int a定义的类型是什么？

Question

在c++ 14工作草案中，N3797声明定义如下：

declaration-seq:
    declaration
    declaration-seq declaration

declaration:
    block-declaration
    function-definition
    template-declaration
    explicit-instantiation
    explicit-specialization
    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

alias-declaration:
    using identifier attribute-specifier-seq_opt= type-id;

simple-declaration:
    decl-specifier-seq_opt init-declarator-list_opt;
    attribute-specifier-seq decl-specifier-seq_opt init-declarator-list;

static_assert-declaration:
    static_assert (constant-expression,string-literal);

empty-declaration:
    ;

attribute-declaration:
    attribute-specifier-seq;

我认为是explicit-instantiation，但我错了。int a;属于哪种类型的声明？

Answer 1

显式实例化是与模板相关的声明，其中模板类通过声明显式地为特定类型实例化。示例(取自N3337草案第14.7.2节)

template<class T> class Array { void mf(); };

// explicit instantiation of Array template class for char
// leads to all functions being instantiated too
template class Array<char>;

// explicit instatiation of only the member function mf for int
template void Array<int>::mf();

int a;是一个简单的声明，就像评论中提到的Joachim一样。