[over.best.ics] - C++17 → C++20

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@@ -1,30 +1,32 @@
 #### Implicit conversion sequences <a id="over.best.ics">[[over.best.ics]]</a>
 An *implicit conversion sequence* is a sequence of conversions used to
 convert an argument in a function call to the type of the corresponding
 parameter of the function being called. The sequence of conversions is
-an implicit conversion as defined in Clause  [[conv]], which means it is
 governed by the rules for initialization of an object or reference by a
 single expression ([[dcl.init]], [[dcl.init.ref]]).
 Implicit conversion sequences are concerned only with the type,
 cv-qualification, and value category of the argument and how these are
-converted to match the corresponding properties of the parameter. Other
-properties, such as the lifetime, storage class, alignment,
-accessibility of the argument, whether the argument is a bit-field, and
-whether a function is deleted ([[dcl.fct.def.delete]]), are ignored.
-So, although an implicit conversion sequence can be defined for a given
-argument-parameter pair, the conversion from the argument to the
-parameter might still be ill-formed in the final analysis.
 A well-formed implicit conversion sequence is one of the following
 forms:
-- a *standard conversion sequence* ([[over.ics.scs]]),
-- a *user-defined conversion sequence* ([[over.ics.user]]), or
-- an *ellipsis conversion sequence* ([[over.ics.ellipsis]]).
 However, if the target is
 - the first parameter of a constructor or
 - the implicit object parameter of a user-defined conversion function
@@ -41,25 +43,25 @@ by
   is the first parameter of a constructor of class `X`, and the
   conversion is to `X` or reference to cv `X`,
 user-defined conversion sequences are not considered.
-[*Note 1*: These rules prevent more than one user-defined conversion
 from being applied during overload resolution, thereby avoiding infinite
 recursion. — *end note*]
 [*Example 1*:
 ``` cpp
 struct Y { Y(int); };
 struct A { operator int(); };
 Y y1 = A();         // error: A::operator int() is not a candidate
- struct X { };
 struct B { operator X(); };
 B b;
- X x({b}); // error: B::operator X() is not a candidate
 ```
 — *end example*]
 For the case where the parameter type is a reference, see
@@ -69,12 +71,12 @@ When the parameter type is not a reference, the implicit conversion
 sequence models a copy-initialization of the parameter from the argument
 expression. The implicit conversion sequence is the one required to
 convert the argument expression to a prvalue of the type of the
 parameter.
-[*Note 2*: When the parameter has a class type, this is a conceptual
-conversion defined for the purposes of Clause  [[over]]; the actual
 initialization is defined in terms of constructors and is not a
 conversion. — *end note*]
 Any difference in top-level cv-qualification is subsumed by the
 initialization itself and does not constitute a conversion.
@@ -86,39 +88,39 @@ case is the identity sequence; it contains no “conversion” from
 When the parameter has a class type and the argument expression has the
 same type, the implicit conversion sequence is an identity conversion.
 When the parameter has a class type and the argument expression has a
 derived class type, the implicit conversion sequence is a
-derived-to-base Conversion from the derived class to the base class.
-[*Note 3*: There is no such standard conversion; this derived-to-base
-Conversion exists only in the description of implicit conversion
 sequences. — *end note*]
-A derived-to-base Conversion has Conversion rank ([[over.ics.scs]]).
 In all contexts, when converting to the implicit object parameter or
 when converting to the left operand of an assignment operation only
 standard conversion sequences are allowed.
 If no conversions are required to match an argument to a parameter type,
 the implicit conversion sequence is the standard conversion sequence
-consisting of the identity conversion ([[over.ics.scs]]).
 If no sequence of conversions can be found to convert an argument to a
 parameter type, an implicit conversion sequence cannot be formed.
-If several different sequences of conversions exist that each convert
-the argument to the parameter type, the implicit conversion sequence
-associated with the parameter is defined to be the unique conversion
-sequence designated the *ambiguous conversion sequence*. For the purpose
-of ranking implicit conversion sequences as described in
 [[over.ics.rank]], the ambiguous conversion sequence is treated as a
 user-defined conversion sequence that is indistinguishable from any
 other user-defined conversion sequence.
-[*Note 4*:
 This rule prevents a function from becoming non-viable because of an
 ambiguous conversion sequence for one of its parameters.
 [*Example 3*:
@@ -129,11 +131,11 @@ class A { A (B&);};
 class B { operator A (); };
 class C { C (B&); };
 void f(A) { }
 void f(C) { }
 B b;
-f(b);               // ill-formed: ambiguous because there is a conversion b → C (via constructor)
                     // and an (ambiguous) conversion b → A (via constructor or conversion function)
 void f(B) { }
 f(b);               // OK, unambiguous
 ```
@@ -148,69 +150,66 @@ conversion of one of the arguments in the call is ambiguous.
 The three forms of implicit conversion sequences mentioned above are
 defined in the following subclauses.
 ##### Standard conversion sequences <a id="over.ics.scs">[[over.ics.scs]]</a>
-Table  [[tab:over.conversions]] summarizes the conversions defined in
-Clause  [[conv]] and partitions them into four disjoint categories:
-Lvalue Transformation, Qualification Adjustment, Promotion, and
-Conversion.
-[*Note 5*: These categories are orthogonal with respect to value
 category, cv-qualification, and data representation: the Lvalue
 Transformations do not change the cv-qualification or data
 representation of the type; the Qualification Adjustments do not change
 the value category or data representation of the type; and the
 Promotions and Conversions do not change the value category or
 cv-qualification of the type. — *end note*]
-[*Note 6*: As described in Clause  [[conv]], a standard conversion
-sequence is either the Identity conversion by itself (that is, no
-conversion) or consists of one to three conversions from the other four
-categories. If there are two or more conversions in the sequence, the
-conversions are applied in the canonical order: **Lvalue
-Transformation**, **Promotion** or **Conversion**, **Qualification
-Adjustment**. — *end note*]
-Each conversion in Table  [[tab:over.conversions]] also has an
-associated rank (Exact Match, Promotion, or Conversion). These are used
-to rank standard conversion sequences ([[over.ics.rank]]). The rank of
-a conversion sequence is determined by considering the rank of each
-conversion in the sequence and the rank of any reference binding (
-[[over.ics.ref]]). If any of those has Conversion rank, the sequence has
-Conversion rank; otherwise, if any of those has Promotion rank, the
-sequence has Promotion rank; otherwise, the sequence has Exact Match
-rank.
-**Table: Conversions** <a id="tab:over.conversions">[tab:over.conversions]</a>
 | Conversion              | Category | Rank | Subclause         |
 | ----------------------- | -------- | ---- | ----------------- |
 | No conversions required | Identity |      |                   |
 | Integral promotions     |          |      | [[conv.prom]]     |
 | Integral conversions    |          |      | [[conv.integral]] |
 ##### User-defined conversion sequences <a id="over.ics.user">[[over.ics.user]]</a>
-A user-defined conversion sequence consists of an initial standard
-conversion sequence followed by a user-defined conversion (
-[[class.conv]]) followed by a second standard conversion sequence. If
-the user-defined conversion is specified by a constructor (
-[[class.conv.ctor]]), the initial standard conversion sequence converts
-the source type to the type required by the argument of the constructor.
-If the user-defined conversion is specified by a conversion function (
-[[class.conv.fct]]), the initial standard conversion sequence converts
-the source type to the implicit object parameter of the conversion
-function.
 The second standard conversion sequence converts the result of the
-user-defined conversion to the target type for the sequence. Since an
-implicit conversion sequence is an initialization, the special rules for
-initialization by user-defined conversion apply when selecting the best
-user-defined conversion for a user-defined conversion sequence (see
-[[over.match.best]] and  [[over.best.ics]]).
 If the user-defined conversion is specified by a specialization of a
 conversion function template, the second standard conversion sequence
 shall have exact match rank.
@@ -226,15 +225,15 @@ An ellipsis conversion sequence occurs when an argument in a function
 call is matched with the ellipsis parameter specification of the
 function called (see  [[expr.call]]).
 ##### Reference binding <a id="over.ics.ref">[[over.ics.ref]]</a>
-When a parameter of reference type binds directly ([[dcl.init.ref]]) to
-an argument expression, the implicit conversion sequence is the identity
 conversion, unless the argument expression has a type that is a derived
 class of the parameter type, in which case the implicit conversion
-sequence is a derived-to-base Conversion ([[over.best.ics]]).
 [*Example 4*:
 ``` cpp
 struct A {};
@@ -246,73 +245,108 @@ int i = f(b);       // calls f(B&), an exact match, rather than f(A&), a convers
 — *end example*]
 If the parameter binds directly to the result of applying a conversion
 function to the argument expression, the implicit conversion sequence is
-a user-defined conversion sequence ([[over.ics.user]]), with the second
 standard conversion sequence either an identity conversion or, if the
 conversion function returns an entity of a type that is a derived class
-of the parameter type, a derived-to-base Conversion.
 When a parameter of reference type is not bound directly to an argument
 expression, the conversion sequence is the one required to convert the
 argument expression to the referenced type according to
 [[over.best.ics]]. Conceptually, this conversion sequence corresponds to
 copy-initializing a temporary of the referenced type with the argument
 expression. Any difference in top-level cv-qualification is subsumed by
 the initialization itself and does not constitute a conversion.
 Except for an implicit object parameter, for which see
-[[over.match.funcs]], a standard conversion sequence cannot be formed if
-it requires binding an lvalue reference other than a reference to a
 non-volatile `const` type to an rvalue or binding an rvalue reference to
 an lvalue other than a function lvalue.
-[*Note 7*: This means, for example, that a candidate function cannot be
 a viable function if it has a non-`const` lvalue reference parameter
 (other than the implicit object parameter) and the corresponding
 argument would require a temporary to be created to initialize the
 lvalue reference (see  [[dcl.init.ref]]). — *end note*]
 Other restrictions on binding a reference to a particular argument that
 are not based on the types of the reference and the argument do not
-affect the formation of a standard conversion sequence, however.
 [*Example 5*: A function with an “lvalue reference to `int`” parameter
 can be a viable candidate even if the corresponding argument is an `int`
 bit-field. The formation of implicit conversion sequences treats the
 `int` bit-field as an `int` lvalue and finds an exact match with the
 parameter. If the function is selected by overload resolution, the call
 will nonetheless be ill-formed because of the prohibition on binding a
-non-`const` lvalue reference to a bit-field (
-[[dcl.init.ref]]). — *end example*]
 ##### List-initialization sequence <a id="over.ics.list">[[over.ics.list]]</a>
-When an argument is an initializer list ([[dcl.init.list]]), it is not
-an expression and special rules apply for converting it to a parameter
 type.
-If the parameter type is an aggregate class `X` and the initializer list
-has a single element of type cv `U`, where `U` is `X` or a class derived
-from `X`, the implicit conversion sequence is the one required to
-convert the element to the parameter type.
-Otherwise, if the parameter type is a character array [^11] and the
 initializer list has a single element that is an appropriately-typed
-string literal ([[dcl.init.string]]), the implicit conversion sequence
 is the identity conversion.
 Otherwise, if the parameter type is `std::initializer_list<X>` and all
 the elements of the initializer list can be implicitly converted to `X`,
 the implicit conversion sequence is the worst conversion necessary to
 convert an element of the list to `X`, or if the initializer list has no
 elements, the identity conversion. This conversion can be a user-defined
 conversion even in the context of a call to an initializer-list
 constructor.
-[*Example 6*:
 ``` cpp
 void f(std::initializer_list<int>);
 f( {} );                        // OK: f(initializer_list<int>) identity conversion
 f( {1,2,3} );                   // OK: f(initializer_list<int>) identity conversion
@@ -334,15 +368,16 @@ void h(const IA&);
 h({ 1, 2, 3 });                 // OK: identity conversion
 ```
 — *end example*]
-Otherwise, if the parameter type is “array of `N` `X`”, if there exists
-an implicit conversion sequence for each element of the array from the
-corresponding element of the initializer list (or from `{}` if there is
-no such element), the implicit conversion sequence is the worst such
-implicit conversion sequence.
 Otherwise, if the parameter is a non-aggregate class `X` and overload
 resolution per  [[over.match.list]] chooses a single best constructor
 `C` of `X` to perform the initialization of an object of type `X` from
 the argument initializer list:
@@ -359,11 +394,11 @@ If multiple constructors are viable but none is better than the others,
 the implicit conversion sequence is the ambiguous conversion sequence.
 User-defined conversions are allowed for conversion of the initializer
 list elements to the constructor parameter types except as noted in
 [[over.best.ics]].
-[*Example 7*:
 ``` cpp
 struct A {
   A(std::initializer_list<int>);
 };
@@ -395,15 +430,15 @@ i({ {1,2}, {"bar"} });  // OK: i(D(A(std::initializer_list<int>{1,2\), C(std::st
 — *end example*]
 Otherwise, if the parameter has an aggregate type which can be
 initialized from the initializer list according to the rules for
-aggregate initialization ([[dcl.init.aggr]]), the implicit conversion
 sequence is a user-defined conversion sequence with the second standard
 conversion sequence an identity conversion.
-[*Example 8*:
 ``` cpp
 struct A {
   int m1;
   double m2;
@@ -416,14 +451,14 @@ f( {1.0} );             // error: narrowing
 — *end example*]
 Otherwise, if the parameter is a reference, see  [[over.ics.ref]].
-[*Note 8*: The rules in this section will apply for initializing the
 underlying temporary for the reference. — *end note*]
-[*Example 9*:
 ``` cpp
 struct A {
   int m1;
   double m2;
@@ -442,21 +477,21 @@ g({1});                 // same conversion as int to double
 Otherwise, if the parameter type is not a class:
 - if the initializer list has one element that is not itself an
   initializer list, the implicit conversion sequence is the one required
   to convert the element to the parameter type;
-  \[*Example 10*:
   ``` cpp
   void f(int);
   f( {'a'} );             // OK: same conversion as char to int
   f( {1.0} );             // error: narrowing
   ```
   — *end example*]
 - if the initializer list has no elements, the implicit conversion
   sequence is the identity conversion.
-  \[*Example 11*:
   ``` cpp
   void f(int);
   f( { } );               // OK: identity conversion
   ```

 #### Implicit conversion sequences <a id="over.best.ics">[[over.best.ics]]</a>
 An *implicit conversion sequence* is a sequence of conversions used to
 convert an argument in a function call to the type of the corresponding
 parameter of the function being called. The sequence of conversions is
+an implicit conversion as defined in [[conv]], which means it is
 governed by the rules for initialization of an object or reference by a
 single expression ([[dcl.init]], [[dcl.init.ref]]).
 Implicit conversion sequences are concerned only with the type,
 cv-qualification, and value category of the argument and how these are
+converted to match the corresponding properties of the parameter.
+[*Note 1*: Other properties, such as the lifetime, storage class,
+alignment, accessibility of the argument, whether the argument is a
+bit-field, and whether a function is deleted [[dcl.fct.def.delete]], are
+ignored. So, although an implicit conversion sequence can be defined for
+a given argument-parameter pair, the conversion from the argument to the
+parameter might still be ill-formed in the final
+analysis. — *end note*]
 A well-formed implicit conversion sequence is one of the following
 forms:
+- a standard conversion sequence [[over.ics.scs]],
+- a user-defined conversion sequence [[over.ics.user]], or
+- an ellipsis conversion sequence [[over.ics.ellipsis]].
 However, if the target is
 - the first parameter of a constructor or
 - the implicit object parameter of a user-defined conversion function
   is the first parameter of a constructor of class `X`, and the
   conversion is to `X` or reference to cv `X`,
 user-defined conversion sequences are not considered.
+[*Note 2*: These rules prevent more than one user-defined conversion
 from being applied during overload resolution, thereby avoiding infinite
 recursion. — *end note*]
 [*Example 1*:
 ``` cpp
 struct Y { Y(int); };
 struct A { operator int(); };
 Y y1 = A();         // error: A::operator int() is not a candidate
+struct X { X(); };
 struct B { operator X(); };
 B b;
+X x{{b}}; // error: B::operator X() is not a candidate
 ```
 — *end example*]
 For the case where the parameter type is a reference, see
 sequence models a copy-initialization of the parameter from the argument
 expression. The implicit conversion sequence is the one required to
 convert the argument expression to a prvalue of the type of the
 parameter.
+[*Note 3*: When the parameter has a class type, this is a conceptual
+conversion defined for the purposes of [[over]]; the actual
 initialization is defined in terms of constructors and is not a
 conversion. — *end note*]
 Any difference in top-level cv-qualification is subsumed by the
 initialization itself and does not constitute a conversion.
 When the parameter has a class type and the argument expression has the
 same type, the implicit conversion sequence is an identity conversion.
 When the parameter has a class type and the argument expression has a
 derived class type, the implicit conversion sequence is a
+derived-to-base conversion from the derived class to the base class.
+[*Note 4*: There is no such standard conversion; this derived-to-base
+conversion exists only in the description of implicit conversion
 sequences. — *end note*]
+A derived-to-base conversion has Conversion rank [[over.ics.scs]].
 In all contexts, when converting to the implicit object parameter or
 when converting to the left operand of an assignment operation only
 standard conversion sequences are allowed.
 If no conversions are required to match an argument to a parameter type,
 the implicit conversion sequence is the standard conversion sequence
+consisting of the identity conversion [[over.ics.scs]].
 If no sequence of conversions can be found to convert an argument to a
 parameter type, an implicit conversion sequence cannot be formed.
+If there are multiple well-formed implicit conversion sequences
+converting the argument to the parameter type, the implicit conversion
+sequence associated with the parameter is defined to be the unique
+conversion sequence designated the *ambiguous conversion sequence*. For
+the purpose of ranking implicit conversion sequences as described in
 [[over.ics.rank]], the ambiguous conversion sequence is treated as a
 user-defined conversion sequence that is indistinguishable from any
 other user-defined conversion sequence.
+[*Note 5*:
 This rule prevents a function from becoming non-viable because of an
 ambiguous conversion sequence for one of its parameters.
 [*Example 3*:
 class B { operator A (); };
 class C { C (B&); };
 void f(A) { }
 void f(C) { }
 B b;
+f(b);               // error: ambiguous because there is a conversion b → C (via constructor)
                     // and an (ambiguous) conversion b → A (via constructor or conversion function)
 void f(B) { }
 f(b);               // OK, unambiguous
 ```
 The three forms of implicit conversion sequences mentioned above are
 defined in the following subclauses.
 ##### Standard conversion sequences <a id="over.ics.scs">[[over.ics.scs]]</a>
+summarizes the conversions defined in [[conv]] and partitions them into
+four disjoint categories: Lvalue Transformation, Qualification
+Adjustment, Promotion, and Conversion.
+[*Note 6*: These categories are orthogonal with respect to value
 category, cv-qualification, and data representation: the Lvalue
 Transformations do not change the cv-qualification or data
 representation of the type; the Qualification Adjustments do not change
 the value category or data representation of the type; and the
 Promotions and Conversions do not change the value category or
 cv-qualification of the type. — *end note*]
+[*Note 7*: As described in [[conv]], a standard conversion sequence
+either is the Identity conversion by itself (that is, no conversion) or
+consists of one to three conversions from the other four categories. If
+there are two or more conversions in the sequence, the conversions are
+applied in the canonical order: **Lvalue Transformation**, **Promotion**
+or **Conversion**, **Qualification Adjustment**. — *end note*]
+Each conversion in [[over.ics.scs]] also has an associated rank (Exact
+Match, Promotion, or Conversion). These are used to rank standard
+conversion sequences [[over.ics.rank]]. The rank of a conversion
+sequence is determined by considering the rank of each conversion in the
+sequence and the rank of any reference binding [[over.ics.ref]]. If any
+of those has Conversion rank, the sequence has Conversion rank;
+otherwise, if any of those has Promotion rank, the sequence has
+Promotion rank; otherwise, the sequence has Exact Match rank.
+**Table: Conversions** <a id="over.ics.scs">[over.ics.scs]</a>
 | Conversion              | Category | Rank | Subclause         |
 | ----------------------- | -------- | ---- | ----------------- |
 | No conversions required | Identity |      |                   |
 | Integral promotions     |          |      | [[conv.prom]]     |
 | Integral conversions    |          |      | [[conv.integral]] |
 ##### User-defined conversion sequences <a id="over.ics.user">[[over.ics.user]]</a>
+A *user-defined conversion sequence* consists of an initial standard
+conversion sequence followed by a user-defined conversion [[class.conv]]
+followed by a second standard conversion sequence. If the user-defined
+conversion is specified by a constructor [[class.conv.ctor]], the
+initial standard conversion sequence converts the source type to the
+type required by the argument of the constructor. If the user-defined
+conversion is specified by a conversion function [[class.conv.fct]], the
+initial standard conversion sequence converts the source type to the
+implicit object parameter of the conversion function.
 The second standard conversion sequence converts the result of the
+user-defined conversion to the target type for the sequence; any
+reference binding is included in the second standard conversion
+sequence. Since an implicit conversion sequence is an initialization,
+the special rules for initialization by user-defined conversion apply
+when selecting the best user-defined conversion for a user-defined
+conversion sequence (see  [[over.match.best]] and  [[over.best.ics]]).
 If the user-defined conversion is specified by a specialization of a
 conversion function template, the second standard conversion sequence
 shall have exact match rank.
 call is matched with the ellipsis parameter specification of the
 function called (see  [[expr.call]]).
 ##### Reference binding <a id="over.ics.ref">[[over.ics.ref]]</a>
+When a parameter of reference type binds directly [[dcl.init.ref]] to an
+argument expression, the implicit conversion sequence is the identity
 conversion, unless the argument expression has a type that is a derived
 class of the parameter type, in which case the implicit conversion
+sequence is a derived-to-base Conversion [[over.best.ics]].
 [*Example 4*:
 ``` cpp
 struct A {};
 — *end example*]
 If the parameter binds directly to the result of applying a conversion
 function to the argument expression, the implicit conversion sequence is
+a user-defined conversion sequence [[over.ics.user]], with the second
 standard conversion sequence either an identity conversion or, if the
 conversion function returns an entity of a type that is a derived class
+of the parameter type, a derived-to-base conversion.
 When a parameter of reference type is not bound directly to an argument
 expression, the conversion sequence is the one required to convert the
 argument expression to the referenced type according to
 [[over.best.ics]]. Conceptually, this conversion sequence corresponds to
 copy-initializing a temporary of the referenced type with the argument
 expression. Any difference in top-level cv-qualification is subsumed by
 the initialization itself and does not constitute a conversion.
 Except for an implicit object parameter, for which see
+[[over.match.funcs]], an implicit conversion sequence cannot be formed
+if it requires binding an lvalue reference other than a reference to a
 non-volatile `const` type to an rvalue or binding an rvalue reference to
 an lvalue other than a function lvalue.
+[*Note 8*: This means, for example, that a candidate function cannot be
 a viable function if it has a non-`const` lvalue reference parameter
 (other than the implicit object parameter) and the corresponding
 argument would require a temporary to be created to initialize the
 lvalue reference (see  [[dcl.init.ref]]). — *end note*]
 Other restrictions on binding a reference to a particular argument that
 are not based on the types of the reference and the argument do not
+affect the formation of an implicit conversion sequence, however.
 [*Example 5*: A function with an “lvalue reference to `int`” parameter
 can be a viable candidate even if the corresponding argument is an `int`
 bit-field. The formation of implicit conversion sequences treats the
 `int` bit-field as an `int` lvalue and finds an exact match with the
 parameter. If the function is selected by overload resolution, the call
 will nonetheless be ill-formed because of the prohibition on binding a
+non-`const` lvalue reference to a bit-field
+[[dcl.init.ref]]. — *end example*]
 ##### List-initialization sequence <a id="over.ics.list">[[over.ics.list]]</a>
+When an argument is an initializer list [[dcl.init.list]], it is not an
+expression and special rules apply for converting it to a parameter
 type.
+If the initializer list is a *designated-initializer-list*, a conversion
+is only possible if the parameter has an aggregate type that can be
+initialized from the initializer list according to the rules for
+aggregate initialization [[dcl.init.aggr]], in which case the implicit
+conversion sequence is a user-defined conversion sequence whose second
+standard conversion sequence is an identity conversion.
+[*Note 9*:
+Aggregate initialization does not require that the members are declared
+in designation order. If, after overload resolution, the order does not
+match for the selected overload, the initialization of the parameter
+will be ill-formed [[dcl.init.list]].
+[*Example 6*:
+``` cpp
+struct A { int x, y; };
+struct B { int y, x; };
+void f(A a, int);               // #1
+void f(B b, ...);               // #2
+void g(A a);                    // #3
+void g(B b);                    // #4
+void h() {
+  f({.x = 1, .y = 2}, 0);       // OK; calls #1
+  f({.y = 2, .x = 1}, 0);       // error: selects #1, initialization of a fails
+                                // due to non-matching member order[dcl.init.list]
+  g({.x = 1, .y = 2});          // error: ambiguous between #3 and #4
+}
+```
+— *end example*]
+— *end note*]
+Otherwise, if the parameter type is an aggregate class `X` and the
+initializer list has a single element of type cv `U`, where `U` is `X`
+or a class derived from `X`, the implicit conversion sequence is the one
+required to convert the element to the parameter type.
+Otherwise, if the parameter type is a character array [^10] and the
 initializer list has a single element that is an appropriately-typed
+*string-literal* [[dcl.init.string]], the implicit conversion sequence
 is the identity conversion.
 Otherwise, if the parameter type is `std::initializer_list<X>` and all
 the elements of the initializer list can be implicitly converted to `X`,
 the implicit conversion sequence is the worst conversion necessary to
 convert an element of the list to `X`, or if the initializer list has no
 elements, the identity conversion. This conversion can be a user-defined
 conversion even in the context of a call to an initializer-list
 constructor.
+[*Example 7*:
 ``` cpp
 void f(std::initializer_list<int>);
 f( {} );                        // OK: f(initializer_list<int>) identity conversion
 f( {1,2,3} );                   // OK: f(initializer_list<int>) identity conversion
 h({ 1, 2, 3 });                 // OK: identity conversion
 ```
 — *end example*]
+Otherwise, if the parameter type is “array of `N` `X`” or “array of
+unknown bound of `X`”, if there exists an implicit conversion sequence
+from each element of the initializer list (and from `{}` in the former
+case if `N` exceeds the number of elements in the initializer list) to
+`X`, the implicit conversion sequence is the worst such implicit
+conversion sequence.
 Otherwise, if the parameter is a non-aggregate class `X` and overload
 resolution per  [[over.match.list]] chooses a single best constructor
 `C` of `X` to perform the initialization of an object of type `X` from
 the argument initializer list:
 the implicit conversion sequence is the ambiguous conversion sequence.
 User-defined conversions are allowed for conversion of the initializer
 list elements to the constructor parameter types except as noted in
 [[over.best.ics]].
+[*Example 8*:
 ``` cpp
 struct A {
   A(std::initializer_list<int>);
 };
 — *end example*]
 Otherwise, if the parameter has an aggregate type which can be
 initialized from the initializer list according to the rules for
+aggregate initialization [[dcl.init.aggr]], the implicit conversion
 sequence is a user-defined conversion sequence with the second standard
 conversion sequence an identity conversion.
+[*Example 9*:
 ``` cpp
 struct A {
   int m1;
   double m2;
 — *end example*]
 Otherwise, if the parameter is a reference, see  [[over.ics.ref]].
+[*Note 10*: The rules in this subclause will apply for initializing the
 underlying temporary for the reference. — *end note*]
+[*Example 10*:
 ``` cpp
 struct A {
   int m1;
   double m2;
 Otherwise, if the parameter type is not a class:
 - if the initializer list has one element that is not itself an
   initializer list, the implicit conversion sequence is the one required
   to convert the element to the parameter type;
+  \[*Example 11*:
   ``` cpp
   void f(int);
   f( {'a'} );             // OK: same conversion as char to int
   f( {1.0} );             // error: narrowing
   ```
   — *end example*]
 - if the initializer list has no elements, the implicit conversion
   sequence is the identity conversion.
+  \[*Example 12*:
   ``` cpp
   void f(int);
   f( { } );               // OK: identity conversion
   ```

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