6 Basics [basic]

A declaration of a name in a nested declarative region hides a declaration of the same name in an enclosing declarative region; see [basic.scope.declarative] and [basic.lookup.unqual].

If a class name ([class.name]) or enumeration name ([dcl.enum]) and a variable, data member, function, or enumerator are declared in the same declarative region (in any order) with the same name (excluding declarations made visible via using-directives ([basic.lookup.unqual])), the class or enumeration name is hidden wherever the variable, data member, function, or enumerator name is visible.

In a member function definition, the declaration of a name at block scope hides the declaration of a member of the class with the same name; see [basic.scope.class].

The declaration of a member in a derived class hides the declaration of a member of a base class of the same name; see [class.member.lookup].

During the lookup of a name qualified by a namespace name, declarations that would otherwise be made visible by a using-directive can be hidden by declarations with the same name in the namespace containing the using-directive; see [namespace.qual].

If a name is in scope and is not hidden it is said to be visible.