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| 1 # =========================================================================== |
| 2 # http://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 CXXFLAGS to |
| 13 # enable support. VERSION may be '11' (for the C++11 standard) or '14' |
| 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 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 # |
| 37 # Copying and distribution of this file, with or without modification, are |
| 38 # permitted in any medium without royalty provided the copyright notice |
| 39 # and this notice are preserved. This file is offered as-is, without any |
| 40 # warranty. |
| 41 |
| 42 #serial 1 |
| 43 |
| 44 dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro |
| 45 dnl (serial version number 13). |
| 46 |
| 47 AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl |
| 48 m4_if([$1], [11], [], |
| 49 [$1], [14], [], |
| 50 [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_C
OMPILE_STDCXX])], |
| 51 [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl |
| 52 m4_if([$2], [], [], |
| 53 [$2], [ext], [], |
| 54 [$2], [noext], [], |
| 55 [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl |
| 56 m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true], |
| 57 [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true], |
| 58 [$3], [optional], [ax_cxx_compile_cxx$1_required=false], |
| 59 [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])]) |
| 60 AC_LANG_PUSH([C++])dnl |
| 61 ac_success=no |
| 62 AC_CACHE_CHECK(whether $CXX supports C++$1 features by default, |
| 63 ax_cv_cxx_compile_cxx$1, |
| 64 [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], |
| 65 [ax_cv_cxx_compile_cxx$1=yes], |
| 66 [ax_cv_cxx_compile_cxx$1=no])]) |
| 67 if test x$ax_cv_cxx_compile_cxx$1 = xyes; then |
| 68 ac_success=yes |
| 69 fi |
| 70 |
| 71 m4_if([$2], [noext], [], [dnl |
| 72 if test x$ac_success = xno; then |
| 73 for switch in -std=gnu++$1 -std=gnu++0x; do |
| 74 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) |
| 75 AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, |
| 76 $cachevar, |
| 77 [ac_save_CXXFLAGS="$CXXFLAGS" |
| 78 CXXFLAGS="$CXXFLAGS $switch" |
| 79 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])
], |
| 80 [eval $cachevar=yes], |
| 81 [eval $cachevar=no]) |
| 82 CXXFLAGS="$ac_save_CXXFLAGS"]) |
| 83 if eval test x\$$cachevar = xyes; then |
| 84 CXXFLAGS="$CXXFLAGS $switch" |
| 85 ac_success=yes |
| 86 break |
| 87 fi |
| 88 done |
| 89 fi]) |
| 90 |
| 91 m4_if([$2], [ext], [], [dnl |
| 92 if test x$ac_success = xno; then |
| 93 dnl HP's aCC needs +std=c++11 according to: |
| 94 dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_
Notes/769149-001.pdf |
| 95 dnl Cray's crayCC needs "-h std=c++11" |
| 96 for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do |
| 97 cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) |
| 98 AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, |
| 99 $cachevar, |
| 100 [ac_save_CXXFLAGS="$CXXFLAGS" |
| 101 CXXFLAGS="$CXXFLAGS $switch" |
| 102 AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])
], |
| 103 [eval $cachevar=yes], |
| 104 [eval $cachevar=no]) |
| 105 CXXFLAGS="$ac_save_CXXFLAGS"]) |
| 106 if eval test x\$$cachevar = xyes; then |
| 107 CXXFLAGS="$CXXFLAGS $switch" |
| 108 ac_success=yes |
| 109 break |
| 110 fi |
| 111 done |
| 112 fi]) |
| 113 AC_LANG_POP([C++]) |
| 114 if test x$ax_cxx_compile_cxx$1_required = xtrue; then |
| 115 if test x$ac_success = xno; then |
| 116 AC_MSG_ERROR([*** A compiler with support for C++$1 language features is r
equired.]) |
| 117 fi |
| 118 else |
| 119 if test x$ac_success = xno; then |
| 120 HAVE_CXX$1=0 |
| 121 AC_MSG_NOTICE([No compiler with C++$1 support was found]) |
| 122 else |
| 123 HAVE_CXX$1=1 |
| 124 AC_DEFINE(HAVE_CXX$1,1, |
| 125 [define if the compiler supports basic C++$1 syntax]) |
| 126 fi |
| 127 |
| 128 AC_SUBST(HAVE_CXX$1) |
| 129 fi |
| 130 ]) |
| 131 |
| 132 |
| 133 dnl Test body for checking C++11 support |
| 134 |
| 135 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11], |
| 136 _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 |
| 137 ) |
| 138 |
| 139 |
| 140 dnl Test body for checking C++14 support |
| 141 |
| 142 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14], |
| 143 _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 |
| 144 _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 |
| 145 ) |
| 146 |
| 147 |
| 148 dnl Tests for new features in C++11 |
| 149 |
| 150 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[ |
| 151 |
| 152 // If the compiler admits that it is not ready for C++11, why torture it? |
| 153 // Hopefully, this will speed up the test. |
| 154 |
| 155 #ifndef __cplusplus |
| 156 |
| 157 #error "This is not a C++ compiler" |
| 158 |
| 159 #elif __cplusplus < 201103L |
| 160 |
| 161 #error "This is not a C++11 compiler" |
| 162 |
| 163 #else |
| 164 |
| 165 namespace cxx11 |
| 166 { |
| 167 |
| 168 namespace test_static_assert |
| 169 { |
| 170 |
| 171 template <typename T> |
| 172 struct check |
| 173 { |
| 174 static_assert(sizeof(int) <= sizeof(T), "not big enough"); |
| 175 }; |
| 176 |
| 177 } |
| 178 |
| 179 namespace test_final_override |
| 180 { |
| 181 |
| 182 struct Base |
| 183 { |
| 184 virtual void f() {} |
| 185 }; |
| 186 |
| 187 struct Derived : public Base |
| 188 { |
| 189 virtual void f() override {} |
| 190 }; |
| 191 |
| 192 } |
| 193 |
| 194 namespace test_double_right_angle_brackets |
| 195 { |
| 196 |
| 197 template < typename T > |
| 198 struct check {}; |
| 199 |
| 200 typedef check<void> single_type; |
| 201 typedef check<check<void>> double_type; |
| 202 typedef check<check<check<void>>> triple_type; |
| 203 typedef check<check<check<check<void>>>> quadruple_type; |
| 204 |
| 205 } |
| 206 |
| 207 namespace test_decltype |
| 208 { |
| 209 |
| 210 int |
| 211 f() |
| 212 { |
| 213 int a = 1; |
| 214 decltype(a) b = 2; |
| 215 return a + b; |
| 216 } |
| 217 |
| 218 } |
| 219 |
| 220 namespace test_type_deduction |
| 221 { |
| 222 |
| 223 template < typename T1, typename T2 > |
| 224 struct is_same |
| 225 { |
| 226 static const bool value = false; |
| 227 }; |
| 228 |
| 229 template < typename T > |
| 230 struct is_same<T, T> |
| 231 { |
| 232 static const bool value = true; |
| 233 }; |
| 234 |
| 235 template < typename T1, typename T2 > |
| 236 auto |
| 237 add(T1 a1, T2 a2) -> decltype(a1 + a2) |
| 238 { |
| 239 return a1 + a2; |
| 240 } |
| 241 |
| 242 int |
| 243 test(const int c, volatile int v) |
| 244 { |
| 245 static_assert(is_same<int, decltype(0)>::value == true, ""); |
| 246 static_assert(is_same<int, decltype(c)>::value == false, ""); |
| 247 static_assert(is_same<int, decltype(v)>::value == false, ""); |
| 248 auto ac = c; |
| 249 auto av = v; |
| 250 auto sumi = ac + av + 'x'; |
| 251 auto sumf = ac + av + 1.0; |
| 252 static_assert(is_same<int, decltype(ac)>::value == true, ""); |
| 253 static_assert(is_same<int, decltype(av)>::value == true, ""); |
| 254 static_assert(is_same<int, decltype(sumi)>::value == true, ""); |
| 255 static_assert(is_same<int, decltype(sumf)>::value == false, ""); |
| 256 static_assert(is_same<int, decltype(add(c, v))>::value == true, ""); |
| 257 return (sumf > 0.0) ? sumi : add(c, v); |
| 258 } |
| 259 |
| 260 } |
| 261 |
| 262 namespace test_noexcept |
| 263 { |
| 264 |
| 265 int f() { return 0; } |
| 266 int g() noexcept { return 0; } |
| 267 |
| 268 static_assert(noexcept(f()) == false, ""); |
| 269 static_assert(noexcept(g()) == true, ""); |
| 270 |
| 271 } |
| 272 |
| 273 namespace test_constexpr |
| 274 { |
| 275 |
| 276 template < typename CharT > |
| 277 unsigned long constexpr |
| 278 strlen_c_r(const CharT *const s, const unsigned long acc) noexcept |
| 279 { |
| 280 return *s ? strlen_c_r(s + 1, acc + 1) : acc; |
| 281 } |
| 282 |
| 283 template < typename CharT > |
| 284 unsigned long constexpr |
| 285 strlen_c(const CharT *const s) noexcept |
| 286 { |
| 287 return strlen_c_r(s, 0UL); |
| 288 } |
| 289 |
| 290 static_assert(strlen_c("") == 0UL, ""); |
| 291 static_assert(strlen_c("1") == 1UL, ""); |
| 292 static_assert(strlen_c("example") == 7UL, ""); |
| 293 static_assert(strlen_c("another\0example") == 7UL, ""); |
| 294 |
| 295 } |
| 296 |
| 297 namespace test_rvalue_references |
| 298 { |
| 299 |
| 300 template < int N > |
| 301 struct answer |
| 302 { |
| 303 static constexpr int value = N; |
| 304 }; |
| 305 |
| 306 answer<1> f(int&) { return answer<1>(); } |
| 307 answer<2> f(const int&) { return answer<2>(); } |
| 308 answer<3> f(int&&) { return answer<3>(); } |
| 309 |
| 310 void |
| 311 test() |
| 312 { |
| 313 int i = 0; |
| 314 const int c = 0; |
| 315 static_assert(decltype(f(i))::value == 1, ""); |
| 316 static_assert(decltype(f(c))::value == 2, ""); |
| 317 static_assert(decltype(f(0))::value == 3, ""); |
| 318 } |
| 319 |
| 320 } |
| 321 |
| 322 namespace test_uniform_initialization |
| 323 { |
| 324 |
| 325 struct test |
| 326 { |
| 327 static const int zero {}; |
| 328 static const int one {1}; |
| 329 }; |
| 330 |
| 331 static_assert(test::zero == 0, ""); |
| 332 static_assert(test::one == 1, ""); |
| 333 |
| 334 } |
| 335 |
| 336 namespace test_lambdas |
| 337 { |
| 338 |
| 339 void |
| 340 test1() |
| 341 { |
| 342 auto lambda1 = [](){}; |
| 343 auto lambda2 = lambda1; |
| 344 lambda1(); |
| 345 lambda2(); |
| 346 } |
| 347 |
| 348 int |
| 349 test2() |
| 350 { |
| 351 auto a = [](int i, int j){ return i + j; }(1, 2); |
| 352 auto b = []() -> int { return '0'; }(); |
| 353 auto c = [=](){ return a + b; }(); |
| 354 auto d = [&](){ return c; }(); |
| 355 auto e = [a, &b](int x) mutable { |
| 356 const auto identity = [](int y){ return y; }; |
| 357 for (auto i = 0; i < a; ++i) |
| 358 a += b--; |
| 359 return x + identity(a + b); |
| 360 }(0); |
| 361 return a + b + c + d + e; |
| 362 } |
| 363 |
| 364 int |
| 365 test3() |
| 366 { |
| 367 const auto nullary = [](){ return 0; }; |
| 368 const auto unary = [](int x){ return x; }; |
| 369 using nullary_t = decltype(nullary); |
| 370 using unary_t = decltype(unary); |
| 371 const auto higher1st = [](nullary_t f){ return f(); }; |
| 372 const auto higher2nd = [unary](nullary_t f1){ |
| 373 return [unary, f1](unary_t f2){ return f2(unary(f1())); }; |
| 374 }; |
| 375 return higher1st(nullary) + higher2nd(nullary)(unary); |
| 376 } |
| 377 |
| 378 } |
| 379 |
| 380 namespace test_variadic_templates |
| 381 { |
| 382 |
| 383 template <int...> |
| 384 struct sum; |
| 385 |
| 386 template <int N0, int... N1toN> |
| 387 struct sum<N0, N1toN...> |
| 388 { |
| 389 static constexpr auto value = N0 + sum<N1toN...>::value; |
| 390 }; |
| 391 |
| 392 template <> |
| 393 struct sum<> |
| 394 { |
| 395 static constexpr auto value = 0; |
| 396 }; |
| 397 |
| 398 static_assert(sum<>::value == 0, ""); |
| 399 static_assert(sum<1>::value == 1, ""); |
| 400 static_assert(sum<23>::value == 23, ""); |
| 401 static_assert(sum<1, 2>::value == 3, ""); |
| 402 static_assert(sum<5, 5, 11>::value == 21, ""); |
| 403 static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, ""); |
| 404 |
| 405 } |
| 406 |
| 407 // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae |
| 408 // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function |
| 409 // because of this. |
| 410 namespace test_template_alias_sfinae |
| 411 { |
| 412 |
| 413 struct foo {}; |
| 414 |
| 415 template<typename T> |
| 416 using member = typename T::member_type; |
| 417 |
| 418 template<typename T> |
| 419 void func(...) {} |
| 420 |
| 421 template<typename T> |
| 422 void func(member<T>*) {} |
| 423 |
| 424 void test(); |
| 425 |
| 426 void test() { func<foo>(0); } |
| 427 |
| 428 } |
| 429 |
| 430 } // namespace cxx11 |
| 431 |
| 432 #endif // __cplusplus >= 201103L |
| 433 |
| 434 ]]) |
| 435 |
| 436 |
| 437 dnl Tests for new features in C++14 |
| 438 |
| 439 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[ |
| 440 |
| 441 // If the compiler admits that it is not ready for C++14, why torture it? |
| 442 // Hopefully, this will speed up the test. |
| 443 |
| 444 #ifndef __cplusplus |
| 445 |
| 446 #error "This is not a C++ compiler" |
| 447 |
| 448 #elif __cplusplus < 201402L |
| 449 |
| 450 #error "This is not a C++14 compiler" |
| 451 |
| 452 #else |
| 453 |
| 454 namespace cxx14 |
| 455 { |
| 456 |
| 457 namespace test_polymorphic_lambdas |
| 458 { |
| 459 |
| 460 int |
| 461 test() |
| 462 { |
| 463 const auto lambda = [](auto&&... args){ |
| 464 const auto istiny = [](auto x){ |
| 465 return (sizeof(x) == 1UL) ? 1 : 0; |
| 466 }; |
| 467 const int aretiny[] = { istiny(args)... }; |
| 468 return aretiny[0]; |
| 469 }; |
| 470 return lambda(1, 1L, 1.0f, '1'); |
| 471 } |
| 472 |
| 473 } |
| 474 |
| 475 namespace test_binary_literals |
| 476 { |
| 477 |
| 478 constexpr auto ivii = 0b0000000000101010; |
| 479 static_assert(ivii == 42, "wrong value"); |
| 480 |
| 481 } |
| 482 |
| 483 namespace test_generalized_constexpr |
| 484 { |
| 485 |
| 486 template < typename CharT > |
| 487 constexpr unsigned long |
| 488 strlen_c(const CharT *const s) noexcept |
| 489 { |
| 490 auto length = 0UL; |
| 491 for (auto p = s; *p; ++p) |
| 492 ++length; |
| 493 return length; |
| 494 } |
| 495 |
| 496 static_assert(strlen_c("") == 0UL, ""); |
| 497 static_assert(strlen_c("x") == 1UL, ""); |
| 498 static_assert(strlen_c("test") == 4UL, ""); |
| 499 static_assert(strlen_c("another\0test") == 7UL, ""); |
| 500 |
| 501 } |
| 502 |
| 503 namespace test_lambda_init_capture |
| 504 { |
| 505 |
| 506 int |
| 507 test() |
| 508 { |
| 509 auto x = 0; |
| 510 const auto lambda1 = [a = x](int b){ return a + b; }; |
| 511 const auto lambda2 = [a = lambda1(x)](){ return a; }; |
| 512 return lambda2(); |
| 513 } |
| 514 |
| 515 } |
| 516 |
| 517 namespace test_digit_seperators |
| 518 { |
| 519 |
| 520 constexpr auto ten_million = 100'000'000; |
| 521 static_assert(ten_million == 100000000, ""); |
| 522 |
| 523 } |
| 524 |
| 525 namespace test_return_type_deduction |
| 526 { |
| 527 |
| 528 auto f(int& x) { return x; } |
| 529 decltype(auto) g(int& x) { return x; } |
| 530 |
| 531 template < typename T1, typename T2 > |
| 532 struct is_same |
| 533 { |
| 534 static constexpr auto value = false; |
| 535 }; |
| 536 |
| 537 template < typename T > |
| 538 struct is_same<T, T> |
| 539 { |
| 540 static constexpr auto value = true; |
| 541 }; |
| 542 |
| 543 int |
| 544 test() |
| 545 { |
| 546 auto x = 0; |
| 547 static_assert(is_same<int, decltype(f(x))>::value, ""); |
| 548 static_assert(is_same<int&, decltype(g(x))>::value, ""); |
| 549 return x; |
| 550 } |
| 551 |
| 552 } |
| 553 |
| 554 } // namespace cxx14 |
| 555 |
| 556 #endif // __cplusplus >= 201402L |
| 557 |
| 558 ]]) |
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