Annex A (informative) Grammar summary [gram]

A.7 Declarators [gram.decl]

init-declarator-list:
    init-declarator
    init-declarator-list , init-declarator

init-declarator:
    declarator initializeropt

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-seqopt
    noptr-declarator parameters-and-qualifiers
    noptr-declarator [ constant-expressionopt ] attribute-specifier-seqopt
    ( ptr-declarator )

parameters-and-qualifiers:
    ( parameter-declaration-clause ) cv-qualifier-seqopt
ref-qualifieropt noexcept-specifieropt attribute-specifier-seqopt

trailing-return-type:
    -> type-id

ptr-operator:
    * attribute-specifier-seqopt cv-qualifier-seqopt
    & attribute-specifier-seqopt
    && attribute-specifier-seqopt
    nested-name-specifier * attribute-specifier-seqopt cv-qualifier-seqopt

cv-qualifier-seq:
    cv-qualifier cv-qualifier-seqopt

cv-qualifier:
    const
    volatile

ref-qualifier:
    &
    &&

declarator-id:
    ...opt id-expression

type-id:
    type-specifier-seq abstract-declaratoropt

defining-type-id:
    defining-type-specifier-seq abstract-declaratoropt

abstract-declarator:
    ptr-abstract-declarator
    noptr-abstract-declaratoropt parameters-and-qualifiers trailing-return-type
    abstract-pack-declarator

ptr-abstract-declarator:
    noptr-abstract-declarator
    ptr-operator ptr-abstract-declaratoropt

noptr-abstract-declarator:
    noptr-abstract-declaratoropt parameters-and-qualifiers
    noptr-abstract-declaratoropt [ constant-expressionopt ] attribute-specifier-seqopt
    ( 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-expressionopt ] attribute-specifier-seqopt
    ...

parameter-declaration-clause:
parameter-declaration-listopt ...opt
    parameter-declaration-list , ...

parameter-declaration-list:
    parameter-declaration
    parameter-declaration-list , parameter-declaration

parameter-declaration:
    attribute-specifier-seqopt decl-specifier-seq declarator
    attribute-specifier-seqopt decl-specifier-seq declarator = initializer-clause
    attribute-specifier-seqopt decl-specifier-seq abstract-declaratoropt
    attribute-specifier-seqopt decl-specifier-seq abstract-declaratoropt = initializer-clause

function-definition:
    attribute-specifier-seqopt decl-specifier-seqopt declarator virt-specifier-seqopt function-body

function-body:
    ctor-initializeropt compound-statement
    function-try-block
    = default ;
    = delete ;

initializer:
    brace-or-equal-initializer
    ( expression-list )

brace-or-equal-initializer:
    = initializer-clause
    braced-init-list

initializer-clause:
    assignment-expression
    braced-init-list

initializer-list:
    initializer-clause ...opt
    initializer-list , initializer-clause ...opt

braced-init-list:
    { initializer-list ,opt }
    { }

expr-or-braced-init-list:
    expression
    braced-init-list