1dnl
2dnl Based on https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
3dnl Author: Anatol Belski <ab@php.net>
4dnl
5dnl PHP_CXX_COMPILE_STDCXX(version, mandatory|optional, var_name_to_put_switch_in)
6dnl
7dnl ARGUMENTS
8dnl
9dnl first arg  - version as 11, 14 or 17
10dnl second arg - if mandatory, the configure will fail when no features found.
11dnl                   Optional will make configure silently continue
12dnl third arg  - a variable name where the corresponding switch would be put. If
13dnl              the variable is already defined, its contents will be overwritten.
14dnl
15dnl EXAMPLE
16dnl
17dnl  PHP_CXX_COMPILE_STDCXX(14, mandatory, MY_STDCXX_SWiTCH)
18dnl  echo $MY_STDCXX_SWITCH
19dnl
20
21dnl
22dnl PHP specific implementation start.
23dnl
24
25AC_DEFUN([PHP_CXX_COMPILE_STDCXX], [dnl
26  m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
27        [$1], [14], [ax_cxx_compile_alternatives="14 1y"],
28        [$1], [17], [ax_cxx_compile_alternatives="17 1z"],
29        [m4_fatal([invalid first argument `$1' to PHP_CXX_COMPILE_STDCXX])])dnl
30  m4_if([$2], [], [ax_cxx_compile_cxx$1_required=true],
31        [$2], [mandatory], [ax_cxx_compile_cxx$1_required=true],
32        [$2], [optional], [ax_cxx_compile_cxx$1_required=false],
33        [m4_fatal([invalid third argument `$2' to PHP_CXX_COMPILE_STDCXX])])dnl
34  AC_LANG_PUSH([C++])dnl
35  ac_success=no
36
37  dnl HP's aCC needs +std=c++11 according to:
38  dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
39  dnl Cray's crayCC needs "-h std=c++11"
40  for alternative in ${ax_cxx_compile_alternatives}; do
41    for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
42      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
43      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
44                     $cachevar,
45          [ac_save_CXX="$CXX"
46           CXX="$CXX $switch"
47           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
48            [eval $cachevar=yes],
49            [eval $cachevar=no])
50           CXX="$ac_save_CXX"])
51      if eval test x\$$cachevar = xyes; then
52        eval AS_TR_SH([$3])="$switch"
53        ac_success=yes
54        break
55      fi
56    done
57    if test x$ac_success = xyes; then
58      break
59    fi
60  done
61
62  AC_LANG_POP([C++])
63  if test x$ax_cxx_compile_cxx$1_required = xtrue; then
64    if test x$ac_success = xno; then
65      AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
66    fi
67  fi
68  if test x$ac_success = xno; then
69    AC_MSG_NOTICE([No compiler with C++$1 support was found])
70  fi
71  AC_SUBST(HAVE_CXX$1)
72])
73
74
75dnl
76dnl PHP specific implementation end.
77dnl The relevant part of the unchanged original implementation is below.
78dnl
79
80#
81# LICENSE
82#
83#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
84#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
85#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
86#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
87#   Copyright (c) 2015 Paul Norman <penorman@mac.com>
88#   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
89#   Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
90#   Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
91#
92#   Copying and distribution of this file, with or without modification, are
93#   permitted in any medium without royalty provided the copyright notice
94#   and this notice are preserved.  This file is offered as-is, without any
95#   warranty.
96
97dnl  Test body for checking C++11 support
98
99m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
100  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
101)
102
103
104dnl  Test body for checking C++14 support
105
106m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
107  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
108  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
109)
110
111m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
112  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
113  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
114  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
115)
116
117dnl  Tests for new features in C++11
118
119m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
120
121// If the compiler admits that it is not ready for C++11, why torture it?
122// Hopefully, this will speed up the test.
123
124#ifndef __cplusplus
125
126#error "This is not a C++ compiler"
127
128#elif __cplusplus < 201103L
129
130#error "This is not a C++11 compiler"
131
132#else
133
134namespace cxx11
135{
136
137  namespace test_static_assert
138  {
139
140    template <typename T>
141    struct check
142    {
143      static_assert(sizeof(int) <= sizeof(T), "not big enough");
144    };
145
146  }
147
148  namespace test_final_override
149  {
150
151    struct Base
152    {
153      virtual ~Base() {}
154      virtual void f() {}
155    };
156
157    struct Derived : public Base
158    {
159      virtual ~Derived() override {}
160      virtual void f() override {}
161    };
162
163  }
164
165  namespace test_double_right_angle_brackets
166  {
167
168    template < typename T >
169    struct check {};
170
171    typedef check<void> single_type;
172    typedef check<check<void>> double_type;
173    typedef check<check<check<void>>> triple_type;
174    typedef check<check<check<check<void>>>> quadruple_type;
175
176  }
177
178  namespace test_decltype
179  {
180
181    int
182    f()
183    {
184      int a = 1;
185      decltype(a) b = 2;
186      return a + b;
187    }
188
189  }
190
191  namespace test_type_deduction
192  {
193
194    template < typename T1, typename T2 >
195    struct is_same
196    {
197      static const bool value = false;
198    };
199
200    template < typename T >
201    struct is_same<T, T>
202    {
203      static const bool value = true;
204    };
205
206    template < typename T1, typename T2 >
207    auto
208    add(T1 a1, T2 a2) -> decltype(a1 + a2)
209    {
210      return a1 + a2;
211    }
212
213    int
214    test(const int c, volatile int v)
215    {
216      static_assert(is_same<int, decltype(0)>::value == true, "");
217      static_assert(is_same<int, decltype(c)>::value == false, "");
218      static_assert(is_same<int, decltype(v)>::value == false, "");
219      auto ac = c;
220      auto av = v;
221      auto sumi = ac + av + 'x';
222      auto sumf = ac + av + 1.0;
223      static_assert(is_same<int, decltype(ac)>::value == true, "");
224      static_assert(is_same<int, decltype(av)>::value == true, "");
225      static_assert(is_same<int, decltype(sumi)>::value == true, "");
226      static_assert(is_same<int, decltype(sumf)>::value == false, "");
227      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
228      return (sumf > 0.0) ? sumi : add(c, v);
229    }
230
231  }
232
233  namespace test_noexcept
234  {
235
236    int f() { return 0; }
237    int g() noexcept { return 0; }
238
239    static_assert(noexcept(f()) == false, "");
240    static_assert(noexcept(g()) == true, "");
241
242  }
243
244  namespace test_constexpr
245  {
246
247    template < typename CharT >
248    unsigned long constexpr
249    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
250    {
251      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
252    }
253
254    template < typename CharT >
255    unsigned long constexpr
256    strlen_c(const CharT *const s) noexcept
257    {
258      return strlen_c_r(s, 0UL);
259    }
260
261    static_assert(strlen_c("") == 0UL, "");
262    static_assert(strlen_c("1") == 1UL, "");
263    static_assert(strlen_c("example") == 7UL, "");
264    static_assert(strlen_c("another\0example") == 7UL, "");
265
266  }
267
268  namespace test_rvalue_references
269  {
270
271    template < int N >
272    struct answer
273    {
274      static constexpr int value = N;
275    };
276
277    answer<1> f(int&)       { return answer<1>(); }
278    answer<2> f(const int&) { return answer<2>(); }
279    answer<3> f(int&&)      { return answer<3>(); }
280
281    void
282    test()
283    {
284      int i = 0;
285      const int c = 0;
286      static_assert(decltype(f(i))::value == 1, "");
287      static_assert(decltype(f(c))::value == 2, "");
288      static_assert(decltype(f(0))::value == 3, "");
289    }
290
291  }
292
293  namespace test_uniform_initialization
294  {
295
296    struct test
297    {
298      static const int zero {};
299      static const int one {1};
300    };
301
302    static_assert(test::zero == 0, "");
303    static_assert(test::one == 1, "");
304
305  }
306
307  namespace test_lambdas
308  {
309
310    void
311    test1()
312    {
313      auto lambda1 = [](){};
314      auto lambda2 = lambda1;
315      lambda1();
316      lambda2();
317    }
318
319    int
320    test2()
321    {
322      auto a = [](int i, int j){ return i + j; }(1, 2);
323      auto b = []() -> int { return '0'; }();
324      auto c = [=](){ return a + b; }();
325      auto d = [&](){ return c; }();
326      auto e = [a, &b](int x) mutable {
327        const auto identity = [](int y){ return y; };
328        for (auto i = 0; i < a; ++i)
329          a += b--;
330        return x + identity(a + b);
331      }(0);
332      return a + b + c + d + e;
333    }
334
335    int
336    test3()
337    {
338      const auto nullary = [](){ return 0; };
339      const auto unary = [](int x){ return x; };
340      using nullary_t = decltype(nullary);
341      using unary_t = decltype(unary);
342      const auto higher1st = [](nullary_t f){ return f(); };
343      const auto higher2nd = [unary](nullary_t f1){
344        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
345      };
346      return higher1st(nullary) + higher2nd(nullary)(unary);
347    }
348
349  }
350
351  namespace test_variadic_templates
352  {
353
354    template <int...>
355    struct sum;
356
357    template <int N0, int... N1toN>
358    struct sum<N0, N1toN...>
359    {
360      static constexpr auto value = N0 + sum<N1toN...>::value;
361    };
362
363    template <>
364    struct sum<>
365    {
366      static constexpr auto value = 0;
367    };
368
369    static_assert(sum<>::value == 0, "");
370    static_assert(sum<1>::value == 1, "");
371    static_assert(sum<23>::value == 23, "");
372    static_assert(sum<1, 2>::value == 3, "");
373    static_assert(sum<5, 5, 11>::value == 21, "");
374    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
375
376  }
377
378  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
379  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
380  // because of this.
381  namespace test_template_alias_sfinae
382  {
383
384    struct foo {};
385
386    template<typename T>
387    using member = typename T::member_type;
388
389    template<typename T>
390    void func(...) {}
391
392    template<typename T>
393    void func(member<T>*) {}
394
395    void test();
396
397    void test() { func<foo>(0); }
398
399  }
400
401}  // namespace cxx11
402
403#endif  // __cplusplus >= 201103L
404
405]])
406
407
408dnl  Tests for new features in C++14
409
410m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
411
412// If the compiler admits that it is not ready for C++14, why torture it?
413// Hopefully, this will speed up the test.
414
415#ifndef __cplusplus
416
417#error "This is not a C++ compiler"
418
419#elif __cplusplus < 201402L
420
421#error "This is not a C++14 compiler"
422
423#else
424
425namespace cxx14
426{
427
428  namespace test_polymorphic_lambdas
429  {
430
431    int
432    test()
433    {
434      const auto lambda = [](auto&&... args){
435        const auto istiny = [](auto x){
436          return (sizeof(x) == 1UL) ? 1 : 0;
437        };
438        const int aretiny[] = { istiny(args)... };
439        return aretiny[0];
440      };
441      return lambda(1, 1L, 1.0f, '1');
442    }
443
444  }
445
446  namespace test_binary_literals
447  {
448
449    constexpr auto ivii = 0b0000000000101010;
450    static_assert(ivii == 42, "wrong value");
451
452  }
453
454  namespace test_generalized_constexpr
455  {
456
457    template < typename CharT >
458    constexpr unsigned long
459    strlen_c(const CharT *const s) noexcept
460    {
461      auto length = 0UL;
462      for (auto p = s; *p; ++p)
463        ++length;
464      return length;
465    }
466
467    static_assert(strlen_c("") == 0UL, "");
468    static_assert(strlen_c("x") == 1UL, "");
469    static_assert(strlen_c("test") == 4UL, "");
470    static_assert(strlen_c("another\0test") == 7UL, "");
471
472  }
473
474  namespace test_lambda_init_capture
475  {
476
477    int
478    test()
479    {
480      auto x = 0;
481      const auto lambda1 = [a = x](int b){ return a + b; };
482      const auto lambda2 = [a = lambda1(x)](){ return a; };
483      return lambda2();
484    }
485
486  }
487
488  namespace test_digit_separators
489  {
490
491    constexpr auto ten_million = 100'000'000;
492    static_assert(ten_million == 100000000, "");
493
494  }
495
496  namespace test_return_type_deduction
497  {
498
499    auto f(int& x) { return x; }
500    decltype(auto) g(int& x) { return x; }
501
502    template < typename T1, typename T2 >
503    struct is_same
504    {
505      static constexpr auto value = false;
506    };
507
508    template < typename T >
509    struct is_same<T, T>
510    {
511      static constexpr auto value = true;
512    };
513
514    int
515    test()
516    {
517      auto x = 0;
518      static_assert(is_same<int, decltype(f(x))>::value, "");
519      static_assert(is_same<int&, decltype(g(x))>::value, "");
520      return x;
521    }
522
523  }
524
525}  // namespace cxx14
526
527#endif  // __cplusplus >= 201402L
528
529]])
530
531
532dnl  Tests for new features in C++17
533
534m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
535
536// If the compiler admits that it is not ready for C++17, why torture it?
537// Hopefully, this will speed up the test.
538
539#ifndef __cplusplus
540
541#error "This is not a C++ compiler"
542
543#elif __cplusplus < 201703L
544
545#error "This is not a C++17 compiler"
546
547#else
548
549#include <initializer_list>
550#include <utility>
551#include <type_traits>
552
553namespace cxx17
554{
555
556  namespace test_constexpr_lambdas
557  {
558
559    constexpr int foo = [](){return 42;}();
560
561  }
562
563  namespace test::nested_namespace::definitions
564  {
565
566  }
567
568  namespace test_fold_expression
569  {
570
571    template<typename... Args>
572    int multiply(Args... args)
573    {
574      return (args * ... * 1);
575    }
576
577    template<typename... Args>
578    bool all(Args... args)
579    {
580      return (args && ...);
581    }
582
583  }
584
585  namespace test_extended_static_assert
586  {
587
588    static_assert (true);
589
590  }
591
592  namespace test_auto_brace_init_list
593  {
594
595    auto foo = {5};
596    auto bar {5};
597
598    static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value);
599    static_assert(std::is_same<int, decltype(bar)>::value);
600  }
601
602  namespace test_typename_in_template_template_parameter
603  {
604
605    template<template<typename> typename X> struct D;
606
607  }
608
609  namespace test_fallthrough_nodiscard_maybe_unused_attributes
610  {
611
612    int f1()
613    {
614      return 42;
615    }
616
617    [[nodiscard]] int f2()
618    {
619      [[maybe_unused]] auto unused = f1();
620
621      switch (f1())
622      {
623      case 17:
624        f1();
625        [[fallthrough]];
626      case 42:
627        f1();
628      }
629      return f1();
630    }
631
632  }
633
634  namespace test_extended_aggregate_initialization
635  {
636
637    struct base1
638    {
639      int b1, b2 = 42;
640    };
641
642    struct base2
643    {
644      base2() {
645        b3 = 42;
646      }
647      int b3;
648    };
649
650    struct derived : base1, base2
651    {
652        int d;
653    };
654
655    derived d1 {{1, 2}, {}, 4};  // full initialization
656    derived d2 {{}, {}, 4};      // value-initialized bases
657
658  }
659
660  namespace test_general_range_based_for_loop
661  {
662
663    struct iter
664    {
665      int i;
666
667      int& operator* ()
668      {
669        return i;
670      }
671
672      const int& operator* () const
673      {
674        return i;
675      }
676
677      iter& operator++()
678      {
679        ++i;
680        return *this;
681      }
682    };
683
684    struct sentinel
685    {
686      int i;
687    };
688
689    bool operator== (const iter& i, const sentinel& s)
690    {
691      return i.i == s.i;
692    }
693
694    bool operator!= (const iter& i, const sentinel& s)
695    {
696      return !(i == s);
697    }
698
699    struct range
700    {
701      iter begin() const
702      {
703        return {0};
704      }
705
706      sentinel end() const
707      {
708        return {5};
709      }
710    };
711
712    void f()
713    {
714      range r {};
715
716      for (auto i : r)
717      {
718        [[maybe_unused]] auto v = i;
719      }
720    }
721
722  }
723
724  namespace test_lambda_capture_asterisk_this_by_value
725  {
726
727    struct t
728    {
729      int i;
730      int foo()
731      {
732        return [*this]()
733        {
734          return i;
735        }();
736      }
737    };
738
739  }
740
741  namespace test_enum_class_construction
742  {
743
744    enum class byte : unsigned char
745    {};
746
747    byte foo {42};
748
749  }
750
751  namespace test_constexpr_if
752  {
753
754    template <bool cond>
755    int f ()
756    {
757      if constexpr(cond)
758      {
759        return 13;
760      }
761      else
762      {
763        return 42;
764      }
765    }
766
767  }
768
769  namespace test_selection_statement_with_initializer
770  {
771
772    int f()
773    {
774      return 13;
775    }
776
777    int f2()
778    {
779      if (auto i = f(); i > 0)
780      {
781        return 3;
782      }
783
784      switch (auto i = f(); i + 4)
785      {
786      case 17:
787        return 2;
788
789      default:
790        return 1;
791      }
792    }
793
794  }
795
796  namespace test_template_argument_deduction_for_class_templates
797  {
798
799    template <typename T1, typename T2>
800    struct pair
801    {
802      pair (T1 p1, T2 p2)
803        : m1 {p1},
804          m2 {p2}
805      {}
806
807      T1 m1;
808      T2 m2;
809    };
810
811    void f()
812    {
813      [[maybe_unused]] auto p = pair{13, 42u};
814    }
815
816  }
817
818  namespace test_non_type_auto_template_parameters
819  {
820
821    template <auto n>
822    struct B
823    {};
824
825    B<5> b1;
826    B<'a'> b2;
827
828  }
829
830  namespace test_structured_bindings
831  {
832
833    int arr[2] = { 1, 2 };
834    std::pair<int, int> pr = { 1, 2 };
835
836    auto f1() -> int(&)[2]
837    {
838      return arr;
839    }
840
841    auto f2() -> std::pair<int, int>&
842    {
843      return pr;
844    }
845
846    struct S
847    {
848      int x1 : 2;
849      volatile double y1;
850    };
851
852    S f3()
853    {
854      return {};
855    }
856
857    auto [ x1, y1 ] = f1();
858    auto& [ xr1, yr1 ] = f1();
859    auto [ x2, y2 ] = f2();
860    auto& [ xr2, yr2 ] = f2();
861    const auto [ x3, y3 ] = f3();
862
863  }
864
865  namespace test_exception_spec_type_system
866  {
867
868    struct Good {};
869    struct Bad {};
870
871    void g1() noexcept;
872    void g2();
873
874    template<typename T>
875    Bad
876    f(T*, T*);
877
878    template<typename T1, typename T2>
879    Good
880    f(T1*, T2*);
881
882    static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
883
884  }
885
886  namespace test_inline_variables
887  {
888
889    template<class T> void f(T)
890    {}
891
892    template<class T> inline T g(T)
893    {
894      return T{};
895    }
896
897    template<> inline void f<>(int)
898    {}
899
900    template<> int g<>(int)
901    {
902      return 5;
903    }
904
905  }
906
907}  // namespace cxx17
908
909#endif  // __cplusplus < 201703L
910
911]])
912