gdb/ax_cxx_compile_stdcxx.m4

   1 # Copyright (c) 2016-2017 Free Software Foundation, Inc.
   2 #
   3 # Originally based on the AX_CXX_COMPILE_STDCXX macro found at the url
   4 # below.
   5 #
   6 # Local GDB customizations:
   7 #
   8 # - AC_SUBST CXX_DIALECT instead of changing CXX/CXXCPP.
   9 #
  10 # ===========================================================================
  11 #   http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
  12 # ===========================================================================
  13 #
  14 # SYNOPSIS
  15 #
  16 #   AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
  17 #
  18 # DESCRIPTION
  19 #
  20 #   Check for baseline language coverage in the compiler for the specified
  21 #   version of the C++ standard.  If necessary, add switches to CXX and
  22 #   CXXCPP to enable support.  VERSION may be '11' (for the C++11 standard)
  23 #   or '14' (for the C++14 standard).
  24 #
  25 #   The second argument, if specified, indicates whether you insist on an
  26 #   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
  27 #   -std=c++11).  If neither is specified, you get whatever works, with
  28 #   preference for an extended mode.
  29 #
  30 #   The third argument, if specified 'mandatory' or if left unspecified,
  31 #   indicates that baseline support for the specified C++ standard is
  32 #   required and that the macro should error out if no mode with that
  33 #   support is found.  If specified 'optional', then configuration proceeds
  34 #   regardless, after defining HAVE_CXX${VERSION} if and only if a
  35 #   supporting mode is found.
  36 #
  37 # LICENSE
  38 #
  39 #   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
  40 #   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
  41 #   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
  42 #   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
  43 #   Copyright (c) 2015 Paul Norman <penorman@mac.com>
  44 #   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
  45 #
  46 #   Copying and distribution of this file, with or without modification, are
  47 #   permitted in any medium without royalty provided the copyright notice
  48 #   and this notice are preserved.  This file is offered as-is, without any
  49 #   warranty.
  50
  51 #serial 4
  52
  53 dnl  This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
  54 dnl  (serial version number 13).
  55
  56 AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
  57   m4_if([$1], [11], [],
  58         [$1], [14], [],
  59         [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])],
  60         [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
  61   m4_if([$2], [], [],
  62         [$2], [ext], [],
  63         [$2], [noext], [],
  64         [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
  65   m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
  66         [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
  67         [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
  68         [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
  69   AC_LANG_PUSH([C++])dnl
  70   CXX_DIALECT=""
  71   ac_success=no
  72   AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
  73   ax_cv_cxx_compile_cxx$1,
  74   [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
  75     [ax_cv_cxx_compile_cxx$1=yes],
  76     [ax_cv_cxx_compile_cxx$1=no])])
  77   if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
  78     ac_success=yes
  79   fi
  80
  81   m4_if([$2], [noext], [], [dnl
  82   if test x$ac_success = xno; then
  83     for switch in -std=gnu++$1 -std=gnu++0x; do
  84       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
  85       AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
  86                      $cachevar,
  87         [ac_save_CXX="$CXX"
  88          CXX="$CXX $switch"
  89          AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
  90           [eval $cachevar=yes],
  91           [eval $cachevar=no])
  92          CXX="$ac_save_CXX"])
  93       if eval test x\$$cachevar = xyes; then
  94         CXX_DIALECT="$switch"
  95         ac_success=yes
  96         break
  97       fi
  98     done
  99   fi])
 100
 101   m4_if([$2], [ext], [], [dnl
 102   if test x$ac_success = xno; then
 103     dnl HP's aCC needs +std=c++11 according to:
 104     dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
 105     dnl Cray's crayCC needs "-h std=c++11"
 106     for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do
 107       cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
 108       AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
 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_DIALECT="$switch"
 118         ac_success=yes
 119         break
 120       fi
 121     done
 122   fi])
 123   AC_LANG_POP([C++])
 124   if test x$ax_cxx_compile_cxx$1_required = xtrue; then
 125     if test x$ac_success = xno; then
 126       AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
 127     fi
 128   fi
 129   if test x$ac_success = xno; then
 130     HAVE_CXX$1=0
 131     AC_MSG_NOTICE([No compiler with C++$1 support was found])
 132   else
 133     HAVE_CXX$1=1
 134     AC_DEFINE(HAVE_CXX$1,1,
 135               [define if the compiler supports basic C++$1 syntax])
 136   fi
 137   AC_SUBST(HAVE_CXX$1)
 138   AC_SUBST(CXX_DIALECT)
 139 ])
 140
 141
 142 dnl  Test body for checking C++11 support
 143
 144 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
 145   _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
 146 )
 147
 148
 149 dnl  Test body for checking C++14 support
 150
 151 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
 152   _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
 153   _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
 154 )
 155
 156
 157 dnl  Tests for new features in C++11
 158
 159 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
 160
 161 // If the compiler admits that it is not ready for C++11, why torture it?
 162 // Hopefully, this will speed up the test.
 163
 164 #ifndef __cplusplus
 165
 166 #error "This is not a C++ compiler"
 167
 168 #elif __cplusplus < 201103L
 169
 170 #error "This is not a C++11 compiler"
 171
 172 #else
 173
 174 namespace cxx11
 175 {
 176
 177   namespace test_static_assert
 178   {
 179
 180     template <typename T>
 181     struct check
 182     {
 183       static_assert(sizeof(int) <= sizeof(T), "not big enough");
 184     };
 185
 186   }
 187
 188   namespace test_final_override
 189   {
 190
 191     struct Base
 192     {
 193       virtual void f() {}
 194     };
 195
 196     struct Derived : public Base
 197     {
 198       virtual void f() override {}
 199     };
 200
 201   }
 202
 203   namespace test_double_right_angle_brackets
 204   {
 205
 206     template < typename T >
 207     struct check {};
 208
 209     typedef check<void> single_type;
 210     typedef check<check<void>> double_type;
 211     typedef check<check<check<void>>> triple_type;
 212     typedef check<check<check<check<void>>>> quadruple_type;
 213
 214   }
 215
 216   namespace test_decltype
 217   {
 218
 219     int
 220     f()
 221     {
 222       int a = 1;
 223       decltype(a) b = 2;
 224       return a + b;
 225     }
 226
 227   }
 228
 229   namespace test_type_deduction
 230   {
 231
 232     template < typename T1, typename T2 >
 233     struct is_same
 234     {
 235       static const bool value = false;
 236     };
 237
 238     template < typename T >
 239     struct is_same<T, T>
 240     {
 241       static const bool value = true;
 242     };
 243
 244     template < typename T1, typename T2 >
 245     auto
 246     add(T1 a1, T2 a2) -> decltype(a1 + a2)
 247     {
 248       return a1 + a2;
 249     }
 250
 251     int
 252     test(const int c, volatile int v)
 253     {
 254       static_assert(is_same<int, decltype(0)>::value == true, "");
 255       static_assert(is_same<int, decltype(c)>::value == false, "");
 256       static_assert(is_same<int, decltype(v)>::value == false, "");
 257       auto ac = c;
 258       auto av = v;
 259       auto sumi = ac + av + 'x';
 260       auto sumf = ac + av + 1.0;
 261       static_assert(is_same<int, decltype(ac)>::value == true, "");
 262       static_assert(is_same<int, decltype(av)>::value == true, "");
 263       static_assert(is_same<int, decltype(sumi)>::value == true, "");
 264       static_assert(is_same<int, decltype(sumf)>::value == false, "");
 265       static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
 266       return (sumf > 0.0) ? sumi : add(c, v);
 267     }
 268
 269   }
 270
 271   namespace test_noexcept
 272   {
 273
 274     int f() { return 0; }
 275     int g() noexcept { return 0; }
 276
 277     static_assert(noexcept(f()) == false, "");
 278     static_assert(noexcept(g()) == true, "");
 279
 280   }
 281
 282   namespace test_constexpr
 283   {
 284
 285     template < typename CharT >
 286     unsigned long constexpr
 287     strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
 288     {
 289       return *s ? strlen_c_r(s + 1, acc + 1) : acc;
 290     }
 291
 292     template < typename CharT >
 293     unsigned long constexpr
 294     strlen_c(const CharT *const s) noexcept
 295     {
 296       return strlen_c_r(s, 0UL);
 297     }
 298
 299     static_assert(strlen_c("") == 0UL, "");
 300     static_assert(strlen_c("1") == 1UL, "");
 301     static_assert(strlen_c("example") == 7UL, "");
 302     static_assert(strlen_c("another\0example") == 7UL, "");
 303
 304   }
 305
 306   namespace test_rvalue_references
 307   {
 308
 309     template < int N >
 310     struct answer
 311     {
 312       static constexpr int value = N;
 313     };
 314
 315     answer<1> f(int&)       { return answer<1>(); }
 316     answer<2> f(const int&) { return answer<2>(); }
 317     answer<3> f(int&&)      { return answer<3>(); }
 318
 319     void
 320     test()
 321     {
 322       int i = 0;
 323       const int c = 0;
 324       static_assert(decltype(f(i))::value == 1, "");
 325       static_assert(decltype(f(c))::value == 2, "");
 326       static_assert(decltype(f(0))::value == 3, "");
 327     }
 328
 329   }
 330
 331   namespace test_uniform_initialization
 332   {
 333
 334     struct test
 335     {
 336       static const int zero {};
 337       static const int one {1};
 338     };
 339
 340     static_assert(test::zero == 0, "");
 341     static_assert(test::one == 1, "");
 342
 343   }
 344
 345   namespace test_lambdas
 346   {
 347
 348     void
 349     test1()
 350     {
 351       auto lambda1 = [](){};
 352       auto lambda2 = lambda1;
 353       lambda1();
 354       lambda2();
 355     }
 356
 357     int
 358     test2()
 359     {
 360       auto a = [](int i, int j){ return i + j; }(1, 2);
 361       auto b = []() -> int { return '0'; }();
 362       auto c = [=](){ return a + b; }();
 363       auto d = [&](){ return c; }();
 364       auto e = [a, &b](int x) mutable {
 365         const auto identity = [](int y){ return y; };
 366         for (auto i = 0; i < a; ++i)
 367           a += b--;
 368         return x + identity(a + b);
 369       }(0);
 370       return a + b + c + d + e;
 371     }
 372
 373     int
 374     test3()
 375     {
 376       const auto nullary = [](){ return 0; };
 377       const auto unary = [](int x){ return x; };
 378       using nullary_t = decltype(nullary);
 379       using unary_t = decltype(unary);
 380       const auto higher1st = [](nullary_t f){ return f(); };
 381       const auto higher2nd = [unary](nullary_t f1){
 382         return [unary, f1](unary_t f2){ return f2(unary(f1())); };
 383       };
 384       return higher1st(nullary) + higher2nd(nullary)(unary);
 385     }
 386
 387   }
 388
 389   namespace test_variadic_templates
 390   {
 391
 392     template <int...>
 393     struct sum;
 394
 395     template <int N0, int... N1toN>
 396     struct sum<N0, N1toN...>
 397     {
 398       static constexpr auto value = N0 + sum<N1toN...>::value;
 399     };
 400
 401     template <>
 402     struct sum<>
 403     {
 404       static constexpr auto value = 0;
 405     };
 406
 407     static_assert(sum<>::value == 0, "");
 408     static_assert(sum<1>::value == 1, "");
 409     static_assert(sum<23>::value == 23, "");
 410     static_assert(sum<1, 2>::value == 3, "");
 411     static_assert(sum<5, 5, 11>::value == 21, "");
 412     static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
 413
 414   }
 415
 416   // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
 417   // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
 418   // because of this.
 419   namespace test_template_alias_sfinae
 420   {
 421
 422     struct foo {};
 423
 424     template<typename T>
 425     using member = typename T::member_type;
 426
 427     template<typename T>
 428     void func(...) {}
 429
 430     template<typename T>
 431     void func(member<T>*) {}
 432
 433     void test();
 434
 435     void test() { func<foo>(0); }
 436
 437   }
 438
 439 }  // namespace cxx11
 440
 441 #endif  // __cplusplus >= 201103L
 442
 443 ]])
 444
 445
 446 dnl  Tests for new features in C++14
 447
 448 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
 449
 450 // If the compiler admits that it is not ready for C++14, why torture it?
 451 // Hopefully, this will speed up the test.
 452
 453 #ifndef __cplusplus
 454
 455 #error "This is not a C++ compiler"
 456
 457 #elif __cplusplus < 201402L
 458
 459 #error "This is not a C++14 compiler"
 460
 461 #else
 462
 463 namespace cxx14
 464 {
 465
 466   namespace test_polymorphic_lambdas
 467   {
 468
 469     int
 470     test()
 471     {
 472       const auto lambda = [](auto&&... args){
 473         const auto istiny = [](auto x){
 474           return (sizeof(x) == 1UL) ? 1 : 0;
 475         };
 476         const int aretiny[] = { istiny(args)... };
 477         return aretiny[0];
 478       };
 479       return lambda(1, 1L, 1.0f, '1');
 480     }
 481
 482   }
 483
 484   namespace test_binary_literals
 485   {
 486
 487     constexpr auto ivii = 0b0000000000101010;
 488     static_assert(ivii == 42, "wrong value");
 489
 490   }
 491
 492   namespace test_generalized_constexpr
 493   {
 494
 495     template < typename CharT >
 496     constexpr unsigned long
 497     strlen_c(const CharT *const s) noexcept
 498     {
 499       auto length = 0UL;
 500       for (auto p = s; *p; ++p)
 501         ++length;
 502       return length;
 503     }
 504
 505     static_assert(strlen_c("") == 0UL, "");
 506     static_assert(strlen_c("x") == 1UL, "");
 507     static_assert(strlen_c("test") == 4UL, "");
 508     static_assert(strlen_c("another\0test") == 7UL, "");
 509
 510   }
 511
 512   namespace test_lambda_init_capture
 513   {
 514
 515     int
 516     test()
 517     {
 518       auto x = 0;
 519       const auto lambda1 = [a = x](int b){ return a + b; };
 520       const auto lambda2 = [a = lambda1(x)](){ return a; };
 521       return lambda2();
 522     }
 523
 524   }
 525
 526   namespace test_digit_seperators
 527   {
 528
 529     constexpr auto ten_million = 100'000'000;
 530     static_assert(ten_million == 100000000, "");
 531
 532   }
 533
 534   namespace test_return_type_deduction
 535   {
 536
 537     auto f(int& x) { return x; }
 538     decltype(auto) g(int& x) { return x; }
 539
 540     template < typename T1, typename T2 >
 541     struct is_same
 542     {
 543       static constexpr auto value = false;
 544     };
 545
 546     template < typename T >
 547     struct is_same<T, T>
 548     {
 549       static constexpr auto value = true;
 550     };
 551
 552     int
 553     test()
 554     {
 555       auto x = 0;
 556       static_assert(is_same<int, decltype(f(x))>::value, "");
 557       static_assert(is_same<int&, decltype(g(x))>::value, "");
 558       return x;
 559     }
 560
 561   }
 562
 563 }  // namespace cxx14
 564
 565 #endif  // __cplusplus >= 201402L
 566
 567 ]])