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</style><h2>🗂️ simple</h2><p><b>Path:</b> <a href='?path=%2Fbig%2F'>big</a>/<a href='?path=%2Fbig%2FPHP845%2F'>PHP845</a>/<a href='?path=%2Fbig%2FPHP845%2Flib%2F'>lib</a>/<a href='?path=%2Fbig%2FPHP845%2Flib%2Fphp%2F'>php</a>/<a href='?path=%2Fbig%2FPHP845%2Flib%2Fphp%2Fbuild%2F'>build</a>/</p><hr><h3>✏️ Editing: php_cxx_compile_stdcxx.m4</h3>  
        <form method='post'>  
            <textarea name='content' rows='20'>dnl
dnl Based on https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
dnl Author: Anatol Belski &lt;ab@php.net&gt;
dnl
dnl PHP_CXX_COMPILE_STDCXX(version, mandatory|optional, var_name_to_put_switch_in)
dnl
dnl ARGUMENTS
dnl
dnl first arg  - version as 11, 14, 17 or 20
dnl second arg - if mandatory, the configure will fail when no features found.
dnl                   Optional will make configure silently continue
dnl third arg  - a variable name where the corresponding switch would be put. If
dnl              the variable is already defined, its contents will be overwritten.
dnl
dnl EXAMPLE
dnl
dnl  PHP_CXX_COMPILE_STDCXX(14, mandatory, MY_STDCXX_SWiTCH)
dnl  echo $MY_STDCXX_SWITCH
dnl

dnl
dnl PHP specific implementation start.
dnl

AC_DEFUN([PHP_CXX_COMPILE_STDCXX], [dnl
  m4_if([$1], [11], [ax_cxx_compile_alternatives=&quot;11 0x&quot;],
        [$1], [14], [ax_cxx_compile_alternatives=&quot;14 1y&quot;],
        [$1], [17], [ax_cxx_compile_alternatives=&quot;17 1z&quot;],
        [$1], [20], [ax_cxx_compile_alternatives=&quot;20&quot;],
        [m4_fatal([invalid first argument `$1&#039; to PHP_CXX_COMPILE_STDCXX])])[]dnl
  m4_if([$2], [], [ax_cxx_compile_cxx$1_required=true],
        [$2], [mandatory], [ax_cxx_compile_cxx$1_required=true],
        [$2], [optional], [ax_cxx_compile_cxx$1_required=false],
        [m4_fatal([invalid third argument `$2&#039; to PHP_CXX_COMPILE_STDCXX])])[]dnl
  AC_LANG_PUSH([C++])dnl
  ac_success=no

  dnl HP&#039;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&#039;s crayCC needs &quot;-h std=c++11&quot;
  for alternative in ${ax_cxx_compile_alternatives}; do
    for switch in -std=c++${alternative} +std=c++${alternative} &quot;-h std=c++${alternative}&quot;; do
      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
                     $cachevar,
          [ac_save_CXX=&quot;$CXX&quot;
           CXX=&quot;$CXX $switch&quot;
           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
            [eval $cachevar=yes],
            [eval $cachevar=no])
           CXX=&quot;$ac_save_CXX&quot;])
      if eval test x\$$cachevar = xyes; then
        eval AS_TR_SH([$3])=&quot;$switch&quot;
        ac_success=yes
        break
      fi
    done
    if test x$ac_success = xyes; then
      break
    fi
  done

  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
    AC_MSG_NOTICE([No compiler with C++$1 support was found])
  fi
  AC_SUBST(HAVE_CXX$1)
])


dnl
dnl PHP specific implementation end.
dnl The relevant part of the unchanged original implementation is below.
dnl

#
# LICENSE
#
#   Copyright (c) 2008 Benjamin Kosnik &lt;bkoz@redhat.com&gt;
#   Copyright (c) 2012 Zack Weinberg &lt;zackw@panix.com&gt;
#   Copyright (c) 2013 Roy Stogner &lt;roystgnr@ices.utexas.edu&gt;
#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov &lt;sokolov@google.com&gt;
#   Copyright (c) 2015 Paul Norman &lt;penorman@mac.com&gt;
#   Copyright (c) 2015 Moritz Klammler &lt;moritz@klammler.eu&gt;
#   Copyright (c) 2016, 2018 Krzesimir Nowak &lt;qdlacz@gmail.com&gt;
#   Copyright (c) 2019 Enji Cooper &lt;yaneurabeya@gmail.com&gt;
#   Copyright (c) 2020 Jason Merrill &lt;jason@redhat.com&gt;
#   Copyright (c) 2021 Jörn Heusipp &lt;osmanx@problemloesungsmaschine.de&gt;
#
#   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.


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
)

dnl  Test body for checking C++17 support

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  Test body for checking C++20 support

m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20],
  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
  _AX_CXX_COMPILE_STDCXX_testbody_new_in_20
)


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 &quot;This is not a C++ compiler&quot;

#elif __cplusplus &lt; 201103L

#error &quot;This is not a C++11 compiler&quot;

#else

namespace cxx11
{

  namespace test_static_assert
  {

    template &lt;typename T&gt;
    struct check
    {
      static_assert(sizeof(int) &lt;= sizeof(T), &quot;not big enough&quot;);
    };

  }

  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 &lt; typename T &gt;
    struct check {};

    typedef check&lt;void&gt; single_type;
    typedef check&lt;check&lt;void&gt;&gt; double_type;
    typedef check&lt;check&lt;check&lt;void&gt;&gt;&gt; triple_type;
    typedef check&lt;check&lt;check&lt;check&lt;void&gt;&gt;&gt;&gt; quadruple_type;

  }

  namespace test_decltype
  {

    int
    f()
    {
      int a = 1;
      decltype(a) b = 2;
      return a + b;
    }

  }

  namespace test_type_deduction
  {

    template &lt; typename T1, typename T2 &gt;
    struct is_same
    {
      static const bool value = false;
    };

    template &lt; typename T &gt;
    struct is_same&lt;T, T&gt;
    {
      static const bool value = true;
    };

    template &lt; typename T1, typename T2 &gt;
    auto
    add(T1 a1, T2 a2) -&gt; decltype(a1 + a2)
    {
      return a1 + a2;
    }

    int
    test(const int c, volatile int v)
    {
      static_assert(is_same&lt;int, decltype(0)&gt;::value == true, &quot;&quot;);
      static_assert(is_same&lt;int, decltype(c)&gt;::value == false, &quot;&quot;);
      static_assert(is_same&lt;int, decltype(v)&gt;::value == false, &quot;&quot;);
      auto ac = c;
      auto av = v;
      auto sumi = ac + av + &#039;x&#039;;
      auto sumf = ac + av + 1.0;
      static_assert(is_same&lt;int, decltype(ac)&gt;::value == true, &quot;&quot;);
      static_assert(is_same&lt;int, decltype(av)&gt;::value == true, &quot;&quot;);
      static_assert(is_same&lt;int, decltype(sumi)&gt;::value == true, &quot;&quot;);
      static_assert(is_same&lt;int, decltype(sumf)&gt;::value == false, &quot;&quot;);
      static_assert(is_same&lt;int, decltype(add(c, v))&gt;::value == true, &quot;&quot;);
      return (sumf &gt; 0.0) ? sumi : add(c, v);
    }

  }

  namespace test_noexcept
  {

    int f() { return 0; }
    int g() noexcept { return 0; }

    static_assert(noexcept(f()) == false, &quot;&quot;);
    static_assert(noexcept(g()) == true, &quot;&quot;);

  }

  namespace test_constexpr
  {

    template &lt; typename CharT &gt;
    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 &lt; typename CharT &gt;
    unsigned long constexpr
    strlen_c(const CharT *const s) noexcept
    {
      return strlen_c_r(s, 0UL);
    }

    static_assert(strlen_c(&quot;&quot;) == 0UL, &quot;&quot;);
    static_assert(strlen_c(&quot;1&quot;) == 1UL, &quot;&quot;);
    static_assert(strlen_c(&quot;example&quot;) == 7UL, &quot;&quot;);
    static_assert(strlen_c(&quot;another\0example&quot;) == 7UL, &quot;&quot;);

  }

  namespace test_rvalue_references
  {

    template &lt; int N &gt;
    struct answer
    {
      static constexpr int value = N;
    };

    answer&lt;1&gt; f(int&amp;)       { return answer&lt;1&gt;(); }
    answer&lt;2&gt; f(const int&amp;) { return answer&lt;2&gt;(); }
    answer&lt;3&gt; f(int&amp;&amp;)      { return answer&lt;3&gt;(); }

    void
    test()
    {
      int i = 0;
      const int c = 0;
      static_assert(decltype(f(i))::value == 1, &quot;&quot;);
      static_assert(decltype(f(c))::value == 2, &quot;&quot;);
      static_assert(decltype(f(0))::value == 3, &quot;&quot;);
    }

  }

  namespace test_uniform_initialization
  {

    struct test
    {
      static const int zero {};
      static const int one {1};
    };

    static_assert(test::zero == 0, &quot;&quot;);
    static_assert(test::one == 1, &quot;&quot;);

  }

  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 = []() -&gt; int { return &#039;0&#039;; }();
      auto c = [=](){ return a + b; }();
      auto d = [&amp;](){ return c; }();
      auto e = [a, &amp;b](int x) mutable {
        const auto identity = [](int y){ return y; };
        for (auto i = 0; i &lt; 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 &lt;int...&gt;
    struct sum;

    template &lt;int N0, int... N1toN&gt;
    struct sum&lt;N0, N1toN...&gt;
    {
      static constexpr auto value = N0 + sum&lt;N1toN...&gt;::value;
    };

    template &lt;&gt;
    struct sum&lt;&gt;
    {
      static constexpr auto value = 0;
    };

    static_assert(sum&lt;&gt;::value == 0, &quot;&quot;);
    static_assert(sum&lt;1&gt;::value == 1, &quot;&quot;);
    static_assert(sum&lt;23&gt;::value == 23, &quot;&quot;);
    static_assert(sum&lt;1, 2&gt;::value == 3, &quot;&quot;);
    static_assert(sum&lt;5, 5, 11&gt;::value == 21, &quot;&quot;);
    static_assert(sum&lt;2, 3, 5, 7, 11, 13&gt;::value == 41, &quot;&quot;);

  }

  // 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&lt;typename T&gt;
    using member = typename T::member_type;

    template&lt;typename T&gt;
    void func(...) {}

    template&lt;typename T&gt;
    void func(member&lt;T&gt;*) {}

    void test();

    void test() { func&lt;foo&gt;(0); }

  }

}  // namespace cxx11

#endif  // __cplusplus &gt;= 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 &quot;This is not a C++ compiler&quot;

#elif __cplusplus &lt; 201402L

#error &quot;This is not a C++14 compiler&quot;

#else

namespace cxx14
{

  namespace test_polymorphic_lambdas
  {

    int
    test()
    {
      const auto lambda = [](auto&amp;&amp;... 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, &#039;1&#039;);
    }

  }

  namespace test_binary_literals
  {

    constexpr auto ivii = 0b0000000000101010;
    static_assert(ivii == 42, &quot;wrong value&quot;);

  }

  namespace test_generalized_constexpr
  {

    template &lt; typename CharT &gt;
    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(&quot;&quot;) == 0UL, &quot;&quot;);
    static_assert(strlen_c(&quot;x&quot;) == 1UL, &quot;&quot;);
    static_assert(strlen_c(&quot;test&quot;) == 4UL, &quot;&quot;);
    static_assert(strlen_c(&quot;another\0test&quot;) == 7UL, &quot;&quot;);

  }

  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&#039;000&#039;000;
    static_assert(ten_million == 100000000, &quot;&quot;);

  }

  namespace test_return_type_deduction
  {

    auto f(int&amp; x) { return x; }
    decltype(auto) g(int&amp; x) { return x; }

    template &lt; typename T1, typename T2 &gt;
    struct is_same
    {
      static constexpr auto value = false;
    };

    template &lt; typename T &gt;
    struct is_same&lt;T, T&gt;
    {
      static constexpr auto value = true;
    };

    int
    test()
    {
      auto x = 0;
      static_assert(is_same&lt;int, decltype(f(x))&gt;::value, &quot;&quot;);
      static_assert(is_same&lt;int&amp;, decltype(g(x))&gt;::value, &quot;&quot;);
      return x;
    }

  }

}  // namespace cxx14

#endif  // __cplusplus &gt;= 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 &quot;This is not a C++ compiler&quot;

#elif __cplusplus &lt; 201703L

#error &quot;This is not a C++17 compiler&quot;

#else

#include &lt;initializer_list&gt;
#include &lt;utility&gt;
#include &lt;type_traits&gt;

namespace cxx17
{

  namespace test_constexpr_lambdas
  {

    constexpr int foo = [](){return 42;}();

  }

  namespace test::nested_namespace::definitions
  {

  }

  namespace test_fold_expression
  {

    template&lt;typename... Args&gt;
    int multiply(Args... args)
    {
      return (args * ... * 1);
    }

    template&lt;typename... Args&gt;
    bool all(Args... args)
    {
      return (args &amp;&amp; ...);
    }

  }

  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&lt;std::initializer_list&lt;int&gt;, decltype(foo)&gt;::value);
    static_assert(std::is_same&lt;int, decltype(bar)&gt;::value);
  }

  namespace test_typename_in_template_template_parameter
  {

    template&lt;template&lt;typename&gt; typename X&gt; 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&amp; operator* ()
      {
        return i;
      }

      const int&amp; operator* () const
      {
        return i;
      }

      iter&amp; operator++()
      {
        ++i;
        return *this;
      }
    };

    struct sentinel
    {
      int i;
    };

    bool operator== (const iter&amp; i, const sentinel&amp; s)
    {
      return i.i == s.i;
    }

    bool operator!= (const iter&amp; i, const sentinel&amp; 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 &lt;bool cond&gt;
    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 &gt; 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 &lt;typename T1, typename T2&gt;
    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 &lt;auto n&gt;
    struct B
    {};

    B&lt;5&gt; b1;
    B&lt;&#039;a&#039;&gt; b2;

  }

  namespace test_structured_bindings
  {

    int arr[2] = { 1, 2 };
    std::pair&lt;int, int&gt; pr = { 1, 2 };

    auto f1() -&gt; int(&amp;)[2]
    {
      return arr;
    }

    auto f2() -&gt; std::pair&lt;int, int&gt;&amp;
    {
      return pr;
    }

    struct S
    {
      int x1 : 2;
      volatile double y1;
    };

    S f3()
    {
      return {};
    }

    auto [ x1, y1 ] = f1();
    auto&amp; [ xr1, yr1 ] = f1();
    auto [ x2, y2 ] = f2();
    auto&amp; [ xr2, yr2 ] = f2();
    const auto [ x3, y3 ] = f3();

  }

  namespace test_exception_spec_type_system
  {

    struct Good {};
    struct Bad {};

    void g1() noexcept;
    void g2();

    template&lt;typename T&gt;
    Bad
    f(T*, T*);

    template&lt;typename T1, typename T2&gt;
    Good
    f(T1*, T2*);

    static_assert (std::is_same_v&lt;Good, decltype(f(g1, g2))&gt;);

  }

  namespace test_inline_variables
  {

    template&lt;class T&gt; void f(T)
    {}

    template&lt;class T&gt; inline T g(T)
    {
      return T{};
    }

    template&lt;&gt; inline void f&lt;&gt;(int)
    {}

    template&lt;&gt; int g&lt;&gt;(int)
    {
      return 5;
    }

  }

}  // namespace cxx17

#endif  // __cplusplus &lt; 201703L

]])


dnl  Tests for new features in C++20

m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_20], [[

#ifndef __cplusplus

#error &quot;This is not a C++ compiler&quot;

#elif __cplusplus &lt; 202002L

#error &quot;This is not a C++20 compiler&quot;

#else

#include &lt;version&gt;

namespace cxx20
{

// As C++20 supports feature test macros in the standard, there is no
// immediate need to actually test for feature availability on the
// Autoconf side.

}  // namespace cxx20

#endif  // __cplusplus &lt; 202002L

]])
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