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