1 # ===========================================================================
2 # http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
3 # ===========================================================================
7 # AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
11 # Check for baseline language coverage in the compiler for the specified
12 # version of the C++ standard. If necessary, add switches to CXXFLAGS to
13 # enable support. VERSION may be '11' (for the C++11 standard) or '14'
14 # (for the C++14 standard).
16 # The second argument, if specified, indicates whether you insist on an
17 # extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
18 # -std=c++11). If neither is specified, you get whatever works, with
19 # preference for an extended mode.
21 # The third argument, if specified 'mandatory' or if left unspecified,
22 # indicates that baseline support for the specified C++ standard is
23 # required and that the macro should error out if no mode with that
24 # support is found. If specified 'optional', then configuration proceeds
25 # regardless, after defining HAVE_CXX${VERSION} if and only if a
26 # supporting mode is found.
30 # Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
31 # Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
32 # Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
33 # Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
34 # Copyright (c) 2015 Paul Norman <penorman@mac.com>
35 # Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
37 # Copying and distribution of this file, with or without modification, are
38 # permitted in any medium without royalty provided the copyright notice
39 # and this notice are preserved. This file is offered as-is, without any
44 dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
45 dnl (serial version number 13).
47 AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
50 [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])],
51 [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
55 [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
56 m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
57 [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
58 [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
59 [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
60 AC_LANG_PUSH([C++])dnl
62 AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
63 ax_cv_cxx_compile_cxx$1,
64 [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
65 [ax_cv_cxx_compile_cxx$1=yes],
66 [ax_cv_cxx_compile_cxx$1=no])])
67 if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
71 m4_if([$2], [noext], [], [dnl
72 if test x$ac_success = xno; then
73 for switch in -std=gnu++$1 -std=gnu++0x; do
74 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
75 AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
77 [ac_save_CXXFLAGS="$CXXFLAGS"
78 CXXFLAGS="$CXXFLAGS $switch"
79 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
82 CXXFLAGS="$ac_save_CXXFLAGS"])
83 if eval test x\$$cachevar = xyes; then
84 CXXFLAGS="$CXXFLAGS $switch"
91 m4_if([$2], [ext], [], [dnl
92 if test x$ac_success = xno; then
93 dnl HP's aCC needs +std=c++11 according to:
94 dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
95 dnl Cray's crayCC needs "-h std=c++11"
96 for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do
97 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
98 AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
100 [ac_save_CXXFLAGS="$CXXFLAGS"
101 CXXFLAGS="$CXXFLAGS $switch"
102 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
103 [eval $cachevar=yes],
105 CXXFLAGS="$ac_save_CXXFLAGS"])
106 if eval test x\$$cachevar = xyes; then
107 CXXFLAGS="$CXXFLAGS $switch"
114 if test x$ax_cxx_compile_cxx$1_required = xtrue; then
115 if test x$ac_success = xno; then
116 AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
119 if test x$ac_success = xno; then
121 AC_MSG_NOTICE([No compiler with C++$1 support was found])
124 AC_DEFINE(HAVE_CXX$1,1,
125 [define if the compiler supports basic C++$1 syntax])
133 dnl Test body for checking C++11 support
135 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
136 _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
140 dnl Test body for checking C++14 support
142 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
143 _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
144 _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
148 dnl Tests for new features in C++11
150 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
152 // If the compiler admits that it is not ready for C++11, why torture it?
153 // Hopefully, this will speed up the test.
157 #error "This is not a C++ compiler"
159 #elif __cplusplus < 201103L
161 #error "This is not a C++11 compiler"
168 namespace test_static_assert
171 template <typename T>
174 static_assert(sizeof(int) <= sizeof(T), "not big enough");
179 namespace test_final_override
187 struct Derived : public Base
189 virtual void f() override {}
194 namespace test_double_right_angle_brackets
197 template < typename T >
200 typedef check<void> single_type;
201 typedef check<check<void>> double_type;
202 typedef check<check<check<void>>> triple_type;
203 typedef check<check<check<check<void>>>> quadruple_type;
207 namespace test_decltype
220 namespace test_type_deduction
223 template < typename T1, typename T2 >
226 static const bool value = false;
229 template < typename T >
232 static const bool value = true;
235 template < typename T1, typename T2 >
237 add(T1 a1, T2 a2) -> decltype(a1 + a2)
243 test(const int c, volatile int v)
245 static_assert(is_same<int, decltype(0)>::value == true, "");
246 static_assert(is_same<int, decltype(c)>::value == false, "");
247 static_assert(is_same<int, decltype(v)>::value == false, "");
250 auto sumi = ac + av + 'x';
251 auto sumf = ac + av + 1.0;
252 static_assert(is_same<int, decltype(ac)>::value == true, "");
253 static_assert(is_same<int, decltype(av)>::value == true, "");
254 static_assert(is_same<int, decltype(sumi)>::value == true, "");
255 static_assert(is_same<int, decltype(sumf)>::value == false, "");
256 static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
257 return (sumf > 0.0) ? sumi : add(c, v);
262 namespace test_noexcept
265 int f() { return 0; }
266 int g() noexcept { return 0; }
268 static_assert(noexcept(f()) == false, "");
269 static_assert(noexcept(g()) == true, "");
273 namespace test_constexpr
276 template < typename CharT >
277 unsigned long constexpr
278 strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
280 return *s ? strlen_c_r(s + 1, acc + 1) : acc;
283 template < typename CharT >
284 unsigned long constexpr
285 strlen_c(const CharT *const s) noexcept
287 return strlen_c_r(s, 0UL);
290 static_assert(strlen_c("") == 0UL, "");
291 static_assert(strlen_c("1") == 1UL, "");
292 static_assert(strlen_c("example") == 7UL, "");
293 static_assert(strlen_c("another\0example") == 7UL, "");
297 namespace test_rvalue_references
303 static constexpr int value = N;
306 answer<1> f(int&) { return answer<1>(); }
307 answer<2> f(const int&) { return answer<2>(); }
308 answer<3> f(int&&) { return answer<3>(); }
315 static_assert(decltype(f(i))::value == 1, "");
316 static_assert(decltype(f(c))::value == 2, "");
317 static_assert(decltype(f(0))::value == 3, "");
322 namespace test_uniform_initialization
327 static const int zero {};
328 static const int one {1};
331 static_assert(test::zero == 0, "");
332 static_assert(test::one == 1, "");
336 namespace test_lambdas
342 auto lambda1 = [](){};
343 auto lambda2 = lambda1;
351 auto a = [](int i, int j){ return i + j; }(1, 2);
352 auto b = []() -> int { return '0'; }();
353 auto c = [=](){ return a + b; }();
354 auto d = [&](){ return c; }();
355 auto e = [a, &b](int x) mutable {
356 const auto identity = [](int y){ return y; };
357 for (auto i = 0; i < a; ++i)
359 return x + identity(a + b);
361 return a + b + c + d + e;
367 const auto nullary = [](){ return 0; };
368 const auto unary = [](int x){ return x; };
369 using nullary_t = decltype(nullary);
370 using unary_t = decltype(unary);
371 const auto higher1st = [](nullary_t f){ return f(); };
372 const auto higher2nd = [unary](nullary_t f1){
373 return [unary, f1](unary_t f2){ return f2(unary(f1())); };
375 return higher1st(nullary) + higher2nd(nullary)(unary);
380 namespace test_variadic_templates
386 template <int N0, int... N1toN>
387 struct sum<N0, N1toN...>
389 static constexpr auto value = N0 + sum<N1toN...>::value;
395 static constexpr auto value = 0;
398 static_assert(sum<>::value == 0, "");
399 static_assert(sum<1>::value == 1, "");
400 static_assert(sum<23>::value == 23, "");
401 static_assert(sum<1, 2>::value == 3, "");
402 static_assert(sum<5, 5, 11>::value == 21, "");
403 static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
407 // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
408 // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
410 namespace test_template_alias_sfinae
416 using member = typename T::member_type;
422 void func(member<T>*) {}
426 void test() { func<foo>(0); }
432 #endif // __cplusplus >= 201103L
437 dnl Tests for new features in C++14
439 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
441 // If the compiler admits that it is not ready for C++14, why torture it?
442 // Hopefully, this will speed up the test.
446 #error "This is not a C++ compiler"
448 #elif __cplusplus < 201402L
450 #error "This is not a C++14 compiler"
457 namespace test_polymorphic_lambdas
463 const auto lambda = [](auto&&... args){
464 const auto istiny = [](auto x){
465 return (sizeof(x) == 1UL) ? 1 : 0;
467 const int aretiny[] = { istiny(args)... };
470 return lambda(1, 1L, 1.0f, '1');
475 namespace test_binary_literals
478 constexpr auto ivii = 0b0000000000101010;
479 static_assert(ivii == 42, "wrong value");
483 namespace test_generalized_constexpr
486 template < typename CharT >
487 constexpr unsigned long
488 strlen_c(const CharT *const s) noexcept
491 for (auto p = s; *p; ++p)
496 static_assert(strlen_c("") == 0UL, "");
497 static_assert(strlen_c("x") == 1UL, "");
498 static_assert(strlen_c("test") == 4UL, "");
499 static_assert(strlen_c("another\0test") == 7UL, "");
503 namespace test_lambda_init_capture
510 const auto lambda1 = [a = x](int b){ return a + b; };
511 const auto lambda2 = [a = lambda1(x)](){ return a; };
517 namespace test_digit_seperators
520 constexpr auto ten_million = 100'000'000;
521 static_assert(ten_million == 100000000, "");
525 namespace test_return_type_deduction
528 auto f(int& x) { return x; }
529 decltype(auto) g(int& x) { return x; }
531 template < typename T1, typename T2 >
534 static constexpr auto value = false;
537 template < typename T >
540 static constexpr auto value = true;
547 static_assert(is_same<int, decltype(f(x))>::value, "");
548 static_assert(is_same<int&, decltype(g(x))>::value, "");
556 #endif // __cplusplus >= 201402L