}  // namespace cxx17
 
-#endif  // __cplusplus >= 201103L
+#endif  // __cplusplus < 201703L && !defined _MSC_VER
 
 
 
@@ -6902,19 +8396,19 @@  ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
 ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
-  if test x$ax_cxx_compile_cxx11_required = xtrue; then
+  if test x$ax_cxx_compile_cxx17_required = xtrue; then
     if test x$ac_success = xno; then
-      as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5
+      as_fn_error $? "*** A compiler with support for C++17 language features is required." "$LINENO" 5
     fi
   fi
   if test x$ac_success = xno; then
-    HAVE_CXX11=0
-    { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5
-$as_echo "$as_me: No compiler with C++11 support was found" >&6;}
+    HAVE_CXX17=0
+    { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++17 support was found" >&5
+$as_echo "$as_me: No compiler with C++17 support was found" >&6;}
   else
-    HAVE_CXX11=1
+    HAVE_CXX17=1
 
-$as_echo "#define HAVE_CXX11 1" >>confdefs.h
+$as_echo "#define HAVE_CXX17 1" >>confdefs.h
 
   fi
 
diff --git a/gdbsupport/configure.ac b/gdbsupport/configure.ac
index 2cb382bd4ec..a0986fab9cd 100644
--- a/gdbsupport/configure.ac
+++ b/gdbsupport/configure.ac
@@ -41,9 +41,9 @@  AC_PROG_RANLIB
 AC_USE_SYSTEM_EXTENSIONS
 ACX_LARGEFILE
 
-# We require a C++11 compiler.  Check if one is available, and if
+# We require a C++17 compiler.  Check if one is available, and if
 # necessary, set CXX_DIALECT to some -std=xxx switch.
-AX_CXX_COMPILE_STDCXX(11, , mandatory)
+AX_CXX_COMPILE_STDCXX(17, , mandatory)
 
 dnl Set up for gettext.
 ZW_GNU_GETTEXT_SISTER_DIR