Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/m4/ax_cxx_compile_stdcxx.m4

Index: third_party/protobuf/m4/ax_cxx_compile_stdcxx.m4
diff --git a/third_party/protobuf/m4/ax_cxx_compile_stdcxx.m4 b/third_party/protobuf/m4/ax_cxx_compile_stdcxx.m4
deleted file mode 100644
index b61fcb6314a3b569c94de08f64cd705447defdde..0000000000000000000000000000000000000000
--- a/third_party/protobuf/m4/ax_cxx_compile_stdcxx.m4
+++ /dev/null
@@ -1,982 +0,0 @@
-# ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
-#
-# DESCRIPTION
-#
-#   Check for baseline language coverage in the compiler for the specified
-#   version of the C++ standard.  If necessary, add switches to CXX and
-#   CXXCPP to enable support.  VERSION may be '11' (for the C++11 standard)
-#   or '14' (for the C++14 standard).
-#
-#   The second argument, if specified, indicates whether you insist on an
-#   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
-#   -std=c++11).  If neither is specified, you get whatever works, with
-#   preference for an extended mode.
-#
-#   The third argument, if specified 'mandatory' or if left unspecified,
-#   indicates that baseline support for the specified C++ standard is
-#   required and that the macro should error out if no mode with that
-#   support is found.  If specified 'optional', then configuration proceeds
-#   regardless, after defining HAVE_CXX${VERSION} if and only if a
-#   supporting mode is found.
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
-#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
-#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
-#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
-#   Copyright (c) 2015 Paul Norman <penorman@mac.com>
-#   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
-#   Copyright (c) 2016 Krzesimir Nowak <qdlacz@gmail.com>
-#
-#   Copying and distribution of this file, with or without modification, are
-#   permitted in any medium without royalty provided the copyright notice
-#   and this notice are preserved.  This file is offered as-is, without any
-#   warranty.
-
-#serial 6
-
-dnl  This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
-dnl  (serial version number 13).
-
-AX_REQUIRE_DEFINED([AC_MSG_WARN])
-AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
-  m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
-        [$1], [14], [ax_cxx_compile_alternatives="14 1y"],
-        [$1], [17], [ax_cxx_compile_alternatives="17 1z"],
-        [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
-  m4_if([$2], [], [],
-        [$2], [ext], [],
-        [$2], [noext], [],
-        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
-  m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
-        [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
-        [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
-        [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
-  AC_LANG_PUSH([C++])dnl
-  ac_success=no
-  AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
-  ax_cv_cxx_compile_cxx$1,
-  [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
-    [ax_cv_cxx_compile_cxx$1=yes],
-    [ax_cv_cxx_compile_cxx$1=no])])
-  if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
-    ac_success=yes
-  fi
-
-  m4_if([$2], [noext], [], [dnl
-  if test x$ac_success = xno; then
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      switch="-std=gnu++${alternative}"
-      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
-      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
-                     $cachevar,
-        [ac_save_CXX="$CXX"
-         CXX="$CXX $switch"
-         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
-          [eval $cachevar=yes],
-          [eval $cachevar=no])
-         CXX="$ac_save_CXX"])
-      if eval test x\$$cachevar = xyes; then
-        CXX="$CXX $switch"
-        if test -n "$CXXCPP" ; then
-          CXXCPP="$CXXCPP $switch"
-        fi
-        ac_success=yes
-        break
-      fi
-    done
-  fi])
-
-  m4_if([$2], [ext], [], [dnl
-  if test x$ac_success = xno; then
-    dnl HP's aCC needs +std=c++11 according to:
-    dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
-    dnl Cray's crayCC needs "-h std=c++11"
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
-        cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
-        AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
-                       $cachevar,
-          [ac_save_CXX="$CXX"
-           CXX="$CXX $switch"
-           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
-            [eval $cachevar=yes],
-            [eval $cachevar=no])
-           CXX="$ac_save_CXX"])
-        if eval test x\$$cachevar = xyes; then
-          CXX="$CXX $switch"
-          if test -n "$CXXCPP" ; then
-            CXXCPP="$CXXCPP $switch"
-          fi
-          ac_success=yes
-          break
-        fi
-      done
-      if test x$ac_success = xyes; then
-        break
-      fi
-    done
-  fi])
-  AC_LANG_POP([C++])
-  if test x$ax_cxx_compile_cxx$1_required = xtrue; then
-    if test x$ac_success = xno; then
-      AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
-    fi
-  fi
-  if test x$ac_success = xno; then
-    HAVE_CXX$1=0
-    AC_MSG_NOTICE([No compiler with C++$1 support was found])
-  else
-    HAVE_CXX$1=1
-    AC_DEFINE(HAVE_CXX$1,1,
-              [define if the compiler supports basic C++$1 syntax])
-  fi
-  AC_SUBST(HAVE_CXX$1)
-  m4_if([$1], [17], [AC_MSG_WARN([C++17 is not yet standardized, so the checks may change in incompatible ways anytime])])
-])
-
-
-dnl  Test body for checking C++11 support
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-)
-
-
-dnl  Test body for checking C++14 support
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
-)
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
-)
-
-dnl  Tests for new features in C++11
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
-
-// 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"
-
-#elif __cplusplus < 201103L
-
-#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 void f() {}
-    };
-
-    struct Derived : public Base
-    {
-      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
-
-]])
-
-
-dnl  Tests for new features in C++14
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
-
-// 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
-
-#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
-
-]])
-
-
-dnl  Tests for new features in C++17
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
-
-// 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 <= 201402L
-
-#error "This is not a C++17 compiler"
-
-#else
-
-#if defined(__clang__)
-  #define REALLY_CLANG
-#else
-  #if defined(__GNUC__)
-    #define REALLY_GCC
-  #endif
-#endif
-
-#include <initializer_list>
-#include <utility>
-#include <type_traits>
-
-namespace cxx17
-{
-
-#if !defined(REALLY_CLANG)
-  namespace test_constexpr_lambdas
-  {
-
-    // TODO: test it with clang++ from git
-
-    constexpr int foo = [](){return 42;}();
-
-  }
-#endif // !defined(REALLY_CLANG)
-
-  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;
-      }
-    }
-
-  }
-
-#if !defined(REALLY_CLANG)
-  namespace test_template_argument_deduction_for_class_templates
-  {
-
-    // TODO: test it with clang++ from git
-
-    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};
-    }
-
-  }
-#endif // !defined(REALLY_CLANG)
-
-  namespace test_non_type_auto_template_parameters
-  {
-
-    template <auto n>
-    struct B
-    {};
-
-    B<5> b1;
-    B<'a'> b2;
-
-  }
-
-#if !defined(REALLY_CLANG)
-  namespace test_structured_bindings
-  {
-
-    // TODO: test it with clang++ from git
-
-    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();
-
-  }
-#endif // !defined(REALLY_CLANG)
-
-#if !defined(REALLY_CLANG)
-  namespace test_exception_spec_type_system
-  {
-
-    // TODO: test it with clang++ from git
-
-    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))>);
-
-  }
-#endif // !defined(REALLY_CLANG)
-
-  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 <= 201402L
-
-]])