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[basic.scope.temp]

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  ### Template parameter scope <a id="basic.scope.temp">[[basic.scope.temp]]</a>
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- The declarative region of the name of a template parameter of a template
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- *template-parameter* is the smallest *template-parameter-list* in which
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- the name was introduced.
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-
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- The declarative region of the name of a template parameter of a template
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- is the smallest *template-declaration* in which the name was introduced.
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- Only template parameter names belong to this declarative region; any
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- other kind of name introduced by the *declaration* of a
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- *template-declaration* is instead introduced into the same declarative
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- region where it would be introduced as a result of a non-template
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- declaration of the same name.
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-
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- [*Example 1*:
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-
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- ``` cpp
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- namespace N {
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- template<class T> struct A { }; // #1
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- template<class U> void f(U) { } // #2
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- struct B {
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- template<class V> friend int g(struct C*); // #3
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- };
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- }
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- ```
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-
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- The declarative regions of `T`, `U` and `V` are the
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- *template-declaration*s on lines \#1, \#2, and \#3, respectively. But
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- the names `A`, `f`, `g` and `C` all belong to the same declarative
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- region — namely, the *namespace-body* of `N`. (`g` is still considered
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- to belong to this declarative region in spite of its being hidden during
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- qualified and unqualified name lookup.)
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-
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- — *end example*]
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-
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- The potential scope of a template parameter name begins at its point of
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- declaration [[basic.scope.pdecl]] and ends at the end of its declarative
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- region.
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-
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- [*Note 1*:
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-
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- This implies that a *template-parameter* can be used in the declaration
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- of subsequent *template-parameter*s and their default arguments but
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- cannot be used in preceding *template-parameter*s or their default
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- arguments. For example,
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-
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- ``` cpp
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- template<class T, T* p, class U = T> class X { ... };
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- template<class T> void f(T* p = new T);
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- ```
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-
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- This also implies that a *template-parameter* can be used in the
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- specification of base classes. For example,
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-
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- ``` cpp
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- template<class T> class X : public Array<T> { ... };
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- template<class T> class Y : public T { ... };
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- ```
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-
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- The use of a template parameter as a base class implies that a class
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- used as a template argument must be defined and not just declared when
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- the class template is instantiated.
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-
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- — *end note*]
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-
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- The declarative region of the name of a template parameter is nested
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- within the immediately-enclosing declarative region.
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-
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- [*Note 2*:
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-
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- As a result, a *template-parameter* hides any entity with the same name
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- in an enclosing scope [[basic.scope.hiding]].
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-
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- [*Example 2*:
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-
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- ``` cpp
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- typedef int N;
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- template<N X, typename N, template<N Y> class T> struct A;
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- ```
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-
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- Here, `X` is a non-type template parameter of type `int` and `Y` is a
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- non-type template parameter of the same type as the second template
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- parameter of `A`.
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-
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- — *end example*]
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-
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- — *end note*]
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-
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- [*Note 3*: Because the name of a template parameter cannot be
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- redeclared within its potential scope [[temp.local]], a template
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- parameter’s scope is often its potential scope. However, it is still
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- possible for a template parameter name to be hidden; see 
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- [[temp.local]]. — *end note*]
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  ### Template parameter scope <a id="basic.scope.temp">[[basic.scope.temp]]</a>
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+ Each template *template-parameter* introduces a
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+ *template parameter scope* that includes the *template-head* of the
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+ *template-parameter*.
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+
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+ Each *template-declaration* D introduces a template parameter scope that
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+ extends from the beginning of its *template-parameter-list* to the end
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+ of the *template-declaration*. Any declaration outside the
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+ *template-parameter-list* that would inhabit that scope instead inhabits
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+ the same scope as D. The parent scope of any scope S that is not a
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+ template parameter scope is the smallest scope that contains S and is
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+ not a template parameter scope.
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+
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+ [*Note 1*: Therefore, only template parameters belong to a template
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+ parameter scope, and only template parameter scopes have a template
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+ parameter scope as a parent scope. — *end note*]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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