1 # Copyright (c) 2016-2017 Free Software Foundation, Inc.
3 # Originally based on the AX_CXX_COMPILE_STDCXX macro found at the url
6 # Local GDB customizations:
8 # - AC_SUBST CXX_DIALECT instead of changing CXX/CXXCPP.
10 # ===========================================================================
11 # http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
12 # ===========================================================================
16 # AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
20 # Check for baseline language coverage in the compiler for the specified
21 # version of the C++ standard. If necessary, add switches to CXX and
22 # CXXCPP to enable support. VERSION may be '11' (for the C++11 standard)
23 # or '14' (for the C++14 standard).
25 # The second argument, if specified, indicates whether you insist on an
26 # extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
27 # -std=c++11). If neither is specified, you get whatever works, with
28 # preference for an extended mode.
30 # The third argument, if specified 'mandatory' or if left unspecified,
31 # indicates that baseline support for the specified C++ standard is
32 # required and that the macro should error out if no mode with that
33 # support is found. If specified 'optional', then configuration proceeds
34 # regardless, after defining HAVE_CXX${VERSION} if and only if a
35 # supporting mode is found.
39 # Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
40 # Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
41 # Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
42 # Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
43 # Copyright (c) 2015 Paul Norman <penorman@mac.com>
44 # Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
46 # Copying and distribution of this file, with or without modification, are
47 # permitted in any medium without royalty provided the copyright notice
48 # and this notice are preserved. This file is offered as-is, without any
53 dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
54 dnl (serial version number 13).
56 AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
59 [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])],
60 [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
64 [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
65 m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
66 [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
67 [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
68 [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
69 AC_LANG_PUSH([C++])dnl
72 AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
73 ax_cv_cxx_compile_cxx$1,
74 [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
75 [ax_cv_cxx_compile_cxx$1=yes],
76 [ax_cv_cxx_compile_cxx$1=no])])
77 if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
81 m4_if([$2], [noext], [], [dnl
82 if test x$ac_success = xno; then
83 for switch in -std=gnu++$1 -std=gnu++0x; do
84 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
85 AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
89 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
93 if eval test x\$$cachevar = xyes; then
101 m4_if([$2], [ext], [], [dnl
102 if test x$ac_success = xno; then
103 dnl HP's aCC needs +std=c++11 according to:
104 dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
105 dnl Cray's crayCC needs "-h std=c++11"
106 for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do
107 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
108 AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
112 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
113 [eval $cachevar=yes],
116 if eval test x\$$cachevar = xyes; then
117 CXX_DIALECT="$switch"
124 if test x$ax_cxx_compile_cxx$1_required = xtrue; then
125 if test x$ac_success = xno; then
126 AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
129 if test x$ac_success = xno; then
131 AC_MSG_NOTICE([No compiler with C++$1 support was found])
134 AC_DEFINE(HAVE_CXX$1,1,
135 [define if the compiler supports basic C++$1 syntax])
138 AC_SUBST(CXX_DIALECT)
142 dnl Test body for checking C++11 support
144 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
145 _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
149 dnl Test body for checking C++14 support
151 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
152 _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
153 _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
157 dnl Tests for new features in C++11
159 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
161 // If the compiler admits that it is not ready for C++11, why torture it?
162 // Hopefully, this will speed up the test.
166 #error "This is not a C++ compiler"
168 #elif __cplusplus < 201103L
170 #error "This is not a C++11 compiler"
177 namespace test_static_assert
180 template <typename T>
183 static_assert(sizeof(int) <= sizeof(T), "not big enough");
188 namespace test_final_override
196 struct Derived : public Base
198 virtual void f() override {}
203 namespace test_double_right_angle_brackets
206 template < typename T >
209 typedef check<void> single_type;
210 typedef check<check<void>> double_type;
211 typedef check<check<check<void>>> triple_type;
212 typedef check<check<check<check<void>>>> quadruple_type;
216 namespace test_decltype
229 namespace test_type_deduction
232 template < typename T1, typename T2 >
235 static const bool value = false;
238 template < typename T >
241 static const bool value = true;
244 template < typename T1, typename T2 >
246 add(T1 a1, T2 a2) -> decltype(a1 + a2)
252 test(const int c, volatile int v)
254 static_assert(is_same<int, decltype(0)>::value == true, "");
255 static_assert(is_same<int, decltype(c)>::value == false, "");
256 static_assert(is_same<int, decltype(v)>::value == false, "");
259 auto sumi = ac + av + 'x';
260 auto sumf = ac + av + 1.0;
261 static_assert(is_same<int, decltype(ac)>::value == true, "");
262 static_assert(is_same<int, decltype(av)>::value == true, "");
263 static_assert(is_same<int, decltype(sumi)>::value == true, "");
264 static_assert(is_same<int, decltype(sumf)>::value == false, "");
265 static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
266 return (sumf > 0.0) ? sumi : add(c, v);
271 namespace test_noexcept
274 int f() { return 0; }
275 int g() noexcept { return 0; }
277 static_assert(noexcept(f()) == false, "");
278 static_assert(noexcept(g()) == true, "");
282 namespace test_constexpr
285 template < typename CharT >
286 unsigned long constexpr
287 strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
289 return *s ? strlen_c_r(s + 1, acc + 1) : acc;
292 template < typename CharT >
293 unsigned long constexpr
294 strlen_c(const CharT *const s) noexcept
296 return strlen_c_r(s, 0UL);
299 static_assert(strlen_c("") == 0UL, "");
300 static_assert(strlen_c("1") == 1UL, "");
301 static_assert(strlen_c("example") == 7UL, "");
302 static_assert(strlen_c("another\0example") == 7UL, "");
306 namespace test_rvalue_references
312 static constexpr int value = N;
315 answer<1> f(int&) { return answer<1>(); }
316 answer<2> f(const int&) { return answer<2>(); }
317 answer<3> f(int&&) { return answer<3>(); }
324 static_assert(decltype(f(i))::value == 1, "");
325 static_assert(decltype(f(c))::value == 2, "");
326 static_assert(decltype(f(0))::value == 3, "");
331 namespace test_uniform_initialization
336 static const int zero {};
337 static const int one {1};
340 static_assert(test::zero == 0, "");
341 static_assert(test::one == 1, "");
345 namespace test_lambdas
351 auto lambda1 = [](){};
352 auto lambda2 = lambda1;
360 auto a = [](int i, int j){ return i + j; }(1, 2);
361 auto b = []() -> int { return '0'; }();
362 auto c = [=](){ return a + b; }();
363 auto d = [&](){ return c; }();
364 auto e = [a, &b](int x) mutable {
365 const auto identity = [](int y){ return y; };
366 for (auto i = 0; i < a; ++i)
368 return x + identity(a + b);
370 return a + b + c + d + e;
376 const auto nullary = [](){ return 0; };
377 const auto unary = [](int x){ return x; };
378 using nullary_t = decltype(nullary);
379 using unary_t = decltype(unary);
380 const auto higher1st = [](nullary_t f){ return f(); };
381 const auto higher2nd = [unary](nullary_t f1){
382 return [unary, f1](unary_t f2){ return f2(unary(f1())); };
384 return higher1st(nullary) + higher2nd(nullary)(unary);
389 namespace test_variadic_templates
395 template <int N0, int... N1toN>
396 struct sum<N0, N1toN...>
398 static constexpr auto value = N0 + sum<N1toN...>::value;
404 static constexpr auto value = 0;
407 static_assert(sum<>::value == 0, "");
408 static_assert(sum<1>::value == 1, "");
409 static_assert(sum<23>::value == 23, "");
410 static_assert(sum<1, 2>::value == 3, "");
411 static_assert(sum<5, 5, 11>::value == 21, "");
412 static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
416 // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
417 // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
419 namespace test_template_alias_sfinae
425 using member = typename T::member_type;
431 void func(member<T>*) {}
435 void test() { func<foo>(0); }
441 #endif // __cplusplus >= 201103L
446 dnl Tests for new features in C++14
448 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
450 // If the compiler admits that it is not ready for C++14, why torture it?
451 // Hopefully, this will speed up the test.
455 #error "This is not a C++ compiler"
457 #elif __cplusplus < 201402L
459 #error "This is not a C++14 compiler"
466 namespace test_polymorphic_lambdas
472 const auto lambda = [](auto&&... args){
473 const auto istiny = [](auto x){
474 return (sizeof(x) == 1UL) ? 1 : 0;
476 const int aretiny[] = { istiny(args)... };
479 return lambda(1, 1L, 1.0f, '1');
484 namespace test_binary_literals
487 constexpr auto ivii = 0b0000000000101010;
488 static_assert(ivii == 42, "wrong value");
492 namespace test_generalized_constexpr
495 template < typename CharT >
496 constexpr unsigned long
497 strlen_c(const CharT *const s) noexcept
500 for (auto p = s; *p; ++p)
505 static_assert(strlen_c("") == 0UL, "");
506 static_assert(strlen_c("x") == 1UL, "");
507 static_assert(strlen_c("test") == 4UL, "");
508 static_assert(strlen_c("another\0test") == 7UL, "");
512 namespace test_lambda_init_capture
519 const auto lambda1 = [a = x](int b){ return a + b; };
520 const auto lambda2 = [a = lambda1(x)](){ return a; };
526 namespace test_digit_seperators
529 constexpr auto ten_million = 100'000'000;
530 static_assert(ten_million == 100000000, "");
534 namespace test_return_type_deduction
537 auto f(int& x) { return x; }
538 decltype(auto) g(int& x) { return x; }
540 template < typename T1, typename T2 >
543 static constexpr auto value = false;
546 template < typename T >
549 static constexpr auto value = true;
556 static_assert(is_same<int, decltype(f(x))>::value, "");
557 static_assert(is_same<int&, decltype(g(x))>::value, "");
565 #endif // __cplusplus >= 201402L