| 1 | # SPDX-License-Identifier: FSFAP |
| 2 | # =========================================================================== |
| 3 | # https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html |
| 4 | # =========================================================================== |
| 5 | # |
| 6 | # SYNOPSIS |
| 7 | # |
| 8 | # AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional]) |
| 9 | # |
| 10 | # DESCRIPTION |
| 11 | # |
| 12 | # Check for baseline language coverage in the compiler for the specified |
| 13 | # version of the C++ standard. If necessary, add switches to CXX and |
| 14 | # CXXCPP to enable support. VERSION may be '11', '14', '17', or '20' for |
| 15 | # the respective C++ standard version. |
| 16 | # |
| 17 | # The second argument, if specified, indicates whether you insist on an |
| 18 | # extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g. |
| 19 | # -std=c++11). If neither is specified, you get whatever works, with |
| 20 | # preference for no added switch, and then for an extended mode. |
| 21 | # |
| 22 | # The third argument, if specified 'mandatory' or if left unspecified, |
| 23 | # indicates that baseline support for the specified C++ standard is |
| 24 | # required and that the macro should error out if no mode with that |
| 25 | # support is found. If specified 'optional', then configuration proceeds |
| 26 | # regardless, after defining HAVE_CXX${VERSION} if and only if a |
| 27 | # supporting mode is found. |
| 28 | # |
| 29 | # LICENSE |
| 30 | # |
| 31 | # Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com> |
| 32 | # Copyright (c) 2012 Zack Weinberg <zackw@panix.com> |
| 33 | # Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu> |
| 34 | # Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com> |
| 35 | # Copyright (c) 2015 Paul Norman <penorman@mac.com> |
| 36 | # Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu> |
| 37 | # Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com> |
| 38 | # Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com> |
| 39 | # Copyright (c) 2020 Jason Merrill <jason@redhat.com> |
| 40 | # Copyright (c) 2021 Jörn Heusipp <osmanx@problemloesungsmaschine.de> |
| 41 | # |
| 42 | # Copying and distribution of this file, with or without modification, are |
| 43 | # permitted in any medium without royalty provided the copyright notice |
| 44 | # and this notice are preserved. This file is offered as-is, without any |
| 45 | # warranty. |
| 46 | |
| 47 | #serial 18 |
| 48 | |
| 49 | dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro |
| 50 | dnl (serial version number 13). |
| 51 | |
| 52 | AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl |
| 53 | m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"], |
| 54 | [$1], [14], [ax_cxx_compile_alternatives="14 1y"], |
| 55 | [$1], [17], [ax_cxx_compile_alternatives="17 1z"], |
| 56 | [$1], [20], [ax_cxx_compile_alternatives="20"], |
| 57 | [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl |
| 58 | m4_if([$2], [], [], |
| 59 | [$2], [ext], [], |
| 60 | [$2], [noext], [], |
| 61 | [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl |
| 62 | m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true], |
| 63 | [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true], |
| 64 | [$3], [optional], [ax_cxx_compile_cxx$1_required=false], |
| 65 | [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])]) |
| 66 | AC_LANG_PUSH([C++])dnl |
| 67 | ac_success=no |
| 68 | |
| 69 | m4_if([$2], [], [dnl |
| 70 | AC_CACHE_CHECK(whether $CXX supports C++$1 features by default, |
| 71 | ax_cv_cxx_compile_cxx$1, |
| 72 | [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], |
| 73 | [ax_cv_cxx_compile_cxx$1=yes], |
| 74 | [ax_cv_cxx_compile_cxx$1=no])]) |
| 75 | if test x$ax_cv_cxx_compile_cxx$1 = xyes; then |
| 76 | ac_success=yes |
| 77 | fi]) |
| 78 | |
| 79 | m4_if([$2], [noext], [], [dnl |
| 80 | if test x$ac_success = xno; then |
| 81 | for alternative in ${ax_cxx_compile_alternatives}; do |
| 82 | switch="-std=gnu++${alternative}" |
| 83 | cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) |
| 84 | AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, |
| 85 | $cachevar, |
| 86 | [ac_save_CXX="$CXX" |
| 87 | CXX="$CXX $switch" |
| 88 | AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], |
| 89 | [eval $cachevar=yes], |
| 90 | [eval $cachevar=no]) |
| 91 | CXX="$ac_save_CXX"]) |
| 92 | if eval test x\$$cachevar = xyes; then |
| 93 | CXX="$CXX $switch" |
| 94 | if test -n "$CXXCPP" ; then |
| 95 | CXXCPP="$CXXCPP $switch" |
| 96 | fi |
| 97 | ac_success=yes |
| 98 | break |
| 99 | fi |
| 100 | done |
| 101 | fi]) |
| 102 | |
| 103 | m4_if([$2], [ext], [], [dnl |
| 104 | if test x$ac_success = xno; then |
| 105 | dnl HP's aCC needs +std=c++11 according to: |
| 106 | dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf |
| 107 | dnl Cray's crayCC needs "-h std=c++11" |
| 108 | dnl MSVC needs -std:c++NN for C++17 and later (default is C++14) |
| 109 | for alternative in ${ax_cxx_compile_alternatives}; do |
| 110 | for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do |
| 111 | if test x"$switch" = xMSVC; then |
| 112 | dnl AS_TR_SH maps both `:` and `=` to `_` so -std:c++17 would collide |
| 113 | dnl with -std=c++17. We suffix the cache variable name with _MSVC to |
| 114 | dnl avoid this. |
| 115 | switch=-std:c++${alternative} |
| 116 | cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_${switch}_MSVC]) |
| 117 | else |
| 118 | cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) |
| 119 | fi |
| 120 | AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, |
| 121 | $cachevar, |
| 122 | [ac_save_CXX="$CXX" |
| 123 | CXX="$CXX $switch" |
| 124 | AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], |
| 125 | [eval $cachevar=yes], |
| 126 | [eval $cachevar=no]) |
| 127 | CXX="$ac_save_CXX"]) |
| 128 | if eval test x\$$cachevar = xyes; then |
| 129 | CXX="$CXX $switch" |
| 130 | if test -n "$CXXCPP" ; then |
| 131 | CXXCPP="$CXXCPP $switch" |
| 132 | fi |
| 133 | ac_success=yes |
| 134 | break |
| 135 | fi |
| 136 | done |
| 137 | if test x$ac_success = xyes; then |
| 138 | break |
| 139 | fi |
| 140 | done |
| 141 | fi]) |
| 142 | AC_LANG_POP([C++]) |
| 143 | if test x$ax_cxx_compile_cxx$1_required = xtrue; then |
| 144 | if test x$ac_success = xno; then |
| 145 | AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.]) |
| 146 | fi |
| 147 | fi |
| 148 | if test x$ac_success = xno; then |
| 149 | HAVE_CXX$1=0 |
| 150 | AC_MSG_NOTICE([No compiler with C++$1 support was found]) |
| 151 | else |
| 152 | HAVE_CXX$1=1 |
| 153 | AC_DEFINE(HAVE_CXX$1,1, |
| 154 | [define if the compiler supports basic C++$1 syntax]) |
| 155 | fi |
| 156 | AC_SUBST(HAVE_CXX$1) |
| 157 | ]) |
| 158 | |
| 159 | |
| 160 | dnl Test body for checking C++11 support |
| 161 | |
| 162 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11], |
| 163 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 |
| 164 | ) |
| 165 | |
| 166 | dnl Test body for checking C++14 support |
| 167 | |
| 168 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14], |
| 169 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 |
| 170 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 |
| 171 | ) |
| 172 | |
| 173 | dnl Test body for checking C++17 support |
| 174 | |
| 175 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17], |
| 176 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 |
| 177 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 |
| 178 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 |
| 179 | ) |
| 180 | |
| 181 | dnl Test body for checking C++20 support |
| 182 | |
| 183 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20], |
| 184 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 |
| 185 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 |
| 186 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 |
| 187 | _AX_CXX_COMPILE_STDCXX_testbody_new_in_20 |
| 188 | ) |
| 189 | |
| 190 | |
| 191 | dnl Tests for new features in C++11 |
| 192 | |
| 193 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[ |
| 194 | |
| 195 | // If the compiler admits that it is not ready for C++11, why torture it? |
| 196 | // Hopefully, this will speed up the test. |
| 197 | |
| 198 | #ifndef __cplusplus |
| 199 | |
| 200 | #error "This is not a C++ compiler" |
| 201 | |
| 202 | // MSVC always sets __cplusplus to 199711L in older versions; newer versions |
| 203 | // only set it correctly if /Zc:__cplusplus is specified as well as a |
| 204 | // /std:c++NN switch: |
| 205 | // https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/ |
| 206 | #elif __cplusplus < 201103L && !defined _MSC_VER |
| 207 | |
| 208 | #error "This is not a C++11 compiler" |
| 209 | |
| 210 | #else |
| 211 | |
| 212 | namespace cxx11 |
| 213 | { |
| 214 | |
| 215 | namespace test_static_assert |
| 216 | { |
| 217 | |
| 218 | template <typename T> |
| 219 | struct check |
| 220 | { |
| 221 | static_assert(sizeof(int) <= sizeof(T), "not big enough"); |
| 222 | }; |
| 223 | |
| 224 | } |
| 225 | |
| 226 | namespace test_final_override |
| 227 | { |
| 228 | |
| 229 | struct Base |
| 230 | { |
| 231 | virtual ~Base() {} |
| 232 | virtual void f() {} |
| 233 | }; |
| 234 | |
| 235 | struct Derived : public Base |
| 236 | { |
| 237 | virtual ~Derived() override {} |
| 238 | virtual void f() override {} |
| 239 | }; |
| 240 | |
| 241 | } |
| 242 | |
| 243 | namespace test_double_right_angle_brackets |
| 244 | { |
| 245 | |
| 246 | template < typename T > |
| 247 | struct check {}; |
| 248 | |
| 249 | typedef check<void> single_type; |
| 250 | typedef check<check<void>> double_type; |
| 251 | typedef check<check<check<void>>> triple_type; |
| 252 | typedef check<check<check<check<void>>>> quadruple_type; |
| 253 | |
| 254 | } |
| 255 | |
| 256 | namespace test_decltype |
| 257 | { |
| 258 | |
| 259 | int |
| 260 | f() |
| 261 | { |
| 262 | int a = 1; |
| 263 | decltype(a) b = 2; |
| 264 | return a + b; |
| 265 | } |
| 266 | |
| 267 | } |
| 268 | |
| 269 | namespace test_type_deduction |
| 270 | { |
| 271 | |
| 272 | template < typename T1, typename T2 > |
| 273 | struct is_same |
| 274 | { |
| 275 | static const bool value = false; |
| 276 | }; |
| 277 | |
| 278 | template < typename T > |
| 279 | struct is_same<T, T> |
| 280 | { |
| 281 | static const bool value = true; |
| 282 | }; |
| 283 | |
| 284 | template < typename T1, typename T2 > |
| 285 | auto |
| 286 | add(T1 a1, T2 a2) -> decltype(a1 + a2) |
| 287 | { |
| 288 | return a1 + a2; |
| 289 | } |
| 290 | |
| 291 | int |
| 292 | test(const int c, volatile int v) |
| 293 | { |
| 294 | static_assert(is_same<int, decltype(0)>::value == true, ""); |
| 295 | static_assert(is_same<int, decltype(c)>::value == false, ""); |
| 296 | static_assert(is_same<int, decltype(v)>::value == false, ""); |
| 297 | auto ac = c; |
| 298 | auto av = v; |
| 299 | auto sumi = ac + av + 'x'; |
| 300 | auto sumf = ac + av + 1.0; |
| 301 | static_assert(is_same<int, decltype(ac)>::value == true, ""); |
| 302 | static_assert(is_same<int, decltype(av)>::value == true, ""); |
| 303 | static_assert(is_same<int, decltype(sumi)>::value == true, ""); |
| 304 | static_assert(is_same<int, decltype(sumf)>::value == false, ""); |
| 305 | static_assert(is_same<int, decltype(add(c, v))>::value == true, ""); |
| 306 | return (sumf > 0.0) ? sumi : add(c, v); |
| 307 | } |
| 308 | |
| 309 | } |
| 310 | |
| 311 | namespace test_noexcept |
| 312 | { |
| 313 | |
| 314 | int f() { return 0; } |
| 315 | int g() noexcept { return 0; } |
| 316 | |
| 317 | static_assert(noexcept(f()) == false, ""); |
| 318 | static_assert(noexcept(g()) == true, ""); |
| 319 | |
| 320 | } |
| 321 | |
| 322 | namespace test_constexpr |
| 323 | { |
| 324 | |
| 325 | template < typename CharT > |
| 326 | unsigned long constexpr |
| 327 | strlen_c_r(const CharT *const s, const unsigned long acc) noexcept |
| 328 | { |
| 329 | return *s ? strlen_c_r(s + 1, acc + 1) : acc; |
| 330 | } |
| 331 | |
| 332 | template < typename CharT > |
| 333 | unsigned long constexpr |
| 334 | strlen_c(const CharT *const s) noexcept |
| 335 | { |
| 336 | return strlen_c_r(s, 0UL); |
| 337 | } |
| 338 | |
| 339 | static_assert(strlen_c("") == 0UL, ""); |
| 340 | static_assert(strlen_c("1") == 1UL, ""); |
| 341 | static_assert(strlen_c("example") == 7UL, ""); |
| 342 | static_assert(strlen_c("another\0example") == 7UL, ""); |
| 343 | |
| 344 | } |
| 345 | |
| 346 | namespace test_rvalue_references |
| 347 | { |
| 348 | |
| 349 | template < int N > |
| 350 | struct answer |
| 351 | { |
| 352 | static constexpr int value = N; |
| 353 | }; |
| 354 | |
| 355 | answer<1> f(int&) { return answer<1>(); } |
| 356 | answer<2> f(const int&) { return answer<2>(); } |
| 357 | answer<3> f(int&&) { return answer<3>(); } |
| 358 | |
| 359 | void |
| 360 | test() |
| 361 | { |
| 362 | int i = 0; |
| 363 | const int c = 0; |
| 364 | static_assert(decltype(f(i))::value == 1, ""); |
| 365 | static_assert(decltype(f(c))::value == 2, ""); |
| 366 | static_assert(decltype(f(0))::value == 3, ""); |
| 367 | } |
| 368 | |
| 369 | } |
| 370 | |
| 371 | namespace test_uniform_initialization |
| 372 | { |
| 373 | |
| 374 | struct test |
| 375 | { |
| 376 | static const int zero {}; |
| 377 | static const int one {1}; |
| 378 | }; |
| 379 | |
| 380 | static_assert(test::zero == 0, ""); |
| 381 | static_assert(test::one == 1, ""); |
| 382 | |
| 383 | } |
| 384 | |
| 385 | namespace test_lambdas |
| 386 | { |
| 387 | |
| 388 | void |
| 389 | test1() |
| 390 | { |
| 391 | auto lambda1 = [](){}; |
| 392 | auto lambda2 = lambda1; |
| 393 | lambda1(); |
| 394 | lambda2(); |
| 395 | } |
| 396 | |
| 397 | int |
| 398 | test2() |
| 399 | { |
| 400 | auto a = [](int i, int j){ return i + j; }(1, 2); |
| 401 | auto b = []() -> int { return '0'; }(); |
| 402 | auto c = [=](){ return a + b; }(); |
| 403 | auto d = [&](){ return c; }(); |
| 404 | auto e = [a, &b](int x) mutable { |
| 405 | const auto identity = [](int y){ return y; }; |
| 406 | for (auto i = 0; i < a; ++i) |
| 407 | a += b--; |
| 408 | return x + identity(a + b); |
| 409 | }(0); |
| 410 | return a + b + c + d + e; |
| 411 | } |
| 412 | |
| 413 | int |
| 414 | test3() |
| 415 | { |
| 416 | const auto nullary = [](){ return 0; }; |
| 417 | const auto unary = [](int x){ return x; }; |
| 418 | using nullary_t = decltype(nullary); |
| 419 | using unary_t = decltype(unary); |
| 420 | const auto higher1st = [](nullary_t f){ return f(); }; |
| 421 | const auto higher2nd = [unary](nullary_t f1){ |
| 422 | return [unary, f1](unary_t f2){ return f2(unary(f1())); }; |
| 423 | }; |
| 424 | return higher1st(nullary) + higher2nd(nullary)(unary); |
| 425 | } |
| 426 | |
| 427 | } |
| 428 | |
| 429 | namespace test_variadic_templates |
| 430 | { |
| 431 | |
| 432 | template <int...> |
| 433 | struct sum; |
| 434 | |
| 435 | template <int N0, int... N1toN> |
| 436 | struct sum<N0, N1toN...> |
| 437 | { |
| 438 | static constexpr auto value = N0 + sum<N1toN...>::value; |
| 439 | }; |
| 440 | |
| 441 | template <> |
| 442 | struct sum<> |
| 443 | { |
| 444 | static constexpr auto value = 0; |
| 445 | }; |
| 446 | |
| 447 | static_assert(sum<>::value == 0, ""); |
| 448 | static_assert(sum<1>::value == 1, ""); |
| 449 | static_assert(sum<23>::value == 23, ""); |
| 450 | static_assert(sum<1, 2>::value == 3, ""); |
| 451 | static_assert(sum<5, 5, 11>::value == 21, ""); |
| 452 | static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, ""); |
| 453 | |
| 454 | } |
| 455 | |
| 456 | // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae |
| 457 | // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function |
| 458 | // because of this. |
| 459 | namespace test_template_alias_sfinae |
| 460 | { |
| 461 | |
| 462 | struct foo {}; |
| 463 | |
| 464 | template<typename T> |
| 465 | using member = typename T::member_type; |
| 466 | |
| 467 | template<typename T> |
| 468 | void func(...) {} |
| 469 | |
| 470 | template<typename T> |
| 471 | void func(member<T>*) {} |
| 472 | |
| 473 | void test(); |
| 474 | |
| 475 | void test() { func<foo>(0); } |
| 476 | |
| 477 | } |
| 478 | |
| 479 | } // namespace cxx11 |
| 480 | |
| 481 | #endif // __cplusplus >= 201103L |
| 482 | |
| 483 | ]]) |
| 484 | |
| 485 | |
| 486 | dnl Tests for new features in C++14 |
| 487 | |
| 488 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[ |
| 489 | |
| 490 | // If the compiler admits that it is not ready for C++14, why torture it? |
| 491 | // Hopefully, this will speed up the test. |
| 492 | |
| 493 | #ifndef __cplusplus |
| 494 | |
| 495 | #error "This is not a C++ compiler" |
| 496 | |
| 497 | #elif __cplusplus < 201402L && !defined _MSC_VER |
| 498 | |
| 499 | #error "This is not a C++14 compiler" |
| 500 | |
| 501 | #else |
| 502 | |
| 503 | namespace cxx14 |
| 504 | { |
| 505 | |
| 506 | namespace test_polymorphic_lambdas |
| 507 | { |
| 508 | |
| 509 | int |
| 510 | test() |
| 511 | { |
| 512 | const auto lambda = [](auto&&... args){ |
| 513 | const auto istiny = [](auto x){ |
| 514 | return (sizeof(x) == 1UL) ? 1 : 0; |
| 515 | }; |
| 516 | const int aretiny[] = { istiny(args)... }; |
| 517 | return aretiny[0]; |
| 518 | }; |
| 519 | return lambda(1, 1L, 1.0f, '1'); |
| 520 | } |
| 521 | |
| 522 | } |
| 523 | |
| 524 | namespace test_binary_literals |
| 525 | { |
| 526 | |
| 527 | constexpr auto ivii = 0b0000000000101010; |
| 528 | static_assert(ivii == 42, "wrong value"); |
| 529 | |
| 530 | } |
| 531 | |
| 532 | namespace test_generalized_constexpr |
| 533 | { |
| 534 | |
| 535 | template < typename CharT > |
| 536 | constexpr unsigned long |
| 537 | strlen_c(const CharT *const s) noexcept |
| 538 | { |
| 539 | auto length = 0UL; |
| 540 | for (auto p = s; *p; ++p) |
| 541 | ++length; |
| 542 | return length; |
| 543 | } |
| 544 | |
| 545 | static_assert(strlen_c("") == 0UL, ""); |
| 546 | static_assert(strlen_c("x") == 1UL, ""); |
| 547 | static_assert(strlen_c("test") == 4UL, ""); |
| 548 | static_assert(strlen_c("another\0test") == 7UL, ""); |
| 549 | |
| 550 | } |
| 551 | |
| 552 | namespace test_lambda_init_capture |
| 553 | { |
| 554 | |
| 555 | int |
| 556 | test() |
| 557 | { |
| 558 | auto x = 0; |
| 559 | const auto lambda1 = [a = x](int b){ return a + b; }; |
| 560 | const auto lambda2 = [a = lambda1(x)](){ return a; }; |
| 561 | return lambda2(); |
| 562 | } |
| 563 | |
| 564 | } |
| 565 | |
| 566 | namespace test_digit_separators |
| 567 | { |
| 568 | |
| 569 | constexpr auto ten_million = 100'000'000; |
| 570 | static_assert(ten_million == 100000000, ""); |
| 571 | |
| 572 | } |
| 573 | |
| 574 | namespace test_return_type_deduction |
| 575 | { |
| 576 | |
| 577 | auto f(int& x) { return x; } |
| 578 | decltype(auto) g(int& x) { return x; } |
| 579 | |
| 580 | template < typename T1, typename T2 > |
| 581 | struct is_same |
| 582 | { |
| 583 | static constexpr auto value = false; |
| 584 | }; |
| 585 | |
| 586 | template < typename T > |
| 587 | struct is_same<T, T> |
| 588 | { |
| 589 | static constexpr auto value = true; |
| 590 | }; |
| 591 | |
| 592 | int |
| 593 | test() |
| 594 | { |
| 595 | auto x = 0; |
| 596 | static_assert(is_same<int, decltype(f(x))>::value, ""); |
| 597 | static_assert(is_same<int&, decltype(g(x))>::value, ""); |
| 598 | return x; |
| 599 | } |
| 600 | |
| 601 | } |
| 602 | |
| 603 | } // namespace cxx14 |
| 604 | |
| 605 | #endif // __cplusplus >= 201402L |
| 606 | |
| 607 | ]]) |
| 608 | |
| 609 | |
| 610 | dnl Tests for new features in C++17 |
| 611 | |
| 612 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[ |
| 613 | |
| 614 | // If the compiler admits that it is not ready for C++17, why torture it? |
| 615 | // Hopefully, this will speed up the test. |
| 616 | |
| 617 | #ifndef __cplusplus |
| 618 | |
| 619 | #error "This is not a C++ compiler" |
| 620 | |
| 621 | #elif __cplusplus < 201703L && !defined _MSC_VER |
| 622 | |
| 623 | #error "This is not a C++17 compiler" |
| 624 | |
| 625 | #else |
| 626 | |
| 627 | #include <initializer_list> |
| 628 | #include <utility> |
| 629 | #include <type_traits> |
| 630 | |
| 631 | namespace cxx17 |
| 632 | { |
| 633 | |
| 634 | namespace test_constexpr_lambdas |
| 635 | { |
| 636 | |
| 637 | constexpr int foo = [](){return 42;}(); |
| 638 | |
| 639 | } |
| 640 | |
| 641 | namespace test::nested_namespace::definitions |
| 642 | { |
| 643 | |
| 644 | } |
| 645 | |
| 646 | namespace test_fold_expression |
| 647 | { |
| 648 | |
| 649 | template<typename... Args> |
| 650 | int multiply(Args... args) |
| 651 | { |
| 652 | return (args * ... * 1); |
| 653 | } |
| 654 | |
| 655 | template<typename... Args> |
| 656 | bool all(Args... args) |
| 657 | { |
| 658 | return (args && ...); |
| 659 | } |
| 660 | |
| 661 | } |
| 662 | |
| 663 | namespace test_extended_static_assert |
| 664 | { |
| 665 | |
| 666 | static_assert (true); |
| 667 | |
| 668 | } |
| 669 | |
| 670 | namespace test_auto_brace_init_list |
| 671 | { |
| 672 | |
| 673 | auto foo = {5}; |
| 674 | auto bar {5}; |
| 675 | |
| 676 | static_assert(std::is_same<std::initializer_list<int>, decltype(foo)>::value); |
| 677 | static_assert(std::is_same<int, decltype(bar)>::value); |
| 678 | } |
| 679 | |
| 680 | namespace test_typename_in_template_template_parameter |
| 681 | { |
| 682 | |
| 683 | template<template<typename> typename X> struct D; |
| 684 | |
| 685 | } |
| 686 | |
| 687 | namespace test_fallthrough_nodiscard_maybe_unused_attributes |
| 688 | { |
| 689 | |
| 690 | int f1() |
| 691 | { |
| 692 | return 42; |
| 693 | } |
| 694 | |
| 695 | [[nodiscard]] int f2() |
| 696 | { |
| 697 | [[maybe_unused]] auto unused = f1(); |
| 698 | |
| 699 | switch (f1()) |
| 700 | { |
| 701 | case 17: |
| 702 | f1(); |
| 703 | [[fallthrough]]; |
| 704 | case 42: |
| 705 | f1(); |
| 706 | } |
| 707 | return f1(); |
| 708 | } |
| 709 | |
| 710 | } |
| 711 | |
| 712 | namespace test_extended_aggregate_initialization |
| 713 | { |
| 714 | |
| 715 | struct base1 |
| 716 | { |
| 717 | int b1, b2 = 42; |
| 718 | }; |
| 719 | |
| 720 | struct base2 |
| 721 | { |
| 722 | base2() { |
| 723 | b3 = 42; |
| 724 | } |
| 725 | int b3; |
| 726 | }; |
| 727 | |
| 728 | struct derived : base1, base2 |
| 729 | { |
| 730 | int d; |
| 731 | }; |
| 732 | |
| 733 | derived d1 {{1, 2}, {}, 4}; // full initialization |
| 734 | derived d2 {{}, {}, 4}; // value-initialized bases |
| 735 | |
| 736 | } |
| 737 | |
| 738 | namespace test_general_range_based_for_loop |
| 739 | { |
| 740 | |
| 741 | struct iter |
| 742 | { |
| 743 | int i; |
| 744 | |
| 745 | int& operator* () |
| 746 | { |
| 747 | return i; |
| 748 | } |
| 749 | |
| 750 | const int& operator* () const |
| 751 | { |
| 752 | return i; |
| 753 | } |
| 754 | |
| 755 | iter& operator++() |
| 756 | { |
| 757 | ++i; |
| 758 | return *this; |
| 759 | } |
| 760 | }; |
| 761 | |
| 762 | struct sentinel |
| 763 | { |
| 764 | int i; |
| 765 | }; |
| 766 | |
| 767 | bool operator== (const iter& i, const sentinel& s) |
| 768 | { |
| 769 | return i.i == s.i; |
| 770 | } |
| 771 | |
| 772 | bool operator!= (const iter& i, const sentinel& s) |
| 773 | { |
| 774 | return !(i == s); |
| 775 | } |
| 776 | |
| 777 | struct range |
| 778 | { |
| 779 | iter begin() const |
| 780 | { |
| 781 | return {0}; |
| 782 | } |
| 783 | |
| 784 | sentinel end() const |
| 785 | { |
| 786 | return {5}; |
| 787 | } |
| 788 | }; |
| 789 | |
| 790 | void f() |
| 791 | { |
| 792 | range r {}; |
| 793 | |
| 794 | for (auto i : r) |
| 795 | { |
| 796 | [[maybe_unused]] auto v = i; |
| 797 | } |
| 798 | } |
| 799 | |
| 800 | } |
| 801 | |
| 802 | namespace test_lambda_capture_asterisk_this_by_value |
| 803 | { |
| 804 | |
| 805 | struct t |
| 806 | { |
| 807 | int i; |
| 808 | int foo() |
| 809 | { |
| 810 | return [*this]() |
| 811 | { |
| 812 | return i; |
| 813 | }(); |
| 814 | } |
| 815 | }; |
| 816 | |
| 817 | } |
| 818 | |
| 819 | namespace test_enum_class_construction |
| 820 | { |
| 821 | |
| 822 | enum class byte : unsigned char |
| 823 | {}; |
| 824 | |
| 825 | byte foo {42}; |
| 826 | |
| 827 | } |
| 828 | |
| 829 | namespace test_constexpr_if |
| 830 | { |
| 831 | |
| 832 | template <bool cond> |
| 833 | int f () |
| 834 | { |
| 835 | if constexpr(cond) |
| 836 | { |
| 837 | return 13; |
| 838 | } |
| 839 | else |
| 840 | { |
| 841 | return 42; |
| 842 | } |
| 843 | } |
| 844 | |
| 845 | } |
| 846 | |
| 847 | namespace test_selection_statement_with_initializer |
| 848 | { |
| 849 | |
| 850 | int f() |
| 851 | { |
| 852 | return 13; |
| 853 | } |
| 854 | |
| 855 | int f2() |
| 856 | { |
| 857 | if (auto i = f(); i > 0) |
| 858 | { |
| 859 | return 3; |
| 860 | } |
| 861 | |
| 862 | switch (auto i = f(); i + 4) |
| 863 | { |
| 864 | case 17: |
| 865 | return 2; |
| 866 | |
| 867 | default: |
| 868 | return 1; |
| 869 | } |
| 870 | } |
| 871 | |
| 872 | } |
| 873 | |
| 874 | namespace test_template_argument_deduction_for_class_templates |
| 875 | { |
| 876 | |
| 877 | template <typename T1, typename T2> |
| 878 | struct pair |
| 879 | { |
| 880 | pair (T1 p1, T2 p2) |
| 881 | : m1 {p1}, |
| 882 | m2 {p2} |
| 883 | {} |
| 884 | |
| 885 | T1 m1; |
| 886 | T2 m2; |
| 887 | }; |
| 888 | |
| 889 | void f() |
| 890 | { |
| 891 | [[maybe_unused]] auto p = pair{13, 42u}; |
| 892 | } |
| 893 | |
| 894 | } |
| 895 | |
| 896 | namespace test_non_type_auto_template_parameters |
| 897 | { |
| 898 | |
| 899 | template <auto n> |
| 900 | struct B |
| 901 | {}; |
| 902 | |
| 903 | B<5> b1; |
| 904 | B<'a'> b2; |
| 905 | |
| 906 | } |
| 907 | |
| 908 | namespace test_structured_bindings |
| 909 | { |
| 910 | |
| 911 | int arr[2] = { 1, 2 }; |
| 912 | std::pair<int, int> pr = { 1, 2 }; |
| 913 | |
| 914 | auto f1() -> int(&)[2] |
| 915 | { |
| 916 | return arr; |
| 917 | } |
| 918 | |
| 919 | auto f2() -> std::pair<int, int>& |
| 920 | { |
| 921 | return pr; |
| 922 | } |
| 923 | |
| 924 | struct S |
| 925 | { |
| 926 | int x1 : 2; |
| 927 | volatile double y1; |
| 928 | }; |
| 929 | |
| 930 | S f3() |
| 931 | { |
| 932 | return {}; |
| 933 | } |
| 934 | |
| 935 | auto [ x1, y1 ] = f1(); |
| 936 | auto& [ xr1, yr1 ] = f1(); |
| 937 | auto [ x2, y2 ] = f2(); |
| 938 | auto& [ xr2, yr2 ] = f2(); |
| 939 | const auto [ x3, y3 ] = f3(); |
| 940 | |
| 941 | } |
| 942 | |
| 943 | namespace test_exception_spec_type_system |
| 944 | { |
| 945 | |
| 946 | struct Good {}; |
| 947 | struct Bad {}; |
| 948 | |
| 949 | void g1() noexcept; |
| 950 | void g2(); |
| 951 | |
| 952 | template<typename T> |
| 953 | Bad |
| 954 | f(T*, T*); |
| 955 | |
| 956 | template<typename T1, typename T2> |
| 957 | Good |
| 958 | f(T1*, T2*); |
| 959 | |
| 960 | static_assert (std::is_same_v<Good, decltype(f(g1, g2))>); |
| 961 | |
| 962 | } |
| 963 | |
| 964 | namespace test_inline_variables |
| 965 | { |
| 966 | |
| 967 | template<class T> void f(T) |
| 968 | {} |
| 969 | |
| 970 | template<class T> inline T g(T) |
| 971 | { |
| 972 | return T{}; |
| 973 | } |
| 974 | |
| 975 | template<> inline void f<>(int) |
| 976 | {} |
| 977 | |
| 978 | template<> int g<>(int) |
| 979 | { |
| 980 | return 5; |
| 981 | } |
| 982 | |
| 983 | } |
| 984 | |
| 985 | } // namespace cxx17 |
| 986 | |
| 987 | #endif // __cplusplus < 201703L && !defined _MSC_VER |
| 988 | |
| 989 | ]]) |
| 990 | |
| 991 | |
| 992 | dnl Tests for new features in C++20 |
| 993 | |
| 994 | m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_20], [[ |
| 995 | |
| 996 | #ifndef __cplusplus |
| 997 | |
| 998 | #error "This is not a C++ compiler" |
| 999 | |
| 1000 | #elif __cplusplus < 202002L && !defined _MSC_VER |
| 1001 | |
| 1002 | #error "This is not a C++20 compiler" |
| 1003 | |
| 1004 | #else |
| 1005 | |
| 1006 | #include <version> |
| 1007 | |
| 1008 | namespace cxx20 |
| 1009 | { |
| 1010 | |
| 1011 | // As C++20 supports feature test macros in the standard, there is no |
| 1012 | // immediate need to actually test for feature availability on the |
| 1013 | // Autoconf side. |
| 1014 | |
| 1015 | } // namespace cxx20 |
| 1016 | |
| 1017 | #endif // __cplusplus < 202002L && !defined _MSC_VER |
| 1018 | |
| 1019 | ]]) |