From Jason Turner

[basic.scope.class]

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  ### Class scope <a id="basic.scope.class">[[basic.scope.class]]</a>
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- The potential scope of a name declared in a class consists not only of
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- the declarative region following the name’s point of declaration, but
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- also of all complete-class contexts [[class.mem]] of that class.
 
 
 
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- A name `N` used in a class `S` shall refer to the same declaration in
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- its context and when re-evaluated in the completed scope of `S`. No
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- diagnostic is required for a violation of this rule.
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- A name declared within a member function hides a declaration of the same
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- name whose scope extends to or past the end of the member function’s
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- class.
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-
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- The potential scope of a declaration in a class that extends to or past
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- the end of a class definition also extends to the regions defined by its
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- member definitions, even if the members are defined lexically outside
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- the class (this includes static data member definitions, nested class
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- definitions, and member function definitions, including the member
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- function body and any portion of the declarator part of such definitions
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- which follows the *declarator-id*, including a
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- *parameter-declaration-clause* and any default arguments
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- [[dcl.fct.default]]).
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  [*Example 1*:
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  ``` cpp
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- typedef int c;
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- enum { i = 1 };
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-
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- class X {
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- char v[i]; // error: i refers to ::i but when reevaluated is X::i
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- int f() { return sizeof(c); } // OK: X::c
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- char c;
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- enum { i = 2 };
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- };
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-
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- typedef char* T;
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- struct Y {
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- T a; // error: T refers to ::T but when reevaluated is Y::T
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- typedef long T;
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- T b;
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  };
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- typedef int I;
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- class D {
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- typedef I I; // error, even though no reordering involved
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- };
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  ```
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  — *end example*]
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- The name of a class member shall only be used as follows:
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-
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- - in the scope of its class (as described above) or a class derived
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- [[class.derived]] from its class,
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- - after the `.` operator applied to an expression of the type of its
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- class [[expr.ref]] or a class derived from its class,
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- - after the `->` operator applied to a pointer to an object of its class
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- [[expr.ref]] or a class derived from its class,
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- - after the `::` scope resolution operator [[expr.prim.id.qual]] applied
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- to the name of its class or a class derived from its class.
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  ### Class scope <a id="basic.scope.class">[[basic.scope.class]]</a>
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+ Any declaration of a class or class template C introduces a
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+ *class scope* that includes the *member-specification* of the
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+ *class-specifier* for C (if any). For each non-friend redeclaration or
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+ specialization whose target scope is or is contained by the scope, the
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+ portion after the *declarator-id*, *class-head-name*, or
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+ *enum-head-name* is also included in the scope.
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+ [*Note 1*:
 
 
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+ Lookup from a program point before the *class-specifier* of a class will
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+ find no bindings in the class scope.
 
 
 
 
 
 
 
 
 
 
 
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  [*Example 1*:
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  ``` cpp
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+ template<class D>
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+ struct B {
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+ D::type x; // #1
 
 
 
 
 
 
 
 
 
 
 
 
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  };
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+ struct A { using type = int; };
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+ struct C : A, B<C> {}; // error at #1: C::type not found
 
 
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  ```
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  — *end example*]
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+ — *end note*]
 
 
 
 
 
 
 
 
 
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