Audience: CWG
S. Davis Herring <>
Los Alamos National Laboratory
October 4, 2019

History

r2:

• Rebased onto N4830 (significant for using enumerators/enumerations)
• Added a locus for a concept-definition
• Extended containing scopes into redeclarations of classes and enumerations
• Properly limited cross-TU qualified lookup in namespaces
• Fixed rules for conflicts between using-declaration⁠s
• Renamed “anonymous union object” to “anonymous union variable”

r1:

• Fixed reversed using-directive containment test
• Updated signature definitions
• Removed residual “point of declaration” usage
• Fixed several uses of (new) “precede” to be (existing) “reachable”
• Removed dangling “considered to refer to a template” reference
• Used “be attached” for modules instead of (new, unrelated) “belong”
• Included class templates with classes for all scope purposes
• Distinguished entities from their associated scopes
• Accounted for missing kinds of declarations
• Removed superfluous definition of “denotes”
• Disentangled “enclose” and “contain” definitions
• Specified no lookup for X in using X=...;
• Allowed a namespace-name to be a member-qualified name
• Allowed in-class lookup of X in p->~X() and decltype(...)::~X()
• Ignored non-type X in struct N::X x;
• Limited this/static prohibition with “current class”
• Deprecated A::template B (as a template template argument or CTAD placeholder)
• Allowed forward declarations of partial specializations
• Removed mention of resolved issue
• Added explanatory examples to aid review

Introduction

The current descriptions of scope and name lookup are confusing, incomplete, and at times incorrect. [basic.scope] defines the word “scope” in two different ways, and then implicitly and indirectly specifies many aspects of name lookup with imperfect correspondence to the descriptions in [basic.lookup]. Lookup is often described for units of program text that may include multiple names and < tokens that must be disambiguated, such as a template-id ([temp.dep]/2), id-expression ([over.call.func]/2), or conversion-type-id ([class.qual]/1.2). Namespaces, and the global namespace in particular, are inconsistently described as being one or many declarative regions ([basic.scope.namespace]/1, /4). There are dozens of Core issues (discussed individually below) on the subject; the general vagueness of the wording on the subject interferes with resolving them individually.

Modules significantly complicate the situation, principally by invalidating the tacit assumption that “every” lookup is restricted to preceding declarations in the same translation unit. There were already exceptions to that rule (e.g., complete class contexts and using-declaration conflicts), which can then easily be (mis)read as applying to all contents of all translation units. Other rules, like those for lookup through a using-directive, that do not make any mention of location may now plausibly be read as being available through an import.

This paper rewrites large sections of [basic.scope] and [basic.lookup] and parts of [temp.res] (and makes the requisite changes elsewhere to adapt to new definitions) to address these issues holistically. 50 Core issues are resolved, as well as 14 points discussed on the reflector but not (yet) on the issues list. Many changes are (collectively) editorial, but their very number demands CWG review. Other changes generally formalize current implementation practice or, in the absence of implementation consensus, establish language consistency.

Approach

To avoid redundant specification of scope and of name lookup, all description of where a name might be used ([basic.scope.block], [basic.scope.enum], etc.) is phrased merely in terms of the total extent of each scope where a name might be introduced. The scopes are always properly nested, although there are situations where unqualified lookup considers a scope that does not contain the point of the lookup. Explicit wording is introduced to require that lookup occur from a program point (replacing lookup “in the context” of something) and consider only previous declarations (except in complete-class contexts) and those made available by import. Most declarations are said to “bind” the names they introduce to themselves, replacing the notion of “not found by lookup”. To avoid confusion, the word “bind” is not used for describing locked-in lookup results as for default arguments (which can instead be described as being looked up from their declarations). The use of the word “visible” to indicate a declaration’s placement is avoided in normative text.

Several kinds of scope search are defined, and several kinds of qualified lookup are combined, to minimize redundancy in the definition of the lookup algorithms. The word “lookup” or phrase “look up” is used only for resolution of a name that is complete (at least in the simple context; it might be reused as a subroutine elsewhere).

The descriptions of the algorithms generally favor local completeness at the expense of additional references to distant clauses (that would otherwise specify special cases for their respective language features). Several rule restatements are turned into notes.

Every lookup is explicitly for a name, not an id-expression or type-id. Template arguments in an id-expression are addressed by defining which names are subject to qualified lookup and by excluding a template-id from being a name. Because labels interact with so little of the language, their identifiers are excluded from names and name lookup entirely.

To avoid confusion when a name is declared multiple times in a scope, careful distinction is made between a name and a declaration of that name. In particular, the “point of declaration” of a name (usually; [basic.scope.pdecl]/3 describes one for an anonymous class or enumeration) is replaced with the “locus” of a declaration.

The phrase “global name” is removed to reduce the apparent special status of the global namespace (but “global scope” still exists because of its lack of syntax and as a shorthand).

Wording for the (possible) declaration of a class by an elaborated-type-specifier is removed from [basic.scope.pdecl]/7, [basic.lookup.elab]/2, [namespace.memdef]/3, and [class.friend]/11 and merged into [dcl.type.elab].

Richard’s proposal for “using-declarations & {,!}export” is followed: a (non-dependent) using-declaration is replaced with its referent(s) during name lookup rather than introducing additional declarations. Because it is consistent with that replacement, and for consistency with existing implementations, the inclusion of hidden type names by a member using-declaration is extended to those not in a class.

Examples

The lookup for the following examples is narrated to help CWG members relate old and new terminology. Cross references prefixed with + are to N4830 as edited here.

using-directive vs. using-declaration

namespace F {float x;}
namespace A {
  namespace I {int x;}
  using namespace I;
  using F::x;
  void f() {
    x=0;     // #1: error
    A::x=1;  // #2: OK: F::x
  }
}

1. At #1, x is looked up as an unqualified name (+[basic.lookup.unqual]/4) via an unqualified search of the function parameter scope of A::f (/3).
2. When continuing on to the namespace scope of A, the unqualified search searches A and also every namespace contained by A and nominated by an active using-directive (/2).
3. The single using-directive is active in the function parameter scope (/1), which is contained by A, as is I.
4. Therefore A and I are searched simultaneously.
5. The using-declaration is replaced with F::x (+[basic.lookup]/5), and the lookup is ambiguous ([basic.lookup]/1).

1. At #2, A is looked up as an unqualified name. x is a qualified name (+[basic.lookup.qual]/2), so undergoes qualified name lookup (/3) which is just a search of A.
2. The search finds F::x, so the using-directive is not considered by +[namespace.qual]/1.

CWG459

struct A {using T=int;};  // given
template<class T>
struct B : A {
  void f() {T i;}
};

1. T (in the template-head), B, and f are not looked up (+[dcl.meaning]/3, +[class]/1).
2. A is looked up as an unqualified name (+[basic.lookup.unqual]/4), ignoring non-type names ([class.derived]/2).
3. T is looked up as an unqualified name when defining the class template B (+[temp.res]/1):
   1. Unqualified name lookup performs an unqualified search in the enclosing scope (+[basic.lookup.unqual]/3), which is the function parameter scope of B::f (+[basic.scope.param]/1, +[basic.scope.block]/2).
   2. For each enclosing scope, an unqualified search is just a search except when considering a namespace (+[basic.lookup.unqual]/2); a search is just a single search except when considering a class (template) (+[class.member.lookup]/1). The function parameter scope is neither and has no binding for T (it has only __func__).
   3. The next enclosing scope is that of B; classes and class templates have scopes (+[basic.scope.class]/1). It is a class template, and a single search in it finds nothing ([class.member.lookup]/4), so its non-dependent base classes are considered (+[class.member.lookup]/5).
   4. A single search in the scope of A finds the typedef-name.
   5. The next enclosing scope is the template parameter scope to which the template parameter T belongs ([basic.scope.temp]/2), but it is never considered.

Calling a conversion function

auto x = s.operator R T::*();

1. x is not looked up (+[dcl.meaning]/3).
2. s is subject to normal unqualified lookup (+[basic.lookup.unqual]/4).
3. The names used in the conversion-type-id are looked up “in the same fashion as the conversion-function-id” (/5).
4. While that lookup can’t happen yet, the conversion-function-id is a member-qualified name (+[basic.lookup.qual]/2) and thus undergoes qualified lookup in the class of s (call it S; /3).
5. If S::R finds nothing, R is looked up as an unqualified name (+[basic.lookup.unqual]/5 again); T is considered the same way (separately), except that non-type names are ignored because of the following :: ([basic.lookup.qual]/1).
6. Once the type named by the conversion-type-id is known ([class.conv.fct]/1), the conversion-function-id is looked up as described above.

Calling destructors

struct A {using X=A;} a;
struct B : A {struct X {};};
void f(B *b) {
  b->A::~X();            // #1: error
  b->decltype(a)::~X();  // #2: OK
}

1. At #1, A undergoes qualified lookup in B (+[basic.lookup.qual]/3).
2. Because its nested-name-specifier is a (member-)qualified name (/2), X is looked up as A was (/5.1.2), which finds B::X.

3. Since that is not the lookup context A, X is then tried as an unqualified name (/5.2), but that finds nothing.

4. At #2, the nested-name-specifier for the qualified name containing X is not itself a qualified name (nor a name of any kind), so X is looked up as a normal terminal name (/5.1).

5. Since decltype(a) refers to A, it is A::X that is found.

Issues

Definitions

CWG554 is resolved by using the word “scope” instead of “declarative region”, consistent with its very common use in phrases like “namespace scope”. The other uses of “scope” are implied by the explicit unqualified lookup algorithm. CWG2165 is resolved by removing the conflicting definition of it in [basic.scope].

CWG405 is resolved by stating that argument-dependent lookup (sometimes) occurs after an ordinary unqualified lookup (making statements like “finding a variable prevents argument-dependent lookup” formally correct).

CWG36 (which has the dubious distinction of having the earliest recorded date) is resolved by limiting the restriction in question to class scopes, where ambiguous accessibility would be a problem, since a using-declaration does not introduce declarations. CWG418 is resolved by trivial rephrasing along with that necessary for the new using-declaration interpretation.

CWG1291 and CWG2396 are resolved by explicitly specifying how to look up names in a conversion-type-id.

CWG600 is resolved by explaining that accessibility affects naming a member in the sense of the ODR.

Lookup completeness

CWG191 and CWG1200 are resolved by defining unqualified lookup in terms of every enclosing scope. CWG536 (long partially resolved) is resolved by specifying that unqualified lookup occurs for any kind of unqualified-id as an id-expression. CWG399 is resolved by explicitly appealing to the lookup for the last component of any suitable nested-name-specifier. CWG562 is resolved by defining lookup as occurring from a program point.

CWG1906 (currently closed as NAD, perhaps because its proposed resolution suffered in attempting to fit the structure of [basic.lookup.unqual] rejected by CWG191) and CWG2370 are resolved by Rachel’s regularization suggested in “Reconsidering CWG1906 and its friend CWG2370”, which may be in conflict with the CWG opinion from San Diego.

My proposed simplification for “Missing associated namespace for member template template arguments?” is incorporated on the assumption that the failure to examine the namespace of an associated class is an oversight. (GCC and ICC, but not Clang or MSVC, accept the example in that message.)

CWG1822 is resolved by specifying that the body of a lambda remains in the surrounding (function parameter) scope.

CWG1894 and its duplicate CWG2199 are resolved per Richard’s proposal for “dr407 still leaves open questions about typedef / tag hiding”, using generic conflicting-declaration rules even for typedef, and discarding a redundant typedef-name when looking up an elaborated-type-specifier.

[namespace.udir]/5 is simply removed; careful backward-lookup rules already allow such usage, and no implementation actually delays any declarations until the end of a namespace-definition.

Jens’ interpretation of “On beyond CWG372” is included as a note (cf. Richard’s proposed restriction). CWG607 is resolved by looking up unqualified names in a mem-initializer-id from outside the parameter scope. CWG1837 is resolved by restricting this to referring to the innermost enclosing class.

CWG2007 is resolved by skipping unqualified lookup for operators that must be member functions.

Richard’s correction to template parameter scope for constrained template template parameters for “CWG186 is NAD (or ‘Resolved’)” is incorporated.

The missing point of declaration for a concept identified by Andrew in “recursive concepts” is supplied (without any prohibition on self-referential concepts).

Complete-class context

The intent for CWG2335 (contra those of the older CWG1890, CWG1626, CWG1255, and CWG287) is supported by retaining the unrestricted forward lookup in complete-class contexts (despite current implementation behavior for non-templates). CWG361 is partially resolved by that confirmation; the rest must be addressed along with CWG2335. CWG2331 is resolved by defining lookup from complete-class contexts and out-of-line member definitions. The rest of CWG2009 is resolved by making it ill-formed NDR for forward lookup outside a complete-class context to change the results (before overload resolution, to avoid differences in instantiation). CWG325 is resolved by preventing forward lookup while first parsing a class from producing a template-id (and relying on the CWG2009 resolution to ban a change of interpretation) while generalizing the template prefix to support lookup in an incomplete class. CWG1635 is partially resolved by also making template default arguments a complete-class context.

Declaration matching

My clarification in “Where can namespace-scope functions and variables be redeclared?” is applied, resolving CWG1821.

CWG1820 is resolved by requiring that a qualified declarator-id declare an entity. CWG386, CWG1839, CWG1900, and Richard’s observation in “are non-type names ignored in a class-head-name or enum-head-name?” are resolved by describing the limited lookup that occurs for a declarator-id, including the changes in Richard’s proposed resolution for CWG1839 and rejecting the example from CWG1477. CWG138 is resolved according to N1229.

CWG110 is resolved by reducing the restriction in [temp] to a note (matching the behavior of GCC, Clang, and ICC).

Modules

Richard’s proposed resolution for “missing restriction on private-module-fragment” is incorporated.

Nathan’s question about export using in “using-declarations & {,!}export” is avoided by not introducing synonyms that might or might not be exported. Richard’s issue submission for using-declaration conflicts is resolved by combining the generic notions of “conflicts with” and “precedes”.

Nothing is done about P1498R1, since its solution does not involve name lookup. For example, the intent is to disallow lookups that use a using-declaration that names a declaration of a name with internal linkage rather than the using-declaration itself.

Parsing

CWG1771 is resolved by describing the lookup of only an identifier, or (per my proposal in “‘Down with template!’”) the name in a recognized template-id (whether or not dependent), preceding a ::. CWG1828 is resolved by disfavoring the interpretation of :: as an entire nested-name-specifier.

My proposal for “‘Down with template!’” is incorporated by generalizing “type-id-only context” to “type-only context” and applying it to template as well as typename. CWG1835 is resolved by removing the special provision for ->/. identifier < in [basic.lookup.classref]/1, requiring that template be used to refer even to a non-member template in that position. CWG1908 is resolved per its suggestion of performing qualified lookup first and stopping if it produces a template-id, always taking < to indicate one (per Richard’s proposal for “On beyond CWG1908”). My further proposal for parsing a qualified-id in a dependent class member access is applied. My proposal for “grammar ambiguities with non-simple template-ids” is applied, allowing any kind of name to be considered to refer to a template, except for a conversion-function-id for which the rules would be more complicated despite never applying. CWG1841 is resolved by considering the injected-class-name of a class template to refer to a template.

CWG1616 is resolved by explicitly characterizing the forbidden case in terms of lookup results.

Templates

CWG459 is not affected: base classes are still searched in unqualified lookup before template parameters are considered.

CWG1936 is resolved by expanding the definition of “dependent name” to include qualified names (i.e., names previously said to be “a member of an unknown specialization”). CWG1500 is resolved by further expanding it to include any conversion-function-id with a dependent type (and clarifying that dependent lookup takes place after substitution). My proposed regularization of conversion-type-id interpretation (which includes resolving CWG2413) in “‘Down with template!’” and proposed rule for considering conversion function templates in “When are conversion function templates hidden?” are incorporated. The assumption that a qualified dependent name names a type is disabled inside a decltype or array bound. CWG1028 is resolved by moving the “lookup from first declaration” rule from [temp.over.link]/5 to [temp.res]/1. CWG1907 is resolved by forbidding dependence on default (template) arguments not found by lookup for a dependent name.

CWG1829 is resolved by checking for direct members of a class that is the current instantiation.

CWG1089 (as reinterpreted after CWG1111) is resolved by performing unqualified lookup for the first component of a nested-name-specifier in a class member access when a dependent type prevents finding anything. CWG1478 is resolved per my interpretation as independently suggested by Richard in “Implementation status of core issue 96”.

CWG2070 is resolved by specifying that a dependent using-declarator is considered to name a constructor if and only if it ends with B::B. CWG852 is resolved by explicitly mentioning using-declaration⁠s in class templates (and making it diagnosable in most cases to refer to a class that is definitely not a base).

CWG1545 is resolved by interpreting entire friend declarations upon instantiation of an enclosing template.

CWG2213 is resolved by allowing an elaborated-type-specifier to contain a simple-template-id without friend.

Wording

Relative to N4830.

[intro.defs]

[defns.signature]

Change the definition (leaving the note):

signature
〈function〉 name, parameter type list ([dcl.fct]), enclosing namespace (if any), and trailing requires-clause ([dcl.decl]) (if any)

[defns.signature.templ]

Change:

signature
〈function template〉 name, parameter type list ([dcl.fct]), enclosing namespace (if any), return type, template-head, and trailing requires-clause ([dcl.decl]) (if any)

[lex.ext]

Change paragraph 2:

A user-defined-literal is treated as a call to a literal operator or literal operator template ([over.literal]). To determine the form of this call for a given user-defined-literal L with ud-suffix X, first let S be the declarations found by unqualified lookup for the literal-operator-id whose literal suffix identifier is X is looked up in the context of L using the rules for unqualified name lookup ([basic.lookup.unqual]). Let S be the set of declarations found by this lookup. S shall not be empty.

[basic]

Change paragraph 5:

A name is a use of an identifier ([lex.name]), operator-function-id ([over.oper]), literal-operator-id ([over.literal]), or conversion-function-id ([class.conv.fct]), or template-id ([temp.names]) that denotes an entity or label ([stmt.goto], [stmt.label]).

Change paragraph 6:

Every name that denotes an entity is introduced by a declaration. Every name that denotes a label is introduced either by a goto statement ([stmt.goto]) or a labeled-statement ([stmt.label]).

Remove bullet (9.4).

[basic.def.odr]

Change paragraph 4:

A variable is named by an expression if the expression is an id-expression that denotes it. A variable x whose named appears asby a potentially-evaluated expression e […]

[basic.scope]

[basic.scope.declarative]

Remove subclause, referring the old stable name to [basic.scope.scope] (added below). Update the 2 surviving cross references (in [basic.def.odr]/9) to refer to [basic.scope.scope]. Replace the 9 surviving mentions of “declarative region” (in [basic.def.odr]/9, [expr.prim.id.unqual]/2, [expr.prim.lambda.capture]/7.3, and [namespace.def]/2) with “scope”.

General [basic.scope.scope]

Add subclause to front of [basic.scope]:

The declarations in a program appear in a number of scopes that are in general discontiguous. The global scope contains the entire program; every other scope is introduced by a declaration or statement (as described in the following subclauses of [basic.scope]) appearing in another scope which thereby contains the scope introduced. An enclosing scope at a program point is any scope that contains it. The smallest scope that contains a scope or program point is said to be its (singular) enclosing scope. A scope intervenes between a program point P and a scope S if it is or contains S but does not contain P.

Every declaration and entity belongs to a single scope. A declaration belongs to its enclosing scope. An entity belongs to the target scope of the declaration that introduces it. Unless otherwise specified:

1. A declaration’s target scope is the scope to which it belongs, and
2. Any names introduced by a declaration are bound to it in its target scope.

A scope that is or contains the scope to which an entity belongs is an enclosing scope for that entity.

For the purpose of introducing entities and names, each

1. init-declarator ([dcl.decl]),
2. identifier in a structured binding declaration ([dcl.struct.bind]),
3. condition with a declarator ([stmt.stmt]),
4. member-declarator ([class.mem]),
5. using-declarator ([namespace.udecl]),
6. parameter-declaration ([dcl.fct]),
7. alias-declaration ([dcl.typedef]),
8. concept-definition ([temp.concept]),
9. type-parameter ([temp.param]),
10. elaborated-type-specifier that introduces a name ([dcl.type.elab]),
11. class-specifier or enum-specifier with a name ([class], [dcl.enum]),
12. opaque-enum-declaration,
13. enumerator-definition, and
14. implicit declaration of an injected-class-name ([class])

is considered to be a declaration. [Note: The interpretation of a for-range-declaration produces one or more of the above ([stmt.ranged]). — end note]

A name denotes an entity if it is introduced by a declaration of that entity or is a typedef-name introduced by a declaration specifying that entity.

Two declarations conflict if the same name denotes distinct entities via each and

1. either declaration declares a typedef-name, or
2. both entities are types, or
3. neither entity is a type and either is not a function or function template, or
4. neither entity is a variable, non-static data member, enumerator, function, or function template, or
5. both entities are functions, or both are function templates, and they cannot be overloaded ([over.load]).

A declaration shall not conflict with another with the same target scope. [Note: Declarations might conflict even if neither binds a name. [Example:

struct A {
  friend short f();  // #1
};
struct B {
  friend float f();  // error: conflicts with #1
};

— end example] — end note] In general, a name can otherwise be bound to multiple declarations in a scope.

When instantiating a templated entity ([temp]), any scope S associated with any part of the template definition is considered to be associated with the instantiated entity and to contain the instantiations of any declarations that belong to S.

[basic.scope.pdecl]

Change each paragraph 1–12:

1. The point of declarationlocus for a namedeclaration that is a declarator is immediately after itsthe complete declarator ([dcl.decl]) and before its initializer (if any), except as noted below. [Example:

   […] — end example]

2. [Note: A name from an outer scope remains visible up to the pointlocus of the declaration of the name that hides it. [Example:

   […] — end example] — end note]
3. The pointlocus of declaration for a class or class template first declared by a class-specifier is immediately after the identifier or simple-template-id (if any) in its class-head ([class]). The pointlocus of declaration for an enumerationan enum-specifier or opaque-enum-declaration is immediately after the identifier (if any) in either its enum-specifier ([dcl.enum]) or its first opaque-enum-declarationit ([dcl.enum]), whichever comes first. The pointlocus of declaration of an alias or alias templatean alias-declaration is immediately follows the defining-type-id to which the alias refersafter it.
4. The point of declarationlocus of a using-declarator that does not name a constructor is immediately after the using-declarator ([namespace.udecl]).

5. The point of declaration for an enumeratorlocus of an enumerator-definition is immediately after its enumerator-definition. [Example:

   […] — end example]
6. [Note: After the point of declaration of a class member, the member name can be looked upfound in the scope of its class. [Note: This is true even if the class is an incomplete class. […] — end note]
7. […]The locus of an elaborated-type-specifier that is a declaration ([dcl.type.elab]) is immediately after it.
8. The point of declaration forlocus of an injected-class-name declaration ([class]) is immediately following the opening brace of the class definition.
9. The pointlocus of the implicit declaration forof a function-local predefined variable ([dcl.fct.def.general]) is immediately before the function-body of aits function’s definition.
10. The pointlocus of the declaration of a structured binding ([dcl.struct.bind]) is immediately after the identifier-list of the structured binding declaration.
11. The point of declaration for the variable or the structured bindings declared in thelocus of a for-range-declaration of a range-based for statement ([stmt.ranged]) is immediately after the for-range-initializer.

12. The point of declaration for a template parameterlocus of a template-parameter is immediately after its complete template-parameter. [Example:

    […]

    — end example]

Insert before paragraph 13:

The locus of a concept-definition is immediately after its concept-name ([temp.concept]). [Note: The constraint-expression cannot use the concept-name. — end note]

[Drafting note: There is no normative wording yet corresponding to this note. — end drafting note]

Change paragraph 13:

[Note: Friend declarations refer tomay introduce functions or classes that are members ofbelong to the nearest enclosing namespace or block scope, but they do not introduce newbind names into that namespaceanywhere ([namespace.memdefclass.friend]). Function declarations at block scope and variable declarations with the extern specifier at block scope refer to declarations that are members of andeclare entities that belong to the nearest enclosing namespace, but they do not introduce newbind names into that scopein it. — end note]

[basic.scope.block]

Replace contents:

A scoped statement is a compound-statement of a function-try-block or either substatement of an if statement with an else part.

For each selection or iteration statement ([stmt.select], [stmt.iter]), handler ([except]), scoped statement, or compound statement ([stmt.block]) that is not

1. the compound-statement of a lambda-expression with a lambda-declarator, of a handler, or of a function-body, or
2. a unique substatement of a selection or iteration statement,

there is a block scope that includes that statement or handler. [Note: A scoped statement that is also a block has only one scope. — end note] A variable that belongs to a block scope is a local variable.

Move the example from [stmt.for]/3 to here.

A declaration whose target scope is the block scope of a scoped statement shall not conflict with a declaration whose target scope is the enclosing scope.

Move the example from [stmt.stmt]/5 to the end of this subclause.

[basic.scope.param]

Replace contents:

For each parameter-declaration-clause P there is a function parameter scope that includes P. [Note: A function parameter cannot be used for its value within the parameter-declaration-clause ([dcl.fct.default]). — end note] If P is associated with a declarator, its scope extends to the end of that function declarator, or to the end of the function-body if the declarator is associated with a function-definition. [Note: A member function’s parameter scope is nested within its class’s scope. The handlers for a function-try-block are part of the function-body. — end note] If P is associated with a lambda-declarator, its scope extends to the end of the compound-statement in the lambda-expression. If P is associated with a requirement-parameter-list, its scope extends to the end of the requirement-body of the requires-expression. If P is associated with a deduction-guide, its scope extends to the end of the deduction-guide.

A declaration whose target scope is the block scope of a handler in a function-try-block shall not conflict with a declaration whose target scope is the enclosing (function parameter) scope.

[basic.funscope]

Remove subclause, referring the stable name (which has no cross references) to [stmt.label].

[basic.scope.namespace]

Replace contents:

For each namespace N there is a namespace scope that includes the namespace-body for every namespace-definition for N. The scope also includes the portion of any redeclaration or specialization of an entity enclosed by it after the declarator-id, class-head-name, or enum-head-name that names the entity. The global scope is the namespace scope of the global namespace ([basic.namespace]).

[basic.scope.class]

Replace contents:

For each class or class template C there is a class scope that includes the class-specifier for C. The scope also includes the portion of any redeclaration or specialization of an entity enclosed by it after the declarator-id, class-head-name, or enum-head-name that names the entity. [Note: Lookup from a program point before the class-specifier of a class will find no bindings in its scope. — end note]

[basic.scope.enum]

Replace contents:

For each enumeration E there is an enumeration scope that includes the enum-specifier for E. [Note: The names of unscoped enumerators are also bound in the enclosing scope ([dcl.enum]). — ⁠end note]

[basic.scope.temp]

Replace contents:

For each template template-parameter there is a template parameter scope that includes the template-head of the template-parameter.

For each template-declaration there is a template parameter scope that includes it. Any declaration outside the template-parameter-list that would belong to the template parameter scope instead belongs to its enclosing scope. [Note: Therefore, only template parameters belong to a template parameter scope. — end note]

[basic.scope.hiding]

Remove subclause, referring the stable name to [basic.lookup].

[basic.lookup]

Change paragraph 1:

[…] Name lookup associates the use of a name with a set of declarations ([basic.def]) of that name. Unless otherwise specified, the program is ill-formed if no declarations are found. The declarations found by name lookup shall either

1. all denote the same entity, or
2. shall all denote functions or function templates;, in the latterwhich case, the declarationsy are said to form a set ofn overloaded functions set ([over.load])., or
3. are ambiguous, and the program is ill-formed.

Overload resolution ([over.match]) takes place after name lookup has succeeded. The access rules ([class.access]) are considered only once name lookup and function overload resolution (if applicable) have succeeded. Only after name lookup, function overload resolution (if applicable) and access checking have succeeded are the semantic properties introduced by the name’s declaration and its reachable ([module.reach]) redeclarations used further in expression processing ([expr]).

Insert before paragraph 2:

A program point P follows any declaration in the same translation unit whose locus ([basic.scope.pdecl]) is before P. [Note: The declaration might appear in a scope that does not contain P. — end note]

A declaration X precedes a program point P in a translation unit L if P follows X, or else X appears in a translation unit D and

1. P follows a module-import-declaration or module-declaration that imports D (directly or indirectly), and
2. X appears after the module-declaration in D (if any) and before the private-module-fragment in D (if any), and
3. either X is exported or D and L are part of the same module, and
4. X does not declare a name with internal linkage. [Note: Names declared by a using-declaration have no linkage. — end note]

Move the note (and example) from [basic.scope.namespace]/2 to the end of this paragraph.

Remove paragraphs 2 and 3.

Append paragraphs:

A single search in a scope S for a name N from a program point P finds the declarations in S that precede P and to which any name that is the same as N ([basic]) is bound. If any such declaration is a using-declarator that is not dependent ([temp.dep.type]), it is replaced by the declarations named by the using-declarator ([namespace.udecl]). If the containing using-declaration is a member-declaration, the replacement declarations are considered to have the access of the using-declaration.

In certain contexts, only certain kinds of declarations are included. After any such restriction, any declarations of classes or enumerations are discarded if any other declarations are found. [Note: A type (but not a typedef-name or template) is therefore hidden by any other entity in its scope. — end note] However, if a lookup is type-only, only declarations of types and templates whose specializations are types are considered; furthermore, if a typedef declarator and a declaration of the type to which it refers are found, the typedef declarator is discarded instead of the type declaration.

If N is a conversion-function-id, conversion function templates that belong to S are considered. For each such template, if template argument deduction succeeds ([temp.deduct.conv]), an invented declaration of the resulting specialization is included in the result.

[class.member.lookup]

Move to front of [basic.lookup], editing as follows:

Remove paragraph 1.

Change paragraph 2:

TA search in a scope C for a name N from a program point P is a single search in C for N from P unless C is a class or class template, in which case the following steps define the result of a member name f in a class scope Cthe search. [Note: The result differs only if the single search would find nothing. — end note]

Replace f with N and C with C in the following paragraphs.

Change paragraph 3:

The lookup set for fN in CC, called S(fN,C), consists of two component sets: the declaration set, a set of members named fN; and the subobject set, a set of subobjects where declarations of these members (possibly including using-declaration⁠s) were found (possibly via using-declaration⁠s). In the declaration set, using-declaration⁠s are replaced by the set of designated members that are not hidden or overridden by members of the derived class ([namespace.udecl]), and type declarations (including injected-class-names) are replaced by the types they designate. S(fN,C) is calculated as follows:

Change paragraph 4:

If C contains a declaration of the name f, the declaration set contains every declaration of f declared in C that satisfies the requirements of the language construct in which the lookup occurs. The declaration set is the result of a single search in C for N from immediately after the class-specifier of C if P is in a complete-class context of C or from P otherwise. [Note: […] — end note][…]

[Drafting note: The plan for CWG2335 is to describe forbidden dependency cycles among the complete-class contexts of a class. — end drafting note]

Change paragraph 5:

[…] If C has base classes, cCalculate the lookup set for fN in each direct non-dependent ([temp.dep.type]) base class subobject B_i, and merge each such lookup set S(fN,B_i) in turn into S(fN,C). [Note: If C is incomplete, only base classes whose base-specifier appears before P are considered. If C is an instantiated class, its base classes are not dependent. — end note]

Change paragraph 7:

The result of name lookup for f in Cthe search is the declaration set of S(fN,C). If it is an invalid set, the program is ill-formed. If the use of N is followed by a < that is not interpreted as part of a template argument list ([temp.names]) and the result contains any declaration of a template, the program is ill-formed, no diagnostic required. If it differs from the result of a search in C for N from immediately after the class-specifier of C, the program is ill-formed, no diagnostic required.

Remove paragraph 8.

[basic.lookup.unqual]

Replace contents (including the existing paragraph 16 at the end):

A using-directive is active in a scope S at a program point P if P appears later in the same translation unit and it belongs to S or to the scope of a namespace nominated by a using-directive that is active in S at P.

An unqualified search in a scope S from a program point P includes the results of searches from P in

1. S, and
2. for any scope U that contains P and is or is contained by S, each namespace contained by S that is nominated by a using-directive that is active in U at P.

If no declarations are found, the unqualified search also includes an unqualified search in the enclosing scope of S, if any, from P. [Note: When a class scope is searched, the scopes of its base classes are also searched ([class.member.lookup]). If it inherits from a single base, it is as if the scope of the base immediately contains the scope of the derived class. — end note]

Unqualified name lookup from a program point performs an unqualified search in its enclosing scope.

An unqualified name is a name that does not follow a nested-name-specifier or the . or -> in a class member access expression ([expr.ref]), possibly after a template keyword or ~. Unless otherwise specified, such a name undergoes unqualified name lookup from the point where it appears.

An unqualified name that appears in a conversion-type-id is looked up in the same fashion as the conversion-function-id in which it appears. If that lookup finds nothing, it undergoes unqualified name lookup; in each case, only names that denote types or templates whose specializations are types are considered.

In a friend declaration, lookup for an unqualified name that appears in a declarator after a declarator-id with a nested-name-specifier that names a class, class template, or namespace S performs an unqualified search in S. If that lookup finds nothing, it undergoes unqualified name lookup.

[Note: The rules for name lookup in template definitions are described in [temp.res]. — end note]

[basic.lookup.argdep]

Change paragraph 1:

When the postfix-expression in a function call ([expr.call]) is an unqualified-id, andother namespaces not considered during the usual unqualified lookup ([basic.lookup.unqual]) may be searched, and in those namespaces, namespace-scope friend function or function template declarations ([class.friend]) not otherwise visible may be found. These modifications to the searchfor the name in the unqualified-id does not find any

1. declaration of a class member, or
2. function declaration belonging to a block scope, or
3. declaration not of a function or function template

then lookup for the name also includes the result of argument-dependent lookup in a set of associated namespaces that depends on the types of the arguments (and for template template arguments, the namespace of the template argument), as specified below. [Example:

[…]

— end example]

Move the note from [basic.lookup.unqual]/3 here, inserting it before paragraph 2.

Change paragraph 2:

For each argument type T in the function call, there is a set of zero or more associated namespaces and a set of zero or more associated entities (other than namespaces) to be considered. The sets of namespaces and entities areis determined entirely by the types of the function arguments (and the namespace of any template template arguments). Typedef names and using-declaration⁠s used to specify the types do not contribute to this set. The sets of namespaces and entities areis determined in the following way:

1. If T is a fundamental type, its associated sets of namespaces and entities are bothis empty.
2. If T is a class type (including unions), its associated entities are: the class itself; the class of which it is a member, if any; and its direct and indirect base classes. Its associated namespaces are the innermost enclosing namespaces of its associated entities. Furthermore, if T is a class template specialization, its associated namespaces and entities also include: the namespaces and entities associated with the types of the template arguments provided for template type parameters (excluding template template parameters); the templates used as template template arguments; the namespaces of which any template template arguments are members; and the classes of which any member templates used as template template arguments are members. [Note: Non-type template arguments do not contribute to the set of associated namespacesentities. — end note]
3. If T is an enumeration type, its associated namespace is the innermost enclosing namespace of its declaration, and its associated entities are T and, if it is a class member, the member’s class.
4. If T is a pointer to U or an array of U, its associated namespaces and entities are those associated with U.
5. If T is a function type, its associated namespaces and entities are those associated with the function parameter types and those associated with the return type.
6. If T is a pointer to a member function of a class X, its associated namespaces and entities are those associated with the function parameter types and return type, together with those associated with X.
7. If T is a pointer to a data member of class X, its associated namespaces and entities are those associated with the member type together with those associated with X.

If an associated namespace is an inline namespace ([namespace.def]), its enclosing namespace is also included in the set. If an associated namespace directly contains inline namespaces, those inline namespaces are also included in the set. In addition, if the argument is the name or address of a set of overloaded functions and/or function templates or the address of such a set, its associated entities and namespaces are the union of those associated with each of the members of the set, i.e., the entities and namespaces associated with its parameter types and return type. Additionally, if the aforementioned set of overloaded functions is named with a template-id, its associated entities and namespaces also include those of its type template-argument⁠s and its template template-argument⁠s and those associated with its type template-argument⁠s.

Change paragraph 3 and move it to the end of the subclause:

Let X be the lookup set produced by unqualified lookup ([basic.lookup.unqual]) and let Y be the lookup set produced by argument dependent lookup (defined as follows). If X contains

1. a declaration of a class member, or
2. a block-scope function declaration that is not a using-declaration, or
3. a declaration that is neither a function nor a function template

then Y is empty. Otherwise Y is the set of declarations found in the namespaces associated with the argument types as described below. The set of declarations found by the lookup of the name is the union of X and Y. [Note: The associated namespaces and entities associated with the argument types can include namespaces and entities already considered by the ordinary unqualified lookup. — end note] [Example:

[…]

— end example]

Change paragraph 4:

When considering anThe associated namespaces for a call are the innermost enclosing non-inline namespaces for its associated entities. Argument-dependent lookup finds the results of qualified name lookup in each associated namespace N, the lookup is the same as the lookup performed when N is used as a qualifier ([namespace.qual]) except that:

1. Anyll using-directive⁠s in N are ignored.
2. All names except thoseOnly declarations of (possibly overloaded) functions and function templates are ignoredconsidered.
3. Any namespace-scopedeclaration of a friend functions or friend function templates ([class.friend]) declared in a classes with a reachable definitions in the set of associated entities are visible within their respective namespaces even if they are not visible during an ordinary lookup ([namespace.memdef])is considered to precede the point of the lookup, and the name declared is considered to be bound to it in its target scope.
4. Any declaration D in N that is in the interface of a named module M ([module.interface]) is visibleconsidered to precede the point of the lookup P if it does not appear in the translation unit containing P and there is an associated entity attached to M with the same innermost enclosing non-inline namespace scope as D.

5. If the lookup is for a dependent name ([temp.dep], [temp.dep.candidate]), any declaration D in N is visible if D would be visible to qualified name lookup ([namespace.qual]) at anythe above lookup is also performed from each point in the instantiation context ([module.context]) of the lookup, unless D is declaredadditionally ignoring any declaration that appears in another translation unit, is attached to the global module, and is either discarded ([module.global]) or has internal linkage.

[basic.lookup.qual]

Change paragraph 1:

The name of a class or namespace member or enumerator can be referred to after the :: scope resolution operator ([expr.prim.id.qual]) applied to a nested-name-specifier that denotes its class, namespace, or enumeration. IfLookup of an identifier, or the name in a template-id, followed by a :: scope resolution operator in a nested-name-specifier is not preceded by a decltype-specifier, lookup of the name preceding that :: considers only namespaces, types, and templates whose specializations are types. [Note: An identifier followed by < is not considered to be part of a template-id during a lookup to determine the interpretation of the < ([temp.names]). — end note] If the name found does nota name, template-id, or decltype-specifier is followed by a ::, it shall designate a namespace or a, class, enumeration, or dependent type, the program is ill-formedand the :: is never interpreted as a complete nested-name-specifier. [Example:

[…]

— end example]

Insert before paragraph 2:

A member-qualified name is an unqualified-id, or a nested-name-specifier of the form type-name :: or namespace-name ::, in the id-expression of a class member access expression ([expr.ref]). A qualified name is a member-qualified name, a qualified-id, a using-declarator, a typename-specifier, or a nested-name-specifier, elaborated-type-specifier, or class-or-decltype that contains a nested-name-specifier ([expr.prim.id.qual]). The lookup context of a member-qualified name is the type of its associated object expression (considered dependent if the object expression is type-dependent). The lookup context of any other qualified name is the type or namespace nominated by its nested-name-specifier. The terminal name of a qualified name is the identifier (including that of a simple-template-id) in it or the (initial) name in the unqualified-id that is or is in the qualified name. [Note: When parsing a class member access, the name following the -> or . is a terminal name even though it is not yet known of which kind. — end note]

Qualified name lookup in a class, namespace, or enumeration performs a search of the scope associated with it ([class.member.lookup]) except as specified below. Unless otherwise specified, a terminal name undergoes qualified name lookup in the lookup context of its qualified name from the point where it appears unless the lookup context either is dependent and is not the current instantiation ([temp.dep.type]) or is not a class or class template. If nothing is found by qualified lookup for the terminal name of a member-qualified name that is a nested-name-specifier, the terminal name undergoes unqualified lookup. [Example:

int f();
struct A {
  template<int> using B=A;
  int C;
  template<int> using D=void;
  typedef A E,T;
  void f();
};
template<int> using C=A;
template<int> using D=A;
template<int> using E=A;

template<class T>
void g(T *p) {
  p->template B<0>::f();     // error: B not found and not dependent
  p->T::template B<0>::f();  // OK: T is the template parameter; A::B found in f<A>
  p->T::T::f();              // OK: second T is A::T in f<A>
  p->C<0>::f();              // OK: (p->C < 0) > ::f()
  p->template D<0>::f();     // OK: ::D found in definition context
}
template void g(A*);

void h(A a) {
  a.template C<0>::f();      // OK: non-type A::C ignored
  a.template E<0>::f();      // error: E is A::E which is not a template
}

— end example]

Remove paragraphs 3 through 5.

Change paragraph 6:

In a qualified-id of the form:

nested-name-specifier_opt type-name :: ~ type-name

the second type-name is looked up in the same scope as the first. If the qualified name is or contains an unqualified-id that begins with ~ identifier:

1. If the qualified name is not a member-qualified name:
   1. Its nested-name-specifier shall nominate a type.
   2. If the nested-name-specifier is a qualified name, the identifier is looked up in the same fashion as its terminal name.
   [Note: Otherwise, the qualified name is looked up normally. — end note]
2. If lookup for the identifier finds nothing or finds it to be a type-name that does not refer to the lookup context (ignoring cv-qualification), it instead undergoes unqualified lookup.
3. Each lookup for the identifier considers only types (if the identifier is not followed by a <) and templates whose specializations are types.
4. The type-name that is or contains the identifier shall ultimately refer to the lookup context (ignoring cv-qualification).

[Example:

struct C {
  typedef int I;
  typedef float I2;
};
typedef int I1, I2;
extern int* p;
extern int* q;
void f() {
  p->C::I::~I2();      // after finding C::I2 is, unqualified looked up in the scope of Cfinds ::I2
  q->I1::~I2();       // I2 isundergoes unqualified looked up in the scope of the postfix-expression
}

struct A {
  typedef A AB;
  ~A();
} a;
typedef A AB;
int main() {
  AB* p;
  p->AB::~AB();      // explicitly calls the destructor for A
  p->decltype(a)::~AB(); // error: AB not found
}

— end example] [Note: [basic.lookup.classref] describes how name lookup proceeds after the . and -> operators. — end note]

[class.qual]

Remove paragraph 1.

Change paragraph 2:

In a lookup in which function names are not ignored^[…] and thefor a qualified name with a nested-name-specifier that nominates a class C:

1. if the name specified after the nested-name-specifier, when looked up in C, issearch finds the injected-class-name of C ([class]), or
2. inf the qualified name is a using-declarator of a using-declaration ([namespace.udecl]) that is a member-declaration, if the name specified after the nested-name-specifier is the same as the identifier or the simple-template-id’s template-name in the last component of the nested-name-specifierdependent and names a constructor,

the name is instead considered to name the constructor of class C. [Note: For example, the constructor is not an acceptable lookup result in an elaborated-type-specifier so the constructor would not be used in place of the injected-class-name. — end note] Such a constructor name shall be used only in the declarator-id of a declaration that names a constructor or in a using-declaration. [Example:

[…]

— end example]

Remove paragraph 3.

[namespace.qual]

Remove paragraphs 1 and 2.

Replace paragraph 3, retaining its example:

Qualified name lookup in a namespace N additionally searches every element of the inline namespace set of N ([namespace.def]), ignoring unnamed namespaces defined in translation units that do not contain the point of the lookup ([namespace.unnamed]). If nothing is found, it includes the results of qualified name lookup in each namespace nominated by a using-directive that is followed by the point of the lookup and belongs to N or to a element of its inline namespace set. [Note: If a using-directive refers to a namespace that has already been considered, it does not affect the result. — end note] [Example:

[…]

— end example]

Change paragraph 6:

During the lookup of a qualified namespace member name, if the lookup finds more than one declaration of the member, and if one declaration introduces a c[Note: Class name orand enumeration name and thedeclarations are not discarded because of other declarations introduce either the same variable, the same enumerator, or a set of functions, the non-type name hides the class or enumeration name if and only if the declarations are from the same namespace; otherwise (the declarations are from different namespaces), the program is ill-formedfound in other searches. — end note] [Example:

[…]

— end example]

Remove paragraph 7.

[basic.lookup.elab]

Remove paragraphs 1 and 2.

Insert before paragraph 3:

If the class-key or enum keyword in an elaborated-type-specifier is followed by an identifier that is not followed by ::, lookup for the identifier is type-only. [Note: In general, the recognition of an elaborated-type-specifier depends on the following tokens. If the identifier is followed by ::, see [basic.lookup.qual]. — end note]

Change paragraph 3:

If the elaborated-type-specifier has a nested-name-specifier, qualified name lookup is performed, as described in [basic.lookup.qual], but ignoring any non-type names that have been declaredfor the following identifier is type-only. If the name lookup does not find a previously declared type-name, the elaborated-type-specifier is ill-formed.

[basic.lookup.classref]

Remove subclause, referring the stable name and the cross reference in [expr.ref]/4 to [basic.lookup.qual].

[basic.link]

Change paragraph 5:

AThe name havingof an entity that belongs to a namespace scope ([basic.scope.namespace]) has internal linkage if it is the name of

[…]

Change paragraph 8:

The name of a function declared in block scope and the name of a variable declared by a block scope extern declaration have linkage. If such a declaration is attached to a named module, the program is ill-formed. If there is a visible declaration of an entity with linkage, ignoring entities declared outside the innermost enclosing namespace scope, such that the block scope declaration would be a (possibly ill-formed) redeclaration if the two declarations appeared in the same declarative region, the block scope declaration declares that same entity and receives the linkage of the previous declaration. If there is more than one such matching entity, the program is ill-formed. Otherwise, if no matching entity is found, the block scope entity receives external linkage. If, within a translation unit, the same entity is declared with both internal and external linkage, the program is ill-formed. [Example:

static void f();
extern "C" void h();
static int i = 0;               // #1
void gq() {
  extern void f();              // internal linkage
  extern void g();              // ::g, external linkage
  extern void h();              // C language linkage
  int i;                        // #2: i has no linkage
  {
    extern void f();            // internal linkage
    extern int i;               // #3: exinternal linkage, ill-formed
  }
}

WithoutEven though the declaration at line #2 hides the declaration at line #1, the declaration at line #3 would link with thestill redeclarationes at line #1. Because the declaration with and receives internal linkage is hidden, however, #3 is given external linkage, making the program ill-formed. — end example]

Remove paragraph 9 (whose example is moved to [dcl.meaning]).

Change bullet (11.2):

both names refer to members ofentities that belong to the same namespace or to members, not by inheritance, of the same class; and

[expr]

[expr.prim]

[expr.prim.this]

Insert before paragraph 2:

The current class at a program point is the class associated with the smallest class scope containing that point. [Note: A lambda-expression does not contain any class scope. — end note]

Change paragraph 2:

If a declaration declares a member function or member function template of a class X, the expression this is a prvalue of type “pointer to cv-qualifier-seq X” wherever X is the current class between the optional cv-qualifier-seq and the end of the function-definition, member-declarator, or declarator. It shall not appear before the optional cv-qualifier-seq and it shall not appear within the declaration of a static member function of the current class (although its type and value category are defined within a static member function as they are within a non-static member function). [Note: This is because declaration matching does not occur until the complete declarator is known. — end note] [Note: In a trailing-return-type, the class being defined is not required to be complete for purposes of class member access ([expr.ref]). Class members declared later are not visible. [Example:

[…]

— end example] — end note]

Change paragraph 3:

Otherwise, if a member-declarator declares a non-static data member ([class.mem]) of a class X, the expression this is a prvalue of type “pointer to X” wherever X is the current class within the optional default member initializer ([class.mem]). It shall not appear elsewhere in the member-declarator.

[expr.prim.id]

[expr.prim.id.unqual]

Change paragraph 2:

The result is the entity denoted by the identifierunqualified-id ([basic.lookup.unqual]). If the entity is a local entity […]

[expr.prim.id.qual]

Change paragraph 1:

The nested-name-specifier :: nominates the global namespace. The type denoted byA nested-name-specifier with a decltype-specifier in a nested-name-specifiernominates the type denoted by the decltype-specifier, which shall be a class or enumeration type. Any other nested-name-specifier nominates the entity denoted by its type-name, namespace-name, or terminal name. [Note: In a template-declaration, a type-name that is a simple-template-id can denote a template ([temp.dep.type]). — end note]

Change paragraph 2:

A nested-name-specifier that denotes a class, optionally followed by the keyword template ([temp.names]), and then followed by the name of a member of either that class ([class.mem]) or one of its base classes ([class.derived]), is a qualified-id; [class.qual] describes name lookup for class members that appear in qualified-id⁠s. The result is the memberentity denoted by the qualified-id ([basic.lookup.qual]). The type of the resultexpression is the type of the memberresult. The result is an lvalue if the member is a function, a variable, a structured binding ([dcl.struct.bind]),a static member function, or a data member and a prvalue otherwise. [Note: A class member can be referred to using a qualified-id at any point in its potential scope ([basic.scope.class]). — end note] Where type-name ::~ type-name is used, the two type-name⁠s shall refer to the same type (ignoring cv-qualifications); this notation denotes the destructor of the type so named ([expr.prim.id.dtor]). The unqualified-id in a qualified-id shall not be of the form ~decltype-specifier.

Remove paragraphs 3 through 5.

[expr.prim.lambda]

[expr.prim.lambda.closure]

Change paragraph 4:

[…] [Note: Names referenced in the lambda-declarator are looked up in the context in which the lambda-expression appears. — end note] [Example:

[…]

— end example]

Change paragraph 12:

The lambda-expression’s compound-statement yields the function-body ([dcl.fct.def]) of the function call operator, but for purposes of name lookup ([basic.lookup]), determining the type and value of this ([class.this]) and transforming id-expression⁠s referring to non-static class members into class member access expressions using (*this) ([class.mfct.non-static]), the compound-statement is considered in the context of the lambda-expressionit is not within the scope of the closure type. [Example:

[…]

— end example] Further, a variable __func__ is implicitly defined at the beginning of the compound-statement of the lambda-expression, with semantics as described in [dcl.fct.def.general].

[expr.prim.lambda.capture]

Change paragraph 6:

An init-capture behaves as if it declares and explicitly captures a variable of the form “auto init-capture ;” whose declarative region isdeclared in the lambda-expression’s compound-statement, except that:

[…]

Change paragraph 17:

A simple-capture followed by an ellipsis is a pack expansion ([temp.variadic]). An init-capture preceded by an ellipsis is a pack expansion that introducesdeclares an init-capture pack ([temp.variadic]) whose declarative region isin the lambda-expression’s compound-statement. [Example:

[…]

— end example]

[expr.prim.req]

Change the grammar in paragraph 1:

[…]

requirement-parameter-list:

( parameter-declaration-clause_opt )

[…]

Change paragraph 4:

A requires-expression may introduce local parameters using a parameter-declaration-clause ([dcl.fct]). A local parameter of a requires-expression shall not have a default argument. Each name introduced by a local parameter is in scope from the point of its declaration until the closing brace of the requirement-body. These parameters have no linkage, storage, or lifetime; they are only used as notation for the purpose of defining requirement⁠s. […]

Remove paragraph 5.

[expr.post]

[expr.call]

Change paragraph 3:

If a function or member function name is usedthe postfix expression names an overload set, the appropriate function and the validity of the call are determined according to the rules in [over.match]. […]

[expr.ref]

Change paragraph 1:

A postfix expression followed by a dot . or an arrow ->, optionally followed by the keyword template ([temp.names]), and then followed by an id-expression, is a postfix expression. The postfix expression before the dot or arrow is evaluated;^[…] the result of that evaluation, together with the id-expression, determines the result of the entire postfix expression. [Note: If the keyword template is used, the following unqualified name is considered to refer to a template ([temp.names]). If a simple-template-id results and is followed by a ::, the id-expression is a qualified-id. — end note]

Change paragraph 4:

Otherwise, the object expression shall be of class type. The class type shall be complete unless the class member access appears in the definition of that class. [Note: If the class is incomplete, lookup inThe program is ill-formed if the result differs from that when the class is complete class type is required to refer to the same declaration ([basic.scope.class.member.lookup]). — end note] The id-expression shall name a member of the class or of one of its base classes. [Note: Because the name of a class is inserted in its class scope ([class]), the name of a class is also considered a nested member of that class. — end note] [Note: [basic.lookup.classref] describes how names are looked up after the . and -> operators. — end note]

[expr.const]

Change bullet (14.7):

a variable whose name appears asnamed by a potentially constant evaluated expression that is either a constexpr variable or is of non-volatile const-qualified integral type or of reference type.

[stmt.stmt]

Remove paragraph 5 (whose example is moved to [basic.scope.block]).

[stmt.label]

Change paragraph 1:

[…]

The optional attribute-specifier-seq appertains to the label. An identifier label declares the identifier. The only use of an identifier label with an identifier is as the target of a goto. The scope of a label is the function in which it appears. LNo two labels shall not be redeclared within a function shall have the same identifier. A label can be used in a goto statement that appears before its declaration. Labels have their own name space and do not interfere with other identifiers. [Note: A label may have the same name as another declaration in the same scope or a template-parameter from an enclosing scope. Unqualified name lookup ([basic.lookup.unqual]) ignores labels. — end note]

[stmt.select]

Change paragraph 2:

The substatement in a[Note: Each selection-statement (and each substatement, in of the else form of the if statement) implicitly defineshas a block scope ([basic.scope.block]). — end note] If the substatement in a selection-statement is a single statement and not a compound-statement, it is as if it was rewritten to be a compound-statement containing the original substatement. [Example:

[…]

can be equivalently rewritten as

[…]

Thus after the if statement, i is no longer in scope. — end example]

[stmt.if]

Change paragraph 3:

[…]

except that names declared in the init-statement areis in the same declarative regionscope as those declared in the condition.

[stmt.switch]

Change paragraph 7 as for [stmt.if]/3.

[stmt.iter]

Remove paragraph 3.

[stmt.while]

Change paragraph 2:

When the condition of a while statement is a declaration, the scope of the variable that is declared extends from its point of declaration ([basic.scope.pdecl]) to the end of the while statement. A while statement is equivalent to

[…]

[Note: The variable created in the condition is destroyed and created with each iteration of the loop. [Example:

[…]

In the while-loop, the constructor and destructor are each called twice, once for the condition that succeeds and once for the condition that fails. — end example] — end note]

[stmt.for]

Change paragraph 1 as for [stmt.if]/3 (up to a comma instead of a period).

Remove paragraph 3 (whose example is moved to [basic.scope.block]).

[stmt.dcl]

Change paragraph 1:

[…]

[Note: If an identifier introduced by a declaration was previously declared in an outer block, the outer declaration is hidden for the remainder of the block ([basic.lookup.unqual]), after which it resumes its force. — end note]

[stmt.ambig]

Change paragraph 3:

[…] Disambiguation precedes parsing, and a statement disambiguated as a declaration may be an ill-formed declaration. If, during parsing, lookup finds that a name in a template parameter is bound differently than it would be bound during a trial parseargument is bound to (part of) the declaration being parsed, the program is ill-formed. No diagnostic is required. [Note: This can occur only when the name is declared earlier in the declaration. — end note] [Example:

[…]

— end example]

[dcl.dcl]

Change paragraph 4:

A declaration occurs in a scope ([basic.scope]); the scope rules are summarized in [basic.lookup]. ACertain declarations that declares a function or defines a class, namespace, template, or function also hascontain one or more scopes nested within it ([basic.scope]). These nested scopes, in turn, can have declarations nested within them. Unless otherwise stated, utterances in [dcl.dcl] about components in, of, or contained by a declaration or subcomponent thereof refer only to those components of the declaration that are not nested within scopes nested within the declaration.

Change paragraph 5:

In a simple-declaration, the optional init-declarator-list can be omitted only when declaring a class ([class]) or enumeration ([dcl.enum]), that is, when the decl-specifier-seq contains either a class-specifier, an elaborated-type-specifier with a class-key ([class.name]), or an enum-specifier. In these cases and whenever a class-specifier or enum-specifier is present in the decl-specifier-seq, the identifiers in these specifiers are among the names beingalso declared by the declaration (as class-name⁠s, enum-name⁠s, or enumerator⁠s, depending on the syntax). In such cases, the decl-specifier-seq shall introduce one or more names into the program, or shall redeclare a name introduced by a previous declaration. [Example:

[…]

— end example]

Change paragraph 9:

Each init-declarator in the init-declarator-list contains exactly one declarator-id, which is the. If the declarator-id is a name, the declared by that init-declarator and (hence) one of the names declared by the declaration introduce that name. [Note: Otherwise, the declarator-id is a qualified-id or its unqualified-id is a template-id and no name is introduced. — end note] The defining-type-specifier⁠s ([dcl.type]) in the decl-specifier-seq and the recursive declarator structure of the init-declarator describe a type ([dcl.meaning]), which is then associated with the name being declared by the init-declaratordeclarator-id.

Change paragraph 10:

If the decl-specifier-seq contains the typedef specifier, the declaration is called a typedef declaration, each declarator-id must be an identifier, and the name of each init-declarator is declared to be a typedef-name, synonymous with its associated type ([dcl.typedef]). If the decl-specifier-seq contains no typedef specifier, the declaration is called a function declaration if the type associated with the namea declarator-id is a function type ([dcl.fct]) and an object declaration otherwise.

[dcl.spec]

[dcl.typedef]

Change paragraph 2:

A typedef-name can also be introduced by an alias-declaration. The identifier following the using keyword is not looked up; it becomes a typedef-name and the optional attribute-specifier-seq following the identifier appertains to that typedef-name. […]

Remove paragraphs 3 through 7.

[dcl.type]

[dcl.type.elab]

Change paragraph 1:

An attribute-specifier-seq shall not appear in an elaborated-type-specifier unless the latter is the sole constituent of a declaration. If an elaborated-type-specifier is the sole constituent of a declaration, the declaration is ill-formed unless it is an explicit specialization ([temp.expl.spec]), an explicit instantiation ([temp.explicit]) or it has one of the following forms:

class-key attribute-specifier-seq_opt identifier ;
class-key attribute-specifier-seq_opt simple-template-id ;
friend class-key ::_opt identifier ;
friend class-key ::_opt simple-template-id ;
friend class-key nested-name-specifier identifier ;
friend class-key nested-name-specifier template_opt simple-template-id ;

In the first case, it declares the identifier as a class-name. The second case shall appear only in a template-declaration; it declares a partial specialization ([temp.class.spec]). The attribute-specifier-seq, if any, appertains to the class or template being declared; the attributes in the attribute-specifier-seq are thereafter considered attributes of the class whenever it is named.

Insert before paragraph 2:

Otherwise, the elaborated-type-specifier shall not have an attribute-specifier-seq. If it contains a identifier but no nested-name-specifier and (unqualified) lookup for the identifier finds nothing, it shall not be introduced by the enum keyword and declares the identifier as a class-name. Its target scope is the nearest enclosing namespace or block scope. If the declaration includes the friend specifier,

1. lookup for the identifier does not consider scopes that contain that scope, and
2. no name is bound.

[Note: [basic.lookup.elab] describes how name lookup proceeds in an elaborated-type-specifier. — end note]

If it appears with the friend specifier as an entire declaration, the declaration shall have one of the following forms:

friend class-key nested-name-specifier_opt identifier ;
friend class-key simple-template-id ;
friend class-key nested-name-specifier template_opt simple-template-id ;

Change paragraph 2:

[Note: [basic.lookup.elab] describes how name lookup proceeds for the identifier in aAn elaborated-type-specifier may be used to refer to a previously declared class-name or enum-name even though the name has been hidden by a non-type declaration. — end note] If the identifier or simple-template-id resolves to a class-name or enum-name, the elaborated-type-specifier introduces it into the declaration the same way a simple-type-specifier introduces its type-name ([dcl.type.simple]). […]

[dcl.spec.auto]

Change paragraph 11:

If the name ofa primary-expression is an id-expression that refers to an entity with an undeduced placeholder type appears in an expression, the program is ill-formed. Once a non-discarded return statement has been seen in a function, however, the return type deduced from that statement can be used in the rest of the function, including in other return statements. [Example:

[…]

— end example]

[dcl.decl]

Change paragraph 2:

The three components of a simple-declaration are the attributes ([dcl.attr]), the specifiers (decl-specifier-seq; [dcl.spec]) and the declarators (init-declarator-list). The specifiers indicate the type, storage class or other properties of the entities being declared. The declarators specify the names of these entities or their names and (optionally) modify the type of the specifiers with operators such as * (pointer to) and () (function returning). Initial values can also be specified in a declarator; initializers are discussed in [dcl.init] and [class.init].

[dcl.meaning]

Change paragraph 1:

A declarator contains exactly one declarator-id; it names the identifierentity that is declared. An unqualified-id occurring in a declarator-id shall be a simple identifier except for the declaration of some special functions ([class.ctor], [class.conv], [class.dtor], [over.oper]) and for the declaration of template specializations or, partial specializations, or explicit instantiations ([temp.spec]). When the declarator-id is qualified, the declaration shall refer to a previously declared member of the class or namespace to which the qualifier refers (or, in the case of a namespace, of an element of the inline namespace set of that namespace ([namespace.def])) or to a specialization thereof; the member shall not merely have been introduced by a using-declaration in the scope of the class or namespace nominated by the nested-name-specifier of the declarator-id. The nested-name-specifier of a qualified declarator-id shall not begin with a decltype-specifier. [Note: If the qualifier is the global :: scope resolution operator, the declarator-id refers to a name declared in the global namespace scope. — end note] The optional attribute-specifier-seq following a declarator-id appertains to the entity that is declared.

Insert before paragraph 2, including the example from [namespace.memdef]/2:

If the id-expression in a declarator-id is a qualified-id or template-id, or the declaration appears in an explicit-instantiation ([temp.explicit]), let S be the lookup context of the qualified-id ([basic.lookup.qual]), or the smallest enclosing namespace scope if the id-expression is a template-id. The declaration, taken as belonging to S and retaining only the unqualified-id in the declarator-id, shall

1. if the unqualified-id is a template-id and the declaration is a friend declaration ([class.friend]), declare a specialization of an entity found by qualified name lookup for the name that is or is in the unqualified-id in S, or else
2. redeclare or declare a specialization of an entity that belongs to S, or if not that to an element of its inline namespace set if S is a namespace ([namespace.def]).

Only entities declared by a declaration that is reachable from the declarator-id and does not belong to a block scope are considered. [Note: The previous declaration might be a friend declaration. — end note] If there is more than one entity that might be redeclared or specialized, the program is ill-formed. If the declaration is not a friend declaration, it shall belong to a namespace that contains the entity. The declarator’s target scope is S; it binds no name. [Example:

[…]

— end example]

[Drafting note: Richard proposed making the restriction on use of a qualified-id grammatical. — end drafting note]

(The example below is moved from [basic.link]/9, with changes as marked.)

If the id-expression in a declarator-id is a name, the name is not looked up.

1. If the declaration is a friend declaration, its target scope is the smallest enclosing namespace or block scope; in the latter case, the declaration shall redeclare a function with a reachable declaration belonging to that scope. The declarator binds no name.
2. If the declaration belongs to a block scope and declares a function ([dcl.fct]) or uses the extern specifier, the declaration shall not be attached to a named module ([module.unit]) and its target scope is the smallest enclosing namespace scope, but the name is bound in its enclosing scope. [Example:

namespace X {
  void p() {
    q();                        // error: q not yet declared
    extern void q();            // q is a member of namespace X
    extern void r();            // r is a member of namespace X
  }

  void middle() {
    q();                        // error: q not yet declaredfound
  }

  void q() { /* ... */ }        // definition of X::q
}

void q() { /* ... */ }          // some other, unrelated q
void X::r() { /* ... */ } // error: r cannot be declared by qualified-id

— end example]

Change paragraph 3:

Thus, (for each init-declarator) a declaration of a particular identifier has the form

T D

where T is of the form attribute-specifier-seq_opt decl-specifier-seq and D is a declarator. Following is a recursive procedure for determining the type specified for the contained declarator-id by such a declaration.

Change paragraph 5:

In a declaration attribute-specifier-seq_opt T D where D is an unadorned identifiername the type of this identifier is “T”.

[dcl.fct]

Change paragraph 15:

An identifier can optionally be provided as a parameter name; if present in a function definition ([dcl.fct.def]), it names a parameter. [Note: In particular, parameter names are also optional in function definitions and names used for a parameter in different declarations and the definition of a function need not be the same. If a parameter name is present in a function declaration that is not a definition, it cannot be used outside of its function declarator because that is the extent of its potentialthe enclosing scope ([basic.scope.param]). — end note]

[dcl.fct.default]

Change paragraph 5:

The default argument has the same semantic constraints as the initializer in a declaration of a variable of the parameter type, using the copy-initialization semantics ([dcl.init]). The names in the default argument are boundlooked up, and the semantic constraints are checked, at the point where the default argument appears. Name lookup and checking of semantic constraints for default arguments in function templates and in member functions of class templates are performed as described in [temp.inst]. [Example: In the following code, g will be called with the value f(2):

[…]

— end example] [Note: In member function declarations, names in default arguments are looked up as described in [basic.lookup.unqual]. Access checking applies to names in default arguments as described in [class.access]. — end note]

Change paragraph 9:

A default argument is evaluated each time the function is called with no argument for the corresponding parameter. A parameter shall not appear as a potentially-evaluated expression in a default argument. [Note: Parameters of a function declared before a default argument are in scope and can hide namespace and class member names. — end note] [Example:

[…]

— end example] A non-static member shall not appear in a default argument unless it appears as the id-expression of a class member access expression ([expr.ref]) or unless it is used to form a pointer to member ([expr.unary.op]). [Example: The declaration of X::mem1() in the following example is ill-formed because no object is supplied for the non-static member X::a used as an initializer.

[…]

The declaration of X::mem2() is meaningful, however, since no object is needed to access the static member X::b. Classes, objects, and members are described in [class]. — end example] A default argument is not part of the type of a function. [Example:

[…]

— end example] When a declaration of a function in a scope S is introducednamed by way of a using-declarationor ([namespace.udecl]), any default argument information associated with theany declaration is made known as wellD in S is available to any call from which D is reachable. If the function is redeclared thereafter in the namespace with additional default arguments, the additional arguments are also known at any point following the redeclaration where the using-declaration is in scope. [Note: D need not be reachable from the using-declaration. — end note]

[dcl.init]

Remove paragraph 13.

[dcl.init.aggr]

Change bullet (4.1):

If the element is an anonymous union objectvariable and the initializer list is a designated-initializer-list, the anonymous union objectvariable is initialized by the designated-initializer-list \{D\}, where D is the designated-initializer-clause naming a member of the anonymous union objectvariable. […]

[enum]

[dcl.enum]

Change paragraph 4:

If an enum-head-name contains a nested-name-specifier, it shall not begin with a decltype-specifier and the enclosing enum-specifier or opaque-enum-declaration shall refer to anthere shall be a preceding declaration of the enumeration that was previously declared directly inbelongs to the scope of the class (template) or namespace to which the nested-name-specifier refers, or in an element of the inline namespace set ([namespace.def]) of that namespace (i.e., neither inherited nor introduced by a using-declaration), and the enum-specifier or opaque-enum-declaration shall appear in a namespace scope enclosing the previous declaration.

Change paragraph 6:

An enumeration whose underlying type is fixed is an incomplete type from its point of declaration ([basic.scope.pdecl]) tountil immediately after its enum-base (if any), at which point it becomes a complete type. An enumeration whose underlying type is not fixed is an incomplete type from its point of declaration to immediately afteruntil the closing } of its enum-specifier, at which point it becomes a complete type.

Change paragraph 11:

Each enum-name andThe name of each unscoped enumeratorenumerator is declaredalso bound in the scope that immediately contains the enum-specifier. Each scoped enumerator is declared in the scope of the enumeration. These names obey the scope rules defined for all names in [basic.scope] and [basic.lookup]. [Example:

[…]

— end example] An enumerator declared in class scope can be referred to using the class member access operators (::, . (dot) and -> (arrow)), see [expr.ref]. [Example:

[…]

— end example]

[enum.udecl]

Change paragraph 2:

A using-enum-declaration introduces the enumerator names of the named enumeration as if byis equivalent to a using-declaration for each enumerator.

Change paragraph 3:

[Note: A using-enum-declaration in class scope addsmakes the enumerators of the named enumeration as members to the scope. This means they are accessible foravailable via member lookup. [Example:

[…]

— end example] — end note]

[basic.namespace]

Change paragraph 1:

A namespace is an optionally-named declarative regionentity whose scope can contain declarations of any kind of entity. The name of a namespace can be used to access entities declared inthat belong to that namespace; that is, the membersmembers of the namespace. Unlike other declarative regionsentities, the definition of a namespace can be split over several parts of one or more translation units and modules.

Change paragraph 2:

[Note: A namespace name with external linkagenamespace-definition is exported if any of its namespace-definition⁠sit is exported, or if it contains any export-declaration⁠s ([module.interface]). A namespace is never attached to a module, and its name never has module linkage even if it is not exported. — end note] [Example:

[…]

— end example]

Change paragraph 3:

The outermost declarative region of a translation unitre is a namespaceglobal namespace with no name and no declaration; see [basic.scope.namespace].

[namespace.def]

Change paragraph 1:

Every namespace-definition shall appear in the global scope or in a namespace scope ([basic.scope.namespace]).

Change paragraph 7:

Members of an inline namespace can be used in most respects as though they were members of the enclosing namespace. Specifically, the inline namespace and its enclosing namespace are both added to the set ofis an associated namespaces used in argument-dependent lookup ([basic.lookup.argdep]) whenever one of them isif a member is an associated entity, and a using-directive ([namespace.udir]) that names the inline namespace is implicitly inserted into the enclosing namespace as for an unnamed namespace ([namespace.unnamed]). Furthermore, each member of the inline namespace can subsequently be partially specialized ([temp.class.spec]), explicitly instantiated ([temp.explicit]), or explicitly specialized ([temp.expl.spec]) as though it were a member of the enclosing namespace. Finally, looking up a name in the enclosing namespace via explicit qualification ([namespace.qual]) will include members of the inline namespace brought in by the using-directive even if there are declarations of that name in the enclosing namespace.

Change paragraph 8:

These properties are transitive: if a namespace N contains an inline namespace M, which in turn contains an inline namespace O, then the members of O can be used as though they were members of M or N. The inline namespace set of N is the transitive closure of all inline namespaces in N. The enclosing namespace set of O is the set of namespaces consisting of the innermost non-inline namespace enclosing an inline namespace O, together with any intervening inline namespaces.

[namespace.memdef]

Remove subclause, referring the stable name to [namespace.def]. Remove the cross references in [namespace.def]/4 and [class.compare.default]/2, and update those in [temp.class.spec]/6 and [temp.expl.spec]/2 to refer to [dcl.meaning].

The examples in paragraphs 2 and 3 are moved to [dcl.meaning] and [class.friend]/11 respectively.

[namespace.udir]

Remove paragraph 2.

Change paragraph 3:

A using-directive does not add any members to the declarative region in which it appearsbind any names. [Note: Instead, unqualified and qualified lookup search the namespace nominated by a using-directive (including for further using-directive⁠s) when considering certain scopes that contain it ([basic.lookup.unqual], [basic.lookup.qual]). — end note] [Example:

[…]

— end example]

Remove paragraphs 4 and 5.

Change paragraph 7:

During overload resolution, all functions from the transitive search are considered for argument matching. The set of declarations found by the transitive search is unordered. [Note: In particular, tThe order in which namespaces weare considered and the relationships among the namespaces implied by the using-directive⁠s do not cause preference to be given to any of the declarations found by the searchaffect overload resolution. — end note] An ambiguity exists if the best match finds two functions withNeither is any function excluded because another has the same signature, even if one is in a namespace reachable through using-directive⁠s in the namespace of the other.^[…] — end note] [Example:

[…]

— end example]

[namespace.udecl]

Change and split paragraph 1:

Each using-declarator in a using-declaration^[…] introduces a set of declarations into the declarative region in which the using-declaration appears. Thenames the set of declarations introduced by the using-declarator is found by performing qualified name lookup ([basic.lookup.qual], [class.member.lookup]) for the name in the using-declarator, excludingexcept that class and enumeration declarations that would be discarded are merely ignored when checking for ambiguity ([basic.lookup]), conversion function templates are ignored, and certain functions that are hidden as described below. If the using-declarator is a qualified dependent name ([temp.dep.type]), it is considered to name a constructor if and only if the unqualified-id is the same as the terminal name of the nested-name-specifier. If the lookup in any instantiation finds that a using-declarator that is not considered to name a constructor does do so, or that a using-declarator that is considered to name a constructor does not, the program is ill-formed.

If the using-declarator does not name a constructor, the unqualified-id is declared in the declarative region in which the using-declaration appears as a synonym for each declaration introduced bybound to the using-declarator. [Note: Only the specified name is so declaredbound; specifying an enumeration name in a using-declaration does not declarebind the names of its enumerators in the using-declaration’s declarative region. During name lookup, the using-declarator is replaced with the declarations it names ([basic.lookup]). — ⁠end note] If the using-declarator names a constructor, it declares that the class inherits the named set of constructor declarations introduced by the using-declarator from the nominated base class. [Note: For the keyword typename, see [temp.res]. — end note]

Remove paragraph 2.

Change paragraph 3:

In a using-declaration used as a member-declaration, each using-declarator shall either name an enumerator or have a nested-name-specifier naming a base class of the enclosing class being defined. [Example:

[…]

— end example] If a using-declarator names a constructor, its nested-name-specifier shall name a direct base class of the enclosing class being defined. If the enclosing class scope is associated with a class template, it shall derive from the specified base class or have at least one dependent base class. [Example:

[…]

— end example] [Example:

[…]

— end example]

Change paragraph 4:

[Note: Since destructors do not have names, a using-declaration cannot refer to a destructor for a base class. Since specializations of member templates for conversion functions are not found by name lookup, they are not considered when a using-declaration specifies a conversion function ([temp.mem]). — end note] If a constructor or assignment operator brought from a base class into a derived class has the signature of a copy/move constructor or assignment operator for the derived class ([class.copy.ctor], [class.copy.assign]), the using-declaration does not by itself suppress the implicit declaration of the derived class member; the member from the base class is hidden or overridden by the implicitly-declared copy/move constructor or assignment operator of the derived class, as described below.

Remove paragraph 8.

Replace paragraph 9:

If a declaration is named by two using-declarator⁠s that belong to the same class scope, the program is ill-formed.

Change paragraph 10:

[Note: For aA using-declarationor whose nested-name-specifier names a namespace, members does not name declarations added to the namespace after the using-declaration are not in the set of introduced declarations, so they are not considered when a use of the name is madeit. Thus, additional overloads added after the using-declaration are ignored, but default function arguments ([dcl.fct.default]), default template arguments ([temp.param]), and template specializations ([temp.class.spec], [temp.expl.spec]) are considered. — end note] [Example:

[…]

— end example]

Change paragraph 12:

Since a using-declaration is a declaration, the restrictions on declarations of the same name in the same declarative region ([basic.scope]) also apply to using-declaration⁠s. A declaration named by a using-declaration that belongs to a scope S shall not conflict with another whose target scope is S. Two declarations named by using-declaration⁠s that belong to a scope shall not conflict unless they both declare functions or function templates. [Note: Overload resolution may not be able to distinguish between conflicting function declarations. — end note] [Example:

namespace A {
  int x;
  int f(int);
  int g;
  void h();
}

namespace B {
  int i;
  struct g { };
  struct x { };
  void f(int);
  void f(double);
  void g(char);     // OK: hides struct g
}

void func() {
  int i;
  using B::i;       // error: i declared twiceconflicts
  void f(char);
  using B::f;       // OK: each f is a function
  using A::f;       // OK, but merely prevents calling B::f(int)
  f(1);             // error: ambiguous
  f(3.5);           // calls B::f(double)
  using B::g;
  g('a');           // calls B::g(char)
  struct g g1;      // g1 has class type B::g
  using A::g;       // error: conflicts with B::g
  void h();
  using A::h;       // error: conflicts
  using B::x;
  using A::x;       // OK: hides struct B::x
  x = 99;           // assigns to A::x
  struct x x1;      // x1 has class type B::x
}

— end example]

Remove paragraph 13 (whose example is merged into the above).

Change paragraph 14:

WhenThe set of declarations named by a using-declarator brings declarations from a base class into a derived class,that belongs to a class C does not include member functions and member function templates in the derivedof a base class override and/or hidefor which C declares member functions and member function templates with the same name, parameter-type-list ([dcl.fct]), cv-qualification, and ref-qualifier (if any) in a base class (rather than conflicting). Such hidden or overridden declarations are excluded from the set of declarations introduced by the using-declarator. [Example:

[…]

— end example]

Chnage paragraph 16:

Constructors that are introducednamed by a using-declaration are treated as though they were constructors of the derived class when looking up the constructors of the derived class ([class.qual]) or forming a set of overload candidates ([over.match.ctor], [over.match.copy], [over.match.list]). [Note: If such a constructor is selected to perform the initialization of an object of class type, all subobjects other than the base class from which the constructor originated are implicitly initialized ([class.inhctor.init]). A constructor of a derived class is sometimes preferred to a constructor of a base class if they would otherwise be ambiguous ([over.match.best]). — end note]

Change paragraph 17:

In a using-declarator that does not name a constructor, all members of the set of introducedevery declarations named shall be accessible. In a using-declarator that names a constructor, no access check is performed. In particular, if a derived class uses a using-declarator to access a member of a base class, the member name shall be accessible. If the name is that of an overloaded member function, then all functions named shall be accessible. TheEvery base class members mentionednamed by a using-declarator shall be visible in the scopea result of a search for the terminal name of the using-declarator in at least one of the direct base classes of the class whereto which the using-declarator is specifiedbelongs.

Change paragraph 19:

A synonym created by a using-declaration has the usual accessibility for a member-declaration. ABase-class constructors considered because of a using-declarator that names a constructor does not create a synonym; instead, the additional constructors are accessible if they would be accessible when used to construct an object of the corresponding base class, and; the accessibility of the using-declaration is ignored. [Example:

[…]

— end example]

Remove paragraph 21.

[dcl.link]

Change paragraph 4:

Linkage specifications nest. When linkage specifications nest, the innermost one determines the language linkage. [Note: A linkage specification does not establish a scope. — end note] A linkage-specification shall occur only inbelong to a namespace scope ([basic.scope]). In a linkage-specification, the specified language linkage applies to the function types of all function declarators, function names with external linkage, and variable names with external linkage declared within the linkage-specification. [Example:

[…]

— end example] A C language linkage is ignored in determining the language linkage of the names of class members and the function type of class member functions. [Example:

[…]

— end example]

Change paragraph 5:

If two declarations declare functions with the same name and parameter-type-list ([dcl.fct]) to be members of the same namespace or declare objects with the same name to be members of the same namespace and the declarations give the names different language linkages, the program is ill-formed; no diagnostic is required if the declarations appear in different translation units. Except for functions with C++ linkage, a function declaration without a linkage specification shall not precede the first linkage specification for that function. A redeclaration of a function can be declared without a linkage specification after an explicit linkage specification has been seen; the linkage explicitly specified in the earlier declaration isdoes not affected by such a function declaration its language linkage.

[module]

[module.interface]

Change paragraph 1:

An export-declaration shall appear only atbelong to a namespace scope and onlyappear in the purview of a module interface unit. An export-declaration shall not appear directly or indirectly within an unnamed namespace or a private-module-fragment. An export-declaration has the declarative effects of its declaration or its declaration-seq (if any). An export-declaration does not establish a scope and itsThe declaration or declaration-seq of an export-declaration shall not contain an export-declaration. [Note: An export-declaration does not establish a scope.

[module.import]

Change paragraph 1:

In a module unit, all module-import-declaration⁠s shall precedeappear before all other top-level-declaration⁠s in the top-level-declaration-seq of the translation-unit and of the private-module-fragment (if any). The optional attribute-specifier-seq appertains to the module-import-declaration.

Change paragraph 2:

A module-import-declaration imports a set of translation units determined as described below. [Note: Namespace-scope names exported by the imported translation units become visiblecan be found by name lookup ([basic.scope.namespacelookup]) in the importing translation unit and declarations within the imported translation units become reachable ([module.reach]) in the importing translation unit after the import declaration. — end note]

[module.context]

Change paragraph 1:

The instantiation context is a set of points within the program that determines which namesdeclarations are visible tofound by argument-dependent name lookup ([basic.lookup.argdep]) and which declarations are reachable ([module.reach]) in the context of a particular declaration or template instantiation.

[module.reach]

Change paragraph 1:

A translation unit U is necessarily reachable from a point P if U is a module interface unit on which the translation unit containing P has an interface dependency, or the translation unit containing P imports U, in either case prior to P ([module.import]). [Note: While module interface units are reachable even when they are only transitively imported via a non-exported import declaration, namespace-scope names from such module interface units are not visible tofound by name lookup ([basic.scope.namespacelookup]). — end note]

Change paragraph 4:

The accumulated properties of all reachable declarations of an entity within a context determine the behavior of the entity within that context. [Note: These reachable semantic properties include type completeness, type definitions, initializers, default arguments of functions or template declarations, attributes, visibility of class or enumeration member names to ordinary lookupbound, etc. Since default arguments are evaluated in the context of the call expression, the reachable semantic properties of the corresponding parameter types apply in that context. [Example:

[…]

— end example] — end note]

Change paragraph 5:

[Note: An entity can have reachable declarations even if it is not visible tono declaration of it can be found by name lookup. — end note] [Example:

[…]

— end example]

[class]

Change paragraph 1:

[…]

A class declaration where the class-name in the class-head-name is a simple-template-id shall be an explicit specialization ([temp.expl.spec]) or a partial specialization ([temp.class.spec]). Otherwise, the identifier is not looked up. A class-specifier whose class-head omits the class-head-name defines an unnamed class. [Note: An unnamed class thus can’t be final. — end note]

Change paragraph 2:

A class-name is inserted into the scope in which it is declared immediately after the class-name is seen. The class-name is also inserted intobound in the scope of the class itself; this is known as the injected-class-name. […]

Change paragraph 3:

If a class-head-name contains a nested-name-specifier, there shall be a preceding declaration of the class-specifier shall refer to a class that was previously declared directly inbelongs to the scope of the class (template) or namespace to which the nested-name-specifier refers, or in an element of the inline namespace set ([namespace.def]) of that namespace (i.e., not merely inherited or introduced by a using-declaration), and the class-specifier shall appear in a namespace scope enclosing the previous declaration. In such cases, the nested-name-specifier of the class-head-name of the definition shall not begin with a decltype-specifier.

[class.name]

Change paragraph 2:

A class declaration introduces the class name into the scope where it is declared and hides any class, variable, function, or other declaration of that name in an enclosing scope ([basic.scope]). If[Note: It may be necessary to use an elaborated-type-specifier to refer to a class name is declared inthat belongs to a scope whereto which a variable, function, or enumerator of the same name is also declared, then when both declarations are in scope, the class can be referred to only using an elaborated-type-specifierbelongs ([basic.lookup.elab]). [Example:

[…]

— end example] — end note] [Note: An elaborated-type-specifier declaration consisting solely of class-key identifier; is either a redeclaration of the name in the current scope or a forward declaration of themay also be used to declare an identifier as a class name. It introduces the class name into the current scope. [Example:

[…]

— end example] — end note] [Note: Such declarations allow definition of classes that refer to each other. [Example:

[…]

Declaration of friends is described in [class.friend], operator functions in [over.oper]. — end example] — end note]

[class.mem]

Change paragraph 1:

[…] A direct member of a class X is a member of X that was first declared within the member-specification of X, including anonymous union objectsvariables ([class.union.anon]) and direct members thereof. […]

Insert before paragraph 6:

A closed context of a class (template) is a function body ([dcl.fct.def.general]) or noexcept-specifier ([except.spec]) within its member-specification.

Change paragraph 6:

A complete-class context of a class (template) is a closed context of the entity or a

1. function body ([dcl.fct.def.general]),
2. default argument ([dcl.fct.default]),
3. noexcept-specifier ([except.spec])default template argument ([temp.param]), or
4. default member initializer

within the member-specification of the class or class template. [Note: […] — end note][…]

[class.mfct]

Change paragraph 1:

AIf a member function may beis defined ([dcl.fct.def]) in its class definition, in which case it is an inline member function ([dcl.inline]), or it may be defined outside of its class definition if it has already been declared but not defined in its class definition. A member function definition that appears outside of the class definition shall appear in a namespace scope enclosing the class definition. Except for member function definitions that appear outside of a class definition, and except for explicit specializations of member functions of class templates and member function templates ([temp.spec]) appearing outside of the class definition, a member function shall not be redeclared.

Remove paragraph 4 except for its example.

[class.this]

Remove paragraphs 1 and 2.

[class.ctor]

Change paragraph 2:

A constructor is used to initialize objects of its class type. [Note: Because constructors do not have names, they are never found during unqualified name lookup; however an explicit type conversion using the functional notation ([expr.type.conv]) will cause a constructor to be called to initialize an object. [Note: The syntax looks like an explicit call of the constructor. — end note] [Example:

[…]

— end example] [Note: For initialization of objects of class type see [class.init]. — end note]

[class.conv]

Change paragraph 5:

User-defined conversions are used implicitly only if they are unambiguous. [Note: A conversion function in a derived class does not hide a conversion function in a base class unless the two functions convert to the same type. Function overload resolution ([over.match.best]) selects the best conversion function to perform the conversion. — end note] [Example:

[…]

— end example]

[class.conv.fct]

Change paragraph 1:

[…] specifies a conversion from X to the type specified by the conversion-type-id, interpreted as a type-id ([dcl.name]). […]

[class.static.data]

Change paragraph 2:

The declaration of a non-inline static data member in its class definition is not a definition and may be of an incomplete type other than cv void. The definition for a static data member that is not defined inline in the class definition shall appear in a namespace scope enclosing the member’s class definition. In the definition at namespace scope, the name of the static data member shall be qualified by its class name using the :: operator. [Note: The initializer expression in the definition of a static data member is in the scope of its class ([basic.scope.class]). — end note] [Example:

[…] — end example]

[Note: […] — end note]

[class.nest]

Change paragraph 1:

A class can be declared within another class. A class declared within another is called a nested class. The name of a nested class is local to its enclosing class. The nested class is in the scope of its enclosing class. [Note: See [expr.prim.id] for restrictions on the use of non-static data members and non-static member functions. — end note]

[Example:

[…]

— end example]

Change paragraph 4:

Like a member function, aA friend function ([class.friend]) defined within a nested class is in the lexical scope of that class; it obeys the same rules for name binding as a static member function of that class, but it has no special access rights to members of an enclosing class.

[class.nested.type]

Remove subclause, referring the stable name to [diff.basic].

[class.union.anon]

Change paragraph 1:

A union of the form

union { member-specification } ;

is called an anonymous union; it defines an unnamed type and an unnamed objectvariable of that type called an anonymous union objectvariable. Each member-declaration in the member-specification of an anonymous union shall either define aone or more non-static data members, in which case each member-declarator is considered to be a declaration of the named member of the anonymous union variable, or be a static_assert-declaration. [Note: Nested types, anonymous unions, and functions cannot be declared within an anonymous union. — end note] The names of the members of an anonymous union are bound in the scope that encloses the union declaration and shall be distinct from the names of any other entity in theat scope in which the anonymous union is declared. For the purpose of name lookup, after the anonymous union definition, the members of the anonymous union are considered to have been defined in the scope in which the anonymous union is declared. [Example:

[…]

Here a and p are used like ordinary (non-member) variables, but since they are union members they have the same address. — end example]

[class.local]

Change paragraph 1:

A class can be declared within a function definition; such a class is called a local class. The name of a local class is local to its enclosing scope. The local class is in the scope of the enclosing scope, and has the same access to names outside the function as does the enclosing function. [Note: […] — end note] [Example:

[…]

— end example]

[class.derived]

Change paragraph 2:

A class-or-decltype shall denote a (possibly cv-qualified) class type that is not an incompletely defined class ([class.mem]); any cv-qualifiers are ignored. The class denoted by the class-or-decltype of a base-specifier is called a direct base class for the class being defined. During the lookup for a base classthe name in the type-name or simple-template-id, non-type names are ignored ([basic.scope.hidinglookup]). A class B is a base class of a class D if it is a direct base class of D or a direct base class of one of D’s base classes. A class is an indirect base class of another if it is a base class but not a direct base class. A class is said to be (directly or indirectly) derived from its (direct or indirect) base classes. [Note: See [class.access] for the meaning of access-specifier. — end note] Unless redeclared in the derived class, members of a base class are also considered to be members of the derived class. Members of a base class other than constructors are said to be inherited by the derived class and are also considered to be members of it. Constructors of a base class can also be inherited as described in [namespace.udecl]. [Note: Inherited members can be referred to in expressions in the same manner as other members of the derived class, unless their names are hidden or ambiguous ([class.member.lookup]). [Note: The scope resolution operator :: ([expr.prim.id.qual]) can be used to refer to a direct or indirect base member explicitly. This allows access to a name that has been redeclared in the derived class. A derived class can itself serve as a base class subject to access control; see [class.access.base]. A pointer to a derived class can be implicitly converted to a pointer to an accessible unambiguous base class ([conv.ptr]). An lvalue of a derived class type can be bound to a reference to an accessible unambiguous base class ([dcl.init.ref]). — end note]

[class.access]

Change paragraph 1:

A member of a class can be

1. private; that is, its name can be usnamed only by members and friends of the class in which it is declared.
2. protected; that is, its name can be usnamed only by members and friends of the class in which it is declared, by classes derived from that class, and by their friends (see [class.protected]).
3. public; that is, its name can be usnamed anywhere without access restriction.

[Note: A constructor or destructor can be named by an expression ([basic.def.odr]) even though it has no name. — end note]

Change paragraph 2:

A member of a class can also access all the namemembers to which the class has access. A local class of a member function may access the same namemembers that the member function itself may access.^[…]

Change paragraph 5:

[Note: Access to members and base classes is controlled, not their visibility ([basic.scope.hiding]). Names of does not prevent members are still visible, andfrom being found by name lookup or implicit conversions to base classes are stillfrom being considered, when those members and base classes are inaccessible. — end note] The interpretation of a given construct is established without regard to access control. If the interpretation established makes use of inaccessible member names or base classes, the construct is ill-formed.

Change paragraph 8:

TAccess is checked for the names in a default argument ([dcl.fct.default]) are bound at the point of declaration, and access is checked at that point rather than at any points of use of the default argument. Access checking for default arguments in function templates and in member functions of class templates is performed as described in [temp.inst].

[class.friend]

Change paragraph 2:

Declaring a class to be a friend implies that the names of private and protected members from the class granting friendship can be accessed in the base-specifier⁠s and member declarations of the befriended class. [Example:

[…]

— end example] [Example:

[…]

— end example]

A class shall not be defined in a friend declaration. [Example:

[…]

— end example]

Change paragraph 5:

When a[Note: A friend declaration refers to an overloadedentity, not (all overloads of) a name or operator, only the function specified by the parameter types becomes a friend. — end note] A member function of a class X can be a friend of a class Y. [Example:

[…]

— end example]

Change paragraph 6:

A function can be defined in a friend declaration of a class if and only if the class is a non-local class ([class.local]), and the function name is unqualified, and the function has namespace scope. [Example:

[…]

— end example]

Change paragraph 7:

Such a function is implicitly an inline function ([dcl.inline]). A[Note: If a friend function is defined inoutside a class, it is not in the (lexical) scope of the class in which it is defined. A friend function defined outside the class is not ([basic.lookup.unqual]).— end note]

Replace paragraph 11, adding the example from [namespace.memdef]/3 and then retaining its example:

[Note: A friend declaration never binds any names ([dcl.meaning], [dcl.type.elab]). — end note] [Example:

[…]

— end example] [Example:

[…]

— end example]

[class.paths]

Change paragraph 1:

If a namedeclaration can be reached by several paths through a multiple inheritance graph, the access is that of the path that gives most access. [Example:

[…] — end example]

[class.base.init]

Change paragraph 2:

ILookup for an unqualified name in a mem-initializer-id an initial unqualified identifier is looked up in the scope of the constructor’s class and, if not found in that scope, it is looked up in the scope containing the constructor’s definitionignores the constructor’s function parameter scope. [Note: If the constructor’s class contains a member with the same name as a direct or virtual base class of the class, a mem-initializer-id naming the member or base class and composed of a single identifier refers to the class member. A mem-initializer-id for the hidden base class may be specified using a qualified name. — end note] Unless the mem-initializer-id names the constructor’s class, a non-static data member of the constructor’s class, or a direct or virtual base of that class, the mem-initializer is ill-formed.

Change paragraph 15:

Names in t[Note: The expression-list or braced-init-list of a mem-initializer are evaluatedis in the function parameter scope of the constructor for which the mem-initializer is specified.and can use this to refer to the object being initialized. — end note] [Example:

[…]

initializes X::r to refer to X::a, initializes X::b with the value of the constructor parameter i, initializes X::i with the value of the constructor parameter i, and initializes X::j with the value of X::i; this takes place each time an object of class X is created. — end example] [Note: Because the mem-initializer are evaluated in the scope of the constructor, the this pointer can be used in the expression-list of a mem-initializer to refer to the object being initialized. — end note]

[class.free]

Change paragraph 7:

Access to the deallocation function is checked statically. Hence, even though a different one might actually be executed, the statically visible deallocation function is required to be accessible. [Example: For the call on line “// 1” above, if B::operator delete() had been private, the delete expression would have been ill-formed. — end example]

[over]

Change paragraph 2:

When a function name is usnamed in a call, which function declaration is being referenced and the validity of the call are determined by comparing the types of the arguments at the point of use with the types of the parameters in the declarations that are visible at the point of usein the overload set. This function selection process is called overload resolution and is defined in [over.match]. [Example:

[…]

— end example]

[over.dcl]

Remove paragraph 2.

[over.match.funcs]

Insert before paragraph 7:

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: This search may find a specialization of a conversion function template ([basic.lookup]). — end note] Each case also defines sets of other permissible types (that are suitable for the initialization) for explicit and non-explicit conversion functions; each such conversion function that is a non-hidden member of S and yields a permissible type is a candidate function. If initializing an object, for any permissible type cv U, cv U& and any cv2 U are also permissible types. If the set of permissible types for explicit conversion functions is empty, any search results that are explicit are not candidates.

Change paragraph 7:

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 aadmits only candidates that isare 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.^[…] A given name can refer to, or a conversion can consider, one or more function templates and also toas well as a set of overloaded 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.

[over.call.func]

Change paragraph 1:

Of interest in [over.call.func] are only those function calls in which the postfix-expression ultimately contains a namen id-expression that denotes one or more functions that might be called. […]

Change paragraph 2:

In qualified function calls, the name to be resolvedfunction is named by 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.^[…] 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 thatname 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]).

Change paragraph 3:

In unqualified function calls, the function is named 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 thatname lookup ([basic.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 current class is or is derived from T and the keyword this ([classexpr.prim.this]) is in scope and refers to class T, or a derived class of Tit, then the implied object argument is (*this). If the keyword this is not in scope or refers to another class, thenOtherwise, a contrived object of type T becomes the implied object argument.^[…]; Iif the argument list is augmented by a contrived object and overload resolution selects one of thea non-static member functions of T, the call is ill-formed.

[over.call.object]

Change paragraph 1:

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 lookupthe results of a search for the name operator() in the contextscope of (E).operator()T.

[over.match.oper]

Change bullet (3.2):

TFor the operators =, [], or ->, the set of non-member candidates is empty; otherwise, it includes the result of the unqualified lookup offor operator@ in the context of the expression according to the usual rules for name lookup in unqualifiedin the rewritten function calls ([basic.lookup.argdep]) except that, ignoring 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.

[over.match.copy]

Change bullet (1.2):

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. 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 possibly cv-qualified T” and the constructor is called with a single argument in the context of direct-initialization of an object of type “cv2 T”, the permissible types for explicit conversion functions are also consideredthe same; otherwise there are none. 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.

[over.match.conv]

Change paragraph 1:

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:

1. The conversion functions of S and its base classes are considered. Thosepermissible types for non-explicit conversion functions that are not hidden within S and yield type T or a typethose that can be converted to type T via a standard conversion sequence ([over.ics.scs]) are candidate functions. For direct-initialization, thosethe permissible types for explicit conversion functions that are not hidden within S and yield type T or a typethose that can be converted to type T with a (possibly trivial) qualification conversion ([conv.qual]) are also candidate functions; otherwise there are none. 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.

[over.match.ref]

Change paragraph 1:

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:

1. The conversion functions of S and its base classes are considered. Those non-explicit conversion functions that are not hidden within S and yieldLet R be a set of types including “lvalue reference to cv2 T2” (when initializing an lvalue reference or an rvalue reference to function) orand “cv2 T2” orand “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”, are candidate functions. For direct-initialization, thosethe permissible types for 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),the members of R where T2 is the same type as T or can be converted to type T with a (possibly trivial) qualification conversion ([conv.qual]), are also candidate functions; otherwise there are none.

[over.match.best]

Change paragraph 4:

If the best viable function resolves to a function for which multiple declarations were found, and if at leastany two of these declarations — or the declarations they refer to in the case of using-declaration⁠s — specify a default argument for the same parameter that made the function viable, the program is ill-formed. [Example:

[…]

— end example]

[over.over]

Change paragraph 1:

A use of an id-expression that names an overloaded function name set without arguments is resolved in certain contexts to a function, a pointer to function or a pointer to member function for a specific function from the overload set. A function template name is considered to name a set of overloaded functions in such contexts. A function with type F is selected for the function type FT of the target type required in the context if F (after possibly applying the function pointer conversion ([conv.fctptr])) is identical to FT. [Note: That is, the class of which the function is a member is ignored when matching a pointer-to-member-function type. — end note] The target can be

1. an object or reference being initialized ([dcl.init], [dcl.init.ref], [dcl.init.list]),
2. the left side of an assignment ([expr.ass]),
3. a parameter of a function ([expr.call]),
4. a parameter of a user-defined operator ([over.oper]),
5. the return value of a function, operator function, or conversion ([stmt.return]),
6. an explicit type conversion ([expr.type.conv], [expr.static.cast], [expr.cast]), or
7. a non-type template-parameter ([temp.arg.nontype]).

The overloaded function nameid-expression can be preceded by the & operator. An id-expression that names an overloaded function name set shall not be used without arguments in contexts other than those listed. [Note: Any redundant set of parentheses surrounding the overloaded function name is ignored ([expr.prim.paren]). — end note]

Change paragraph 2:

If the id-expression is a template-id or name is a function template, template argument deduction is done ([temp.deduct.funcaddr]), and if the argument deduction succeeds, the resulting template argument list is used to generate a single function template specialization, which is added to the set of overloaded functions considered. [Note: […] — end note]

Change paragraph 3:

Non-member functions and static member functions match targets of function pointer type or reference to function type. Non-static member functions match targets of pointer-to-member-function type. [Note: If a non-static member function is selected, the reference to the overloaded function name is required to have the form ofresult can be used only to form a pointer to member as described in ([expr.unary.op]). — end note]

[over.oper]

[over.unary]

Change paragraph 2:

[Note: The unary and binary forms of the same operator are considered to have the same name. [Note: Consequently, a unary operator can hide a binary operator from an enclosing scope, and vice versa. — end note]

[over.literal]

Change paragraph 2:

A declaration whose declarator-id is a literal-operator-id shall be a declaration ofe a namespace-scope function or function template that belongs to a namespace (it could be a friend function ([class.friend])), or an explicit instantiation or specialization of a function template, or a using-declaration ([namespace.udecl]). A function declared with a literal-operator-id is a literal operator. A function template declared with a literal-operator-id is a literal operator template.

[temp]

Change paragraph 4:

A template-declaration can appear only as a namespace scope or class scope declaration. Its declaration shall not be an export-declaration. In a function template declaration, the last component of the declarator-id shall not be a template-idname. [Note: That last component may be an identifier, an operator-function-id, a conversion-function-id, or a literal-operator-id. In a class template declaration, if the class nameclass-name is a simple-template-id, the declaration declares a class template partial specialization ([temp.class.spec]). — end note]

Change paragraph 8:

[Note: A class template shall not have the same name as any other template, class, function, variable, enumeration, enumerator, namespace, or typename bound in the same scope ([basic.scope]), except as specified in [temp.class.spec]. Except that a function template can be overloaded either bywith non-template functions ([dcl.fct]) with the same name or by otherand/or function templates with the same name ([temp.over]), a template name declared in namespace scope or in class scope shall be unique in that scope. Specializations, including partial specializations ([temp.class.spec]), do not bind names. — end note]

[temp.param]

Change paragraph 14:

A template-parameter shall not be given default arguments by two different declarations in the same scopeif one is reachable from the other. [Example:

[…]

— end example]

[temp.names]

Remove the note in paragraph 1.

Change paragraph 2:

For a template-name to be explicitly qualified by the template arguments, the name must be considered to refer to a template. [Note: Whether a name actually refers to a template cannot be known in some cases until after argument dependent lookup is done ([basic.lookup.argdep]). — end note] A name< is considered to refer tointerpreted as the delimiter of a templatetemplate-argument-list if it follows a name, other than a conversion-function-id,

1. that follows the keyword template after a nested-name-specifier or in a class member access expression, or
2. for which name lookup finds the injected-class-name of a class template or finds a template-name or an overload set that contains a function template.ny declaration of a template that, unless the name is in a closed context of a class or class template ([class.mem]), precedes the name, or
3. A name is also considered to refer to a template if itthat is an unqualified-idunqualified name followed by a < and name lookup either finds one or more functions or finds nothing., or
4. that is an unqualified or terminal name in a using-declarator ([namespace.udecl]), a declarator-id ([dcl.meaning]), or a type-only context ([temp.res]).

[Note: If the name is an identifier, it is then interpreted as a template-name. The keyword template is used to indicate that a qualified dependent name ([temp.dep.type]) denotes a template where an expression might appear or that a name in a class member access ([expr.ref]) is not dependent because it is part of a nested-name-specifier. — end note] If a simple-template-id results and is followed by a ::, the name is looked up as part of a nested-name-specifier, discarding any previous lookup result.

Move the example from paragraph 4 to the end of paragraph 2.

Change paragraph 3:

When a name is considered to be a template-name, and it is followed by a <, the < is always taken as the delimiter of a template-argument-list and never as the less-than operator. When parsing a template-argument-list, the first non-nested >^[…] is taken as the ending delimiter rather than a greater-than operator. Similarly, the first non-nested >> is treated as two consecutive but distinct > tokens, the first of which is taken as the end of the template-argument-list and completes the template-id. [Note: The second > token produced by this replacement rule may terminate an enclosing template-id construct or it may be part of a different construct (e.g., a cast).— end note] [Example:

[…]

— end example]

Change paragraph 4:

The keyword template is said toshall not appear at the top leveldirectly in a qualified-id if it appears outside of a template-argument-list or decltype-specifier. In a qualified-id of a declarator-id or in a qualified-id formed by a class-head-name ([class]) or enum-head-name ([dcl.enum]), the keyword template shall not appear at the top levelnor directly in the nested-name-specifier of such a qualified-id or (recursively) of such a nested-name-specifier. In a qualified-id used as the name in a typename-specifier ([temp.res]), elaborated-type-specifier ([dcl.type.elab]), using-declaration ([namespace.udecl]), or class-or-decltype ([class.derived]), an optional keyword template appearing at the top level is ignored. In these contexts, a < token is always assumed to introduce a template-argument-list. In all other contexts, when naming a template specialization of a member of an unknown specialization ([temp.dep.type]), the member template name shall be prefixed by the keyword template. [Example:

[…]

— end example]

Change paragraph 5:

A name prefixed by the keyword template shall be a template-idfollowed by a template argument list or the name shall refer to a class template or an alias template. The latter case is deprecated ([depr.template.template]). The keyword template shall not appear immediately before a ~ token (as to name a destructor). [Note: The keyword template may not be applied to non-template members of class templates. — end note][Note: As is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the nested-name-specifier or the expression on the left of the -> or . is not dependent on a template-parameter, or the use does not appear in the scope ofeven when lookup for the name would already find a template. — end note] [Example:

[…]

— end example]

Change paragraph 8:

When the template-name of a simple-template-id names a constrained non-function template or a constrained template template-parameter, but not a member template that is a member of an unknown specialization ([temp.res]), and all template-argument⁠s in the simple-template-id are non-dependent ([temp.dep.temp]), the associated constraints ([temp.constr.decl]) of the constrained template shall be satisfied ([temp.constr.constr]). [Example:

[…]

— end example]

[temp.arg]

Change paragraph 3:

The nNames ofused in a template-argument shall be accessible at the point where it is used as a template-argumentare subject to access control where they appear. [Note: If the name of the template-argument is accessible at the point where it is used as a template-argument, there is no further access restriction in the resulting instantiation where the correspondingSince a template-parameter name is usednot a class member, no access control applies. — end note] [Example:

[…]

— end example] For a template-argument that is a class type or a class template, the template definition has no special access rights to the members of the template-argument. [Example:

[…]

— end example]

Change paragraph 7:

When name lookup for the name in a template-id finds an overload set, both non-template functions in the overload set and function templates in the overload set for which the template-argument⁠s do not match the template-parameter⁠s are ignored. [Note: If none of the function templates have matching template-parameter⁠s, the program is ill-formed. — end note]

[temp.arg.template]

Change paragraph 2:

Any partial specializations ([temp.class.spec]) associated with the primary class template or primary variable template are considered when a specialization based on the template template-parameter is instantiated. If a specialization is not visible atreachable from the point of instantiation, and it would have been selected had it been visible, the program is ill-formed, no diagnostic required. [Example:

[…]

— end example]

[temp.decls]

[temp.mem]

Remove paragraph 6.

[temp.friend]

Change paragraph 1:

A friend of a class or class template can be a function template or class template, a specialization of a function template or class template, or a non-template function or class. For a friend function declaration that is not a template declaration:

1. if the name of the friendunqualified-id in the declarator-id is a qualified or unqualified template-id, the friend declaration refers to a specialization of a function template, otherwise,
2. if the name of the frienddeclarator-id is a qualified-id and a matching non-template function is found in the specified class or namespace, the friend declaration refers to that function, otherwise,
3. if the name of the frienddeclarator-id is a qualified-id and a matching function template is found in the specified class or namespace, the friend declaration refers to the deduced specialization of that function template ([temp.deduct.decl]), otherwise,
4. the namedeclarator-id shall be an unqualified-id that declares (or redeclares) a non-template function.

[Example:

[…] — end example]

[temp.class.spec]

Change paragraph 1:

A primary class template declaration is one in which the class template nameclass-name is an identifier. A template declaration in which the class template nameclass-name is a simple-template-id is a partial specialization of the class template named in the simple-template-id. A partial specialization of a class template provides an alternative definition of the template that is used instead of the primary definition when the arguments in a specialization match those given in the partial specialization ([temp.class.spec.match]). TA declaration of the primary template shall be declared beforeprecede any specializations of that template. A partial specialization shall be declared before the firstbe reachable from any use of a class template specialization that would make use of the partial specialization as the result of an implicit or explicit instantiation in every translation unit in which such a use occurs; no diagnostic is required.

Change paragraph 7:

Partial specialization declarations themselves are not found by name lookupdo not introduce a name. RatherInstead, when the primary template name is used, any previously-declaredreachable partial specializations of the primary template are also considered. One consequence is that a using-declaration which refers to a class template does not restrict the set of partial specializations which may be found through the using-declaration. [Example:

[…]

— end example]

Insert before paragraph 8:

A specialization of a class template partial specialization that has been declared but not defined is an incomplete type ([basic.types]).

[temp.over.link]

Change paragraph 5:

Two expressions involving template parameters are considered equivalent if two function definitions containing the expressions would satisfy the one-definition rule ([basic.def.odr]), except that the tokens used to name the template parameters may differ as long as a token used to name a template parameter in one expression is replaced by another token that names the same template parameter in the other expression. Two lambda-expression⁠s are never considered equivalent. [Note: The intent is to avoid lambda-expression⁠s appearing in the signature of a function template with external linkage. — end note] For determining whether two dependent names ([temp.dep]) are equivalent, only the name itself is considered, not the result of name lookup in the context of the template. [Note: If multiple declarations of the same function template differ in the result of thissuch a dependent name lookupis unqualified, the result forit is looked up from the first declaration is usedof the function template ([temp.dep.candidate]). — end note] [Example:

[…]

— end example] Two expressions involving template parameters that are not equivalent are functionally equivalent if, for any given set of template arguments, the evaluation of the expression results in the same value.

[temp.res]

Replace paragraph 1:

A name that appears in a template declaration is looked up from where it appears in the first declaration of the template that contains it. A dependent name is looked up for each specialization (after substitution) because the lookup depends on a template parameter, as described in [temp.dep]. [Note: Uses of other names might be type-dependent or value-dependent ([temp.dep.expr], [temp.dep.constexpr]). A using-declarator is never dependent in a specialization and is therefore replaced during lookup for a dependent name ([basic.lookup]). — end note] [Example:

struct A {operator int();};
template<class B,class T>
struct D : B {
  T get() {return operator T();}     // conversion-function-id is dependent
};
int f(D<A,int> d) {return d.get();}  // OK: lookup finds A::operator int

— end example]

Move the example from paragraph 10 and the second example from [temp.dep]/4 to the end of paragraph 1.

Replace paragraph 2 (but not the grammar following it):

If the validity or meaning of the program would be changed by considering a default argument or default template argument introduced in a declaration that is reachable from the point of instantiation of a specialization ([temp.point]) but is not found by lookup for the specialization, the program is ill-formed, no diagnostic required.

Change paragraph 3:

A typename-specifier denotes the type or class template denoted by the simple-type-specifier ([dcl.type.simple]) formed by omitting the keyword typename. [Note: The usual qualified name lookup ([basic.lookup.qual]) is used to find the qualified-idapplies even in the presence of typename. — end note] [Example:

[…]

— end example]

Replace paragraph 4:

A name appears as a type in a construct if it is the construct or appears in it outside of any enclosed expression or template argument.

Change paragraph 5:

A qualified-idqualified or unqualified name is assumedsaid to namebe in a type-only context if

1. it appears as a type in a typename-specifier, nested-name-specifier, elaborated-type-specifier, or class-or-decltype,
2. it appears as a type in a new-type-id, defining-type-id, or conversion-type-id,
3. it is a qualified name in a type-id-only context (see below)appears as a type in a type-id that is a trailing-return-type, the default argument of a type-parameter, or the type-id of a static_cast, const_cast, reinterpret_cast, or dynamic_cast, or
4. it, or a template-id of which it is the name, is a decl-specifier of the decl-specifier-seq of a
   1. simple-declaration or a function-definition in namespace scope,
   2. member-declaration,
   3. parameter-declaration in a member-declaration^[…], unless that parameter-declaration appears in a default argument,
   4. parameter-declaration in a declarator of a function or function template declaration whose declarator-id is qualified, unless that parameter-declaration appears in a default argument,
   5. parameter-declaration in a lambda-declarator, unless that parameter-declaration appears in a default argument, or
   6. parameter-declaration of a (non-type) template-parameter.

A qualified name is said to be in a type-id-only context if it appears in a type-id, new-type-id, or defining-type-id and the smallest enclosing type-id, new-type-id, or defining-type-id is a new-type-id, defining-type-id, trailing-return-type, default argument of a type-parameter of a template, or type-id of a static_cast, const_cast, reinterpret_cast, or dynamic_cast. [Example:

[…]

— end example]

Change paragraph 6:

A qualified-id that refers to a member of an unknown specialization, that is not prefixed by typename, andqualified dependent name that is not otherwise assumed to namein a type-only context (see above) denotesis interpreted as a non-qualified-id, not a type. A name that refers to a dependent using-declarator is interpreted as a typedef-name if the using-declarator uses the keyword typename and as an unqualified-id otherwise. [Example:

[…]

— end example]

Remove paragraphs 7, 9, and 10 (whose example is moved to paragraph 1).

[temp.local]

Change paragraph 3:

The injected-class-name of a class template or class template specialization can be used as either a template-name or a type-name wherever it is in scopenamed. [Example:

[…]

— end example]

Change paragraph 6:

AThe name of a template-parameter shall not be redeclared within itsby a subsequent declaration contained by the scope (including nested scopes)to which the template-parameter belongs. A template-parameter shall not have the same name as the template name. [Example:

[…]

— end example]

Change paragraph 7:

In the definition of a memberUnqualified name lookup considers the template parameter scope of a template-declaration before any scope that contains the template declared (even if it does not contain the template-parameter-list). [Note: The scope of a class template that appears outside of the class template definition, the name of a member of the class template hides the name of a template-parameter of any enclosing class templates (but not a template-parameter of the member if the member is a class or function template), including its non-dependent base classes ([temp.dep.type], [class.member.lookup]), is searched before its template parameter scope. — end note] [Example:

struct B { };
namespace N {
  typedef void V;
  template<class T> struct A : B {
  struct B { /* ... */ };
    typedef void C;
    void f();
    template<class U> void g(U);
  };
}

template<class BV> void N::A<BV>::f() {
  BV bv;              // A's B, notV is the template parameter, not N::V
}

template<class B> template<class C> void N::A<B>::g(C) {
  B b;              // A's Bthe base class, not the template parameter
  C c;              // the template parameter C, not A's C
}

— end example]

Remove paragraphs 8 and 9 (whose examples are merged into the above).

[temp.dep]

Change paragraph 2:

IThe name in an unqualified-id is dependent if it is a conversion-function-id whose conversion-type-id is dependent or the unqualified-id is the postfix-expression in an expression of the form:

postfix-expression ( expression-list_opt )

where the postfix-expression is an unqualified-id, the unqualified-id denotes a dependent name ifincluding when finding non-member candidates for an operator ([over.match.oper]), and

1. any of the expressions in the expression-list is a pack expansion ([temp.variadic]),
2. any of the expressions or braced-init-list⁠s in the expression-list is type-dependent ([temp.dep.expr]), or
3. the unqualified-id is a template-id in which any of the template arguments depends on a template parameter.

If an operand of an operator is a type-dependent expression, the operator also denotes a dependent name. [Note: Such names are unbound and are looked up only at the point of the template instantiation ([temp.point]) in both the context of the template definition and the context of the point of instantiation ([temp.dep.candidate]). — end note]

Remove paragraph 4.

[temp.dep.type]

Change paragraph 1:

A name or template-id refers to the current instantiation if it is

[…]

Change paragraph 5:

A qualified ([basic.lookup.qual]) or unqualified name is a member of the current instantiation if it is

1. its lookup context, if it is a qualified name, is the current instantiation, and
2. An unqualified name that, when looked up, refers to at least onelookup for it (or its terminal name) finds any (perhaps inherited) member of a class that is the current instantiation or a non-dependent base class thereof. [Note: This can only occur when looking up a name in a scope enclosed by the definition of a class template. — end note]
3. A qualified-id in which the nested-name-specifier refers to the current instantiation and that, when looked up, refers to at least one member of a class that is the current instantiation or a non-dependent base class thereof. [Note: If no such member is found, and the current instantiation has any dependent base classes, then the qualified-id is a member of an unknown specialization; see below. — end note]
4. An id-expression denoting the member in a class member access expression ([expr.ref]) for which the type of the object expression is the current instantiation, and the id-expression, when looked up ([basic.lookup.classref]), refers to at least one member of a class that is the current instantiation or a non-dependent base class thereof. [Note: If no such member is found, and the current instantiation has any dependent base classes, then the id-expression is a member of an unknown specialization; see below. — end note]

[Example:

[…]

— end example]

A qualified or unqualified name is a dependent member of the current instantiation if it is a member of the current instantiation that, when looked up, refers to denotes at least one direct member of a class that is the current instantiation.

Change paragraph 6:

A qualified name ([basic.lookup.qual]) is a member of an unknown specializationdependent if it is not a member-qualified name that is a nested-name-specifier and

1. its terminal name is a conversion-function-id whose conversion-type-id is dependent, or
2. A qualified-id in which the nested-name-specifier namesits lookup context is a dependent type thatand is not the current instantiation., or
3. A qualified-id in which the nested-name-specifier refers toits lookup context is the current instantiation, the current instantiation and has at least one dependent base class, and name lookup offor the terminal name of the qualified-idqualified name does not find any member of a class that is the current instantiation or a non-dependent base class thereofs nothing ([basic.lookup.qual]).
4. […]

A class member access expression is dependent if its id-expression is.

Change paragraph 7:

If a qualified-id in which the nested-name-specifier refers toqualified name (but not a member-qualified name that is a nested-name-specifier) whose lookup context is the current instantiation is not dependent and is not a member of the current instantiation or a member of an unknown specialization, the program is ill-formed even if the template whose definition containings the qualified-idqualified name is not instantiated; no diagnostic required. Similarly, if the id-expression in a class member access expression for which the type of the object expression is the current instantiation does not refer to a member of the current instantiation or a member of an unknown specialization, the program is ill-formed even if the template containing the member access expression is not instantiated; no diagnostic required. [Example:

[…]

— end example]

Change paragraph 8:

If, for a given set of template arguments, a specialization of a template is instantiated that refers to a member of the current instantiation with a qualified-id or class member access expressionqualified name, theits terminal name in the qualified-id or class member access expression is looked up in the template instantiation context. If the result of this lookup differs from the result of name lookup in the template definition context, name lookup is ambiguous. [Example:

[…]

— end example]

Change paragraph 9:

A type is dependent if it is

1. a template parameter,
2. denoted by a member of an unknown specialization(qualified) dependent name,
3. a nested class or enumeration that is a dependentdirect member of a class that is the current instantiation,
4. a cv-qualified type where the cv-unqualified type is dependent,
5. a compound type constructed from any dependent type,
6. an array type whose element type is dependent or whose bound (if any) is value-dependent,
7. a function type whose exception specification is value-dependent,
8. denoted by a simple-template-id in which either the template name is a template parameter or any of the template arguments is a dependent type or an expression that is type-dependent or value-dependent or is a pack expansion [Note: This includes an injected-class-name ([class]) of a class template used without a template-argument-list. — end note], or
9. denoted by decltype(expression), where expression is type-dependent ([temp.dep.expr]).

[temp.dep.expr]

Change paragraph 2:

this is type-dependent if the current class type of the enclosing member function is dependent ([temp.dep.type]).

Change paragraph 3:

An id-expression is type-dependent if it contains

1. an identifier name associated by name lookup with one or more declarations declared with a dependent type,
2. an identifier name associated by name lookup with a non-type template-parameter declared with a type that contains a placeholder type ([dcl.spec.auto]),
3. an identifier name associated by name lookup with a variable declared with a type that contains a placeholder type ([dcl.spec.auto]) where the initializer is type-dependent,
4. an identifier name associated by name lookup with one or more declarations of member functions of a class that is the current instantiation declared with a return type that contains a placeholder type,
5. an identifier name associated by name lookup with a structured binding declaration ([dcl.struct.bind]) whose brace-or-equal-initializer is type-dependent,
6. the identifier __func__ ([dcl.fct.def.general]), where any enclosing function is a template, a member of a class template, or a generic lambda,
7. a template-id that is dependent,
8. a conversion-function-id that specifies a dependent type, or
9. a nested-name-specifier or a qualified-id that names a member of an unknown specializationdependent name;

or if it names a dependentdirect member of a class that is the current instantiation that is a static data member of type “array of unknown bound of T” for some T ([temp.static]). Expressions of the following forms are type-dependent only if the type specified by the type-id, simple-type-specifier or new-type-id is dependent, even if any subexpression is type-dependent:

[…]

Change paragraph 5:

A class member access expression ([expr.ref]) is type-dependent if the expressionit is dependent or it refers to a member of the current instantiation and the type of the referenced member is dependent, or the class member access expression refers to a member of an unknown specialization. [Note: In an expression of the form x.y or xp->y the type of the expression is usually the type of the member y of the class of x (or the class pointed to by xp). However, if x or xp refers to a dependent type that is not the current instantiation, the type of y is always dependent. If x or xp refers to a non-dependent type or refers to the current instantiation, the type of y is the type of the class member access expression. — end note]

[temp.dep.temp]

Change paragraph 4:

A template template-argument is dependent if it names a template-parameter or is a qualified-id that refers to a member of an unknown specializationdependent name.

[temp.nondep]

Remove subclause, referring the stable name to [temp.res] and removing the one cross reference (in [basic.def.odr]/12).

[temp.dep.candidate]

Change paragraph 1:

For a function call where the postfix-expression is a dependent name, the candidate functions are found using the usual lookup rules from the template definition context ([basic.lookup.unqual], [basic.lookup.argdep]). [Note: For the part of the lookup using associated namespaces ([basic.lookup.argdep]), function declarations found in the template instantiation context are found by this lookup, as described in [basic.lookup.argdep]. — end note] If thea function call whose postfix-expression is an unqualified dependent name would be ill-formed or would find a better match had the lookup for the name within the associated namespaces considered all the function declarations with external linkage introduced in those namespaces in all translation units, not just considering those declarations found in the template definition and template instantiation contexts ([basic.lookup.argdep]), then the program has undefined behavioris ill-formed, no diagnostic required.

[temp.inject]

Change paragraph 1:

Friend classes or, class templates, functions, or function templates can be declared within a class template. When a template is instantiated, the names of its friends declarations are treated as if the specialization had been explicitly declared at its point of instantiation.

Remove paragraph 2.

[temp.spec]

Change paragraph 3:

An explicit specialization may be declared for a function template, a variable template, a class template, a member of a class template, or a member template. An explicit specialization declaration is introduced by template<>. In an explicit specialization declaration for a variable template, a class template, a member of a class template or a class member template, the name of the variable or class that is explicitly specialized shall be specified with a simple-template-id. In the explicit specialization declaration for a function template or a member function template, the name of the function or member function explicitly specialized may be specified using a template-id. [Example:

[…]

— end example]

[temp.explicit]

Change paragraph 4:

If the explicit instantiation is for a class or member class, the elaborated-type-specifier in the declaration shall include a simple-template-id; otherwise, the declaration shall be a simple-declaration whose init-declarator-list comprises a single init-declarator that does not have an initializer. If the explicit instantiation is for a function or member function, the unqualified-id in the declarator shall be either a template-id or, where all template arguments can be deduced, a template-name or operator-function-id. [Note: The declaration may declare a qualified-id, in which case the unqualified-id of the qualified-id must be a template-id. — end note] If the explicit instantiation is for a member function, a member class or a static data member of a class template specialization, the name of the class template specialization shall be named in the qualified-id for the member name shall bewith a simple-template-id. If the explicit instantiation is for a variable template specialization, the unqualified-id in the declarator shall be a simple-template-id. An explicit instantiation shall appear in an enclosing namespace of its template. If the name declared in the explicit instantiation is an unqualified name, the explicit instantiation shall appear in the namespace where its template is declared or, if that namespace is inline ([namespace.def]), any namespace from its enclosing namespace set. [Note: Regarding qualified names in declarators, see [dcl.meaning]. — end note] [Example:

[…]

— end example]

Change paragraph 5:

An explicit instantiation does not introduce a name ([basic.scope.scope]). A declaration of a function template, a variable template, a member function or static data member of a class template, or a member function template of a class or class template shall precedebe reachable from any explicit instantiation of that entity. A definition of a class template, a member class of a class template, or a member class template of a class or class template shall precedebe reachable from any explicit instantiation of that entity unless the explicit instantiation is preceded by an explicit specialization of the entity with the same template arguments is reachable therefrom. If the declaration of the explicit instantiation names an implicitly-declared special member function ([special]), the program is ill-formed.

Remove paragraph 8.

Change paragraph 9:

A trailing template-argument can be left unspecified in an explicit instantiation of a function template specialization or of a member function template specialization provided it can be deduced from the type of a function parameter ([temp.deduct]). If all template arguments can be deduced, the empty template argument list <> may be omitted. [Example:

[…]

— end example]

[temp.expl.spec]

Change paragraph 4:

An explicit specialization does not introduce a name ([basic.scope.scope]). A declaration of a function template, class template, or variable template being explicitly specialized shall precedebe reachable from the declaration of the explicit specialization. [Note: A declaration, but not a definition of the template is required. — end note] The definition of a class or class template shall precedebe reachable from the declaration of an explicit specialization for a member template of the class or class template. [Example:

[…]

— end example]

Change paragraph 5:

A member function, a member function template, a member class, a member enumeration, a member class template, a static data member, or a static data member template of a class template may be explicitly specialized for a class specialization that is implicitly instantiated; in this case, the definition of the class template shall precedebe reachable from the explicit specialization for the member of the class template. If such an explicit specialization for the member of a class template names an implicitly-declared special member function ([special]), the program is ill-formed.

Remove paragraph 9.

[temp.fct.spec]

[temp.deduct.conv]

Change paragraph 1:

Template argument deduction is done by comparing the return type of the conversion function template (call it P) with the type that is required as the resultspecified by the conversion-type-id of the conversionconversion-function-id (call it A; see [dcl.init], [over.match.conv], and [over.match.ref] for the determination of that type) as described in [temp.deduct.type]. If the conversion-function-id is constructed during overload resolution ([over.match.funcs]), the following transformations apply.

Change paragraph 5:

In general, the deduction process attempts to find template argument values that will make the deduced A identical to A. However, there are four cases that allow a differencecertain attributes of A may be ignored:

1. If the original A is a reference type, any cv-qualifiers of A can be more cv-qualified than the deduced A (i.e., the type referred to by the reference),
2. If the original A is a function pointer or pointer-to-member-function type, A can be “pointer to function” even if the deduced A is “pointer to its noexcept function”., if any, and
3. If the original A is a pointer-to-member-function type, A can be “pointer to member of type function” even if the deduced A is “pointer to member of type noexcept function”.
4. The deducedAny cv-qualifiers in A can be another pointer or pointer-to-member type that can be converted to A viarestored by a qualification conversion.

Change paragraph 6:

These alternativesattributes are consideredignored only if type deduction would otherwise fail. If they yieldignoring them allows more than one possible deduced A, the type deduction fails.

[temp.over]

Change paragraph 1:

When a call to the name of a function or function template is written (explicitly, or implicitly using the operator notation), template argument deduction ([temp.deduct]) and checking of any explicit template arguments ([temp.arg]) are performed for each function template to find the template argument values (if any) that can be used with that function template to instantiate a function template specialization that can be invoked with the call arguments. For each function template, if the argument deduction and checking succeeds, the template-argument⁠s (deduced and/or explicit) are used to synthesize the declaration of a single function template specialization which is added to the candidate functions set to be used in overload resolution. If, for a given function template, argument deduction fails or the synthesized function template specialization would be ill-formed, no such function is added to the set of candidate functions for that template. The complete set of candidate functions includes all the synthesized declarations and all of the non-template overloaded functions of the same namefound by name lookup. The synthesized declarations are treated like any other functions in the remainder of overload resolution, except as explicitly noted in [over.match.best].^[…]

[except.handle]

Remove paragraph 11.

[diff.basic]

Change paragraph 2 (the example is based on that from the removed [class.nested.type]):

Affected subclause: [basic.scope]
Change: A struct is a scope in C++, not in C.
For example,

struct X {
  struct Y { int a; } b;
};
struct Y c;

is valid in C but not in C++, which would require X::Y c;.
Rationale: Class scope is crucial to C++, and a struct is a class.
Effect on original feature: Change to semantics of well-defined feature.
Difficulty of converting: Semantic transformation.
How widely used: C programs use struct extremely frequently, but the change is only noticeable when struct, enumeration, or enumerator names are referred to outside the struct. The latter is probably rare.

[depr.template.template]

Add this subclause before [depr.c.headers]:

The use of the keyword template before the qualified name of a class or alias template without a template argument list is deprecated.

Acknowledgments

Thanks to Richard Smith for helping discover and interpret several of the issues addressed and for feedback on their resolutions, and to Rachel Ertl for helping decide on them.