Annex A (informative) Grammar summary [gram]

A.6 Declarations [gram.dcl]

declaration-seq:
	declaration
	declaration-seq declaration
declaration:
	block-declaration
	nodeclspec-function-declaration
	function-definition
	template-declaration
	deduction-guide
	explicit-instantiation
	explicit-specialization
	export-declaration
	linkage-specification
	namespace-definition
	empty-declaration
	attribute-declaration
block-declaration:
	simple-declaration
	asm-definition
	namespace-alias-definition
	using-declaration
	using-directive
	static_assert-declaration
	alias-declaration
	opaque-enum-declaration
nodeclspec-function-declaration:
	attribute-specifier-seq declarator ;
alias-declaration:
	using identifier attribute-specifier-seq = defining-type-id ;
simple-declaration:
	decl-specifier-seq init-declarator-list ;
	attribute-specifier-seq decl-specifier-seq init-declarator-list ;
	attribute-specifier-seq decl-specifier-seq ref-qualifier [ identifier-list ] initializer ;
static_assert-declaration:
	static_­assert ( constant-expression ) ;
	static_­assert ( constant-expression , string-literal ) ;
empty-declaration:
	;
attribute-declaration:
	attribute-specifier-seq ;
decl-specifier:
	storage-class-specifier
	defining-type-specifier
	function-specifier
	friend
	typedef
	constexpr
	consteval
	inline
decl-specifier-seq:
	decl-specifier attribute-specifier-seq
	decl-specifier decl-specifier-seq
storage-class-specifier:
	static
	thread_­local
	extern
	mutable
function-specifier:
	virtual
	explicit-specifier
explicit-specifier:
	explicit ( constant-expression )
	explicit
typedef-name:
	identifier
	simple-template-id
type-specifier:
	simple-type-specifier
	elaborated-type-specifier
	typename-specifier
	cv-qualifier
type-specifier-seq:
	type-specifier attribute-specifier-seq
	type-specifier type-specifier-seq
defining-type-specifier:
	type-specifier
	class-specifier
	enum-specifier
defining-type-specifier-seq:
	defining-type-specifier attribute-specifier-seq
	defining-type-specifier defining-type-specifier-seq
simple-type-specifier:
	nested-name-specifier type-name
	nested-name-specifier template simple-template-id
	decltype-specifier
	placeholder-type-specifier
	nested-name-specifier template-name
	char
	char8_­t
	char16_­t
	char32_­t
	wchar_­t
	bool
	short
	int
	long
	signed
	unsigned
	float
	double
	void
type-name:
	class-name
	enum-name
	typedef-name
elaborated-type-specifier:
	class-key attribute-specifier-seq nested-name-specifier identifier
	class-key simple-template-id
	class-key nested-name-specifier template simple-template-id
	enum nested-name-specifier identifier
decltype-specifier:
	decltype ( expression )
placeholder-type-specifier:
	type-constraint auto
	type-constraint decltype ( auto )
init-declarator-list:
	init-declarator
	init-declarator-list , init-declarator
init-declarator:
	declarator initializer
	declarator requires-clause
declarator:
	ptr-declarator
	noptr-declarator parameters-and-qualifiers trailing-return-type
ptr-declarator:
	noptr-declarator
	ptr-operator ptr-declarator
noptr-declarator:
	declarator-id attribute-specifier-seq
	noptr-declarator parameters-and-qualifiers
	noptr-declarator [ constant-expression ] attribute-specifier-seq
	( ptr-declarator )
parameters-and-qualifiers:
	( parameter-declaration-clause ) cv-qualifier-seq
		ref-qualifier noexcept-specifier attribute-specifier-seq
trailing-return-type:
	-> type-id
ptr-operator:
	* attribute-specifier-seq cv-qualifier-seq
	& attribute-specifier-seq
	&& attribute-specifier-seq
	nested-name-specifier * attribute-specifier-seq cv-qualifier-seq
cv-qualifier-seq:
	cv-qualifier cv-qualifier-seq
cv-qualifier:
	const
	volatile
ref-qualifier:
	&
	&&
declarator-id:
	... id-expression
type-id:
	type-specifier-seq abstract-declarator
defining-type-id:
	defining-type-specifier-seq abstract-declarator
abstract-declarator:
	ptr-abstract-declarator
	noptr-abstract-declarator parameters-and-qualifiers trailing-return-type
	abstract-pack-declarator
ptr-abstract-declarator:
	noptr-abstract-declarator
	ptr-operator ptr-abstract-declarator
noptr-abstract-declarator:
	noptr-abstract-declarator parameters-and-qualifiers
	noptr-abstract-declarator [ constant-expression ] attribute-specifier-seq
	( ptr-abstract-declarator )
abstract-pack-declarator:
	noptr-abstract-pack-declarator
	ptr-operator abstract-pack-declarator
noptr-abstract-pack-declarator:
	noptr-abstract-pack-declarator parameters-and-qualifiers
	noptr-abstract-pack-declarator [ constant-expression ] attribute-specifier-seq
	...
parameter-declaration-clause:
	parameter-declaration-list ...
	parameter-declaration-list , ...
parameter-declaration-list:
	parameter-declaration
	parameter-declaration-list , parameter-declaration
parameter-declaration:
	attribute-specifier-seq decl-specifier-seq declarator
	attribute-specifier-seq decl-specifier-seq declarator = initializer-clause
	attribute-specifier-seq decl-specifier-seq abstract-declarator
	attribute-specifier-seq decl-specifier-seq abstract-declarator = initializer-clause
initializer:
	brace-or-equal-initializer
	( expression-list )
brace-or-equal-initializer:
	= initializer-clause
	braced-init-list
initializer-clause:
	assignment-expression
	braced-init-list
braced-init-list:
	{ initializer-list , }
	{ designated-initializer-list , }
	{ }
initializer-list:
	initializer-clause ...
	initializer-list , initializer-clause ...
designated-initializer-list:
	designated-initializer-clause
	designated-initializer-list , designated-initializer-clause
designated-initializer-clause:
	designator brace-or-equal-initializer
designator:
	. identifier
expr-or-braced-init-list:
	expression
	braced-init-list
function-definition:
	attribute-specifier-seq decl-specifier-seq declarator virt-specifier-seq function-body
	attribute-specifier-seq decl-specifier-seq declarator requires-clause function-body
function-body:
	ctor-initializer compound-statement
	function-try-block
	= default ;
	= delete ;
enum-name:
	identifier
enum-specifier:
	enum-head { enumerator-list }
	enum-head { enumerator-list , }
enum-head:
	enum-key attribute-specifier-seq enum-head-name enum-base
enum-head-name:
	nested-name-specifier identifier
opaque-enum-declaration:
	enum-key attribute-specifier-seq enum-head-name enum-base ;
enum-key:
	enum
	enum class
	enum struct
enum-base:
	: type-specifier-seq
enumerator-list:
	enumerator-definition
	enumerator-list , enumerator-definition
enumerator-definition:
	enumerator
	enumerator = constant-expression
enumerator:
	identifier attribute-specifier-seq
namespace-name:
	identifier
	namespace-alias
namespace-definition:
	named-namespace-definition
	unnamed-namespace-definition
	nested-namespace-definition
named-namespace-definition:
	inline namespace attribute-specifier-seq identifier { namespace-body }
unnamed-namespace-definition:
	inline namespace attribute-specifier-seq { namespace-body }
nested-namespace-definition:
	namespace enclosing-namespace-specifier :: inline identifier { namespace-body }
enclosing-namespace-specifier:
	identifier
	enclosing-namespace-specifier :: inline identifier
namespace-body:
	declaration-seq
namespace-alias:
	identifier
namespace-alias-definition:
	namespace identifier = qualified-namespace-specifier ;
qualified-namespace-specifier:
	nested-name-specifier namespace-name
using-directive:
	attribute-specifier-seq using namespace nested-name-specifier namespace-name ;
using-declaration:
	using using-declarator-list ;
using-declarator-list:
	using-declarator ...
	using-declarator-list , using-declarator ...
using-declarator:
	typename nested-name-specifier unqualified-id
asm-definition:
	attribute-specifier-seq asm ( string-literal ) ;
linkage-specification:
	extern string-literal { declaration-seq }
	extern string-literal declaration
attribute-specifier-seq:
	attribute-specifier-seq attribute-specifier
attribute-specifier:
	[ [ attribute-using-prefix attribute-list ] ]
	contract-attribute-specifier
	alignment-specifier
alignment-specifier:
	alignas ( type-id ... )
	alignas ( constant-expression ... )
attribute-using-prefix:
	using attribute-namespace :
attribute-list:
	attribute
	attribute-list , attribute
	attribute ...
	attribute-list , attribute ...
attribute:
	attribute-token attribute-argument-clause
attribute-token:
	identifier
	attribute-scoped-token
attribute-scoped-token:
	attribute-namespace :: identifier
attribute-namespace:
	identifier
attribute-argument-clause:
	( balanced-token-seq )
balanced-token-seq:
	balanced-token
	balanced-token-seq balanced-token
balanced-token:
	( balanced-token-seq )
	[ balanced-token-seq ]
	{ balanced-token-seq }
	any token other than a parenthesis, a bracket, or a brace
contract-attribute-specifier:
	[ [ expects contract-level : conditional-expression ] ]
	[ [ ensures contract-level identifier : conditional-expression ] ]
	[ [ assert contract-level : conditional-expression ] ]
contract-level:
	default
	audit
	axiom