From Jason Turner

[class.mi]

C++17 → C++20 4.9 KB 46 lines
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  1. tmp/tmpju8fri8d/{from.md → to.md} +19 -19
tmp/tmpju8fri8d/{from.md → to.md} RENAMED
@@ -1,6 +1,6 @@
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- ## Multiple base classes <a id="class.mi">[[class.mi]]</a>
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  A class can be derived from any number of base classes.
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  [*Note 1*: The use of more than one direct base class is often called
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  multiple inheritance. — *end note*]
@@ -15,13 +15,13 @@ class D : public A, public B, public C { ... };
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  ```
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  — *end example*]
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  [*Note 2*: The order of derivation is not significant except as
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- specified by the semantics of initialization by constructor (
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- [[class.base.init]]), cleanup ([[class.dtor]]), and storage layout (
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- [[class.mem]],  [[class.access.spec]]). — *end note*]
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  A class shall not be specified as a direct base class of a derived class
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  more than once.
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  [*Note 3*: A class can be an indirect base class more than once and can
@@ -33,11 +33,11 @@ can be unambiguously referred to. — *end note*]
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  [*Example 2*:
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  ``` cpp
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  class X { ... };
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- class Y : public X, public X { ... }; // ill-formed
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  ```
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  ``` cpp
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  class L { public: int next; ... };
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  class A : public L { ... };
@@ -50,38 +50,38 @@ class D : public A, public L { void f(); ... }; // well-formed
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  A base class specifier that does not contain the keyword `virtual`
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  specifies a *non-virtual base class*. A base class specifier that
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  contains the keyword `virtual` specifies a *virtual base class*. For
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  each distinct occurrence of a non-virtual base class in the class
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- lattice of the most derived class, the most derived object (
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- [[intro.object]]) shall contain a corresponding distinct base class
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  subobject of that type. For each distinct base class that is specified
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  virtual, the most derived object shall contain a single base class
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  subobject of that type.
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  [*Note 4*:
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  For an object of class type `C`, each distinct occurrence of a
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  (non-virtual) base class `L` in the class lattice of `C` corresponds
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  one-to-one with a distinct `L` subobject within the object of type `C`.
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  Given the class `C` defined above, an object of class `C` will have two
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- subobjects of class `L` as shown in Figure  [[fig:nonvirt]].
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- <a id="fig:nonvirt"></a>
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- ![Non-virtual base \[fig:nonvirt\]](images/fignonvirt.svg)
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  In such lattices, explicit qualification can be used to specify which
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  subobject is meant. The body of function `C::f` could refer to the
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  member `next` of each `L` subobject:
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  ``` cpp
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  void C::f() { A::next = B::next; } // well-formed
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  ```
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  Without the `A::` or `B::` qualifiers, the definition of `C::f` above
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- would be ill-formed because of ambiguity ([[class.member.lookup]]).
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  — *end note*]
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  [*Note 5*:
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@@ -92,19 +92,19 @@ class V { ... };
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  class A : virtual public V { ... };
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  class B : virtual public V { ... };
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  class C : public A, public B { ... };
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  ```
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- <a id="fig:virt"></a>
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- ![Virtual base \[fig:virt\]](images/figvirt.svg)
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  For an object `c` of class type `C`, a single subobject of type `V` is
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  shared by every base class subobject of `c` that has a `virtual` base
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  class of type `V`. Given the class `C` defined above, an object of class
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- `C` will have one subobject of class `V`, as shown in Figure 
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- [[fig:virt]].
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107
  — *end note*]
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  [*Note 6*:
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@@ -123,14 +123,14 @@ For an object of class `AA`, all `virtual` occurrences of base class `B`
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  in the class lattice of `AA` correspond to a single `B` subobject within
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  the object of type `AA`, and every other occurrence of a (non-virtual)
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  base class `B` in the class lattice of `AA` corresponds one-to-one with
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  a distinct `B` subobject within the object of type `AA`. Given the class
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  `AA` defined above, class `AA` has two subobjects of class `B`: `Z`’s
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- `B` and the virtual `B` shared by `X` and `Y`, as shown in Figure 
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- [[fig:virtnonvirt]].
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- <a id="fig:virtnonvirt"></a>
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- ![Virtual and non-virtual base \[fig:virtnonvirt\]](images/figvirtnonvirt.svg)
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  — *end note*]
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+ ### Multiple base classes <a id="class.mi">[[class.mi]]</a>
2
 
3
  A class can be derived from any number of base classes.
4
 
5
  [*Note 1*: The use of more than one direct base class is often called
6
  multiple inheritance. — *end note*]
 
15
  ```
16
 
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  — *end example*]
18
 
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  [*Note 2*: The order of derivation is not significant except as
20
+ specified by the semantics of initialization by constructor
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+ [[class.base.init]], cleanup [[class.dtor]], and storage layout (
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+ [[class.mem]], [[class.access.spec]]). — *end note*]
23
 
24
  A class shall not be specified as a direct base class of a derived class
25
  more than once.
26
 
27
  [*Note 3*: A class can be an indirect base class more than once and can
 
33
 
34
  [*Example 2*:
35
 
36
  ``` cpp
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  class X { ... };
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+ class Y : public X, public X { ... }; // error
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  ```
40
 
41
  ``` cpp
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  class L { public: int next; ... };
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  class A : public L { ... };
 
50
 
51
  A base class specifier that does not contain the keyword `virtual`
52
  specifies a *non-virtual base class*. A base class specifier that
53
  contains the keyword `virtual` specifies a *virtual base class*. For
54
  each distinct occurrence of a non-virtual base class in the class
55
+ lattice of the most derived class, the most derived object
56
+ [[intro.object]] shall contain a corresponding distinct base class
57
  subobject of that type. For each distinct base class that is specified
58
  virtual, the most derived object shall contain a single base class
59
  subobject of that type.
60
 
61
  [*Note 4*:
62
 
63
  For an object of class type `C`, each distinct occurrence of a
64
  (non-virtual) base class `L` in the class lattice of `C` corresponds
65
  one-to-one with a distinct `L` subobject within the object of type `C`.
66
  Given the class `C` defined above, an object of class `C` will have two
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+ subobjects of class `L` as shown in Figure [[fig:class.nonvirt]].
68
 
69
+ <a id="fig:class.nonvirt"></a>
70
 
71
+ ![Non-virtual base \[fig:class.nonvirt\]](images/fignonvirt.svg)
72
 
73
  In such lattices, explicit qualification can be used to specify which
74
  subobject is meant. The body of function `C::f` could refer to the
75
  member `next` of each `L` subobject:
76
 
77
  ``` cpp
78
  void C::f() { A::next = B::next; } // well-formed
79
  ```
80
 
81
  Without the `A::` or `B::` qualifiers, the definition of `C::f` above
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+ would be ill-formed because of ambiguity [[class.member.lookup]].
83
 
84
  — *end note*]
85
 
86
  [*Note 5*:
87
 
 
92
  class A : virtual public V { ... };
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  class B : virtual public V { ... };
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  class C : public A, public B { ... };
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  ```
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97
+ <a id="fig:class.virt"></a>
98
 
99
+ ![Virtual base \[fig:class.virt\]](images/figvirt.svg)
100
 
101
  For an object `c` of class type `C`, a single subobject of type `V` is
102
  shared by every base class subobject of `c` that has a `virtual` base
103
  class of type `V`. Given the class `C` defined above, an object of class
104
+ `C` will have one subobject of class `V`, as shown in Figure
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+ [[fig:class.virt]].
106
 
107
  — *end note*]
108
 
109
  [*Note 6*:
110
 
 
123
  in the class lattice of `AA` correspond to a single `B` subobject within
124
  the object of type `AA`, and every other occurrence of a (non-virtual)
125
  base class `B` in the class lattice of `AA` corresponds one-to-one with
126
  a distinct `B` subobject within the object of type `AA`. Given the class
127
  `AA` defined above, class `AA` has two subobjects of class `B`: `Z`’s
128
+ `B` and the virtual `B` shared by `X` and `Y`, as shown in Figure
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+ [[fig:class.virtnonvirt]].
130
 
131
+ <a id="fig:class.virtnonvirt"></a>
132
 
133
+ ![Virtual and non-virtual base \[fig:class.virtnonvirt\]](images/figvirtnonvirt.svg)
134
 
135
  — *end note*]
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