From Jason Turner

[class.compare.secondary]

C++23 → Trunk 9.4 KB 83 lines
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Archived: C++23
Markdown: C++23 | Trunk
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  1. tmp/tmpow_gv29j/{from.md → to.md} +35 -38
tmp/tmpow_gv29j/{from.md → to.md} RENAMED
@@ -6,18 +6,22 @@ a secondary comparison operator `@` shall have a declared return type
6
  `bool`.
7
 
8
  The operator function with parameters `x` and `y` is defined as deleted
9
  if
10
 
11
- - overload resolution [[over.match]], as applied to `x @ y`, does not
12
- result in a usable candidate, or
13
- - the candidate selected by overload resolution is not a rewritten
14
- candidate.
 
 
 
 
15
 
16
- Otherwise, the operator function yields `x @ y`. The defaulted operator
17
- function is not considered as a candidate in the overload resolution for
18
- the `@` operator.
19
 
20
  [*Example 1*:
21
 
22
  ``` cpp
23
  struct HasNoLessThan { };
@@ -33,10 +37,12 @@ struct C {
33
  <!-- Link reference definitions -->
34
  [basic.align]: basic.md#basic.align
35
  [basic.compound]: basic.md#basic.compound
36
  [basic.def]: basic.md#basic.def
37
  [basic.def.odr]: basic.md#basic.def.odr
 
 
38
  [basic.life]: basic.md#basic.life
39
  [basic.link]: basic.md#basic.link
40
  [basic.lookup]: basic.md#basic.lookup
41
  [basic.lookup.elab]: basic.md#basic.lookup.elab
42
  [basic.lval]: expr.md#basic.lval
@@ -48,10 +54,11 @@ struct C {
48
  [basic.start.term]: basic.md#basic.start.term
49
  [basic.stc.auto]: basic.md#basic.stc.auto
50
  [basic.stc.static]: basic.md#basic.stc.static
51
  [basic.stc.thread]: basic.md#basic.stc.thread
52
  [basic.types]: basic.md#basic.types
 
53
  [class]: #class
54
  [class.abstract]: #class.abstract
55
  [class.access]: #class.access
56
  [class.access.base]: #class.access.base
57
  [class.access.general]: #class.access.general
@@ -115,13 +122,15 @@ struct C {
115
  [cmp.weakord]: support.md#cmp.weakord
116
  [conv]: expr.md#conv
117
  [conv.mem]: expr.md#conv.mem
118
  [conv.ptr]: expr.md#conv.ptr
119
  [conv.rval]: expr.md#conv.rval
 
 
120
  [dcl.array]: dcl.md#dcl.array
121
  [dcl.attr.nouniqueaddr]: dcl.md#dcl.attr.nouniqueaddr
122
- [dcl.constexpr]: dcl.md#dcl.constexpr
123
  [dcl.decl]: dcl.md#dcl.decl
124
  [dcl.enum]: dcl.md#dcl.enum
125
  [dcl.fct]: dcl.md#dcl.fct
126
  [dcl.fct.def]: dcl.md#dcl.fct.def
127
  [dcl.fct.def.coroutine]: dcl.md#dcl.fct.def.coroutine
@@ -135,10 +144,11 @@ struct C {
135
  [dcl.init.general]: dcl.md#dcl.init.general
136
  [dcl.init.list]: dcl.md#dcl.init.list
137
  [dcl.init.ref]: dcl.md#dcl.init.ref
138
  [dcl.inline]: dcl.md#dcl.inline
139
  [dcl.meaning]: dcl.md#dcl.meaning
 
140
  [dcl.name]: dcl.md#dcl.name
141
  [dcl.spec.auto]: dcl.md#dcl.spec.auto
142
  [dcl.stc]: dcl.md#dcl.stc
143
  [dcl.type.cv]: dcl.md#dcl.type.cv
144
  [dcl.type.elab]: dcl.md#dcl.type.elab
@@ -147,14 +157,13 @@ struct C {
147
  [depr.impldec]: future.md#depr.impldec
148
  [depr.static.constexpr]: future.md#depr.static.constexpr
149
  [diff.class]: compatibility.md#diff.class
150
  [except.ctor]: except.md#except.ctor
151
  [except.handle]: except.md#except.handle
152
- [except.pre]: except.md#except.pre
153
  [except.spec]: except.md#except.spec
154
  [except.throw]: except.md#except.throw
155
- [expr.ass]: expr.md#expr.ass
156
  [expr.call]: expr.md#expr.call
157
  [expr.cast]: expr.md#expr.cast
158
  [expr.const]: expr.md#expr.const
159
  [expr.const.cast]: expr.md#expr.const.cast
160
  [expr.delete]: expr.md#expr.delete
@@ -174,39 +183,42 @@ struct C {
174
  [expr.type.conv]: expr.md#expr.type.conv
175
  [expr.typeid]: expr.md#expr.typeid
176
  [expr.unary.op]: expr.md#expr.unary.op
177
  [intro.execution]: basic.md#intro.execution
178
  [intro.object]: basic.md#intro.object
 
 
179
  [namespace.udecl]: dcl.md#namespace.udecl
180
  [over]: over.md#over
181
- [over.ass]: over.md#over.ass
182
  [over.best.ics]: over.md#over.best.ics
183
  [over.binary]: over.md#over.binary
184
- [over.ics.ref]: over.md#over.ics.ref
185
  [over.match]: over.md#over.match
186
  [over.match.best]: over.md#over.match.best
187
  [over.match.call]: over.md#over.match.call
188
  [over.match.copy]: over.md#over.match.copy
189
  [over.match.funcs]: over.md#over.match.funcs
 
 
190
  [over.oper]: over.md#over.oper
191
  [over.over]: over.md#over.over
192
  [special]: #special
193
  [stmt.dcl]: stmt.md#stmt.dcl
194
  [stmt.return]: stmt.md#stmt.return
195
  [string.classes]: strings.md#string.classes
196
  [temp.arg]: temp.md#temp.arg
197
  [temp.constr]: temp.md#temp.constr
198
  [temp.constr.order]: temp.md#temp.constr.order
199
  [temp.deduct.guide]: temp.md#temp.deduct.guide
200
- [temp.dep.type]: temp.md#temp.dep.type
201
  [temp.expl.spec]: temp.md#temp.expl.spec
202
  [temp.explicit]: temp.md#temp.explicit
203
  [temp.friend]: temp.md#temp.friend
204
  [temp.inst]: temp.md#temp.inst
205
  [temp.mem]: temp.md#temp.mem
206
  [temp.param]: temp.md#temp.param
207
  [temp.pre]: temp.md#temp.pre
 
208
  [temp.spec.partial]: temp.md#temp.spec.partial
209
  [temp.variadic]: temp.md#temp.variadic
210
  [term.incomplete.type]: basic.md#term.incomplete.type
211
  [term.layout.compatible.type]: basic.md#term.layout.compatible.type
212
  [term.object.representation]: basic.md#term.object.representation
@@ -215,61 +227,46 @@ struct C {
215
 
216
  [^1]: This ensures that two subobjects that have the same class type and
217
  that belong to the same most derived object are not allocated at the
218
  same address [[expr.eq]].
219
 
220
- [^2]: See, for example, `<cstring>`.
221
-
222
- [^3]: This implies that the reference parameter of the
223
  implicitly-declared copy constructor cannot bind to a `volatile`
224
  lvalue; see  [[diff.class]].
225
 
226
- [^4]: Because a template assignment operator or an assignment operator
227
  taking an rvalue reference parameter is never a copy assignment
228
  operator, the presence of such an assignment operator does not
229
  suppress the implicit declaration of a copy assignment operator.
230
  Such assignment operators participate in overload resolution with
231
  other assignment operators, including copy assignment operators,
232
  and, if selected, will be used to assign an object.
233
 
234
- [^5]: This implies that the reference parameter of the
235
  implicitly-declared copy assignment operator cannot bind to a
236
  `volatile` lvalue; see  [[diff.class]].
237
 
238
- [^6]: These conversions are considered as standard conversions for the
239
- purposes of overload resolution [[over.best.ics]], [[over.ics.ref]]
240
- and therefore initialization [[dcl.init]] and explicit casts
241
- [[expr.static.cast]]. A conversion to `void` does not invoke any
242
- conversion function [[expr.static.cast]]. Even though never directly
243
- called to perform a conversion, such conversion functions can be
244
- declared and can potentially be reached through a call to a virtual
245
- conversion function in a base class.
246
-
247
- [^7]: The use of the `virtual` specifier in the declaration of an
248
  overriding function is valid but redundant (has empty semantics).
249
 
250
- [^8]: If all virtual functions are immediate functions, the class is
251
  still polymorphic even if its internal representation does not
252
  otherwise require any additions for that polymorphic behavior.
253
 
254
- [^9]: A function with the same name but a different parameter list
255
  [[over]] as a virtual function is not necessarily virtual and does
256
  not override. Access control [[class.access]] is not considered in
257
  determining overriding.
258
 
259
- [^10]: Multi-level pointers to classes or references to multi-level
260
  pointers to classes are not allowed.
261
 
262
- [^11]: Access permissions are thus transitive and cumulative to nested
263
  and local classes.
264
 
265
- [^12]: As specified previously in [[class.access]], private members of a
266
  base class remain inaccessible even to derived classes unless friend
267
  declarations within the base class definition are used to grant
268
  access explicitly.
269
 
270
- [^13]: This additional check does not apply to other members, e.g.,
271
  static data members or enumerator member constants.
272
-
273
- [^14]: Because only one object is destroyed instead of two, and one
274
- copy/move constructor is not executed, there is still one object
275
- destroyed for each one constructed.
 
6
  `bool`.
7
 
8
  The operator function with parameters `x` and `y` is defined as deleted
9
  if
10
 
11
+ - a first overload resolution [[over.match]], as applied to `x @ y`,
12
+ - does not result in a usable candidate, or
13
+ - the selected candidate is not a rewritten candidate, or
14
+ - a second overload resolution for the expression resulting from the
15
+ interpretation of `x @ y` using the selected rewritten candidate
16
+ [[over.match.oper]] does not result in a usable candidate (for
17
+ example, that expression might be `(x <=> y) @ 0`), or
18
+ - `x @ y` cannot be implicitly converted to `bool`.
19
 
20
+ In any of the two overload resolutions above, the defaulted operator
21
+ function is not considered as a candidate for the `@` operator.
22
+ Otherwise, the operator function yields `x @ y`.
23
 
24
  [*Example 1*:
25
 
26
  ``` cpp
27
  struct HasNoLessThan { };
 
37
  <!-- Link reference definitions -->
38
  [basic.align]: basic.md#basic.align
39
  [basic.compound]: basic.md#basic.compound
40
  [basic.def]: basic.md#basic.def
41
  [basic.def.odr]: basic.md#basic.def.odr
42
+ [basic.fundamental]: basic.md#basic.fundamental
43
+ [basic.indet]: basic.md#basic.indet
44
  [basic.life]: basic.md#basic.life
45
  [basic.link]: basic.md#basic.link
46
  [basic.lookup]: basic.md#basic.lookup
47
  [basic.lookup.elab]: basic.md#basic.lookup.elab
48
  [basic.lval]: expr.md#basic.lval
 
54
  [basic.start.term]: basic.md#basic.start.term
55
  [basic.stc.auto]: basic.md#basic.stc.auto
56
  [basic.stc.static]: basic.md#basic.stc.static
57
  [basic.stc.thread]: basic.md#basic.stc.thread
58
  [basic.types]: basic.md#basic.types
59
+ [basic.types.general]: basic.md#basic.types.general
60
  [class]: #class
61
  [class.abstract]: #class.abstract
62
  [class.access]: #class.access
63
  [class.access.base]: #class.access.base
64
  [class.access.general]: #class.access.general
 
122
  [cmp.weakord]: support.md#cmp.weakord
123
  [conv]: expr.md#conv
124
  [conv.mem]: expr.md#conv.mem
125
  [conv.ptr]: expr.md#conv.ptr
126
  [conv.rval]: expr.md#conv.rval
127
+ [cpp.cond]: cpp.md#cpp.cond
128
+ [dcl.align]: dcl.md#dcl.align
129
  [dcl.array]: dcl.md#dcl.array
130
  [dcl.attr.nouniqueaddr]: dcl.md#dcl.attr.nouniqueaddr
131
+ [dcl.contract.func]: dcl.md#dcl.contract.func
132
  [dcl.decl]: dcl.md#dcl.decl
133
  [dcl.enum]: dcl.md#dcl.enum
134
  [dcl.fct]: dcl.md#dcl.fct
135
  [dcl.fct.def]: dcl.md#dcl.fct.def
136
  [dcl.fct.def.coroutine]: dcl.md#dcl.fct.def.coroutine
 
144
  [dcl.init.general]: dcl.md#dcl.init.general
145
  [dcl.init.list]: dcl.md#dcl.init.list
146
  [dcl.init.ref]: dcl.md#dcl.init.ref
147
  [dcl.inline]: dcl.md#dcl.inline
148
  [dcl.meaning]: dcl.md#dcl.meaning
149
+ [dcl.meaning.general]: dcl.md#dcl.meaning.general
150
  [dcl.name]: dcl.md#dcl.name
151
  [dcl.spec.auto]: dcl.md#dcl.spec.auto
152
  [dcl.stc]: dcl.md#dcl.stc
153
  [dcl.type.cv]: dcl.md#dcl.type.cv
154
  [dcl.type.elab]: dcl.md#dcl.type.elab
 
157
  [depr.impldec]: future.md#depr.impldec
158
  [depr.static.constexpr]: future.md#depr.static.constexpr
159
  [diff.class]: compatibility.md#diff.class
160
  [except.ctor]: except.md#except.ctor
161
  [except.handle]: except.md#except.handle
 
162
  [except.spec]: except.md#except.spec
163
  [except.throw]: except.md#except.throw
164
+ [expr.assign]: expr.md#expr.assign
165
  [expr.call]: expr.md#expr.call
166
  [expr.cast]: expr.md#expr.cast
167
  [expr.const]: expr.md#expr.const
168
  [expr.const.cast]: expr.md#expr.const.cast
169
  [expr.delete]: expr.md#expr.delete
 
183
  [expr.type.conv]: expr.md#expr.type.conv
184
  [expr.typeid]: expr.md#expr.typeid
185
  [expr.unary.op]: expr.md#expr.unary.op
186
  [intro.execution]: basic.md#intro.execution
187
  [intro.object]: basic.md#intro.object
188
+ [meta.reflection.define.aggregate]: meta.md#meta.reflection.define.aggregate
189
+ [module.reach]: module.md#module.reach
190
  [namespace.udecl]: dcl.md#namespace.udecl
191
  [over]: over.md#over
192
+ [over.assign]: over.md#over.assign
193
  [over.best.ics]: over.md#over.best.ics
194
  [over.binary]: over.md#over.binary
 
195
  [over.match]: over.md#over.match
196
  [over.match.best]: over.md#over.match.best
197
  [over.match.call]: over.md#over.match.call
198
  [over.match.copy]: over.md#over.match.copy
199
  [over.match.funcs]: over.md#over.match.funcs
200
+ [over.match.general]: over.md#over.match.general
201
+ [over.match.oper]: over.md#over.match.oper
202
  [over.oper]: over.md#over.oper
203
  [over.over]: over.md#over.over
204
  [special]: #special
205
  [stmt.dcl]: stmt.md#stmt.dcl
206
  [stmt.return]: stmt.md#stmt.return
207
  [string.classes]: strings.md#string.classes
208
  [temp.arg]: temp.md#temp.arg
209
  [temp.constr]: temp.md#temp.constr
210
  [temp.constr.order]: temp.md#temp.constr.order
211
  [temp.deduct.guide]: temp.md#temp.deduct.guide
 
212
  [temp.expl.spec]: temp.md#temp.expl.spec
213
  [temp.explicit]: temp.md#temp.explicit
214
  [temp.friend]: temp.md#temp.friend
215
  [temp.inst]: temp.md#temp.inst
216
  [temp.mem]: temp.md#temp.mem
217
  [temp.param]: temp.md#temp.param
218
  [temp.pre]: temp.md#temp.pre
219
+ [temp.spec.general]: temp.md#temp.spec.general
220
  [temp.spec.partial]: temp.md#temp.spec.partial
221
  [temp.variadic]: temp.md#temp.variadic
222
  [term.incomplete.type]: basic.md#term.incomplete.type
223
  [term.layout.compatible.type]: basic.md#term.layout.compatible.type
224
  [term.object.representation]: basic.md#term.object.representation
 
227
 
228
  [^1]: This ensures that two subobjects that have the same class type and
229
  that belong to the same most derived object are not allocated at the
230
  same address [[expr.eq]].
231
 
232
+ [^2]: This implies that the reference parameter of the
 
 
233
  implicitly-declared copy constructor cannot bind to a `volatile`
234
  lvalue; see  [[diff.class]].
235
 
236
+ [^3]: Because a template assignment operator or an assignment operator
237
  taking an rvalue reference parameter is never a copy assignment
238
  operator, the presence of such an assignment operator does not
239
  suppress the implicit declaration of a copy assignment operator.
240
  Such assignment operators participate in overload resolution with
241
  other assignment operators, including copy assignment operators,
242
  and, if selected, will be used to assign an object.
243
 
244
+ [^4]: This implies that the reference parameter of the
245
  implicitly-declared copy assignment operator cannot bind to a
246
  `volatile` lvalue; see  [[diff.class]].
247
 
248
+ [^5]: The use of the `virtual` specifier in the declaration of an
 
 
 
 
 
 
 
 
 
249
  overriding function is valid but redundant (has empty semantics).
250
 
251
+ [^6]: If all virtual functions are immediate functions, the class is
252
  still polymorphic even if its internal representation does not
253
  otherwise require any additions for that polymorphic behavior.
254
 
255
+ [^7]: A function with the same name but a different parameter list
256
  [[over]] as a virtual function is not necessarily virtual and does
257
  not override. Access control [[class.access]] is not considered in
258
  determining overriding.
259
 
260
+ [^8]: Multi-level pointers to classes or references to multi-level
261
  pointers to classes are not allowed.
262
 
263
+ [^9]: Access permissions are thus transitive and cumulative to nested
264
  and local classes.
265
 
266
+ [^10]: As specified previously in [[class.access]], private members of a
267
  base class remain inaccessible even to derived classes unless friend
268
  declarations within the base class definition are used to grant
269
  access explicitly.
270
 
271
+ [^11]: This additional check does not apply to other members, e.g.,
272
  static data members or enumerator member constants.