[over.match] - C++20 → C++23

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@@ -1,15 +1,17 @@
 ## Overload resolution <a id="over.match">[[over.match]]</a>
 Overload resolution is a mechanism for selecting the best function to
 call given a list of expressions that are to be the arguments of the
 call and a set of *candidate functions* that can be called based on the
 context of the call. The selection criteria for the best function are
 the number of arguments, how well the arguments match the
 parameter-type-list of the candidate function, how well (for non-static
-member functions) the object matches the implicit object parameter, and
-certain other properties of the candidate function.
 [*Note 1*: The function selected by overload resolution is not
 guaranteed to be appropriate for the context. Other restrictions, such
 as the accessibility of the function, can make its use in the calling
 context ill-formed. — *end note*]
@@ -59,31 +61,36 @@ resolution succeeds and the selected candidate is either not a function
 [[over.built]], or is a function that is not deleted and is accessible
 from the context in which overload resolution was performed.
 ### Candidate functions and argument lists <a id="over.match.funcs">[[over.match.funcs]]</a>
 The subclauses of  [[over.match.funcs]] describe the set of candidate
 functions and the argument list submitted to overload resolution in each
 context in which overload resolution is used. The source transformations
 and constructions defined in these subclauses are only for the purpose
 of describing the overload resolution process. An implementation is not
 required to use such transformations and constructions.
 The set of candidate functions can contain both member and non-member
-functions to be resolved against the same argument list. So that
-argument and parameter lists are comparable within this heterogeneous
-set, a member function is considered to have an extra first parameter,
-called the *implicit object parameter*, which represents the object for
-which the member function has been called. For the purposes of overload
-resolution, both static and non-static member functions have an implicit
-object parameter, but constructors do not.
 Similarly, when appropriate, the context can construct an argument list
 that contains an *implied object argument* as the first argument in the
 list to denote the object to be operated on.
-For non-static member functions, the type of the implicit object
 parameter is
 - “lvalue reference to cv `X`” for functions declared without a
   *ref-qualifier* or with the `&` *ref-qualifier*
 - “rvalue reference to cv `X`” for functions declared with the `&&`
@@ -91,44 +98,46 @@ parameter is
 where `X` is the class of which the function is a member and cv is the
 cv-qualification on the member function declaration.
 [*Example 1*: For a `const` member function of class `X`, the extra
-parameter is assumed to have type “reference to
 `const X`”. — *end example*]
-For conversion functions, the function is considered to be a member of
-the class of the implied object argument for the purpose of defining the
-type of the implicit object parameter. For non-conversion functions
-introduced by a *using-declaration* into a derived class, the function
-is considered to be a member of the derived class for the purpose of
-defining the type of the implicit object parameter. For static member
-functions, the implicit object parameter is considered to match any
-object (since if the function is selected, the object is discarded).
 [*Note 1*: No actual type is established for the implicit object
 parameter of a static member function, and no attempt will be made to
 determine a conversion sequence for that parameter
 [[over.match.best]]. — *end note*]
 During overload resolution, the implied object argument is
 indistinguishable from other arguments. The implicit object parameter,
 however, retains its identity since no user-defined conversions can be
-applied to achieve a type match with it. For non-static member functions
-declared without a *ref-qualifier*, even if the implicit object
-parameter is not const-qualified, an rvalue can be bound to the
 parameter as long as in all other respects the argument can be converted
 to the type of the implicit object parameter.
 [*Note 2*: The fact that such an argument is an rvalue does not affect
 the ranking of implicit conversion sequences
 [[over.ics.rank]]. — *end note*]
 Because other than in list-initialization only one user-defined
 conversion is allowed in an implicit conversion sequence, special rules
-apply when selecting the best user-defined conversion (
-[[over.match.best]], [[over.best.ics]]).
 [*Example 2*:
 ``` cpp
 class T {
@@ -143,33 +152,57 @@ public:
 T a = 1;            // error: no viable conversion (T(C(1)) not considered)
 ```
 — *end example*]
 In each case where a candidate is a function template, candidate
 function template specializations are generated using template argument
-deduction ([[temp.over]], [[temp.deduct]]). If a constructor template
-or conversion function template has an *explicit-specifier* whose
 *constant-expression* is value-dependent [[temp.dep]], template argument
-deduction is performed first and then, if the context requires a
-candidate that is not explicit and the generated specialization is
 explicit [[dcl.fct.spec]], it will be removed from the candidate set.
 Those candidates are then handled as candidate functions in the usual
-way.[^2] A given name can refer to one or more function templates and
-also to a set of non-template functions. In such a case, the candidate
-functions generated from each function template are combined with the
-set of non-template candidate functions.
-A defaulted move special member function ([[class.copy.ctor]],
-[[class.copy.assign]]) that is defined as deleted is excluded from the
-set of candidate functions in all contexts. A constructor inherited from
-class type `C` [[class.inhctor.init]] that has a first parameter of type
-“reference to *cv1* `P`” (including such a constructor instantiated from
-a template) is excluded from the set of candidate functions when
-constructing an object of type *cv2* `D` if the argument list has
-exactly one argument and `C` is reference-related to `P` and `P` is
-reference-related to `D`.
 [*Example 3*:
 ``` cpp
 struct A {
@@ -192,10 +225,12 @@ B b3 = C();                             // calls #4
 — *end example*]
 #### Function call syntax <a id="over.match.call">[[over.match.call]]</a>
 In a function call [[expr.call]]
 ``` bnf
 postfix-expression '(' expression-listₒₚₜ ')'
 ```
@@ -205,24 +240,27 @@ template, overload resolution is applied as specified in
 [[over.call.func]]. If the *postfix-expression* denotes an object of
 class type, overload resolution is applied as specified in
 [[over.call.object]].
 If the *postfix-expression* is the address of an overload set, overload
-resolution is applied using that set as described above. If the function
-selected by overload resolution is a non-static member function, the
-program is ill-formed.
-[*Note 1*: The resolution of the address of an overload set in other
 contexts is described in [[over.over]]. — *end note*]
 ##### Call to named function <a id="over.call.func">[[over.call.func]]</a>
 Of interest in  [[over.call.func]] are only those function calls in
-which the *postfix-expression* ultimately contains a name that denotes
-one or more functions that might be called. Such a *postfix-expression*,
-perhaps nested arbitrarily deep in parentheses, has one of the following
-forms:
 ``` bnf
 postfix-expression:
     postfix-expression '.' id-expression
     postfix-expression '->' id-expression
@@ -230,52 +268,94 @@ postfix-expression:
 ```
 These represent two syntactic subcategories of function calls: qualified
 function calls and unqualified function calls.
-In qualified function calls, the name to be resolved is an
-*id-expression* and is preceded by an `->` or `.` operator. Since the
-construct `A->B` is generally equivalent to `(*A).B`, the rest of
-[[over]] assumes, without loss of generality, that all member function
-calls have been normalized to the form that uses an object and the `.`
-operator. Furthermore, [[over]] assumes that the *postfix-expression*
-that is the left operand of the `.` operator has type “cv `T`” where `T`
-denotes a class.[^3] Under this assumption, the *id-expression* in the
-call is looked up as a member function of `T` following the rules for
-looking up names in classes [[class.member.lookup]]. The function
-declarations found by that lookup constitute the set of candidate
-functions. The argument list is the *expression-list* in the call
-augmented by the addition of the left operand of the `.` operator in the
-normalized member function call as the implied object argument
-[[over.match.funcs]].
-In unqualified function calls, the name is not qualified by an `->` or
-`.` operator and has the more general form of a *primary-expression*.
-The name is looked up in the context of the function call following the
-normal rules for name lookup in expressions [[basic.lookup]]. The
-function declarations found by that lookup constitute the set of
-candidate functions. Because of the rules for name lookup, the set of
-candidate functions consists (1) entirely of non-member functions or (2)
-entirely of member functions of some class `T`. In case (1), the
-argument list is the same as the *expression-list* in the call. In case
-(2), the argument list is the *expression-list* in the call augmented by
-the addition of an implied object argument as in a qualified function
-call. If the keyword `this` [[class.this]] is in scope and refers to
-class `T`, or a derived class of `T`, then the implied object argument
-is `(*this)`. If the keyword `this` is not in scope or refers to another
-class, then a contrived object of type `T` becomes the implied object
-argument.[^4] If the argument list is augmented by a contrived object
-and overload resolution selects one of the non-static member functions
-of `T`, the call is ill-formed.
 ##### Call to object of class type <a id="over.call.object">[[over.call.object]]</a>
 If the *postfix-expression* `E` in the function call syntax evaluates to
 a class object of type “cv `T`”, then the set of candidate functions
 includes at least the function call operators of `T`. The function call
-operators of `T` are obtained by ordinary lookup of the name
-`operator()` in the context of `(E).operator()`.
 In addition, for each non-explicit conversion function declared in `T`
 of the form
 ``` bnf
@@ -297,27 +377,23 @@ returning `R`”, a *surrogate call function* with the unique name
 is also considered as a candidate function. Similarly, surrogate call
 functions are added to the set of candidate functions for each
 non-explicit conversion function declared in a base class of `T`
 provided the function is not hidden within `T` by another intervening
-declaration.[^5]
 The argument list submitted to overload resolution consists of the
 argument expressions present in the function call syntax preceded by the
 implied object argument `(E)`.
-[*Note 2*: When comparing the call against the function call operators,
-the implied object argument is compared against the implicit object
-parameter of the function call operator. When comparing the call against
-a surrogate call function, the implied object argument is compared
-against the first parameter of the surrogate call function. The
-conversion function from which the surrogate call function was derived
-will be used in the conversion sequence for that parameter since it
-converts the implied object argument to the appropriate function pointer
-or reference required by that first parameter. — *end note*]
-[*Example 1*:
 ``` cpp
 int f1(int);
 int f2(float);
 typedef int (*fp1)(int);
@@ -363,11 +439,11 @@ void f() {
 ```
 — *end example*]
 If either operand has a type that is a class or an enumeration, a
-user-defined operator function might be declared that implements this
 operator or a user-defined conversion can be necessary to convert the
 operand to a type that is appropriate for a built-in operator. In this
 case, overload resolution is used to determine which operator function
 or built-in operator is to be invoked to implement the operator.
 Therefore, the operator notation is first transformed to the equivalent
@@ -393,21 +469,21 @@ binary operator `@` with a left operand of type *cv1* `T1` and a right
 operand of type *cv2* `T2`, four sets of candidate functions, designated
 *member candidates*, *non-member candidates*, *built-in candidates*, and
 *rewritten candidates*, are constructed as follows:
 - If `T1` is a complete class type or a class currently being defined,
-  the set of member candidates is the result of the qualified lookup of
-  `T1::operator@` [[over.call.func]]; otherwise, the set of member
- candidates is empty.
-- The set of non-member candidates is the result of the unqualified
- lookup of `operator@` in the context of the expression according to
- the usual rules for name lookup in unqualified function calls
-  [[basic.lookup.argdep]] except that all member functions are ignored.
-  However, if no operand has a class type, only those non-member
-  functions in the lookup set that have a first parameter of type `T1`
-  or “reference to cv `T1`”, when `T1` is an enumeration type, or (if
-  there is a right operand) a second parameter of type `T2` or
   “reference to cv `T2`”, when `T2` is an enumeration type, are
   candidate functions.
 - For the operator `,`, the unary operator `&`, or the operator `->`,
   the built-in candidates set is empty. For all other operators, the
   built-in candidates include all of the candidate operator functions
@@ -415,32 +491,76 @@ operand of type *cv2* `T2`, four sets of candidate functions, designated
   - have the same operator name, and
   - accept the same number of operands, and
   - accept operand types to which the given operand or operands can be
     converted according to [[over.best.ics]], and
   - do not have the same parameter-type-list as any non-member candidate
-    that is not a function template specialization.
 - The rewritten candidate set is determined as follows:
   - For the relational [[expr.rel]] operators, the rewritten candidates
     include all non-rewritten candidates for the expression `x <=> y`.
   - For the relational [[expr.rel]] and three-way comparison
     [[expr.spaceship]] operators, the rewritten candidates also include
     a synthesized candidate, with the order of the two parameters
     reversed, for each non-rewritten candidate for the expression
     `y <=> x`.
   - For the `!=` operator [[expr.eq]], the rewritten candidates include
-    all non-rewritten candidates for the expression `x == y`.
   - For the equality operators, the rewritten candidates also include a
     synthesized candidate, with the order of the two parameters
     reversed, for each non-rewritten candidate for the expression
-    `y == x`.
   - For all other operators, the rewritten candidate set is empty.
   \[*Note 2*: A candidate synthesized from a member candidate has its
- implicit object parameter as the second parameter, thus implicit
- conversions are considered for the first, but not for the second,
   parameter. — *end note*]
 For the built-in assignment operators, conversions of the left operand
 are restricted as follows:
 - no temporaries are introduced to hold the left operand, and
 - no user-defined conversions are applied to the left operand to achieve
@@ -453,13 +573,13 @@ The set of candidate functions for overload resolution for some operator
 the built-in candidates, and the rewritten candidates for that operator
 `@`.
 The argument list contains all of the operands of the operator. The best
 function from the set of candidate functions is selected according to
-[[over.match.viable]] and  [[over.match.best]].[^6]
-[*Example 2*:
 ``` cpp
 struct A {
   operator int();
 };
@@ -497,11 +617,11 @@ of the selected operation function, except that the second standard
 conversion sequence of a user-defined conversion sequence
 [[over.ics.user]] is not applied. Then the operator is treated as the
 corresponding built-in operator and interpreted according to
 [[expr.compound]].
-[*Example 3*:
 ``` cpp
 struct X {
   operator double();
 };
@@ -517,11 +637,11 @@ int *b = Y() + X();             // error: pointer arithmetic requires integral o
 — *end example*]
 The second operand of operator `->` is ignored in selecting an
 `operator->` function, and is not an argument when the `operator->`
 function is called. When `operator->` returns, the operator `->` is
-applied to the value returned, with the original second operand.[^7]
 If the operator is the operator `,`, the unary operator `&`, or the
 operator `->`, and there are no viable functions, then the operator is
 assumed to be the built-in operator and interpreted according to
 [[expr.compound]].
@@ -543,11 +663,11 @@ struct B {
 A a;
 void B::f() {
   operator+ (a,a);              // error: global operator hidden by member
-  a + a;                        // OK: calls global operator+
 }
 ```
 — *end note*]
@@ -581,90 +701,75 @@ Assuming that “*cv1* `T`” is the type of the object being initialized,
 with `T` a class type, the candidate functions are selected as follows:
 - The converting constructors [[class.conv.ctor]] of `T` are candidate
   functions.
 - When the type of the initializer expression is a class type “cv `S`”,
- the non-explicit conversion functions of `S` and its base classes are
- considered. When initializing a temporary object [[class.mem]] to be
- bound to the first parameter of a constructor where the parameter is
- of type “reference to *cv2* `T`” and the constructor is called with a
- single argument in the context of direct-initialization of an object
- of type “*cv3* `T`”, explicit conversion functions are also
- considered. Those that are not hidden within `S` and yield a type
- whose cv-unqualified version is the same type as `T` or is a derived
-  class thereof are candidate functions. A call to a conversion function
-  returning “reference to `X`” is a glvalue of type `X`, and such a
-  conversion function is therefore considered to yield `X` for this
-  process of selecting candidate functions.
 In both cases, the argument list has one argument, which is the
 initializer expression.
 [*Note 2*: This argument will be compared against the first parameter
-of the constructors and against the implicit object parameter of the
-conversion functions. — *end note*]
 #### Initialization by conversion function <a id="over.match.conv">[[over.match.conv]]</a>
 Under the conditions specified in  [[dcl.init]], as part of an
 initialization of an object of non-class type, a conversion function can
 be invoked to convert an initializer expression of class type to the
 type of the object being initialized. Overload resolution is used to
-select the conversion function to be invoked. Assuming that “*cv1* `T`”
-is the type of the object being initialized, and “cv `S`” is the type of
-the initializer expression, with `S` a class type, the candidate
-functions are selected as follows:
-- The conversion functions of `S` and its base classes are considered.
- Those non-explicit conversion functions that are not hidden within `S`
- and yield type `T` or a type that can be converted to type `T` via a
- standard conversion sequence [[over.ics.scs]] are candidate functions.
- For direct-initialization, those explicit conversion functions that
- are not hidden within `S` and yield type `T` or a type that can be
-  converted to type `T` with a qualification conversion [[conv.qual]]
-  are also candidate functions. Conversion functions that return a
-  cv-qualified type are considered to yield the cv-unqualified version
-  of that type for this process of selecting candidate functions. A call
-  to a conversion function returning “reference to `X`” is a glvalue of
-  type `X`, and such a conversion function is therefore considered to
-  yield `X` for this process of selecting candidate functions.
 The argument list has one argument, which is the initializer expression.
-[*Note 1*: This argument will be compared against the implicit object
-parameter of the conversion functions. — *end note*]
 #### Initialization by conversion function for direct reference binding <a id="over.match.ref">[[over.match.ref]]</a>
 Under the conditions specified in  [[dcl.init.ref]], a reference can be
 bound directly to the result of applying a conversion function to an
 initializer expression. Overload resolution is used to select the
 conversion function to be invoked. Assuming that “reference to *cv1*
-`T`” is the type of the reference being initialized, and “cv `S`” is the
-type of the initializer expression, with `S` a class type, the candidate
 functions are selected as follows:
-- The conversion functions of `S` and its base classes are considered.
- Those non-explicit conversion functions that are not hidden within `S`
-  and yield type “lvalue reference to *cv2* `T2`” (when initializing an
- lvalue reference or an rvalue reference to function) or “*cv2* `T2`”
-  or “rvalue reference to *cv2* `T2`” (when initializing an rvalue
-  reference or an lvalue reference to function), where “*cv1* `T`” is
- reference-compatible [[dcl.init.ref]] with “*cv2* `T2`”, are candidate
-  functions. For direct-initialization, those explicit conversion
- functions that are not hidden within `S` and yield type “lvalue
- reference to *cv2* `T2`” (when initializing an lvalue reference or an
- rvalue reference to function) or “rvalue reference to *cv2* `T2`”
- (when initializing an rvalue reference or an lvalue reference to
- function), where `T2` is the same type as `T` or can be converted to
-  type `T` with a qualification conversion [[conv.qual]], are also
-  candidate functions.
 The argument list has one argument, which is the initializer expression.
-[*Note 1*: This argument will be compared against the implicit object
-parameter of the conversion functions. — *end note*]
 #### Initialization by list-initialization <a id="over.match.list">[[over.match.list]]</a>
 When objects of non-aggregate class type `T` are list-initialized such
 that [[dcl.init.list]] specifies that overload resolution is performed
@@ -683,15 +788,15 @@ resolution selects the constructor in two phases:
   consists of the elements of the initializer list.
 In copy-list-initialization, if an explicit constructor is chosen, the
 initialization is ill-formed.
-[*Note 1*: This differs from other situations ([[over.match.ctor]],
-[[over.match.copy]]), where only converting constructors are considered
-for copy-initialization. This restriction only applies if this
-initialization is part of the final result of overload
-resolution. — *end note*]
 #### Class template argument deduction <a id="over.match.class.deduct">[[over.match.class.deduct]]</a>
 When resolving a placeholder for a deduced class type
 [[dcl.type.class.deduct]] where the *template-name* names a primary
@@ -730,35 +835,112 @@ the elements of the *initializer-list* or *designated-initializer-list*
 of the *braced-init-list*, or of the *expression-list*. For each xᵢ, let
 eᵢ be the corresponding aggregate element of `C` or of one of its
 (possibly recursive) subaggregates that would be initialized by xᵢ
 [[dcl.init.aggr]] if
-- brace elision is not considered for any aggregate element that has a
-  dependent non-array type or an array type with a value-dependent
-  bound, and
 - each non-trailing aggregate element that is a pack expansion is
   assumed to correspond to no elements of the initializer list, and
 - a trailing aggregate element that is a pack expansion is assumed to
   correspond to all remaining elements of the initializer list (if any).
 If there is no such aggregate element eᵢ for any xᵢ, the aggregate
 deduction candidate is not added to the set. The aggregate deduction
 candidate is derived as above from a hypothetical constructor
 `C`(`T₁`, …, `Tₙ`), where
-- if eᵢ is of array type and xᵢ is a *braced-init-list* or
- *string-literal*, `Tᵢ` is an rvalue reference to the declared type of
- eᵢ, and
 - otherwise, `Tᵢ` is the declared type of eᵢ,
 except that additional parameter packs of the form `Pⱼ` `...` are
 inserted into the parameter list in their original aggregate element
 position corresponding to each non-trailing aggregate element of type
 `Pⱼ` that was skipped because it was a parameter pack, and the trailing
 sequence of parameters corresponding to a trailing aggregate element
 that is a pack expansion (if any) is replaced by a single parameter of
-the form `Tₙ` `...`.
 When resolving a placeholder for a deduced class type
 [[dcl.type.simple]] where the *template-name* names an alias template
 `A`, the *defining-type-id* of `A` must be of the form
@@ -770,14 +952,16 @@ as specified in [[dcl.type.simple]]. The guides of `A` are the set of
 functions or function templates formed as follows. For each function or
 function template `f` in the guides of the template named by the
 *simple-template-id* of the *defining-type-id*, the template arguments
 of the return type of `f` are deduced from the *defining-type-id* of `A`
 according to the process in [[temp.deduct.type]] with the exception that
-deduction does not fail if not all template arguments are deduced. Let
-`g` denote the result of substituting these deductions into `f`. If
-substitution succeeds, form a function or function template `f'` with
-the following properties and add it to the set of guides of `A`:
 - The function type of `f'` is the function type of `g`.
 - If `f` is a function template, `f'` is a function template whose
   template parameter list consists of all the template parameters of `A`
   (including their default template arguments) that appear in the above
@@ -787,14 +971,14 @@ the following properties and add it to the set of guides of `A`:
   function template.
 - The associated constraints [[temp.constr.decl]] are the conjunction of
   the associated constraints of `g` and a constraint that is satisfied
   if and only if the arguments of `A` are deducible (see below) from the
   return type.
-- If `f` is a copy deduction candidate [[over.match.class.deduct]], then
- `f'` is considered to be so as well.
-- If `f` was generated from a *deduction-guide*
- [[over.match.class.deduct]], then `f'` is considered to be so as well.
 - The *explicit-specifier* of `f'` is the *explicit-specifier* of `g`
   (if any).
 The arguments of a template `A` are said to be deducible from a type `T`
 if, given a class template
@@ -832,11 +1016,11 @@ If the function or function template was generated from a constructor or
 *deduction-guide* that had an *explicit-specifier*, each such notional
 constructor is considered to have that same *explicit-specifier*. All
 such notional constructors are considered to be public members of the
 hypothetical class type.
-[*Example 1*:
 ``` cpp
 template <class T> struct A {
   explicit A(const T&, ...) noexcept;               // #1
   A(T&&, ...);                                      // #2
@@ -914,11 +1098,11 @@ F f2 = {Types<X, Y, Z>{}, X{}, Y{}};    // OK, F<X, Y, Z> deduced
 F f3 = {Types<X, Y, Z>{}, X{}, W{}};    // error: conflicting types deduced; operator Y not considered
 ```
 — *end example*]
-[*Example 2*:
 ``` cpp
 template <class T, class U> struct C {
   C(T, U);                                      // #1
 };
@@ -945,11 +1129,11 @@ Possible exposition-only implementation of the above procedure:
 template <class> class AA;
 template <class V> class AA<A<V>> { };
 template <class T> concept deduces_A = requires { sizeof(AA<T>); };
 // f1 is formed from the constructor #1 of C, generating the following function template
-template<T, U>
   auto f1(T, U) -> C<T, U>;
 // Deducing arguments for C<T, U> from C<V *, V*> deduces T as V * and U as V *;
 // f1' is obtained by transforming f1 as described by the above procedure.
 template<class V> requires deduces_A<C<V *, V *>>
@@ -993,64 +1177,60 @@ associated constraints, if any, and relationships between arguments and
 function parameters other than the ranking of conversion sequences.
 First, to be a viable function, a candidate function shall have enough
 parameters to agree in number with the arguments in the list.
-- If there are *m* arguments in the list, all candidate functions having
-  exactly *m* parameters are viable.
-- A candidate function having fewer than *m* parameters is viable only
- if it has an ellipsis in its parameter list [[dcl.fct]]. For the
- purposes of overload resolution, any argument for which there is no
   corresponding parameter is considered to “match the ellipsis”
   [[over.ics.ellipsis]].
-- A candidate function having more than *m* parameters is viable only if
   all parameters following the mᵗʰ have default arguments
   [[dcl.fct.default]]. For the purposes of overload resolution, the
-  parameter list is truncated on the right, so that there are exactly
- *m* parameters.
 Second, for a function to be viable, if it has associated constraints
 [[temp.constr.decl]], those constraints shall be satisfied
 [[temp.constr.constr]].
 Third, for `F` to be a viable function, there shall exist for each
 argument an implicit conversion sequence [[over.best.ics]] that converts
 that argument to the corresponding parameter of `F`. If the parameter
 has reference type, the implicit conversion sequence includes the
 operation of binding the reference, and the fact that an lvalue
-reference to non-`const` cannot be bound to an rvalue and that an rvalue
-reference cannot be bound to an lvalue can affect the viability of the
 function (see  [[over.ics.ref]]).
 ### Best viable function <a id="over.match.best">[[over.match.best]]</a>
-Define ICS*i*(`F`) as follows:
-- If `F` is a static member function, ICS*1*(`F`) is defined such that
-  ICS*1*(`F`) is neither better nor worse than ICS*1*(`G`) for any
- function `G`, and, symmetrically, ICS*1*(`G`) is neither better nor
-  worse than ICS*1*(`F`);[^8] otherwise,
-- let ICS*i*(`F`) denote the implicit conversion sequence that converts
-  the *i*-th argument in the list to the type of the *i*-th parameter of
-  viable function `F`. [[over.best.ics]] defines the implicit conversion
 sequences and [[over.ics.rank]] defines what it means for one implicit
 conversion sequence to be a better conversion sequence or worse
 conversion sequence than another.
-Given these definitions, a viable function `F1` is defined to be a
-*better* function than another viable function `F2` if for all arguments
-*i*, ICS*i*(`F1`) is not a worse conversion sequence than ICS*i*(`F2`),
-and then
-- for some argument *j*, ICS*j*(`F1`) is a better conversion sequence
- than ICS*j*(`F2`), or, if not that,
 - the context is an initialization by user-defined conversion (see
   [[dcl.init]], [[over.match.conv]], and  [[over.match.ref]]) and the
-  standard conversion sequence from the return type of `F1` to the
   destination type (i.e., the type of the entity being initialized) is a
   better conversion sequence than the standard conversion sequence from
-  the return type of `F2` to the destination type
   \[*Example 1*:
   ``` cpp
   struct A {
     A();
     operator int();
@@ -1093,11 +1273,11 @@ and then
   parameter-type-lists, and `F1` is more constrained than `F2` according
   to the partial ordering of constraints described in
   [[temp.constr.order]], or if not that,
 - `F1` is a constructor for a class `D`, `F2` is a constructor for a
   base class `B` of `D`, and for all arguments the corresponding
-  parameters of `F1` and `F2` have the same type.
   \[*Example 3*:
   ``` cpp
   struct A {
     A(int = 0);
   };
@@ -1137,10 +1317,16 @@ and then
   bool b = 1 < S();                                               // calls #2
   ```
   — *end example*]
   or, if not that
 - `F1` is generated from a *deduction-guide* [[over.match.class.deduct]]
   and `F2` is not, or, if not that,
 - `F1` is the copy deduction candidate [[over.match.class.deduct]] and
   `F2` is not, or, if not that,
 - `F1` is generated from a non-template constructor and `F2` is
@@ -1173,11 +1359,11 @@ and then
   — *end example*]
 If there is exactly one viable function that is a better function than
 all other viable functions, then it is the one selected by overload
-resolution; otherwise the call is ill-formed.[^9]
 [*Example 7*:
 ``` cpp
 void Fcn(const int*,  short);
@@ -1192,21 +1378,20 @@ void f() {
   Fcn(&i, 1L);      // calls Fcn(int*, int), because &i → int* is better than &i → const int*
                     // and 1L → short and 1L → int are indistinguishable
   Fcn(&i, 'c');     // calls Fcn(int*, int), because &i → int* is better than &i → const int*
-                    // and c → int is better than c → short
 }
 ```
 — *end example*]
 If the best viable function resolves to a function for which multiple
-declarations were found, and if at least two of these declarations — or
-the declarations they refer to in the case of *using-declaration*s —
-specify a default argument that made the function viable, the program is
-ill-formed.
 [*Example 8*:
 ``` cpp
 namespace A {
@@ -1227,16 +1412,18 @@ void use() {
 — *end example*]
 #### 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.
@@ -1256,11 +1443,11 @@ forms:
 - 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
 and the constructor or user-defined conversion function is a candidate
 by
 -  [[over.match.ctor]], when the argument is the temporary in the second
@@ -1317,22 +1504,29 @@ 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 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
@@ -1345,11 +1539,11 @@ 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*:
@@ -1383,19 +1577,19 @@ defined in the following subclauses.
 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*]
@@ -1423,14 +1617,14 @@ Promotion rank; otherwise, the sequence has Exact Match rank.
 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,
@@ -1458,11 +1652,11 @@ function called (see  [[expr.call]]).
 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 {};
@@ -1474,12 +1668,12 @@ 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
@@ -1493,11 +1687,11 @@ 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*]
@@ -1525,11 +1719,11 @@ 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]].
@@ -1558,14 +1752,15 @@ void h() {
 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
@@ -1575,13 +1770,13 @@ 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
-f( {'a','b'} );                 // OK: f(initializer_list<int>) integral promotion
 f( {1.0} );                     // error: narrowing
 struct A {
   A(std::initializer_list<double>);             // #1
   A(std::initializer_list<complex<double>>);    // #2
@@ -1592,11 +1787,11 @@ A a{ 1.0,2.0 };                 // OK, uses #1
 void g(A);
 g({ "foo", "bar" });            // OK, uses #3
 typedef int IA[3];
 void h(const IA&);
-h({ 1, 2, 3 });                 // OK: identity conversion
 ```
 — *end example*]
 Otherwise, if the parameter type is “array of `N` `X`” or “array of
@@ -1614,11 +1809,11 @@ the argument initializer list:
 - If `C` is not an initializer-list constructor 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 has Exact Match
   rank if `U` is `X`, or Conversion rank if `U` is derived from `X`.
 - Otherwise, the implicit conversion sequence is a user-defined
-  conversion sequence with the second standard conversion sequence an
   identity conversion.
 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
@@ -1630,61 +1825,61 @@ list elements to the constructor parameter types except as noted in
 ``` cpp
 struct A {
   A(std::initializer_list<int>);
 };
 void f(A);
-f( {'a', 'b'} );        // OK: f(A(std::initializer_list<int>)) user-defined conversion
 struct B {
   B(int, double);
 };
 void g(B);
-g( {'a', 'b'} );        // OK: g(B(int, double)) user-defined conversion
 g( {1.0, 1.0} );        // error: narrowing
 void f(B);
 f( {'a', 'b'} );        // error: ambiguous f(A) or f(B)
 struct C {
   C(std::string);
 };
 void h(C);
-h({"foo"});             // OK: h(C(std::string("foo")))
 struct D {
   D(A, C);
 };
 void i(D);
-i({ {1,2}, {"bar"} });  // OK: i(D(A(std::initializer_list<int>{1,2\), C(std::string("bar"))))}
 ```
 — *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;
 };
 void f(A);
-f( {'a', 'b'} );        // OK: f(A(int,double)) user-defined conversion
 f( {1.0} );             // error: narrowing
 ```
 — *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
@@ -1692,11 +1887,11 @@ struct A {
   int m1;
   double m2;
 };
 void f(const A&);
-f( {'a', 'b'} );        // OK: f(A(int,double)) user-defined conversion
 f( {1.0} );             // error: narrowing
 void g(const double &);
 g({1});                 // same conversion as int to double
 ```
@@ -1709,21 +1904,21 @@ Otherwise, if the parameter type is not a class:
   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
   ```
   — *end example*]
 In all cases other than those enumerated above, no conversion is
@@ -1912,19 +2107,41 @@ indistinguishable unless one of the following rules applies:
 - A conversion that does not convert a pointer or a pointer to member to
   `bool` is better than one that does.
 - A conversion that promotes an enumeration whose underlying type is
   fixed to its underlying type is better than one that promotes to the
   promoted underlying type, if the two are different.
 - If class `B` is derived directly or indirectly from class `A`,
   conversion of `B*` to `A*` is better than conversion of `B*` to
   `void*`, and conversion of `A*` to `void*` is better than conversion
   of `B*` to `void*`.
 - If class `B` is derived directly or indirectly from class `A` and
   class `C` is derived directly or indirectly from `B`,
   - conversion of `C*` to `B*` is better than conversion of `C*` to
     `A*`,
-    \[*Example 8*:
     ``` cpp
     struct A {};
     struct B : public A {};
     struct C : public B {};
     C* pc;

 ## Overload resolution <a id="over.match">[[over.match]]</a>
+### General <a id="over.match.general">[[over.match.general]]</a>
 Overload resolution is a mechanism for selecting the best function to
 call given a list of expressions that are to be the arguments of the
 call and a set of *candidate functions* that can be called based on the
 context of the call. The selection criteria for the best function are
 the number of arguments, how well the arguments match the
 parameter-type-list of the candidate function, how well (for non-static
+member functions) the object matches the object parameter, and certain
+other properties of the candidate function.
 [*Note 1*: The function selected by overload resolution is not
 guaranteed to be appropriate for the context. Other restrictions, such
 as the accessibility of the function, can make its use in the calling
 context ill-formed. — *end note*]
 [[over.built]], or is a function that is not deleted and is accessible
 from the context in which overload resolution was performed.
 ### Candidate functions and argument lists <a id="over.match.funcs">[[over.match.funcs]]</a>
+#### General <a id="over.match.funcs.general">[[over.match.funcs.general]]</a>
 The subclauses of  [[over.match.funcs]] describe the set of candidate
 functions and the argument list submitted to overload resolution in each
 context in which overload resolution is used. The source transformations
 and constructions defined in these subclauses are only for the purpose
 of describing the overload resolution process. An implementation is not
 required to use such transformations and constructions.
 The set of candidate functions can contain both member and non-member
+functions to be resolved against the same argument list. If a member
+function is
+- an implicit object member function that is not a constructor, or
+- a static member function and the argument list includes an implied
+  object argument,
+it is considered to have an extra first parameter, called the
+*implicit object parameter*, which represents the object for which the
+member function has been called.
 Similarly, when appropriate, the context can construct an argument list
 that contains an *implied object argument* as the first argument in the
 list to denote the object to be operated on.
+For implicit object member functions, the type of the implicit object
 parameter is
 - “lvalue reference to cv `X`” for functions declared without a
   *ref-qualifier* or with the `&` *ref-qualifier*
 - “rvalue reference to cv `X`” for functions declared with the `&&`
 where `X` is the class of which the function is a member and cv is the
 cv-qualification on the member function declaration.
 [*Example 1*: For a `const` member function of class `X`, the extra
+parameter is assumed to have type “lvalue reference to
 `const X`”. — *end example*]
+For conversion functions that are implicit object member functions, the
+function is considered to be a member of the class of the implied object
+argument for the purpose of defining the type of the implicit object
+parameter. For non-conversion functions that are implicit object member
+functions nominated by a *using-declaration* in a derived class, the
+function is considered to be a member of the derived class for the
+purpose of defining the type of the implicit object parameter. For
+static member functions, the implicit object parameter is considered to
+match any object (since if the function is selected, the object is
+discarded).
 [*Note 1*: No actual type is established for the implicit object
 parameter of a static member function, and no attempt will be made to
 determine a conversion sequence for that parameter
 [[over.match.best]]. — *end note*]
 During overload resolution, the implied object argument is
 indistinguishable from other arguments. The implicit object parameter,
 however, retains its identity since no user-defined conversions can be
+applied to achieve a type match with it. For implicit object member
+functions declared without a *ref-qualifier*, even if the implicit
+object parameter is not const-qualified, an rvalue can be bound to the
 parameter as long as in all other respects the argument can be converted
 to the type of the implicit object parameter.
 [*Note 2*: The fact that such an argument is an rvalue does not affect
 the ranking of implicit conversion sequences
 [[over.ics.rank]]. — *end note*]
 Because other than in list-initialization only one user-defined
 conversion is allowed in an implicit conversion sequence, special rules
+apply when selecting the best user-defined conversion
+[[over.match.best]], [[over.best.ics]].
 [*Example 2*:
 ``` cpp
 class T {
 T a = 1;            // error: no viable conversion (T(C(1)) not considered)
 ```
 — *end example*]
+In each case where conversion functions of a class `S` are considered
+for initializing an object or reference of type `T`, the candidate
+functions include the result of a search for the
+*conversion-function-id* `operator T` in `S`.
+[*Note 3*: This search can find a specialization of a conversion
+function template [[basic.lookup]]. — *end note*]
+Each such case also defines sets of *permissible types* for explicit and
+non-explicit conversion functions; each (non-template) conversion
+function that
+- is a non-hidden member of `S`,
+- yields a permissible type, and,
+- for the former set, is non-explicit
+is also a candidate function. If initializing an object, for any
+permissible type cv `U`, any *cv2* `U`, *cv2* `U&`, or *cv2* `U&&` is
+also a permissible type. If the set of permissible types for explicit
+conversion functions is empty, any candidates that are explicit are
+discarded.
 In each case where a candidate is a function template, candidate
 function template specializations are generated using template argument
+deduction [[temp.over]], [[temp.deduct]]. If a constructor template or
+conversion function template has an *explicit-specifier* whose
 *constant-expression* is value-dependent [[temp.dep]], template argument
+deduction is performed first and then, if the context admits only
+candidates that are not explicit and the generated specialization is
 explicit [[dcl.fct.spec]], it will be removed from the candidate set.
 Those candidates are then handled as candidate functions in the usual
+way.[^1]
+A given name can refer to, or a conversion can consider, one or more
+function templates as well as a set of non-template functions. In such a
+case, the candidate functions generated from each function template are
+combined with the set of non-template candidate functions.
+A defaulted move special member function
+[[class.copy.ctor]], [[class.copy.assign]] that is defined as deleted is
+excluded from the set of candidate functions in all contexts. A
+constructor inherited from class type `C` [[class.inhctor.init]] that
+has a first parameter of type “reference to *cv1* `P`” (including such a
+constructor instantiated from a template) is excluded from the set of
+candidate functions when constructing an object of type *cv2* `D` if the
+argument list has exactly one argument and `C` is reference-related to
+`P` and `P` is reference-related to `D`.
 [*Example 3*:
 ``` cpp
 struct A {
 — *end example*]
 #### Function call syntax <a id="over.match.call">[[over.match.call]]</a>
+##### General <a id="over.match.call.general">[[over.match.call.general]]</a>
 In a function call [[expr.call]]
 ``` bnf
 postfix-expression '(' expression-listₒₚₜ ')'
 ```
 [[over.call.func]]. If the *postfix-expression* denotes an object of
 class type, overload resolution is applied as specified in
 [[over.call.object]].
 If the *postfix-expression* is the address of an overload set, overload
+resolution is applied using that set as described above.
+[*Note 1*: No implied object argument is added in this
+case. — *end note*]
+If the function selected by overload resolution is an implicit object
+member function, the program is ill-formed.
+[*Note 2*: The resolution of the address of an overload set in other
 contexts is described in [[over.over]]. — *end note*]
 ##### Call to named function <a id="over.call.func">[[over.call.func]]</a>
 Of interest in  [[over.call.func]] are only those function calls in
+which the *postfix-expression* ultimately contains an *id-expression*
+that denotes one or more functions. Such a *postfix-expression*, perhaps
+nested arbitrarily deep in parentheses, has one of the following forms:
 ``` bnf
 postfix-expression:
     postfix-expression '.' id-expression
     postfix-expression '->' id-expression
 ```
 These represent two syntactic subcategories of function calls: qualified
 function calls and unqualified function calls.
+In qualified function calls, the function is named by an *id-expression*
+preceded by an `->` or `.` operator. Since the construct `A->B` is
+generally equivalent to `(*A).B`, the rest of [[over]] assumes, without
+loss of generality, that all member function calls have been normalized
+to the form that uses an object and the `.` operator. Furthermore,
+[[over]] assumes that the *postfix-expression* that is the left operand
+of the `.` operator has type “cv `T`” where `T` denotes a class.[^2]
+The function declarations found by name lookup [[class.member.lookup]]
+constitute the set of candidate functions. The argument list is the
+*expression-list* in the call augmented by the addition of the left
+operand of the `.` operator in the normalized member function call as
+the implied object argument [[over.match.funcs]].
+In unqualified function calls, the function is named by a
+*primary-expression*. The function declarations found by name lookup
+[[basic.lookup]] constitute the set of candidate functions. Because of
+the rules for name lookup, the set of candidate functions consists
+either entirely of non-member functions or entirely of member functions
+of some class `T`. In the former case or if the *primary-expression* is
+the address of an overload set, the argument list is the same as the
+*expression-list* in the call. Otherwise, the argument list is the
+*expression-list* in the call augmented by the addition of an implied
+object argument as in a qualified function call. If the current class
+is, or is derived from, `T`, and the keyword `this` [[expr.prim.this]]
+refers to it, then the implied object argument is `(*this)`. Otherwise,
+a contrived object of type `T` becomes the implied object argument;[^3]
+if overload resolution selects a non-static member function, the call is
+ill-formed.
+[*Example 1*:
+``` cpp
+struct C {
+  void a();
+  void b() {
+    a();                // OK, (*this).a()
+  }
+void c(this const C&);      // #1
+void c()&;                  // #2
+static void c(int = 0);     // #3
+void d() {
+  c();                  // error: ambiguous between #2 and #3
+  (C::c)();             // error: as above
+  (&(C::c))();          // error: cannot resolve address of overloaded this->C::c[over.over]
+  (&C::c)(C{});         // selects #1
+  (&C::c)(*this);       // error: selects #2, and is ill-formed[over.match.call.general]
+  (&C::c)();            // selects #3
+}
+  void f(this const C&);
+  void g() const {
+    f();                // OK, (*this).f()
+    f(*this);           // error: no viable candidate for (*this).f(*this)
+    this->f();          // OK
+  }
+  static void h() {
+    f();                // error: contrived object argument, but overload resolution
+                        // picked a non-static member function
+    f(C{});             // error: no viable candidate
+    C{}.f();            // OK
+  }
+  void k(this int);
+  operator int() const;
+  void m(this const C& c) {
+    c.k();              // OK
+  }
+};
+```
+— *end example*]
 ##### Call to object of class type <a id="over.call.object">[[over.call.object]]</a>
 If the *postfix-expression* `E` in the function call syntax evaluates to
 a class object of type “cv `T`”, then the set of candidate functions
 includes at least the function call operators of `T`. The function call
+operators of `T` are the results of a search for the name `operator()`
+in the scope of `T`.
 In addition, for each non-explicit conversion function declared in `T`
 of the form
 ``` bnf
 is also considered as a candidate function. Similarly, surrogate call
 functions are added to the set of candidate functions for each
 non-explicit conversion function declared in a base class of `T`
 provided the function is not hidden within `T` by another intervening
+declaration.[^4]
 The argument list submitted to overload resolution consists of the
 argument expressions present in the function call syntax preceded by the
 implied object argument `(E)`.
+[*Note 3*: When comparing the call against the function call operators,
+the implied object argument is compared against the object parameter of
+the function call operator. When comparing the call against a surrogate
+call function, the implied object argument is compared against the first
+parameter of the surrogate call function. — *end note*]
+[*Example 2*:
 ``` cpp
 int f1(int);
 int f2(float);
 typedef int (*fp1)(int);
 ```
 — *end example*]
 If either operand has a type that is a class or an enumeration, a
+user-defined operator function can be declared that implements this
 operator or a user-defined conversion can be necessary to convert the
 operand to a type that is appropriate for a built-in operator. In this
 case, overload resolution is used to determine which operator function
 or built-in operator is to be invoked to implement the operator.
 Therefore, the operator notation is first transformed to the equivalent
 operand of type *cv2* `T2`, four sets of candidate functions, designated
 *member candidates*, *non-member candidates*, *built-in candidates*, and
 *rewritten candidates*, are constructed as follows:
 - If `T1` is a complete class type or a class currently being defined,
+  the set of member candidates is the result of a search for `operator@`
+ in the scope of `T1`; otherwise, the set of member candidates is
+  empty.
+- For the operators `=`, `[]`, or `->`, the set of non-member candidates
+ is empty; otherwise, it includes the result of unqualified lookup for
+ `operator@` in the rewritten function call
+  [[basic.lookup.unqual]], [[basic.lookup.argdep]], ignoring all member
+ functions. However, if no operand has a class type, only those
+ non-member functions in the lookup set that have a first parameter of
+ type `T1` or “reference to cv `T1`”, when `T1` is an enumeration type,
+ or (if there is a right operand) a second parameter of type `T2` or
   “reference to cv `T2`”, when `T2` is an enumeration type, are
   candidate functions.
 - For the operator `,`, the unary operator `&`, or the operator `->`,
   the built-in candidates set is empty. For all other operators, the
   built-in candidates include all of the candidate operator functions
   - have the same operator name, and
   - accept the same number of operands, and
   - accept operand types to which the given operand or operands can be
     converted according to [[over.best.ics]], and
   - do not have the same parameter-type-list as any non-member candidate
+ or rewritten non-member candidate that is not a function template
+    specialization.
 - The rewritten candidate set is determined as follows:
   - For the relational [[expr.rel]] operators, the rewritten candidates
     include all non-rewritten candidates for the expression `x <=> y`.
   - For the relational [[expr.rel]] and three-way comparison
     [[expr.spaceship]] operators, the rewritten candidates also include
     a synthesized candidate, with the order of the two parameters
     reversed, for each non-rewritten candidate for the expression
     `y <=> x`.
   - For the `!=` operator [[expr.eq]], the rewritten candidates include
+    all non-rewritten candidates for the expression `x == y` that are
+    rewrite targets with first operand `x` (see below).
   - For the equality operators, the rewritten candidates also include a
     synthesized candidate, with the order of the two parameters
     reversed, for each non-rewritten candidate for the expression
+    `y == x` that is a rewrite target with first operand `y`.
   - For all other operators, the rewritten candidate set is empty.
   \[*Note 2*: A candidate synthesized from a member candidate has its
+  object parameter as the second parameter, thus implicit conversions
+  are considered for the first, but not for the second,
   parameter. — *end note*]
+A non-template function or function template `F` named `operator==` is a
+rewrite target with first operand `o` unless a search for the name
+`operator!=` in the scope S from the instantiation context of the
+operator expression finds a function or function template that would
+correspond [[basic.scope.scope]] to `F` if its name were `operator==`,
+where S is the scope of the class type of `o` if `F` is a class member,
+and the namespace scope of which `F` is a member otherwise. A function
+template specialization named `operator==` is a rewrite target if its
+function template is a rewrite target.
+[*Example 2*:
+``` cpp
+struct A {};
+template<typename T> bool operator==(A, T);     // #1
+bool a1 = 0 == A();                             // OK, calls reversed #1
+template<typename T> bool operator!=(A, T);
+bool a2 = 0 == A();                             // error, #1 is not a rewrite target
+struct B {
+  bool operator==(const B&);    // #2
+};
+struct C : B {
+  C();
+  C(B);
+  bool operator!=(const B&);    // #3
+};
+bool c1 = B() == C();           // OK, calls #2; reversed #2 is not a candidate
+                                // because search for operator!= in C finds #3
+bool c2 = C() == B();           // error: ambiguous between #2 found when searching C and
+                                // reversed #2 found when searching B
+struct D {};
+template<typename T> bool operator==(D, T);     // #4
+inline namespace N {
+  template<typename T> bool operator!=(D, T);   // #5
+}
+bool d1 = 0 == D();             // OK, calls reversed #4; #5 does not forbid #4 as a rewrite target
+```
+— *end example*]
 For the built-in assignment operators, conversions of the left operand
 are restricted as follows:
 - no temporaries are introduced to hold the left operand, and
 - no user-defined conversions are applied to the left operand to achieve
 the built-in candidates, and the rewritten candidates for that operator
 `@`.
 The argument list contains all of the operands of the operator. The best
 function from the set of candidate functions is selected according to
+[[over.match.viable]] and  [[over.match.best]].[^5]
+[*Example 3*:
 ``` cpp
 struct A {
   operator int();
 };
 conversion sequence of a user-defined conversion sequence
 [[over.ics.user]] is not applied. Then the operator is treated as the
 corresponding built-in operator and interpreted according to
 [[expr.compound]].
+[*Example 4*:
 ``` cpp
 struct X {
   operator double();
 };
 — *end example*]
 The second operand of operator `->` is ignored in selecting an
 `operator->` function, and is not an argument when the `operator->`
 function is called. When `operator->` returns, the operator `->` is
+applied to the value returned, with the original second operand.[^6]
 If the operator is the operator `,`, the unary operator `&`, or the
 operator `->`, and there are no viable functions, then the operator is
 assumed to be the built-in operator and interpreted according to
 [[expr.compound]].
 A a;
 void B::f() {
   operator+ (a,a);              // error: global operator hidden by member
+  a + a;                        // OK, calls global operator+
 }
 ```
 — *end note*]
 with `T` a class type, the candidate functions are selected as follows:
 - The converting constructors [[class.conv.ctor]] of `T` are candidate
   functions.
 - When the type of the initializer expression is a class type “cv `S`”,
+  conversion functions are considered. The permissible types for
+ non-explicit conversion functions are `T` and any class derived from
+ `T`. When initializing a temporary object [[class.mem]] to be bound to
+ the first parameter of a constructor where the parameter is of type
+ “reference to *cv2* `T`” and the constructor is called with a single
+ argument in the context of direct-initialization of an object of type
+ “*cv3* `T`”, the permissible types for explicit conversion functions
+ are the same; otherwise there are none.
 In both cases, the argument list has one argument, which is the
 initializer expression.
 [*Note 2*: This argument will be compared against the first parameter
+of the constructors and against the object parameter of the conversion
+functions. — *end note*]
 #### Initialization by conversion function <a id="over.match.conv">[[over.match.conv]]</a>
 Under the conditions specified in  [[dcl.init]], as part of an
 initialization of an object of non-class type, a conversion function can
 be invoked to convert an initializer expression of class type to the
 type of the object being initialized. Overload resolution is used to
+select the conversion function to be invoked. Assuming that “cv `T`” is
+the type of the object being initialized, the candidate functions are
+selected as follows:
+- The permissible types for non-explicit conversion functions are those
+ that can be converted to type `T` via a standard conversion sequence
+ [[over.ics.scs]]. For direct-initialization, the permissible types for
+ explicit conversion functions are those that can be converted to type
+ `T` with a (possibly trivial) qualification conversion [[conv.qual]];
+ otherwise there are none.
 The argument list has one argument, which is the initializer expression.
+[*Note 1*: This argument will be compared against the object parameter
+of the conversion functions. — *end note*]
 #### Initialization by conversion function for direct reference binding <a id="over.match.ref">[[over.match.ref]]</a>
 Under the conditions specified in  [[dcl.init.ref]], a reference can be
 bound directly to the result of applying a conversion function to an
 initializer expression. Overload resolution is used to select the
 conversion function to be invoked. Assuming that “reference to *cv1*
+`T`” is the type of the reference being initialized, the candidate
 functions are selected as follows:
+- Let R be a set of types including
+  - “lvalue reference to *cv2* `T2`” (when initializing an lvalue
+    reference or an rvalue reference to function) and
+ - “*cv2* `T2`” and “rvalue reference to *cv2* `T2`” (when initializing
+    an rvalue reference or an lvalue reference to function)
+ for any `T2`. The permissible types for non-explicit conversion
+  functions are the members of R where “*cv1* `T`” is
+ reference-compatible [[dcl.init.ref]] with “*cv2* `T2`”. For
+ direct-initialization, the permissible types for explicit conversion
+ functions are the members of R where `T2` can be converted to type `T`
+ with a (possibly trivial) qualification conversion [[conv.qual]];
+ otherwise there are none.
 The argument list has one argument, which is the initializer expression.
+[*Note 1*: This argument will be compared against the object parameter
+of the conversion functions. — *end note*]
 #### Initialization by list-initialization <a id="over.match.list">[[over.match.list]]</a>
 When objects of non-aggregate class type `T` are list-initialized such
 that [[dcl.init.list]] specifies that overload resolution is performed
   consists of the elements of the initializer list.
 In copy-list-initialization, if an explicit constructor is chosen, the
 initialization is ill-formed.
+[*Note 1*: This differs from other situations
+[[over.match.ctor]], [[over.match.copy]], where only converting
+constructors are considered for copy-initialization. This restriction
+only applies if this initialization is part of the final result of
+overload resolution. — *end note*]
 #### Class template argument deduction <a id="over.match.class.deduct">[[over.match.class.deduct]]</a>
 When resolving a placeholder for a deduced class type
 [[dcl.type.class.deduct]] where the *template-name* names a primary
 of the *braced-init-list*, or of the *expression-list*. For each xᵢ, let
 eᵢ be the corresponding aggregate element of `C` or of one of its
 (possibly recursive) subaggregates that would be initialized by xᵢ
 [[dcl.init.aggr]] if
+- brace elision is not considered for any aggregate element that has
+ - a dependent non-array type,
+ - an array type with a value-dependent bound, or
+  - an array type with a dependent array element type and xᵢ is a string
+    literal; and
 - each non-trailing aggregate element that is a pack expansion is
   assumed to correspond to no elements of the initializer list, and
 - a trailing aggregate element that is a pack expansion is assumed to
   correspond to all remaining elements of the initializer list (if any).
 If there is no such aggregate element eᵢ for any xᵢ, the aggregate
 deduction candidate is not added to the set. The aggregate deduction
 candidate is derived as above from a hypothetical constructor
 `C`(`T₁`, …, `Tₙ`), where
+- if eᵢ is of array type and xᵢ is a *braced-init-list*, `Tᵢ` is an
+  rvalue reference to the declared type of eᵢ, and
+- if eᵢ is of array type and xᵢ is a *string-literal*, `Tᵢ` is an lvalue
+  reference to the const-qualified declared type of eᵢ, and
 - otherwise, `Tᵢ` is the declared type of eᵢ,
 except that additional parameter packs of the form `Pⱼ` `...` are
 inserted into the parameter list in their original aggregate element
 position corresponding to each non-trailing aggregate element of type
 `Pⱼ` that was skipped because it was a parameter pack, and the trailing
 sequence of parameters corresponding to a trailing aggregate element
 that is a pack expansion (if any) is replaced by a single parameter of
+the form `Tₙ` `...`. In addition, if `C` is defined and inherits
+constructors [[namespace.udecl]] from a direct base class denoted in the
+*base-specifier-list* by a *class-or-decltype* `B`, let `A` be an alias
+template whose template parameter list is that of `C` and whose
+*defining-type-id* is `B`. If `A` is a deducible template
+[[dcl.type.simple]], the set contains the guides of `A` with the return
+type `R` of each guide replaced with `typename CC<R>::type` given a
+class template
+``` cpp
+template <typename> class CC;
+```
+whose primary template is not defined and with a single partial
+specialization whose template parameter list is that of `A` and whose
+template argument list is a specialization of `A` with the template
+argument list of `A` [[temp.dep.type]] having a member typedef `type`
+designating a template specialization with the template argument list of
+`A` but with `C` as the template.
+[*Note 1*: Equivalently, the template parameter list of the
+specialization is that of `C`, the template argument list of the
+specialization is `B`, and the member typedef names `C` with the
+template argument list of `C`. — *end note*]
+[*Example 1*:
+``` cpp
+template <typename T> struct B {
+  B(T);
+};
+template <typename T> struct C : public B<T> {
+  using B<T>::B;
+};
+template <typename T> struct D : public B<T> {};
+C c(42);            // OK, deduces C<int>
+D d(42);            // error: deduction failed, no inherited deduction guides
+B(int) -> B<char>;
+C c2(42);           // OK, deduces C<char>
+template <typename T> struct E : public B<int> {
+  using B<int>::B;
+};
+E e(42);            // error: deduction failed, arguments of E cannot be deduced from introduced guides
+template <typename T, typename U, typename V> struct F {
+  F(T, U, V);
+};
+template <typename T, typename U> struct G : F<U, T, int> {
+  using G::F::F;
+}
+G g(true, 'a', 1);  // OK, deduces G<char, bool>
+template<class T, std::size_t N>
+struct H {
+  T array[N];
+};
+template<class T, std::size_t N>
+struct I {
+  volatile T array[N];
+};
+template<std::size_t N>
+struct J {
+  unsigned char array[N];
+};
+H h = { "abc" };    // OK, deduces H<char, 4> (not T = const char)
+I i = { "def" };    // OK, deduces I<char, 4>
+J j = { "ghi" };    // error: cannot bind reference to array of unsigned char to array of char in deduction
+```
+— *end example*]
 When resolving a placeholder for a deduced class type
 [[dcl.type.simple]] where the *template-name* names an alias template
 `A`, the *defining-type-id* of `A` must be of the form
 functions or function templates formed as follows. For each function or
 function template `f` in the guides of the template named by the
 *simple-template-id* of the *defining-type-id*, the template arguments
 of the return type of `f` are deduced from the *defining-type-id* of `A`
 according to the process in [[temp.deduct.type]] with the exception that
+deduction does not fail if not all template arguments are deduced. If
+deduction fails for another reason, proceed with an empty set of deduced
+template arguments. Let `g` denote the result of substituting these
+deductions into `f`. If substitution succeeds, form a function or
+function template `f'` with the following properties and add it to the
+set of guides of `A`:
 - The function type of `f'` is the function type of `g`.
 - If `f` is a function template, `f'` is a function template whose
   template parameter list consists of all the template parameters of `A`
   (including their default template arguments) that appear in the above
   function template.
 - The associated constraints [[temp.constr.decl]] are the conjunction of
   the associated constraints of `g` and a constraint that is satisfied
   if and only if the arguments of `A` are deducible (see below) from the
   return type.
+- If `f` is a copy deduction candidate, then `f'` is considered to be so
+  as well.
+- If `f` was generated from a *deduction-guide* [[temp.deduct.guide]],
+  then `f'` is considered to be so as well.
 - The *explicit-specifier* of `f'` is the *explicit-specifier* of `g`
   (if any).
 The arguments of a template `A` are said to be deducible from a type `T`
 if, given a class template
 *deduction-guide* that had an *explicit-specifier*, each such notional
 constructor is considered to have that same *explicit-specifier*. All
 such notional constructors are considered to be public members of the
 hypothetical class type.
+[*Example 2*:
 ``` cpp
 template <class T> struct A {
   explicit A(const T&, ...) noexcept;               // #1
   A(T&&, ...);                                      // #2
 F f3 = {Types<X, Y, Z>{}, X{}, W{}};    // error: conflicting types deduced; operator Y not considered
 ```
 — *end example*]
+[*Example 3*:
 ``` cpp
 template <class T, class U> struct C {
   C(T, U);                                      // #1
 };
 template <class> class AA;
 template <class V> class AA<A<V>> { };
 template <class T> concept deduces_A = requires { sizeof(AA<T>); };
 // f1 is formed from the constructor #1 of C, generating the following function template
+template<class T, class U>
   auto f1(T, U) -> C<T, U>;
 // Deducing arguments for C<T, U> from C<V *, V*> deduces T as V * and U as V *;
 // f1' is obtained by transforming f1 as described by the above procedure.
 template<class V> requires deduces_A<C<V *, V *>>
 function parameters other than the ranking of conversion sequences.
 First, to be a viable function, a candidate function shall have enough
 parameters to agree in number with the arguments in the list.
+- If there are m arguments in the list, all candidate functions having
+  exactly m parameters are viable.
+- A candidate function having fewer than m parameters is viable only if
+  it has an ellipsis in its parameter list [[dcl.fct]]. For the purposes
+  of overload resolution, any argument for which there is no
   corresponding parameter is considered to “match the ellipsis”
   [[over.ics.ellipsis]].
+- A candidate function having more than m parameters is viable only if
   all parameters following the mᵗʰ have default arguments
   [[dcl.fct.default]]. For the purposes of overload resolution, the
+  parameter list is truncated on the right, so that there are exactly m
+  parameters.
 Second, for a function to be viable, if it has associated constraints
 [[temp.constr.decl]], those constraints shall be satisfied
 [[temp.constr.constr]].
 Third, for `F` to be a viable function, there shall exist for each
 argument an implicit conversion sequence [[over.best.ics]] that converts
 that argument to the corresponding parameter of `F`. If the parameter
 has reference type, the implicit conversion sequence includes the
 operation of binding the reference, and the fact that an lvalue
+reference to non-`const` cannot bind to an rvalue and that an rvalue
+reference cannot bind to an lvalue can affect the viability of the
 function (see  [[over.ics.ref]]).
 ### Best viable function <a id="over.match.best">[[over.match.best]]</a>
+#### General <a id="over.match.best.general">[[over.match.best.general]]</a>
+Define ICSⁱ(`F`) as the implicit conversion sequence that converts the
+iᵗʰ argument in the list to the type of the iᵗʰ parameter of viable
+function `F`. [[over.best.ics]] defines the implicit conversion
 sequences and [[over.ics.rank]] defines what it means for one implicit
 conversion sequence to be a better conversion sequence or worse
 conversion sequence than another.
+Given these definitions, a viable function `F₁` is defined to be a
+*better* function than another viable function `F₂` if for all arguments
+i, ICSⁱ(`F₁`) is not a worse conversion sequence than ICSⁱ(`F₂`), and
+then
+- for some argument j, ICSʲ(`F₁`) is a better conversion sequence than
+ ICSʲ(`F₂`), or, if not that,
 - the context is an initialization by user-defined conversion (see
   [[dcl.init]], [[over.match.conv]], and  [[over.match.ref]]) and the
+  standard conversion sequence from the return type of `F₁` to the
   destination type (i.e., the type of the entity being initialized) is a
   better conversion sequence than the standard conversion sequence from
+  the return type of `F₂` to the destination type
   \[*Example 1*:
   ``` cpp
   struct A {
     A();
     operator int();
   parameter-type-lists, and `F1` is more constrained than `F2` according
   to the partial ordering of constraints described in
   [[temp.constr.order]], or if not that,
 - `F1` is a constructor for a class `D`, `F2` is a constructor for a
   base class `B` of `D`, and for all arguments the corresponding
+  parameters of `F1` and `F2` have the same type
   \[*Example 3*:
   ``` cpp
   struct A {
     A(int = 0);
   };
   bool b = 1 < S();                                               // calls #2
   ```
   — *end example*]
   or, if not that
+- `F1` and `F2` are generated from class template argument deduction
+  [[over.match.class.deduct]] for a class `D`, and `F2` is generated
+  from inheriting constructors from a base class of `D` while `F1` is
+  not, and for each explicit function argument, the corresponding
+  parameters of `F1` and `F2` are either both ellipses or have the same
+  type, or, if not that,
 - `F1` is generated from a *deduction-guide* [[over.match.class.deduct]]
   and `F2` is not, or, if not that,
 - `F1` is the copy deduction candidate [[over.match.class.deduct]] and
   `F2` is not, or, if not that,
 - `F1` is generated from a non-template constructor and `F2` is
   — *end example*]
 If there is exactly one viable function that is a better function than
 all other viable functions, then it is the one selected by overload
+resolution; otherwise the call is ill-formed.[^7]
 [*Example 7*:
 ``` cpp
 void Fcn(const int*,  short);
   Fcn(&i, 1L);      // calls Fcn(int*, int), because &i → int* is better than &i → const int*
                     // and 1L → short and 1L → int are indistinguishable
   Fcn(&i, 'c');     // calls Fcn(int*, int), because &i → int* is better than &i → const int*
+                    // and 'c' → int is better than 'c' → short
 }
 ```
 — *end example*]
 If the best viable function resolves to a function for which multiple
+declarations were found, and if any two of these declarations inhabit
+different scopes and specify a default argument that made the function
+viable, the program is ill-formed.
 [*Example 8*:
 ``` cpp
 namespace A {
 — *end example*]
 #### Implicit conversion sequences <a id="over.best.ics">[[over.best.ics]]</a>
+##### General <a id="over.best.ics.general">[[over.best.ics.general]]</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.
 - an ellipsis conversion sequence [[over.ics.ellipsis]].
 However, if the target is
 - the first parameter of a constructor or
+- the object parameter of a user-defined conversion function
 and the constructor or user-defined conversion function is a candidate
 by
 -  [[over.match.ctor]], when the argument is the temporary in the second
 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. A
+derived-to-base conversion has Conversion rank [[over.ics.scs]].
 [*Note 4*: There is no such standard conversion; this derived-to-base
 conversion exists only in the description of implicit conversion
 sequences. — *end note*]
+When the parameter is the implicit object parameter of a static member
+function, the implicit conversion sequence is a standard conversion
+sequence that is neither better nor worse than any other standard
+conversion sequence.
 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.
+[*Note 5*: When converting to the explicit object parameter, if any,
+user-defined conversion sequences are allowed. — *end note*]
 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
 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 6*:
 This rule prevents a function from becoming non-viable because of an
 ambiguous conversion sequence for one of its parameters.
 [*Example 3*:
 summarizes the conversions defined in [[conv]] and partitions them into
 four disjoint categories: Lvalue Transformation, Qualification
 Adjustment, Promotion, and Conversion.
+[*Note 7*: 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 8*: 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*]
 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 of the first parameter of that 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
+type of the object parameter of that 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,
 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]] whose second
+standard conversion sequence is 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
 [[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 9*: 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*]
 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 10*:
 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]].
 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[^8]
+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
 [*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
+f( {'a','b'} );                 // OK, f(initializer_list<int>) integral promotion
 f( {1.0} );                     // error: narrowing
 struct A {
   A(std::initializer_list<double>);             // #1
   A(std::initializer_list<complex<double>>);    // #2
 void g(A);
 g({ "foo", "bar" });            // OK, uses #3
 typedef int IA[3];
 void h(const IA&);
+h({ 1, 2, 3 });                 // OK, identity conversion
 ```
 — *end example*]
 Otherwise, if the parameter type is “array of `N` `X`” or “array of
 - If `C` is not an initializer-list constructor 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 has Exact Match
   rank if `U` is `X`, or Conversion rank if `U` is derived from `X`.
 - Otherwise, the implicit conversion sequence is a user-defined
+  conversion sequence whose second standard conversion sequence is an
   identity conversion.
 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
 ``` cpp
 struct A {
   A(std::initializer_list<int>);
 };
 void f(A);
+f( {'a', 'b'} );        // OK, f(A(std::initializer_list<int>)) user-defined conversion
 struct B {
   B(int, double);
 };
 void g(B);
+g( {'a', 'b'} );        // OK, g(B(int, double)) user-defined conversion
 g( {1.0, 1.0} );        // error: narrowing
 void f(B);
 f( {'a', 'b'} );        // error: ambiguous f(A) or f(B)
 struct C {
   C(std::string);
 };
 void h(C);
+h({"foo"});             // OK, h(C(std::string("foo")))
 struct D {
   D(A, C);
 };
 void i(D);
+i({ {1,2}, {"bar"} });  // OK, i(D(A(std::initializer_list<int>{1,2\), C(std::string("bar"))))}
 ```
 — *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 whose second standard
+conversion sequence is an identity conversion.
 [*Example 9*:
 ``` cpp
 struct A {
   int m1;
   double m2;
 };
 void f(A);
+f( {'a', 'b'} );        // OK, f(A(int,double)) user-defined conversion
 f( {1.0} );             // error: narrowing
 ```
 — *end example*]
 Otherwise, if the parameter is a reference, see  [[over.ics.ref]].
+[*Note 11*: The rules in this subclause will apply for initializing the
 underlying temporary for the reference. — *end note*]
 [*Example 10*:
 ``` cpp
   int m1;
   double m2;
 };
 void f(const A&);
+f( {'a', 'b'} );        // OK, f(A(int,double)) user-defined conversion
 f( {1.0} );             // error: narrowing
 void g(const double &);
 g({1});                 // same conversion as int to double
 ```
   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
   ```
   — *end example*]
 In all cases other than those enumerated above, no conversion is
 - A conversion that does not convert a pointer or a pointer to member to
   `bool` is better than one that does.
 - A conversion that promotes an enumeration whose underlying type is
   fixed to its underlying type is better than one that promotes to the
   promoted underlying type, if the two are different.
+- A conversion in either direction between floating-point type `FP1` and
+  floating-point type `FP2` is better than a conversion in the same
+  direction between `FP1` and arithmetic type `T3` if
+  - the floating-point conversion rank [[conv.rank]] of `FP1` is equal
+    to the rank of `FP2`, and
+  - `T3` is not a floating-point type, or `T3` is a floating-point type
+    whose rank is not equal to the rank of `FP1`, or the floating-point
+    conversion subrank [[conv.rank]] of `FP2` is greater than the
+    subrank of `T3`.
+    \[*Example 8*:
+    ``` cpp
+    int f(std::float32_t);
+    int f(std::float64_t);
+    int f(long long);
+    float x;
+    std::float16_t y;
+    int i = f(x);           // calls f(std::float32_t) on implementations where
+                            // float and std::float32_t have equal conversion ranks
+    int j = f(y);           // error: ambiguous, no equal conversion rank
+    ```
+    — *end example*]
 - If class `B` is derived directly or indirectly from class `A`,
   conversion of `B*` to `A*` is better than conversion of `B*` to
   `void*`, and conversion of `A*` to `void*` is better than conversion
   of `B*` to `void*`.
 - If class `B` is derived directly or indirectly from class `A` and
   class `C` is derived directly or indirectly from `B`,
   - conversion of `C*` to `B*` is better than conversion of `C*` to
     `A*`,
+    \[*Example 9*:
     ``` cpp
     struct A {};
     struct B : public A {};
     struct C : public B {};
     C* pc;

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