1 // Implementation of std::function -*- C++ -*- 2 3 // Copyright (C) 2004-2018 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the 7 // terms of the GNU General Public License as published by the 8 // Free Software Foundation; either version 3, or (at your option) 9 // any later version. 10 11 // This library is distributed in the hope that it will be useful, 12 // but WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 // GNU General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file include/bits/std_function.h 26 * This is an internal header file, included by other library headers. 27 * Do not attempt to use it directly. @headername{functional} 28 */ 29 30 #ifndef _GLIBCXX_STD_FUNCTION_H 31 #define _GLIBCXX_STD_FUNCTION_H 1 32 33 #pragma GCC system_header 34 35 #if __cplusplus < 201103L 36 # include <bits/c++0x_warning.h> 37 #else 38 39 #if __cpp_rtti 40 # include <typeinfo> 41 #endif 42 #include <bits/stl_function.h> 43 #include <bits/invoke.h> 44 #include <bits/refwrap.h> 45 #include <bits/functexcept.h> 46 47 namespace std _GLIBCXX_VISIBILITY(default) 48 { 49 _GLIBCXX_BEGIN_NAMESPACE_VERSION 50 51 /** 52 * @brief Exception class thrown when class template function's 53 * operator() is called with an empty target. 54 * @ingroup exceptions 55 */ 56 class bad_function_call : public std::exception 57 { 58 public: 59 virtual ~bad_function_call() noexcept; 60 61 const char* what() const noexcept; 62 }; 63 64 /** 65 * Trait identifying "location-invariant" types, meaning that the 66 * address of the object (or any of its members) will not escape. 67 * Trivially copyable types are location-invariant and users can 68 * specialize this trait for other types. 69 */ 70 template<typename _Tp> 71 struct __is_location_invariant 72 : is_trivially_copyable<_Tp>::type 73 { }; 74 75 class _Undefined_class; 76 77 union _Nocopy_types 78 { 79 void* _M_object; 80 const void* _M_const_object; 81 void (*_M_function_pointer)(); 82 void (_Undefined_class::*_M_member_pointer)(); 83 }; 84 85 union [[gnu::may_alias]] _Any_data 86 { 87 void* _M_access() { return &_M_pod_data[0]; } 88 const void* _M_access() const { return &_M_pod_data[0]; } 89 90 template<typename _Tp> 91 _Tp& 92 _M_access() 93 { return *static_cast<_Tp*>(_M_access()); } 94 95 template<typename _Tp> 96 const _Tp& 97 _M_access() const 98 { return *static_cast<const _Tp*>(_M_access()); } 99 100 _Nocopy_types _M_unused; 101 char _M_pod_data[sizeof(_Nocopy_types)]; 102 }; 103 104 enum _Manager_operation 105 { 106 __get_type_info, 107 __get_functor_ptr, 108 __clone_functor, 109 __destroy_functor 110 }; 111 112 // Simple type wrapper that helps avoid annoying const problems 113 // when casting between void pointers and pointers-to-pointers. 114 template<typename _Tp> 115 struct _Simple_type_wrapper 116 { 117 _Simple_type_wrapper(_Tp __value) : __value(__value) { } 118 119 _Tp __value; 120 }; 121 122 template<typename _Tp> 123 struct __is_location_invariant<_Simple_type_wrapper<_Tp> > 124 : __is_location_invariant<_Tp> 125 { }; 126 127 template<typename _Signature> 128 class function; 129 130 /// Base class of all polymorphic function object wrappers. 131 class _Function_base 132 { 133 public: 134 static const std::size_t _M_max_size = sizeof(_Nocopy_types); 135 static const std::size_t _M_max_align = __alignof__(_Nocopy_types); 136 137 template<typename _Functor> 138 class _Base_manager 139 { 140 protected: 141 static const bool __stored_locally = 142 (__is_location_invariant<_Functor>::value 143 && sizeof(_Functor) <= _M_max_size 144 && __alignof__(_Functor) <= _M_max_align 145 && (_M_max_align % __alignof__(_Functor) == 0)); 146 147 typedef integral_constant<bool, __stored_locally> _Local_storage; 148 149 // Retrieve a pointer to the function object 150 static _Functor* 151 _M_get_pointer(const _Any_data& __source) 152 { 153 const _Functor* __ptr = 154 __stored_locally? std::__addressof(__source._M_access<_Functor>()) 155 /* have stored a pointer */ : __source._M_access<_Functor*>(); 156 return const_cast<_Functor*>(__ptr); 157 } 158 159 // Clone a location-invariant function object that fits within 160 // an _Any_data structure. 161 static void 162 _M_clone(_Any_data& __dest, const _Any_data& __source, true_type) 163 { 164 ::new (__dest._M_access()) _Functor(__source._M_access<_Functor>()); 165 } 166 167 // Clone a function object that is not location-invariant or 168 // that cannot fit into an _Any_data structure. 169 static void 170 _M_clone(_Any_data& __dest, const _Any_data& __source, false_type) 171 { 172 __dest._M_access<_Functor*>() = 173 new _Functor(*__source._M_access<_Functor*>()); 174 } 175 176 // Destroying a location-invariant object may still require 177 // destruction. 178 static void 179 _M_destroy(_Any_data& __victim, true_type) 180 { 181 __victim._M_access<_Functor>().~_Functor(); 182 } 183 184 // Destroying an object located on the heap. 185 static void 186 _M_destroy(_Any_data& __victim, false_type) 187 { 188 delete __victim._M_access<_Functor*>(); 189 } 190 191 public: 192 static bool 193 _M_manager(_Any_data& __dest, const _Any_data& __source, 194 _Manager_operation __op) 195 { 196 switch (__op) 197 { 198 #if __cpp_rtti 199 case __get_type_info: 200 __dest._M_access<const type_info*>() = &typeid(_Functor); 201 break; 202 #endif 203 case __get_functor_ptr: 204 __dest._M_access<_Functor*>() = _M_get_pointer(__source); 205 break; 206 207 case __clone_functor: 208 _M_clone(__dest, __source, _Local_storage()); 209 break; 210 211 case __destroy_functor: 212 _M_destroy(__dest, _Local_storage()); 213 break; 214 } 215 return false; 216 } 217 218 static void 219 _M_init_functor(_Any_data& __functor, _Functor&& __f) 220 { _M_init_functor(__functor, std::move(__f), _Local_storage()); } 221 222 template<typename _Signature> 223 static bool 224 _M_not_empty_function(const function<_Signature>& __f) 225 { return static_cast<bool>(__f); } 226 227 template<typename _Tp> 228 static bool 229 _M_not_empty_function(_Tp* __fp) 230 { return __fp != nullptr; } 231 232 template<typename _Class, typename _Tp> 233 static bool 234 _M_not_empty_function(_Tp _Class::* __mp) 235 { return __mp != nullptr; } 236 237 template<typename _Tp> 238 static bool 239 _M_not_empty_function(const _Tp&) 240 { return true; } 241 242 private: 243 static void 244 _M_init_functor(_Any_data& __functor, _Functor&& __f, true_type) 245 { ::new (__functor._M_access()) _Functor(std::move(__f)); } 246 247 static void 248 _M_init_functor(_Any_data& __functor, _Functor&& __f, false_type) 249 { __functor._M_access<_Functor*>() = new _Functor(std::move(__f)); } 250 }; 251 252 _Function_base() : _M_manager(nullptr) { } 253 254 ~_Function_base() 255 { 256 if (_M_manager) 257 _M_manager(_M_functor, _M_functor, __destroy_functor); 258 } 259 260 bool _M_empty() const { return !_M_manager; } 261 262 typedef bool (*_Manager_type)(_Any_data&, const _Any_data&, 263 _Manager_operation); 264 265 _Any_data _M_functor; 266 _Manager_type _M_manager; 267 }; 268 269 template<typename _Signature, typename _Functor> 270 class _Function_handler; 271 272 template<typename _Res, typename _Functor, typename... _ArgTypes> 273 class _Function_handler<_Res(_ArgTypes...), _Functor> 274 : public _Function_base::_Base_manager<_Functor> 275 { 276 typedef _Function_base::_Base_manager<_Functor> _Base; 277 278 public: 279 static _Res 280 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 281 { 282 return (*_Base::_M_get_pointer(__functor))( 283 std::forward<_ArgTypes>(__args)...); 284 } 285 }; 286 287 template<typename _Functor, typename... _ArgTypes> 288 class _Function_handler<void(_ArgTypes...), _Functor> 289 : public _Function_base::_Base_manager<_Functor> 290 { 291 typedef _Function_base::_Base_manager<_Functor> _Base; 292 293 public: 294 static void 295 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 296 { 297 (*_Base::_M_get_pointer(__functor))( 298 std::forward<_ArgTypes>(__args)...); 299 } 300 }; 301 302 template<typename _Class, typename _Member, typename _Res, 303 typename... _ArgTypes> 304 class _Function_handler<_Res(_ArgTypes...), _Member _Class::*> 305 : public _Function_handler<void(_ArgTypes...), _Member _Class::*> 306 { 307 typedef _Function_handler<void(_ArgTypes...), _Member _Class::*> 308 _Base; 309 310 public: 311 static _Res 312 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 313 { 314 return std::__invoke(_Base::_M_get_pointer(__functor)->__value, 315 std::forward<_ArgTypes>(__args)...); 316 } 317 }; 318 319 template<typename _Class, typename _Member, typename... _ArgTypes> 320 class _Function_handler<void(_ArgTypes...), _Member _Class::*> 321 : public _Function_base::_Base_manager< 322 _Simple_type_wrapper< _Member _Class::* > > 323 { 324 typedef _Member _Class::* _Functor; 325 typedef _Simple_type_wrapper<_Functor> _Wrapper; 326 typedef _Function_base::_Base_manager<_Wrapper> _Base; 327 328 public: 329 static bool 330 _M_manager(_Any_data& __dest, const _Any_data& __source, 331 _Manager_operation __op) 332 { 333 switch (__op) 334 { 335 #if __cpp_rtti 336 case __get_type_info: 337 __dest._M_access<const type_info*>() = &typeid(_Functor); 338 break; 339 #endif 340 case __get_functor_ptr: 341 __dest._M_access<_Functor*>() = 342 &_Base::_M_get_pointer(__source)->__value; 343 break; 344 345 default: 346 _Base::_M_manager(__dest, __source, __op); 347 } 348 return false; 349 } 350 351 static void 352 _M_invoke(const _Any_data& __functor, _ArgTypes&&... __args) 353 { 354 std::__invoke(_Base::_M_get_pointer(__functor)->__value, 355 std::forward<_ArgTypes>(__args)...); 356 } 357 }; 358 359 template<typename _From, typename _To> 360 using __check_func_return_type 361 = __or_<is_void<_To>, is_same<_From, _To>, is_convertible<_From, _To>>; 362 363 /** 364 * @brief Primary class template for std::function. 365 * @ingroup functors 366 * 367 * Polymorphic function wrapper. 368 */ 369 template<typename _Res, typename... _ArgTypes> 370 class function<_Res(_ArgTypes...)> 371 : public _Maybe_unary_or_binary_function<_Res, _ArgTypes...>, 372 private _Function_base 373 { 374 template<typename _Func, 375 typename _Res2 = typename result_of<_Func&(_ArgTypes...)>::type> 376 struct _Callable : __check_func_return_type<_Res2, _Res> { }; 377 378 // Used so the return type convertibility checks aren't done when 379 // performing overload resolution for copy construction/assignment. 380 template<typename _Tp> 381 struct _Callable<function, _Tp> : false_type { }; 382 383 template<typename _Cond, typename _Tp> 384 using _Requires = typename enable_if<_Cond::value, _Tp>::type; 385 386 public: 387 typedef _Res result_type; 388 389 // [3.7.2.1] construct/copy/destroy 390 391 /** 392 * @brief Default construct creates an empty function call wrapper. 393 * @post @c !(bool)*this 394 */ 395 function() noexcept 396 : _Function_base() { } 397 398 /** 399 * @brief Creates an empty function call wrapper. 400 * @post @c !(bool)*this 401 */ 402 function(nullptr_t) noexcept 403 : _Function_base() { } 404 405 /** 406 * @brief %Function copy constructor. 407 * @param __x A %function object with identical call signature. 408 * @post @c bool(*this) == bool(__x) 409 * 410 * The newly-created %function contains a copy of the target of @a 411 * __x (if it has one). 412 */ 413 function(const function& __x); 414 415 /** 416 * @brief %Function move constructor. 417 * @param __x A %function object rvalue with identical call signature. 418 * 419 * The newly-created %function contains the target of @a __x 420 * (if it has one). 421 */ 422 function(function&& __x) noexcept : _Function_base() 423 { 424 __x.swap(*this); 425 } 426 427 /** 428 * @brief Builds a %function that targets a copy of the incoming 429 * function object. 430 * @param __f A %function object that is callable with parameters of 431 * type @c T1, @c T2, ..., @c TN and returns a value convertible 432 * to @c Res. 433 * 434 * The newly-created %function object will target a copy of 435 * @a __f. If @a __f is @c reference_wrapper<F>, then this function 436 * object will contain a reference to the function object @c 437 * __f.get(). If @a __f is a NULL function pointer or NULL 438 * pointer-to-member, the newly-created object will be empty. 439 * 440 * If @a __f is a non-NULL function pointer or an object of type @c 441 * reference_wrapper<F>, this function will not throw. 442 */ 443 template<typename _Functor, 444 typename = _Requires<__not_<is_same<_Functor, function>>, void>, 445 typename = _Requires<_Callable<_Functor>, void>> 446 function(_Functor); 447 448 /** 449 * @brief %Function assignment operator. 450 * @param __x A %function with identical call signature. 451 * @post @c (bool)*this == (bool)x 452 * @returns @c *this 453 * 454 * The target of @a __x is copied to @c *this. If @a __x has no 455 * target, then @c *this will be empty. 456 * 457 * If @a __x targets a function pointer or a reference to a function 458 * object, then this operation will not throw an %exception. 459 */ 460 function& 461 operator=(const function& __x) 462 { 463 function(__x).swap(*this); 464 return *this; 465 } 466 467 /** 468 * @brief %Function move-assignment operator. 469 * @param __x A %function rvalue with identical call signature. 470 * @returns @c *this 471 * 472 * The target of @a __x is moved to @c *this. If @a __x has no 473 * target, then @c *this will be empty. 474 * 475 * If @a __x targets a function pointer or a reference to a function 476 * object, then this operation will not throw an %exception. 477 */ 478 function& 479 operator=(function&& __x) noexcept 480 { 481 function(std::move(__x)).swap(*this); 482 return *this; 483 } 484 485 /** 486 * @brief %Function assignment to zero. 487 * @post @c !(bool)*this 488 * @returns @c *this 489 * 490 * The target of @c *this is deallocated, leaving it empty. 491 */ 492 function& 493 operator=(nullptr_t) noexcept 494 { 495 if (_M_manager) 496 { 497 _M_manager(_M_functor, _M_functor, __destroy_functor); 498 _M_manager = nullptr; 499 _M_invoker = nullptr; 500 } 501 return *this; 502 } 503 504 /** 505 * @brief %Function assignment to a new target. 506 * @param __f A %function object that is callable with parameters of 507 * type @c T1, @c T2, ..., @c TN and returns a value convertible 508 * to @c Res. 509 * @return @c *this 510 * 511 * This %function object wrapper will target a copy of @a 512 * __f. If @a __f is @c reference_wrapper<F>, then this function 513 * object will contain a reference to the function object @c 514 * __f.get(). If @a __f is a NULL function pointer or NULL 515 * pointer-to-member, @c this object will be empty. 516 * 517 * If @a __f is a non-NULL function pointer or an object of type @c 518 * reference_wrapper<F>, this function will not throw. 519 */ 520 template<typename _Functor> 521 _Requires<_Callable<typename decay<_Functor>::type>, function&> 522 operator=(_Functor&& __f) 523 { 524 function(std::forward<_Functor>(__f)).swap(*this); 525 return *this; 526 } 527 528 /// @overload 529 template<typename _Functor> 530 function& 531 operator=(reference_wrapper<_Functor> __f) noexcept 532 { 533 function(__f).swap(*this); 534 return *this; 535 } 536 537 // [3.7.2.2] function modifiers 538 539 /** 540 * @brief Swap the targets of two %function objects. 541 * @param __x A %function with identical call signature. 542 * 543 * Swap the targets of @c this function object and @a __f. This 544 * function will not throw an %exception. 545 */ 546 void swap(function& __x) noexcept 547 { 548 std::swap(_M_functor, __x._M_functor); 549 std::swap(_M_manager, __x._M_manager); 550 std::swap(_M_invoker, __x._M_invoker); 551 } 552 553 // [3.7.2.3] function capacity 554 555 /** 556 * @brief Determine if the %function wrapper has a target. 557 * 558 * @return @c true when this %function object contains a target, 559 * or @c false when it is empty. 560 * 561 * This function will not throw an %exception. 562 */ 563 explicit operator bool() const noexcept 564 { return !_M_empty(); } 565 566 // [3.7.2.4] function invocation 567 568 /** 569 * @brief Invokes the function targeted by @c *this. 570 * @returns the result of the target. 571 * @throws bad_function_call when @c !(bool)*this 572 * 573 * The function call operator invokes the target function object 574 * stored by @c this. 575 */ 576 _Res operator()(_ArgTypes... __args) const; 577 578 #if __cpp_rtti 579 // [3.7.2.5] function target access 580 /** 581 * @brief Determine the type of the target of this function object 582 * wrapper. 583 * 584 * @returns the type identifier of the target function object, or 585 * @c typeid(void) if @c !(bool)*this. 586 * 587 * This function will not throw an %exception. 588 */ 589 const type_info& target_type() const noexcept; 590 591 /** 592 * @brief Access the stored target function object. 593 * 594 * @return Returns a pointer to the stored target function object, 595 * if @c typeid(_Functor).equals(target_type()); otherwise, a NULL 596 * pointer. 597 * 598 * This function does not throw exceptions. 599 * 600 * @{ 601 */ 602 template<typename _Functor> _Functor* target() noexcept; 603 604 template<typename _Functor> const _Functor* target() const noexcept; 605 // @} 606 #endif 607 608 private: 609 using _Invoker_type = _Res (*)(const _Any_data&, _ArgTypes&&...); 610 _Invoker_type _M_invoker; 611 }; 612 613 #if __cpp_deduction_guides >= 201606 614 template<typename> 615 struct __function_guide_helper 616 { }; 617 618 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 619 struct __function_guide_helper< 620 _Res (_Tp::*) (_Args...) noexcept(_Nx) 621 > 622 { using type = _Res(_Args...); }; 623 624 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 625 struct __function_guide_helper< 626 _Res (_Tp::*) (_Args...) & noexcept(_Nx) 627 > 628 { using type = _Res(_Args...); }; 629 630 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 631 struct __function_guide_helper< 632 _Res (_Tp::*) (_Args...) const noexcept(_Nx) 633 > 634 { using type = _Res(_Args...); }; 635 636 template<typename _Res, typename _Tp, bool _Nx, typename... _Args> 637 struct __function_guide_helper< 638 _Res (_Tp::*) (_Args...) const & noexcept(_Nx) 639 > 640 { using type = _Res(_Args...); }; 641 642 template<typename _Res, typename... _ArgTypes> 643 function(_Res(*)(_ArgTypes...)) -> function<_Res(_ArgTypes...)>; 644 645 template<typename _Functor, typename _Signature = typename 646 __function_guide_helper<decltype(&_Functor::operator())>::type> 647 function(_Functor) -> function<_Signature>; 648 #endif 649 650 // Out-of-line member definitions. 651 template<typename _Res, typename... _ArgTypes> 652 function<_Res(_ArgTypes...)>:: 653 function(const function& __x) 654 : _Function_base() 655 { 656 if (static_cast<bool>(__x)) 657 { 658 __x._M_manager(_M_functor, __x._M_functor, __clone_functor); 659 _M_invoker = __x._M_invoker; 660 _M_manager = __x._M_manager; 661 } 662 } 663 664 template<typename _Res, typename... _ArgTypes> 665 template<typename _Functor, typename, typename> 666 function<_Res(_ArgTypes...)>:: 667 function(_Functor __f) 668 : _Function_base() 669 { 670 typedef _Function_handler<_Res(_ArgTypes...), _Functor> _My_handler; 671 672 if (_My_handler::_M_not_empty_function(__f)) 673 { 674 _My_handler::_M_init_functor(_M_functor, std::move(__f)); 675 _M_invoker = &_My_handler::_M_invoke; 676 _M_manager = &_My_handler::_M_manager; 677 } 678 } 679 680 template<typename _Res, typename... _ArgTypes> 681 _Res 682 function<_Res(_ArgTypes...)>:: 683 operator()(_ArgTypes... __args) const 684 { 685 if (_M_empty()) 686 __throw_bad_function_call(); 687 return _M_invoker(_M_functor, std::forward<_ArgTypes>(__args)...); 688 } 689 690 #if __cpp_rtti 691 template<typename _Res, typename... _ArgTypes> 692 const type_info& 693 function<_Res(_ArgTypes...)>:: 694 target_type() const noexcept 695 { 696 if (_M_manager) 697 { 698 _Any_data __typeinfo_result; 699 _M_manager(__typeinfo_result, _M_functor, __get_type_info); 700 return *__typeinfo_result._M_access<const type_info*>(); 701 } 702 else 703 return typeid(void); 704 } 705 706 template<typename _Res, typename... _ArgTypes> 707 template<typename _Functor> 708 _Functor* 709 function<_Res(_ArgTypes...)>:: 710 target() noexcept 711 { 712 const function* __const_this = this; 713 const _Functor* __func = __const_this->template target<_Functor>(); 714 return const_cast<_Functor*>(__func); 715 } 716 717 template<typename _Res, typename... _ArgTypes> 718 template<typename _Functor> 719 const _Functor* 720 function<_Res(_ArgTypes...)>:: 721 target() const noexcept 722 { 723 if (typeid(_Functor) == target_type() && _M_manager) 724 { 725 _Any_data __ptr; 726 _M_manager(__ptr, _M_functor, __get_functor_ptr); 727 return __ptr._M_access<const _Functor*>(); 728 } 729 else 730 return nullptr; 731 } 732 #endif 733 734 // [20.7.15.2.6] null pointer comparisons 735 736 /** 737 * @brief Compares a polymorphic function object wrapper against 0 738 * (the NULL pointer). 739 * @returns @c true if the wrapper has no target, @c false otherwise 740 * 741 * This function will not throw an %exception. 742 */ 743 template<typename _Res, typename... _Args> 744 inline bool 745 operator==(const function<_Res(_Args...)>& __f, nullptr_t) noexcept 746 { return !static_cast<bool>(__f); } 747 748 /// @overload 749 template<typename _Res, typename... _Args> 750 inline bool 751 operator==(nullptr_t, const function<_Res(_Args...)>& __f) noexcept 752 { return !static_cast<bool>(__f); } 753 754 /** 755 * @brief Compares a polymorphic function object wrapper against 0 756 * (the NULL pointer). 757 * @returns @c false if the wrapper has no target, @c true otherwise 758 * 759 * This function will not throw an %exception. 760 */ 761 template<typename _Res, typename... _Args> 762 inline bool 763 operator!=(const function<_Res(_Args...)>& __f, nullptr_t) noexcept 764 { return static_cast<bool>(__f); } 765 766 /// @overload 767 template<typename _Res, typename... _Args> 768 inline bool 769 operator!=(nullptr_t, const function<_Res(_Args...)>& __f) noexcept 770 { return static_cast<bool>(__f); } 771 772 773 // [20.7.15.2.7] specialized algorithms 774 775 /** 776 * @brief Swap the targets of two polymorphic function object wrappers. 777 * 778 * This function will not throw an %exception. 779 */ 780 // _GLIBCXX_RESOLVE_LIB_DEFECTS 781 // 2062. Effect contradictions w/o no-throw guarantee of std::function swaps 782 template<typename _Res, typename... _Args> 783 inline void 784 swap(function<_Res(_Args...)>& __x, function<_Res(_Args...)>& __y) noexcept 785 { __x.swap(__y); } 786 787 _GLIBCXX_END_NAMESPACE_VERSION 788 } // namespace std 789 790 #endif // C++11 791 792 #endif // _GLIBCXX_STD_FUNCTION_H 793