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[conforming]

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tmp/tmparyjqvlo/{from.md → to.md} RENAMED
@@ -3,16 +3,21 @@
3
  #### Overview <a id="conforming.overview">[[conforming.overview]]</a>
4
 
5
  Subclause [[conforming]] describes the constraints upon, and latitude
6
  of, implementations of the C++ standard library.
7
 
8
- An implementation’s use of headers is discussed in  [[res.on.headers]],
9
- its use of macros in  [[res.on.macro.definitions]], non-member functions
10
- in  [[global.functions]], member functions in  [[member.functions]],
11
- data race avoidance in  [[res.on.data.races]], access specifiers in 
12
- [[protection.within.classes]], class derivation in  [[derivation]], and
13
- exceptions in  [[res.on.exception.handling]].
 
 
 
 
 
14
 
15
  #### Headers <a id="res.on.headers">[[res.on.headers]]</a>
16
 
17
  A C++ header may include other C++ headers. A C++ header shall provide
18
  the declarations and definitions that appear in its synopsis. A C++
@@ -42,11 +47,11 @@ stated otherwise.
42
 
43
  It is unspecified whether any non-member functions in the C++ standard
44
  library are defined as inline [[dcl.inline]].
45
 
46
  A call to a non-member function signature described in [[support]]
47
- through [[thread]] and [[depr]] shall behave as if the implementation
48
  declared no additional non-member function signatures.[^25]
49
 
50
  An implementation shall not declare a non-member function signature with
51
  additional default arguments.
52
 
@@ -94,12 +99,12 @@ signatures for a member function name. — *end note*]
94
  Whenever this document specifies a friend declaration of a function or
95
  function template within a class or class template definition, that
96
  declaration shall be the only declaration of that function or function
97
  template provided by an implementation.
98
 
99
- [*Note 1*: In particular, an implementation is not allowed to provide
100
- an additional declaration of that function or function template at
101
  namespace scope. — *end note*]
102
 
103
  [*Note 2*: Such a friend function or function template declaration is
104
  known as a hidden friend, as it is visible neither to ordinary
105
  unqualified lookup [[basic.lookup.unqual]] nor to qualified lookup
@@ -109,12 +114,12 @@ unqualified lookup [[basic.lookup.unqual]] nor to qualified lookup
109
 
110
  This document explicitly requires that certain standard library
111
  functions are `constexpr` [[dcl.constexpr]]. An implementation shall not
112
  declare any standard library function signature as `constexpr` except
113
  for those where it is explicitly required. Within any header that
114
- provides any non-defining declarations of constexpr functions or
115
- constructors an implementation shall provide corresponding definitions.
116
 
117
  #### Requirements for stable algorithms <a id="algorithm.stable">[[algorithm.stable]]</a>
118
 
119
  When the requirements for an algorithm state that it is “stable” without
120
  further elaboration, it means:
@@ -179,14 +184,32 @@ all operations solely within the current thread if those operations have
179
  effects that are visible [[intro.multithread]] to users.
180
 
181
  [*Note 3*: This allows implementations to parallelize operations if
182
  there are no visible side effects. — *end note*]
183
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
184
  #### Protection within classes <a id="protection.within.classes">[[protection.within.classes]]</a>
185
 
186
  It is unspecified whether any function signature or class described in
187
- [[support]] through [[thread]] and [[depr]] is a friend of another class
188
  in the C++ standard library.
189
 
190
  #### Derived classes <a id="derivation">[[derivation]]</a>
191
 
192
  An implementation may derive any class in the C++ standard library from
@@ -214,21 +237,22 @@ types unless otherwise specified.
214
  #### Restrictions on exception handling <a id="res.on.exception.handling">[[res.on.exception.handling]]</a>
215
 
216
  Any of the functions defined in the C++ standard library can report a
217
  failure by throwing an exception of a type described in its *Throws:*
218
  paragraph, or of a type derived from a type named in the *Throws:*
219
- paragraph that would be caught by an exception handler for the base
220
- type.
221
 
222
  Functions from the C standard library shall not throw exceptions [^26]
223
 
224
  except when such a function calls a program-supplied function that
225
  throws an exception.[^27]
226
 
227
  Destructor operations defined in the C++ standard library shall not
228
  throw exceptions. Every destructor in the C++ standard library shall
229
- behave as if it had a non-throwing exception specification.
 
230
 
231
  Functions defined in the C++ standard library that do not have a
232
  *Throws:* paragraph but do have a potentially-throwing exception
233
  specification may throw *implementation-defined* exceptions.[^28]
234
 
@@ -237,15 +261,22 @@ derived from the standard exception classes
237
  [[bad.alloc]], [[support.exception]], [[std.exceptions]].
238
 
239
  An implementation may strengthen the exception specification for a
240
  non-virtual function by adding a non-throwing exception specification.
241
 
 
 
 
 
 
 
 
242
  #### Value of error codes <a id="value.error.codes">[[value.error.codes]]</a>
243
 
244
  Certain functions in the C++ standard library report errors via a
245
- `std::error_code` [[syserr.errcode.overview]] object. That object’s
246
- `category()` member shall return `std::system_category()` for errors
247
  originating from the operating system, or a reference to an
248
  *implementation-defined* `error_category` object for errors originating
249
  elsewhere. The implementation shall define the possible values of
250
  `value()` for each of these error categories.
251
 
@@ -261,56 +292,65 @@ associated values. — *end example*]
261
  #### Moved-from state of library types <a id="lib.types.movedfrom">[[lib.types.movedfrom]]</a>
262
 
263
  Objects of types defined in the C++ standard library may be moved from
264
  [[class.copy.ctor]]. Move operations may be explicitly specified or
265
  implicitly generated. Unless otherwise specified, such moved-from
266
- objects shall be placed in a valid but unspecified state.
 
267
 
268
  An object of a type defined in the C++ standard library may be
269
  move-assigned [[class.copy.assign]] to itself. Unless otherwise
270
  specified, such an assignment places the object in a valid but
271
  unspecified state.
272
 
273
  <!-- Link reference definitions -->
274
  [alg.c.library]: algorithms.md#alg.c.library
 
275
  [alg.sorting]: algorithms.md#alg.sorting
276
  [algorithm.stable]: #algorithm.stable
277
  [algorithms]: algorithms.md#algorithms
278
  [algorithms.requirements]: algorithms.md#algorithms.requirements
279
  [alloc.errors]: support.md#alloc.errors
280
  [allocator.requirements]: #allocator.requirements
281
  [allocator.requirements.completeness]: #allocator.requirements.completeness
282
  [allocator.requirements.general]: #allocator.requirements.general
283
  [allocator.traits]: mem.md#allocator.traits
284
  [alt.headers]: #alt.headers
 
285
  [array.creation]: containers.md#array.creation
286
  [atomics]: thread.md#atomics
287
  [bad.alloc]: support.md#bad.alloc
 
 
288
  [basic.def.odr]: basic.md#basic.def.odr
289
  [basic.fundamental]: basic.md#basic.fundamental
 
290
  [basic.life]: basic.md#basic.life
291
  [basic.link]: basic.md#basic.link
292
  [basic.lookup.argdep]: basic.md#basic.lookup.argdep
293
  [basic.lookup.qual]: basic.md#basic.lookup.qual
294
  [basic.lookup.unqual]: basic.md#basic.lookup.unqual
295
  [basic.scope.namespace]: basic.md#basic.scope.namespace
296
- [basic.start]: basic.md#basic.start
297
  [basic.stc.dynamic]: basic.md#basic.stc.dynamic
298
  [bit]: utilities.md#bit
299
  [bitmask.types]: #bitmask.types
300
  [byte.strings]: #byte.strings
301
  [c.annex.k.names]: #c.annex.k.names
 
 
302
  [cassert.syn]: diagnostics.md#cassert.syn
303
  [cerrno.syn]: diagnostics.md#cerrno.syn
304
  [character.seq]: #character.seq
305
  [character.seq.general]: #character.seq.general
 
306
  [class.copy.assign]: class.md#class.copy.assign
307
  [class.copy.ctor]: class.md#class.copy.ctor
308
  [class.dtor]: class.md#class.dtor
309
  [class.mem]: class.md#class.mem
 
310
  [class.virtual]: class.md#class.virtual
311
- [clocale.syn]: localization.md#clocale.syn
312
  [cmp]: support.md#cmp
313
  [compliance]: #compliance
314
  [concept.destructible]: concepts.md#concept.destructible
315
  [concept.invocable]: concepts.md#concept.invocable
316
  [concept.totallyordered]: concepts.md#concept.totallyordered
@@ -328,40 +368,51 @@ unspecified state.
328
  [conv]: expr.md#conv
329
  [conv.func]: expr.md#conv.func
330
  [conventions]: #conventions
331
  [conventions.general]: #conventions.general
332
  [cpp.include]: cpp.md#cpp.include
333
- [cpp.replace]: cpp.md#cpp.replace
334
  [cpp17.copyassignable]: #cpp17.copyassignable
335
  [cpp17.copyconstructible]: #cpp17.copyconstructible
336
  [cpp17.destructible]: #cpp17.destructible
337
  [cpp17.hash]: #cpp17.hash
338
  [cpp17.moveassignable]: #cpp17.moveassignable
339
  [cpp17.nullablepointer]: #cpp17.nullablepointer
340
  [cstdarg.syn]: support.md#cstdarg.syn
341
  [cstddef.syn]: support.md#cstddef.syn
342
  [cstdint.syn]: support.md#cstdint.syn
 
343
  [customization.point.object]: #customization.point.object
344
  [dcl.array]: dcl.md#dcl.array
345
- [dcl.attr]: dcl.md#dcl.attr
346
  [dcl.constexpr]: dcl.md#dcl.constexpr
 
 
347
  [dcl.fct.default]: dcl.md#dcl.fct.default
348
  [dcl.init]: dcl.md#dcl.init
349
  [dcl.inline]: dcl.md#dcl.inline
350
  [dcl.link]: dcl.md#dcl.link
351
  [dcl.pre]: dcl.md#dcl.pre
352
  [dcl.typedef]: dcl.md#dcl.typedef
 
 
353
  [defns.nonconst.libcall]: intro.md#defns.nonconst.libcall
 
354
  [depr]: future.md#depr
355
  [derivation]: #derivation
356
  [derived.classes]: #derived.classes
357
  [description]: #description
358
  [description.general]: #description.general
359
  [diagnostics]: diagnostics.md#diagnostics
360
  [enumerated.types]: #enumerated.types
 
361
  [except]: except.md#except
 
 
 
 
 
362
  [expos.only.entity]: #expos.only.entity
 
363
  [expr.delete]: expr.md#expr.delete
364
  [expr.new]: expr.md#expr.new
365
  [expr.unary.op]: expr.md#expr.unary.op
366
  [extern.names]: #extern.names
367
  [extern.types]: #extern.types
@@ -374,28 +425,29 @@ unspecified state.
374
  [headers]: #headers
375
  [headers.cpp]: #headers.cpp
376
  [headers.cpp.c]: #headers.cpp.c
377
  [headers.cpp.fs]: #headers.cpp.fs
378
  [hidden.friends]: #hidden.friends
 
379
  [input.output]: input.md#input.output
380
  [intro.compliance]: intro.md#intro.compliance
381
  [intro.multithread]: basic.md#intro.multithread
 
382
  [intro.refs]: intro.md#intro.refs
383
  [iterator.requirements]: iterators.md#iterator.requirements
384
  [iterators]: iterators.md#iterators
385
  [lex.charset]: lex.md#lex.charset
386
  [lex.name]: lex.md#lex.name
387
- [lex.name.special]: #lex.name.special
388
  [lex.phases]: lex.md#lex.phases
389
  [lex.separate]: lex.md#lex.separate
390
  [lib.types.movedfrom]: #lib.types.movedfrom
391
  [library]: #library
392
  [library.c]: #library.c
393
  [library.categories]: #library.categories
 
394
  [library.general]: #library.general
395
- [locales]: localization.md#locales
396
- [localization]: localization.md#localization
397
  [macro.names]: #macro.names
398
  [mem]: mem.md#mem
399
  [member.functions]: #member.functions
400
  [memory]: mem.md#memory
401
  [meta]: meta.md#meta
@@ -405,32 +457,34 @@ unspecified state.
405
  [namespace.def]: dcl.md#namespace.def
406
  [namespace.future]: #namespace.future
407
  [namespace.posix]: #namespace.posix
408
  [namespace.std]: #namespace.std
409
  [namespace.udecl]: dcl.md#namespace.udecl
410
- [new.delete]: support.md#new.delete
411
  [new.handler]: support.md#new.handler
412
- [new.syn]: support.md#new.syn
413
  [nullablepointer.requirements]: #nullablepointer.requirements
414
  [numeric.requirements]: numerics.md#numeric.requirements
415
  [numerics]: numerics.md#numerics
 
416
  [objects.within.classes]: #objects.within.classes
 
417
  [organization]: #organization
418
  [organization.general]: #organization.general
419
  [ostream.iterator.ops]: iterators.md#ostream.iterator.ops
420
  [over.literal]: over.md#over.literal
421
  [over.match]: over.md#over.match
422
  [over.match.oper]: over.md#over.match.oper
423
  [protection.within.classes]: #protection.within.classes
 
424
  [random.access.iterators]: iterators.md#random.access.iterators
425
  [ranges]: ranges.md#ranges
426
  [ratio]: meta.md#ratio
427
- [re]: re.md#re
428
  [reentrancy]: #reentrancy
429
  [replacement.functions]: #replacement.functions
430
  [requirements]: #requirements
431
  [requirements.general]: #requirements.general
 
432
  [res.on.arguments]: #res.on.arguments
433
  [res.on.data.races]: #res.on.data.races
434
  [res.on.exception.handling]: #res.on.exception.handling
435
  [res.on.functions]: #res.on.functions
436
  [res.on.headers]: #res.on.headers
@@ -440,31 +494,34 @@ unspecified state.
440
  [reserved.names]: #reserved.names
441
  [reserved.names.general]: #reserved.names.general
442
  [specialized.addressof]: mem.md#specialized.addressof
443
  [std.exceptions]: diagnostics.md#std.exceptions
444
  [std.modules]: #std.modules
 
445
  [stmt.return]: stmt.md#stmt.return
446
  [stream.types]: input.md#stream.types
 
 
447
  [strings]: strings.md#strings
448
  [structure]: #structure
449
  [structure.elements]: #structure.elements
450
  [structure.requirements]: #structure.requirements
451
  [structure.see.also]: #structure.see.also
452
  [structure.specifications]: #structure.specifications
453
  [structure.summary]: #structure.summary
454
  [support]: support.md#support
455
  [support.c.headers]: support.md#support.c.headers
456
  [support.c.headers.other]: support.md#support.c.headers.other
 
457
  [support.coroutine]: support.md#support.coroutine
458
  [support.dynamic]: support.md#support.dynamic
459
  [support.exception]: support.md#support.exception
460
  [support.initlist]: support.md#support.initlist
461
  [support.limits]: support.md#support.limits
462
  [support.rtti]: support.md#support.rtti
463
  [support.runtime]: support.md#support.runtime
464
  [support.srcloc]: support.md#support.srcloc
465
- [support.start.term]: support.md#support.start.term
466
  [support.types]: support.md#support.types
467
  [swappable.requirements]: #swappable.requirements
468
  [syserr]: diagnostics.md#syserr
469
  [syserr.errcode.overview]: diagnostics.md#syserr.errcode.overview
470
  [tab:cpp17.destructible]: #tab:cpp17.destructible
@@ -474,11 +531,13 @@ unspecified state.
474
  [temp.constr.decl]: temp.md#temp.constr.decl
475
  [temp.deduct.call]: temp.md#temp.deduct.call
476
  [template.bitset]: utilities.md#template.bitset
477
  [term.incomplete.type]: basic.md#term.incomplete.type
478
  [term.object.type]: basic.md#term.object.type
 
479
  [terminate.handler]: support.md#terminate.handler
 
480
  [thread]: thread.md#thread
481
  [time]: time.md#time
482
  [tuple]: utilities.md#tuple
483
  [type.descriptions]: #type.descriptions
484
  [type.descriptions.general]: #type.descriptions.general
@@ -492,13 +551,20 @@ unspecified state.
492
  [utility]: utilities.md#utility
493
  [utility.arg.requirements]: #utility.arg.requirements
494
  [utility.requirements]: #utility.requirements
495
  [utility.requirements.general]: #utility.requirements.general
496
  [value.error.codes]: #value.error.codes
 
 
 
497
  [zombie.names]: #zombie.names
 
 
 
 
498
 
499
- [^1]: See also ISO/IEC 9899:2018 section 7.6.
500
 
501
  [^2]: To save space, items that do not apply to a Clause are omitted.
502
  For example, if a Clause does not specify any requirements, there
503
  will be no “Requirements” subclause.
504
 
@@ -567,11 +633,12 @@ unspecified state.
567
 
568
  [^19]: This is the same as the C standard library.
569
 
570
  [^20]: The only reliable way to declare an object or function signature
571
  from the C standard library is by including the header that declares
572
- it, notwithstanding the latitude granted in 7.1.4 of the C Standard.
 
573
 
574
  [^21]: Any library code that instantiates other library templates must
575
  be prepared to work adequately with any user-supplied specialization
576
  that meets the minimum requirements of this document.
577
 
@@ -590,12 +657,12 @@ unspecified state.
590
 
591
  [^25]: A valid C++ program always calls the expected library non-member
592
  function. An implementation can also define additional non-member
593
  functions that would otherwise not be called by a valid C++ program.
594
 
595
- [^26]: That is, the C library functions can all be treated as if they
596
- are marked `noexcept`. This allows implementations to make
597
  performance optimizations based on the absence of exceptions at
598
  runtime.
599
 
600
  [^27]: The functions `qsort()` and `bsearch()` [[alg.c.library]] meet
601
  this condition.
 
3
  #### Overview <a id="conforming.overview">[[conforming.overview]]</a>
4
 
5
  Subclause [[conforming]] describes the constraints upon, and latitude
6
  of, implementations of the C++ standard library.
7
 
8
+ An implementation’s use of
9
+
10
+ - headers is discussed in  [[res.on.headers]],
11
+ - macros in  [[res.on.macro.definitions]],
12
+ - non-member functions in  [[global.functions]],
13
+ - member functions in  [[member.functions]],
14
+ - data race avoidance in  [[res.on.data.races]],
15
+ - access specifiers in  [[protection.within.classes]],
16
+ - class derivation in  [[derivation]],
17
+ - exceptions in  [[res.on.exception.handling]], and
18
+ - contract assertions in  [[res.contract.assertions]].
19
 
20
  #### Headers <a id="res.on.headers">[[res.on.headers]]</a>
21
 
22
  A C++ header may include other C++ headers. A C++ header shall provide
23
  the declarations and definitions that appear in its synopsis. A C++
 
47
 
48
  It is unspecified whether any non-member functions in the C++ standard
49
  library are defined as inline [[dcl.inline]].
50
 
51
  A call to a non-member function signature described in [[support]]
52
+ through [[exec]] and [[depr]] shall behave as if the implementation
53
  declared no additional non-member function signatures.[^25]
54
 
55
  An implementation shall not declare a non-member function signature with
56
  additional default arguments.
57
 
 
99
  Whenever this document specifies a friend declaration of a function or
100
  function template within a class or class template definition, that
101
  declaration shall be the only declaration of that function or function
102
  template provided by an implementation.
103
 
104
+ [*Note 1*: In particular, a conforming implementation does not provide
105
+ any additional declarations of that function or function template at
106
  namespace scope. — *end note*]
107
 
108
  [*Note 2*: Such a friend function or function template declaration is
109
  known as a hidden friend, as it is visible neither to ordinary
110
  unqualified lookup [[basic.lookup.unqual]] nor to qualified lookup
 
114
 
115
  This document explicitly requires that certain standard library
116
  functions are `constexpr` [[dcl.constexpr]]. An implementation shall not
117
  declare any standard library function signature as `constexpr` except
118
  for those where it is explicitly required. Within any header that
119
+ provides any non-defining declarations of constexpr functions an
120
+ implementation shall provide corresponding definitions.
121
 
122
  #### Requirements for stable algorithms <a id="algorithm.stable">[[algorithm.stable]]</a>
123
 
124
  When the requirements for an algorithm state that it is “stable” without
125
  further elaboration, it means:
 
184
  effects that are visible [[intro.multithread]] to users.
185
 
186
  [*Note 3*: This allows implementations to parallelize operations if
187
  there are no visible side effects. — *end note*]
188
 
189
+ #### Properties of library classes <a id="library.class.props">[[library.class.props]]</a>
190
+
191
+ Unless explicitly stated otherwise, it is unspecified whether any class
192
+ described in [[support]] through [[exec]] and [[depr]] is a trivially
193
+ copyable class, a standard-layout class, or an implicit-lifetime class
194
+ [[class.prop]].
195
+
196
+ Unless explicitly stated otherwise, it is unspecified whether any class
197
+ for which trivial relocation (i.e., the effects of `trivially_relocate`
198
+ [[obj.lifetime]]) would be semantically equivalent to move-construction
199
+ of the destination object followed by destruction of the source object
200
+ is a trivially relocatable class [[class.prop]].
201
+
202
+ Unless explicitly stated otherwise, it is unspecified whether a class
203
+ `C` is a replaceable class [[class.prop]] if assigning an xvalue `a` of
204
+ type `C` to an object `b` of type `C` is semantically equivalent to
205
+ destroying `b` and then constructing from `a` in `b`’s place.
206
+
207
  #### Protection within classes <a id="protection.within.classes">[[protection.within.classes]]</a>
208
 
209
  It is unspecified whether any function signature or class described in
210
+ [[support]] through [[exec]] and [[depr]] is a friend of another class
211
  in the C++ standard library.
212
 
213
  #### Derived classes <a id="derivation">[[derivation]]</a>
214
 
215
  An implementation may derive any class in the C++ standard library from
 
237
  #### Restrictions on exception handling <a id="res.on.exception.handling">[[res.on.exception.handling]]</a>
238
 
239
  Any of the functions defined in the C++ standard library can report a
240
  failure by throwing an exception of a type described in its *Throws:*
241
  paragraph, or of a type derived from a type named in the *Throws:*
242
+ paragraph that would be caught by a *handler* [[except.handle]] for the
243
+ base type.
244
 
245
  Functions from the C standard library shall not throw exceptions [^26]
246
 
247
  except when such a function calls a program-supplied function that
248
  throws an exception.[^27]
249
 
250
  Destructor operations defined in the C++ standard library shall not
251
  throw exceptions. Every destructor in the C++ standard library shall
252
+ behave as if it had a non-throwing exception specification
253
+ [[except.spec]].
254
 
255
  Functions defined in the C++ standard library that do not have a
256
  *Throws:* paragraph but do have a potentially-throwing exception
257
  specification may throw *implementation-defined* exceptions.[^28]
258
 
 
261
  [[bad.alloc]], [[support.exception]], [[std.exceptions]].
262
 
263
  An implementation may strengthen the exception specification for a
264
  non-virtual function by adding a non-throwing exception specification.
265
 
266
+ #### Contract assertions <a id="res.contract.assertions">[[res.contract.assertions]]</a>
267
+
268
+ Unless specified otherwise, an implementation may check the specified
269
+ preconditions and postconditions of a function in the C++ standard
270
+ library using contract assertions
271
+ [[basic.contract]], [[structure.specifications]].
272
+
273
  #### Value of error codes <a id="value.error.codes">[[value.error.codes]]</a>
274
 
275
  Certain functions in the C++ standard library report errors via a
276
+ `error_code` [[syserr.errcode.overview]] object. That object’s
277
+ `category()` member shall return `system_category()` for errors
278
  originating from the operating system, or a reference to an
279
  *implementation-defined* `error_category` object for errors originating
280
  elsewhere. The implementation shall define the possible values of
281
  `value()` for each of these error categories.
282
 
 
292
  #### Moved-from state of library types <a id="lib.types.movedfrom">[[lib.types.movedfrom]]</a>
293
 
294
  Objects of types defined in the C++ standard library may be moved from
295
  [[class.copy.ctor]]. Move operations may be explicitly specified or
296
  implicitly generated. Unless otherwise specified, such moved-from
297
+ objects shall be placed in a valid but unspecified state
298
+ [[defns.valid]].
299
 
300
  An object of a type defined in the C++ standard library may be
301
  move-assigned [[class.copy.assign]] to itself. Unless otherwise
302
  specified, such an assignment places the object in a valid but
303
  unspecified state.
304
 
305
  <!-- Link reference definitions -->
306
  [alg.c.library]: algorithms.md#alg.c.library
307
+ [alg.func.obj]: #alg.func.obj
308
  [alg.sorting]: algorithms.md#alg.sorting
309
  [algorithm.stable]: #algorithm.stable
310
  [algorithms]: algorithms.md#algorithms
311
  [algorithms.requirements]: algorithms.md#algorithms.requirements
312
  [alloc.errors]: support.md#alloc.errors
313
  [allocator.requirements]: #allocator.requirements
314
  [allocator.requirements.completeness]: #allocator.requirements.completeness
315
  [allocator.requirements.general]: #allocator.requirements.general
316
  [allocator.traits]: mem.md#allocator.traits
317
  [alt.headers]: #alt.headers
318
+ [array]: containers.md#array
319
  [array.creation]: containers.md#array.creation
320
  [atomics]: thread.md#atomics
321
  [bad.alloc]: support.md#bad.alloc
322
+ [basic.contract]: basic.md#basic.contract
323
+ [basic.contract.eval]: basic.md#basic.contract.eval
324
  [basic.def.odr]: basic.md#basic.def.odr
325
  [basic.fundamental]: basic.md#basic.fundamental
326
+ [basic.indet]: basic.md#basic.indet
327
  [basic.life]: basic.md#basic.life
328
  [basic.link]: basic.md#basic.link
329
  [basic.lookup.argdep]: basic.md#basic.lookup.argdep
330
  [basic.lookup.qual]: basic.md#basic.lookup.qual
331
  [basic.lookup.unqual]: basic.md#basic.lookup.unqual
332
  [basic.scope.namespace]: basic.md#basic.scope.namespace
 
333
  [basic.stc.dynamic]: basic.md#basic.stc.dynamic
334
  [bit]: utilities.md#bit
335
  [bitmask.types]: #bitmask.types
336
  [byte.strings]: #byte.strings
337
  [c.annex.k.names]: #c.annex.k.names
338
+ [c.math]: numerics.md#c.math
339
+ [c.strings]: strings.md#c.strings
340
  [cassert.syn]: diagnostics.md#cassert.syn
341
  [cerrno.syn]: diagnostics.md#cerrno.syn
342
  [character.seq]: #character.seq
343
  [character.seq.general]: #character.seq.general
344
+ [charconv]: text.md#charconv
345
  [class.copy.assign]: class.md#class.copy.assign
346
  [class.copy.ctor]: class.md#class.copy.ctor
347
  [class.dtor]: class.md#class.dtor
348
  [class.mem]: class.md#class.mem
349
+ [class.prop]: class.md#class.prop
350
  [class.virtual]: class.md#class.virtual
351
+ [clocale.syn]: text.md#clocale.syn
352
  [cmp]: support.md#cmp
353
  [compliance]: #compliance
354
  [concept.destructible]: concepts.md#concept.destructible
355
  [concept.invocable]: concepts.md#concept.invocable
356
  [concept.totallyordered]: concepts.md#concept.totallyordered
 
368
  [conv]: expr.md#conv
369
  [conv.func]: expr.md#conv.func
370
  [conventions]: #conventions
371
  [conventions.general]: #conventions.general
372
  [cpp.include]: cpp.md#cpp.include
 
373
  [cpp17.copyassignable]: #cpp17.copyassignable
374
  [cpp17.copyconstructible]: #cpp17.copyconstructible
375
  [cpp17.destructible]: #cpp17.destructible
376
  [cpp17.hash]: #cpp17.hash
377
  [cpp17.moveassignable]: #cpp17.moveassignable
378
  [cpp17.nullablepointer]: #cpp17.nullablepointer
379
  [cstdarg.syn]: support.md#cstdarg.syn
380
  [cstddef.syn]: support.md#cstddef.syn
381
  [cstdint.syn]: support.md#cstdint.syn
382
+ [cstdlib.syn]: support.md#cstdlib.syn
383
  [customization.point.object]: #customization.point.object
384
  [dcl.array]: dcl.md#dcl.array
 
385
  [dcl.constexpr]: dcl.md#dcl.constexpr
386
+ [dcl.contract.func]: dcl.md#dcl.contract.func
387
+ [dcl.fct.def.delete]: dcl.md#dcl.fct.def.delete
388
  [dcl.fct.default]: dcl.md#dcl.fct.default
389
  [dcl.init]: dcl.md#dcl.init
390
  [dcl.inline]: dcl.md#dcl.inline
391
  [dcl.link]: dcl.md#dcl.link
392
  [dcl.pre]: dcl.md#dcl.pre
393
  [dcl.typedef]: dcl.md#dcl.typedef
394
+ [debugging]: diagnostics.md#debugging
395
+ [defns.const.subexpr]: intro.md#defns.const.subexpr
396
  [defns.nonconst.libcall]: intro.md#defns.nonconst.libcall
397
+ [defns.valid]: intro.md#defns.valid
398
  [depr]: future.md#depr
399
  [derivation]: #derivation
400
  [derived.classes]: #derived.classes
401
  [description]: #description
402
  [description.general]: #description.general
403
  [diagnostics]: diagnostics.md#diagnostics
404
  [enumerated.types]: #enumerated.types
405
+ [errno]: diagnostics.md#errno
406
  [except]: except.md#except
407
+ [except.handle]: except.md#except.handle
408
+ [except.spec]: except.md#except.spec
409
+ [exec]: exec.md#exec
410
+ [execpol]: algorithms.md#execpol
411
+ [expected]: utilities.md#expected
412
  [expos.only.entity]: #expos.only.entity
413
+ [expr.call]: expr.md#expr.call
414
  [expr.delete]: expr.md#expr.delete
415
  [expr.new]: expr.md#expr.new
416
  [expr.unary.op]: expr.md#expr.unary.op
417
  [extern.names]: #extern.names
418
  [extern.types]: #extern.types
 
425
  [headers]: #headers
426
  [headers.cpp]: #headers.cpp
427
  [headers.cpp.c]: #headers.cpp.c
428
  [headers.cpp.fs]: #headers.cpp.fs
429
  [hidden.friends]: #hidden.friends
430
+ [inplace.vector]: containers.md#inplace.vector
431
  [input.output]: input.md#input.output
432
  [intro.compliance]: intro.md#intro.compliance
433
  [intro.multithread]: basic.md#intro.multithread
434
+ [intro.races]: basic.md#intro.races
435
  [intro.refs]: intro.md#intro.refs
436
  [iterator.requirements]: iterators.md#iterator.requirements
437
  [iterators]: iterators.md#iterators
438
  [lex.charset]: lex.md#lex.charset
439
  [lex.name]: lex.md#lex.name
 
440
  [lex.phases]: lex.md#lex.phases
441
  [lex.separate]: lex.md#lex.separate
442
  [lib.types.movedfrom]: #lib.types.movedfrom
443
  [library]: #library
444
  [library.c]: #library.c
445
  [library.categories]: #library.categories
446
+ [library.class.props]: #library.class.props
447
  [library.general]: #library.general
448
+ [locales]: text.md#locales
 
449
  [macro.names]: #macro.names
450
  [mem]: mem.md#mem
451
  [member.functions]: #member.functions
452
  [memory]: mem.md#memory
453
  [meta]: meta.md#meta
 
457
  [namespace.def]: dcl.md#namespace.def
458
  [namespace.future]: #namespace.future
459
  [namespace.posix]: #namespace.posix
460
  [namespace.std]: #namespace.std
461
  [namespace.udecl]: dcl.md#namespace.udecl
 
462
  [new.handler]: support.md#new.handler
 
463
  [nullablepointer.requirements]: #nullablepointer.requirements
464
  [numeric.requirements]: numerics.md#numeric.requirements
465
  [numerics]: numerics.md#numerics
466
+ [obj.lifetime]: mem.md#obj.lifetime
467
  [objects.within.classes]: #objects.within.classes
468
+ [optional]: utilities.md#optional
469
  [organization]: #organization
470
  [organization.general]: #organization.general
471
  [ostream.iterator.ops]: iterators.md#ostream.iterator.ops
472
  [over.literal]: over.md#over.literal
473
  [over.match]: over.md#over.match
474
  [over.match.oper]: over.md#over.match.oper
475
  [protection.within.classes]: #protection.within.classes
476
+ [rand]: numerics.md#rand
477
  [random.access.iterators]: iterators.md#random.access.iterators
478
  [ranges]: ranges.md#ranges
479
  [ratio]: meta.md#ratio
480
+ [re]: text.md#re
481
  [reentrancy]: #reentrancy
482
  [replacement.functions]: #replacement.functions
483
  [requirements]: #requirements
484
  [requirements.general]: #requirements.general
485
+ [res.contract.assertions]: #res.contract.assertions
486
  [res.on.arguments]: #res.on.arguments
487
  [res.on.data.races]: #res.on.data.races
488
  [res.on.exception.handling]: #res.on.exception.handling
489
  [res.on.functions]: #res.on.functions
490
  [res.on.headers]: #res.on.headers
 
494
  [reserved.names]: #reserved.names
495
  [reserved.names.general]: #reserved.names.general
496
  [specialized.addressof]: mem.md#specialized.addressof
497
  [std.exceptions]: diagnostics.md#std.exceptions
498
  [std.modules]: #std.modules
499
+ [stdbit.h.syn]: utilities.md#stdbit.h.syn
500
  [stmt.return]: stmt.md#stmt.return
501
  [stream.types]: input.md#stream.types
502
+ [string.classes]: strings.md#string.classes
503
+ [string.view]: strings.md#string.view
504
  [strings]: strings.md#strings
505
  [structure]: #structure
506
  [structure.elements]: #structure.elements
507
  [structure.requirements]: #structure.requirements
508
  [structure.see.also]: #structure.see.also
509
  [structure.specifications]: #structure.specifications
510
  [structure.summary]: #structure.summary
511
  [support]: support.md#support
512
  [support.c.headers]: support.md#support.c.headers
513
  [support.c.headers.other]: support.md#support.c.headers.other
514
+ [support.contract]: support.md#support.contract
515
  [support.coroutine]: support.md#support.coroutine
516
  [support.dynamic]: support.md#support.dynamic
517
  [support.exception]: support.md#support.exception
518
  [support.initlist]: support.md#support.initlist
519
  [support.limits]: support.md#support.limits
520
  [support.rtti]: support.md#support.rtti
521
  [support.runtime]: support.md#support.runtime
522
  [support.srcloc]: support.md#support.srcloc
 
523
  [support.types]: support.md#support.types
524
  [swappable.requirements]: #swappable.requirements
525
  [syserr]: diagnostics.md#syserr
526
  [syserr.errcode.overview]: diagnostics.md#syserr.errcode.overview
527
  [tab:cpp17.destructible]: #tab:cpp17.destructible
 
531
  [temp.constr.decl]: temp.md#temp.constr.decl
532
  [temp.deduct.call]: temp.md#temp.deduct.call
533
  [template.bitset]: utilities.md#template.bitset
534
  [term.incomplete.type]: basic.md#term.incomplete.type
535
  [term.object.type]: basic.md#term.object.type
536
+ [term.replaceable.function]: dcl.md#term.replaceable.function
537
  [terminate.handler]: support.md#terminate.handler
538
+ [text]: text.md#text
539
  [thread]: thread.md#thread
540
  [time]: time.md#time
541
  [tuple]: utilities.md#tuple
542
  [type.descriptions]: #type.descriptions
543
  [type.descriptions.general]: #type.descriptions.general
 
551
  [utility]: utilities.md#utility
552
  [utility.arg.requirements]: #utility.arg.requirements
553
  [utility.requirements]: #utility.requirements
554
  [utility.requirements.general]: #utility.requirements.general
555
  [value.error.codes]: #value.error.codes
556
+ [variant]: utilities.md#variant
557
+ [views.contiguous]: containers.md#views.contiguous
558
+ [views.multidim]: containers.md#views.multidim
559
  [zombie.names]: #zombie.names
560
+ [zombie.names.fnmacro]: #zombie.names.fnmacro
561
+ [zombie.names.header]: #zombie.names.header
562
+ [zombie.names.objmacro]: #zombie.names.objmacro
563
+ [zombie.names.std]: #zombie.names.std
564
 
565
+ [^1]: See also ISO/IEC 9899:2018 (C), 7.6.
566
 
567
  [^2]: To save space, items that do not apply to a Clause are omitted.
568
  For example, if a Clause does not specify any requirements, there
569
  will be no “Requirements” subclause.
570
 
 
633
 
634
  [^19]: This is the same as the C standard library.
635
 
636
  [^20]: The only reliable way to declare an object or function signature
637
  from the C standard library is by including the header that declares
638
+ it, notwithstanding the latitude granted in ISO/IEC 9899:2018 (C),
639
+ 7.1.4.
640
 
641
  [^21]: Any library code that instantiates other library templates must
642
  be prepared to work adequately with any user-supplied specialization
643
  that meets the minimum requirements of this document.
644
 
 
657
 
658
  [^25]: A valid C++ program always calls the expected library non-member
659
  function. An implementation can also define additional non-member
660
  functions that would otherwise not be called by a valid C++ program.
661
 
662
+ [^26]: That is, the C standard library functions can all be treated as
663
+ if they are marked `noexcept`. This allows implementations to make
664
  performance optimizations based on the absence of exceptions at
665
  runtime.
666
 
667
  [^27]: The functions `qsort()` and `bsearch()` [[alg.c.library]] meet
668
  this condition.