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b571f84c | 1 | # =========================================================================== |
c64bc75d | 2 | # https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html |
b571f84c MS |
3 | # =========================================================================== |
4 | # | |
5 | # SYNOPSIS | |
6 | # | |
7 | # AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional]) | |
8 | # | |
9 | # DESCRIPTION | |
10 | # | |
11 | # Check for baseline language coverage in the compiler for the specified | |
12 | # version of the C++ standard. If necessary, add switches to CXX and | |
c64bc75d GS |
13 | # CXXCPP to enable support. VERSION may be '11', '14', '17', or '20' for |
14 | # the respective C++ standard version. | |
b571f84c MS |
15 | # |
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 | |
c64bc75d | 19 | # preference for no added switch, and then for an extended mode. |
b571f84c MS |
20 | # |
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. | |
27 | # | |
28 | # LICENSE | |
29 | # | |
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> | |
c64bc75d GS |
36 | # Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com> |
37 | # Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com> | |
38 | # Copyright (c) 2020 Jason Merrill <jason@redhat.com> | |
39 | # Copyright (c) 2021 Jörn Heusipp <osmanx@problemloesungsmaschine.de> | |
b571f84c MS |
40 | # |
41 | # Copying and distribution of this file, with or without modification, are | |
42 | # permitted in any medium without royalty provided the copyright notice | |
43 | # and this notice are preserved. This file is offered as-is, without any | |
44 | # warranty. | |
45 | ||
c64bc75d | 46 | #serial 15 |
b571f84c MS |
47 | |
48 | dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro | |
49 | dnl (serial version number 13). | |
50 | ||
51 | AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl | |
c64bc75d GS |
52 | m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"], |
53 | [$1], [14], [ax_cxx_compile_alternatives="14 1y"], | |
54 | [$1], [17], [ax_cxx_compile_alternatives="17 1z"], | |
55 | [$1], [20], [ax_cxx_compile_alternatives="20"], | |
b571f84c MS |
56 | [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl |
57 | m4_if([$2], [], [], | |
58 | [$2], [ext], [], | |
59 | [$2], [noext], [], | |
60 | [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl | |
61 | m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true], | |
62 | [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true], | |
63 | [$3], [optional], [ax_cxx_compile_cxx$1_required=false], | |
64 | [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])]) | |
65 | AC_LANG_PUSH([C++])dnl | |
66 | ac_success=no | |
c64bc75d GS |
67 | |
68 | m4_if([$2], [], [dnl | |
69 | AC_CACHE_CHECK(whether $CXX supports C++$1 features by default, | |
70 | ax_cv_cxx_compile_cxx$1, | |
71 | [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], | |
72 | [ax_cv_cxx_compile_cxx$1=yes], | |
73 | [ax_cv_cxx_compile_cxx$1=no])]) | |
74 | if test x$ax_cv_cxx_compile_cxx$1 = xyes; then | |
75 | ac_success=yes | |
76 | fi]) | |
b571f84c MS |
77 | |
78 | m4_if([$2], [noext], [], [dnl | |
79 | if test x$ac_success = xno; then | |
c64bc75d GS |
80 | for alternative in ${ax_cxx_compile_alternatives}; do |
81 | switch="-std=gnu++${alternative}" | |
b571f84c MS |
82 | cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) |
83 | AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, | |
84 | $cachevar, | |
85 | [ac_save_CXX="$CXX" | |
86 | CXX="$CXX $switch" | |
87 | AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], | |
88 | [eval $cachevar=yes], | |
89 | [eval $cachevar=no]) | |
90 | CXX="$ac_save_CXX"]) | |
91 | if eval test x\$$cachevar = xyes; then | |
92 | CXX="$CXX $switch" | |
93 | if test -n "$CXXCPP" ; then | |
94 | CXXCPP="$CXXCPP $switch" | |
95 | fi | |
96 | ac_success=yes | |
97 | break | |
98 | fi | |
99 | done | |
100 | fi]) | |
101 | ||
102 | m4_if([$2], [ext], [], [dnl | |
103 | if test x$ac_success = xno; then | |
104 | dnl HP's aCC needs +std=c++11 according to: | |
105 | dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf | |
106 | dnl Cray's crayCC needs "-h std=c++11" | |
c64bc75d GS |
107 | for alternative in ${ax_cxx_compile_alternatives}; do |
108 | for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do | |
109 | cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) | |
110 | AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, | |
111 | $cachevar, | |
112 | [ac_save_CXX="$CXX" | |
113 | CXX="$CXX $switch" | |
114 | AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], | |
115 | [eval $cachevar=yes], | |
116 | [eval $cachevar=no]) | |
117 | CXX="$ac_save_CXX"]) | |
118 | if eval test x\$$cachevar = xyes; then | |
119 | CXX="$CXX $switch" | |
120 | if test -n "$CXXCPP" ; then | |
121 | CXXCPP="$CXXCPP $switch" | |
122 | fi | |
123 | ac_success=yes | |
124 | break | |
b571f84c | 125 | fi |
c64bc75d GS |
126 | done |
127 | if test x$ac_success = xyes; then | |
b571f84c MS |
128 | break |
129 | fi | |
130 | done | |
131 | fi]) | |
132 | AC_LANG_POP([C++]) | |
133 | if test x$ax_cxx_compile_cxx$1_required = xtrue; then | |
134 | if test x$ac_success = xno; then | |
135 | AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.]) | |
136 | fi | |
137 | fi | |
138 | if test x$ac_success = xno; then | |
139 | HAVE_CXX$1=0 | |
140 | AC_MSG_NOTICE([No compiler with C++$1 support was found]) | |
141 | else | |
142 | HAVE_CXX$1=1 | |
143 | AC_DEFINE(HAVE_CXX$1,1, | |
144 | [define if the compiler supports basic C++$1 syntax]) | |
145 | fi | |
146 | AC_SUBST(HAVE_CXX$1) | |
147 | ]) | |
148 | ||
149 | ||
150 | dnl Test body for checking C++11 support | |
151 | ||
152 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11], | |
153 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 | |
154 | ) | |
155 | ||
b571f84c MS |
156 | dnl Test body for checking C++14 support |
157 | ||
158 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14], | |
159 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 | |
160 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 | |
161 | ) | |
162 | ||
c64bc75d GS |
163 | dnl Test body for checking C++17 support |
164 | ||
165 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17], | |
166 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 | |
167 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 | |
168 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 | |
169 | ) | |
170 | ||
171 | dnl Test body for checking C++20 support | |
172 | ||
173 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20], | |
174 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 | |
175 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 | |
176 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 | |
177 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_20 | |
178 | ) | |
179 | ||
b571f84c MS |
180 | |
181 | dnl Tests for new features in C++11 | |
182 | ||
183 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[ | |
184 | ||
185 | // If the compiler admits that it is not ready for C++11, why torture it? | |
186 | // Hopefully, this will speed up the test. | |
187 | ||
188 | #ifndef __cplusplus | |
189 | ||
190 | #error "This is not a C++ compiler" | |
191 | ||
c64bc75d GS |
192 | // MSVC always sets __cplusplus to 199711L in older versions; newer versions |
193 | // only set it correctly if /Zc:__cplusplus is specified as well as a | |
194 | // /std:c++NN switch: | |
195 | // https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/ | |
196 | #elif __cplusplus < 201103L && !defined _MSC_VER | |
b571f84c MS |
197 | |
198 | #error "This is not a C++11 compiler" | |
199 | ||
200 | #else | |
201 | ||
202 | namespace cxx11 | |
203 | { | |
204 | ||
205 | namespace test_static_assert | |
206 | { | |
207 | ||
208 | template <typename T> | |
209 | struct check | |
210 | { | |
211 | static_assert(sizeof(int) <= sizeof(T), "not big enough"); | |
212 | }; | |
213 | ||
214 | } | |
215 | ||
216 | namespace test_final_override | |
217 | { | |
218 | ||
219 | struct Base | |
220 | { | |
c64bc75d | 221 | virtual ~Base() {} |
b571f84c MS |
222 | virtual void f() {} |
223 | }; | |
224 | ||
225 | struct Derived : public Base | |
226 | { | |
c64bc75d | 227 | virtual ~Derived() override {} |
b571f84c MS |
228 | virtual void f() override {} |
229 | }; | |
230 | ||
231 | } | |
232 | ||
233 | namespace test_double_right_angle_brackets | |
234 | { | |
235 | ||
236 | template < typename T > | |
237 | struct check {}; | |
238 | ||
239 | typedef check<void> single_type; | |
240 | typedef check<check<void>> double_type; | |
241 | typedef check<check<check<void>>> triple_type; | |
242 | typedef check<check<check<check<void>>>> quadruple_type; | |
243 | ||
244 | } | |
245 | ||
246 | namespace test_decltype | |
247 | { | |
248 | ||
249 | int | |
250 | f() | |
251 | { | |
252 | int a = 1; | |
253 | decltype(a) b = 2; | |
254 | return a + b; | |
255 | } | |
256 | ||
257 | } | |
258 | ||
259 | namespace test_type_deduction | |
260 | { | |
261 | ||
262 | template < typename T1, typename T2 > | |
263 | struct is_same | |
264 | { | |
265 | static const bool value = false; | |
266 | }; | |
267 | ||
268 | template < typename T > | |
269 | struct is_same<T, T> | |
270 | { | |
271 | static const bool value = true; | |
272 | }; | |
273 | ||
274 | template < typename T1, typename T2 > | |
275 | auto | |
276 | add(T1 a1, T2 a2) -> decltype(a1 + a2) | |
277 | { | |
278 | return a1 + a2; | |
279 | } | |
280 | ||
281 | int | |
282 | test(const int c, volatile int v) | |
283 | { | |
284 | static_assert(is_same<int, decltype(0)>::value == true, ""); | |
285 | static_assert(is_same<int, decltype(c)>::value == false, ""); | |
286 | static_assert(is_same<int, decltype(v)>::value == false, ""); | |
287 | auto ac = c; | |
288 | auto av = v; | |
289 | auto sumi = ac + av + 'x'; | |
290 | auto sumf = ac + av + 1.0; | |
291 | static_assert(is_same<int, decltype(ac)>::value == true, ""); | |
292 | static_assert(is_same<int, decltype(av)>::value == true, ""); | |
293 | static_assert(is_same<int, decltype(sumi)>::value == true, ""); | |
294 | static_assert(is_same<int, decltype(sumf)>::value == false, ""); | |
295 | static_assert(is_same<int, decltype(add(c, v))>::value == true, ""); | |
296 | return (sumf > 0.0) ? sumi : add(c, v); | |
297 | } | |
298 | ||
299 | } | |
300 | ||
301 | namespace test_noexcept | |
302 | { | |
303 | ||
304 | int f() { return 0; } | |
305 | int g() noexcept { return 0; } | |
306 | ||
307 | static_assert(noexcept(f()) == false, ""); | |
308 | static_assert(noexcept(g()) == true, ""); | |
309 | ||
310 | } | |
311 | ||
312 | namespace test_constexpr | |
313 | { | |
314 | ||
315 | template < typename CharT > | |
316 | unsigned long constexpr | |
317 | strlen_c_r(const CharT *const s, const unsigned long acc) noexcept | |
318 | { | |
319 | return *s ? strlen_c_r(s + 1, acc + 1) : acc; | |
320 | } | |
321 | ||
322 | template < typename CharT > | |
323 | unsigned long constexpr | |
324 | strlen_c(const CharT *const s) noexcept | |
325 | { | |
326 | return strlen_c_r(s, 0UL); | |
327 | } | |
328 | ||
329 | static_assert(strlen_c("") == 0UL, ""); | |
330 | static_assert(strlen_c("1") == 1UL, ""); | |
331 | static_assert(strlen_c("example") == 7UL, ""); | |
332 | static_assert(strlen_c("another\0example") == 7UL, ""); | |
333 | ||
334 | } | |
335 | ||
336 | namespace test_rvalue_references | |
337 | { | |
338 | ||
339 | template < int N > | |
340 | struct answer | |
341 | { | |
342 | static constexpr int value = N; | |
343 | }; | |
344 | ||
345 | answer<1> f(int&) { return answer<1>(); } | |
346 | answer<2> f(const int&) { return answer<2>(); } | |
347 | answer<3> f(int&&) { return answer<3>(); } | |
348 | ||
349 | void | |
350 | test() | |
351 | { | |
352 | int i = 0; | |
353 | const int c = 0; | |
354 | static_assert(decltype(f(i))::value == 1, ""); | |
355 | static_assert(decltype(f(c))::value == 2, ""); | |
356 | static_assert(decltype(f(0))::value == 3, ""); | |
357 | } | |
358 | ||
359 | } | |
360 | ||
361 | namespace test_uniform_initialization | |
362 | { | |
363 | ||
364 | struct test | |
365 | { | |
366 | static const int zero {}; | |
367 | static const int one {1}; | |
368 | }; | |
369 | ||
370 | static_assert(test::zero == 0, ""); | |
371 | static_assert(test::one == 1, ""); | |
372 | ||
373 | } | |
374 | ||
375 | namespace test_lambdas | |
376 | { | |
377 | ||
378 | void | |
379 | test1() | |
380 | { | |
381 | auto lambda1 = [](){}; | |
382 | auto lambda2 = lambda1; | |
383 | lambda1(); | |
384 | lambda2(); | |
385 | } | |
386 | ||
387 | int | |
388 | test2() | |
389 | { | |
390 | auto a = [](int i, int j){ return i + j; }(1, 2); | |
391 | auto b = []() -> int { return '0'; }(); | |
392 | auto c = [=](){ return a + b; }(); | |
393 | auto d = [&](){ return c; }(); | |
394 | auto e = [a, &b](int x) mutable { | |
395 | const auto identity = [](int y){ return y; }; | |
396 | for (auto i = 0; i < a; ++i) | |
397 | a += b--; | |
398 | return x + identity(a + b); | |
399 | }(0); | |
400 | return a + b + c + d + e; | |
401 | } | |
402 | ||
403 | int | |
404 | test3() | |
405 | { | |
406 | const auto nullary = [](){ return 0; }; | |
407 | const auto unary = [](int x){ return x; }; | |
408 | using nullary_t = decltype(nullary); | |
409 | using unary_t = decltype(unary); | |
410 | const auto higher1st = [](nullary_t f){ return f(); }; | |
411 | const auto higher2nd = [unary](nullary_t f1){ | |
412 | return [unary, f1](unary_t f2){ return f2(unary(f1())); }; | |
413 | }; | |
414 | return higher1st(nullary) + higher2nd(nullary)(unary); | |
415 | } | |
416 | ||
417 | } | |
418 | ||
419 | namespace test_variadic_templates | |
420 | { | |
421 | ||
422 | template <int...> | |
423 | struct sum; | |
424 | ||
425 | template <int N0, int... N1toN> | |
426 | struct sum<N0, N1toN...> | |
427 | { | |
428 | static constexpr auto value = N0 + sum<N1toN...>::value; | |
429 | }; | |
430 | ||
431 | template <> | |
432 | struct sum<> | |
433 | { | |
434 | static constexpr auto value = 0; | |
435 | }; | |
436 | ||
437 | static_assert(sum<>::value == 0, ""); | |
438 | static_assert(sum<1>::value == 1, ""); | |
439 | static_assert(sum<23>::value == 23, ""); | |
440 | static_assert(sum<1, 2>::value == 3, ""); | |
441 | static_assert(sum<5, 5, 11>::value == 21, ""); | |
442 | static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, ""); | |
443 | ||
444 | } | |
445 | ||
446 | // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae | |
447 | // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function | |
448 | // because of this. | |
449 | namespace test_template_alias_sfinae | |
450 | { | |
451 | ||
452 | struct foo {}; | |
453 | ||
454 | template<typename T> | |
455 | using member = typename T::member_type; | |
456 | ||
457 | template<typename T> | |
458 | void func(...) {} | |
459 | ||
460 | template<typename T> | |
461 | void func(member<T>*) {} | |
462 | ||
463 | void test(); | |
464 | ||
465 | void test() { func<foo>(0); } | |
466 | ||
467 | } | |
468 | ||
469 | } // namespace cxx11 | |
470 | ||
471 | #endif // __cplusplus >= 201103L | |
472 | ||
473 | ]]) | |
474 | ||
475 | ||
476 | dnl Tests for new features in C++14 | |
477 | ||
478 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[ | |
479 | ||
480 | // If the compiler admits that it is not ready for C++14, why torture it? | |
481 | // Hopefully, this will speed up the test. | |
482 | ||
483 | #ifndef __cplusplus | |
484 | ||
485 | #error "This is not a C++ compiler" | |
486 | ||
c64bc75d | 487 | #elif __cplusplus < 201402L && !defined _MSC_VER |
b571f84c MS |
488 | |
489 | #error "This is not a C++14 compiler" | |
490 | ||
491 | #else | |
492 | ||
493 | namespace cxx14 | |
494 | { | |
495 | ||
496 | namespace test_polymorphic_lambdas | |
497 | { | |
498 | ||
499 | int | |
500 | test() | |
501 | { | |
502 | const auto lambda = [](auto&&... args){ | |
503 | const auto istiny = [](auto x){ | |
504 | return (sizeof(x) == 1UL) ? 1 : 0; | |
505 | }; | |
506 | const int aretiny[] = { istiny(args)... }; | |
507 | return aretiny[0]; | |
508 | }; | |
509 | return lambda(1, 1L, 1.0f, '1'); | |
510 | } | |
511 | ||
512 | } | |
513 | ||
514 | namespace test_binary_literals | |
515 | { | |
516 | ||
517 | constexpr auto ivii = 0b0000000000101010; | |
518 | static_assert(ivii == 42, "wrong value"); | |
519 | ||
520 | } | |
521 | ||
522 | namespace test_generalized_constexpr | |
523 | { | |
524 | ||
525 | template < typename CharT > | |
526 | constexpr unsigned long | |
527 | strlen_c(const CharT *const s) noexcept | |
528 | { | |
529 | auto length = 0UL; | |
530 | for (auto p = s; *p; ++p) | |
531 | ++length; | |
532 | return length; | |
533 | } | |
534 | ||
535 | static_assert(strlen_c("") == 0UL, ""); | |
536 | static_assert(strlen_c("x") == 1UL, ""); | |
537 | static_assert(strlen_c("test") == 4UL, ""); | |
538 | static_assert(strlen_c("another\0test") == 7UL, ""); | |
539 | ||
540 | } | |
541 | ||
542 | namespace test_lambda_init_capture | |
543 | { | |
544 | ||
545 | int | |
546 | test() | |
547 | { | |
548 | auto x = 0; | |
549 | const auto lambda1 = [a = x](int b){ return a + b; }; | |
550 | const auto lambda2 = [a = lambda1(x)](){ return a; }; | |
551 | return lambda2(); | |
552 | } | |
553 | ||
554 | } | |
555 | ||
c64bc75d | 556 | namespace test_digit_separators |
b571f84c MS |
557 | { |
558 | ||
559 | constexpr auto ten_million = 100'000'000; | |
560 | static_assert(ten_million == 100000000, ""); | |
561 | ||
562 | } | |
563 | ||
564 | namespace test_return_type_deduction | |
565 | { | |
566 | ||
567 | auto f(int& x) { return x; } | |
568 | decltype(auto) g(int& x) { return x; } | |
569 | ||
570 | template < typename T1, typename T2 > | |
571 | struct is_same | |
572 | { | |
573 | static constexpr auto value = false; | |
574 | }; | |
575 | ||
576 | template < typename T > | |
577 | struct is_same<T, T> | |
578 | { | |
579 | static constexpr auto value = true; | |
580 | }; | |
581 | ||
582 | int | |
583 | test() | |
584 | { | |
585 | auto x = 0; | |
586 | static_assert(is_same<int, decltype(f(x))>::value, ""); | |
587 | static_assert(is_same<int&, decltype(g(x))>::value, ""); | |
588 | return x; | |
589 | } | |
590 | ||
591 | } | |
592 | ||
593 | } // namespace cxx14 | |
594 | ||
595 | #endif // __cplusplus >= 201402L | |
596 | ||
597 | ]]) | |
c64bc75d GS |
598 | |
599 | ||
600 | dnl Tests for new features in C++17 | |
601 | ||
602 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[ | |
603 | ||
604 | // If the compiler admits that it is not ready for C++17, why torture it? | |
605 | // Hopefully, this will speed up the test. | |
606 | ||
607 | #ifndef __cplusplus | |
608 | ||
609 | #error "This is not a C++ compiler" | |
610 | ||
611 | #elif __cplusplus < 201703L && !defined _MSC_VER | |
612 | ||
613 | #error "This is not a C++17 compiler" | |
614 | ||
615 | #else | |
616 | ||
617 | #include <initializer_list> | |
618 | #include <utility> | |
619 | #include <type_traits> | |
620 | ||
621 | namespace cxx17 | |
622 | { | |
623 | ||
624 | namespace test_constexpr_lambdas | |
625 | { | |
626 | ||
627 | constexpr int foo = [](){return 42;}(); | |
628 | ||
629 | } | |
630 | ||
631 | namespace test::nested_namespace::definitions | |
632 | { | |
633 | ||
634 | } | |
635 | ||
636 | namespace test_fold_expression | |
637 | { | |
638 | ||
639 | template<typename... Args> | |
640 | int multiply(Args... args) | |
641 | { | |
642 | return (args * ... * 1); | |
643 | } | |
644 | ||
645 | template<typename... Args> | |
646 | bool all(Args... args) | |
647 | { | |
648 | return (args && ...); | |
649 | } | |
650 | ||
651 | } | |
652 | ||
653 | namespace test_extended_static_assert | |
654 | { | |
655 | ||
656 | static_assert (true); | |
657 | ||
658 | } | |
659 | ||
660 | namespace test_auto_brace_init_list | |
661 | { | |
662 | ||
663 | auto foo = {5}; | |
664 | auto bar {5}; | |
665 | ||
666 | static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value); | |
667 | static_assert(std::is_same<int, decltype(bar)>::value); | |
668 | } | |
669 | ||
670 | namespace test_typename_in_template_template_parameter | |
671 | { | |
672 | ||
673 | template<template<typename> typename X> struct D; | |
674 | ||
675 | } | |
676 | ||
677 | namespace test_fallthrough_nodiscard_maybe_unused_attributes | |
678 | { | |
679 | ||
680 | int f1() | |
681 | { | |
682 | return 42; | |
683 | } | |
684 | ||
685 | [[nodiscard]] int f2() | |
686 | { | |
687 | [[maybe_unused]] auto unused = f1(); | |
688 | ||
689 | switch (f1()) | |
690 | { | |
691 | case 17: | |
692 | f1(); | |
693 | [[fallthrough]]; | |
694 | case 42: | |
695 | f1(); | |
696 | } | |
697 | return f1(); | |
698 | } | |
699 | ||
700 | } | |
701 | ||
702 | namespace test_extended_aggregate_initialization | |
703 | { | |
704 | ||
705 | struct base1 | |
706 | { | |
707 | int b1, b2 = 42; | |
708 | }; | |
709 | ||
710 | struct base2 | |
711 | { | |
712 | base2() { | |
713 | b3 = 42; | |
714 | } | |
715 | int b3; | |
716 | }; | |
717 | ||
718 | struct derived : base1, base2 | |
719 | { | |
720 | int d; | |
721 | }; | |
722 | ||
723 | derived d1 {{1, 2}, {}, 4}; // full initialization | |
724 | derived d2 {{}, {}, 4}; // value-initialized bases | |
725 | ||
726 | } | |
727 | ||
728 | namespace test_general_range_based_for_loop | |
729 | { | |
730 | ||
731 | struct iter | |
732 | { | |
733 | int i; | |
734 | ||
735 | int& operator* () | |
736 | { | |
737 | return i; | |
738 | } | |
739 | ||
740 | const int& operator* () const | |
741 | { | |
742 | return i; | |
743 | } | |
744 | ||
745 | iter& operator++() | |
746 | { | |
747 | ++i; | |
748 | return *this; | |
749 | } | |
750 | }; | |
751 | ||
752 | struct sentinel | |
753 | { | |
754 | int i; | |
755 | }; | |
756 | ||
757 | bool operator== (const iter& i, const sentinel& s) | |
758 | { | |
759 | return i.i == s.i; | |
760 | } | |
761 | ||
762 | bool operator!= (const iter& i, const sentinel& s) | |
763 | { | |
764 | return !(i == s); | |
765 | } | |
766 | ||
767 | struct range | |
768 | { | |
769 | iter begin() const | |
770 | { | |
771 | return {0}; | |
772 | } | |
773 | ||
774 | sentinel end() const | |
775 | { | |
776 | return {5}; | |
777 | } | |
778 | }; | |
779 | ||
780 | void f() | |
781 | { | |
782 | range r {}; | |
783 | ||
784 | for (auto i : r) | |
785 | { | |
786 | [[maybe_unused]] auto v = i; | |
787 | } | |
788 | } | |
789 | ||
790 | } | |
791 | ||
792 | namespace test_lambda_capture_asterisk_this_by_value | |
793 | { | |
794 | ||
795 | struct t | |
796 | { | |
797 | int i; | |
798 | int foo() | |
799 | { | |
800 | return [*this]() | |
801 | { | |
802 | return i; | |
803 | }(); | |
804 | } | |
805 | }; | |
806 | ||
807 | } | |
808 | ||
809 | namespace test_enum_class_construction | |
810 | { | |
811 | ||
812 | enum class byte : unsigned char | |
813 | {}; | |
814 | ||
815 | byte foo {42}; | |
816 | ||
817 | } | |
818 | ||
819 | namespace test_constexpr_if | |
820 | { | |
821 | ||
822 | template <bool cond> | |
823 | int f () | |
824 | { | |
825 | if constexpr(cond) | |
826 | { | |
827 | return 13; | |
828 | } | |
829 | else | |
830 | { | |
831 | return 42; | |
832 | } | |
833 | } | |
834 | ||
835 | } | |
836 | ||
837 | namespace test_selection_statement_with_initializer | |
838 | { | |
839 | ||
840 | int f() | |
841 | { | |
842 | return 13; | |
843 | } | |
844 | ||
845 | int f2() | |
846 | { | |
847 | if (auto i = f(); i > 0) | |
848 | { | |
849 | return 3; | |
850 | } | |
851 | ||
852 | switch (auto i = f(); i + 4) | |
853 | { | |
854 | case 17: | |
855 | return 2; | |
856 | ||
857 | default: | |
858 | return 1; | |
859 | } | |
860 | } | |
861 | ||
862 | } | |
863 | ||
864 | namespace test_template_argument_deduction_for_class_templates | |
865 | { | |
866 | ||
867 | template <typename T1, typename T2> | |
868 | struct pair | |
869 | { | |
870 | pair (T1 p1, T2 p2) | |
871 | : m1 {p1}, | |
872 | m2 {p2} | |
873 | {} | |
874 | ||
875 | T1 m1; | |
876 | T2 m2; | |
877 | }; | |
878 | ||
879 | void f() | |
880 | { | |
881 | [[maybe_unused]] auto p = pair{13, 42u}; | |
882 | } | |
883 | ||
884 | } | |
885 | ||
886 | namespace test_non_type_auto_template_parameters | |
887 | { | |
888 | ||
889 | template <auto n> | |
890 | struct B | |
891 | {}; | |
892 | ||
893 | B<5> b1; | |
894 | B<'a'> b2; | |
895 | ||
896 | } | |
897 | ||
898 | namespace test_structured_bindings | |
899 | { | |
900 | ||
901 | int arr[2] = { 1, 2 }; | |
902 | std::pair<int, int> pr = { 1, 2 }; | |
903 | ||
904 | auto f1() -> int(&)[2] | |
905 | { | |
906 | return arr; | |
907 | } | |
908 | ||
909 | auto f2() -> std::pair<int, int>& | |
910 | { | |
911 | return pr; | |
912 | } | |
913 | ||
914 | struct S | |
915 | { | |
916 | int x1 : 2; | |
917 | volatile double y1; | |
918 | }; | |
919 | ||
920 | S f3() | |
921 | { | |
922 | return {}; | |
923 | } | |
924 | ||
925 | auto [ x1, y1 ] = f1(); | |
926 | auto& [ xr1, yr1 ] = f1(); | |
927 | auto [ x2, y2 ] = f2(); | |
928 | auto& [ xr2, yr2 ] = f2(); | |
929 | const auto [ x3, y3 ] = f3(); | |
930 | ||
931 | } | |
932 | ||
933 | namespace test_exception_spec_type_system | |
934 | { | |
935 | ||
936 | struct Good {}; | |
937 | struct Bad {}; | |
938 | ||
939 | void g1() noexcept; | |
940 | void g2(); | |
941 | ||
942 | template<typename T> | |
943 | Bad | |
944 | f(T*, T*); | |
945 | ||
946 | template<typename T1, typename T2> | |
947 | Good | |
948 | f(T1*, T2*); | |
949 | ||
950 | static_assert (std::is_same_v<Good, decltype(f(g1, g2))>); | |
951 | ||
952 | } | |
953 | ||
954 | namespace test_inline_variables | |
955 | { | |
956 | ||
957 | template<class T> void f(T) | |
958 | {} | |
959 | ||
960 | template<class T> inline T g(T) | |
961 | { | |
962 | return T{}; | |
963 | } | |
964 | ||
965 | template<> inline void f<>(int) | |
966 | {} | |
967 | ||
968 | template<> int g<>(int) | |
969 | { | |
970 | return 5; | |
971 | } | |
972 | ||
973 | } | |
974 | ||
975 | } // namespace cxx17 | |
976 | ||
977 | #endif // __cplusplus < 201703L && !defined _MSC_VER | |
978 | ||
979 | ]]) | |
980 | ||
981 | ||
982 | dnl Tests for new features in C++20 | |
983 | ||
984 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_20], [[ | |
985 | ||
986 | #ifndef __cplusplus | |
987 | ||
988 | #error "This is not a C++ compiler" | |
989 | ||
990 | #elif __cplusplus < 202002L && !defined _MSC_VER | |
991 | ||
992 | #error "This is not a C++20 compiler" | |
993 | ||
994 | #else | |
995 | ||
996 | #include <version> | |
997 | ||
998 | namespace cxx20 | |
999 | { | |
1000 | ||
1001 | // As C++20 supports feature test macros in the standard, there is no | |
1002 | // immediate need to actually test for feature availability on the | |
1003 | // Autoconf side. | |
1004 | ||
1005 | } // namespace cxx20 | |
1006 | ||
1007 | #endif // __cplusplus < 202002L && !defined _MSC_VER | |
1008 | ||
1009 | ]]) |