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1.2 KiB
[hidden.friends]
16 Library introduction [library]
16.4 Library-wide requirements [requirements]
16.4.6 Conforming implementations [conforming]
16.4.6.6 Friend functions [hidden.friends]
Whenever this document specifies a friend declaration of a function or function template within a class or class template definition, that declaration shall be the only declaration of that function or function template provided by an implementation.
[Note 1:
In particular, a conforming implementation does not provide any additional declarations of that function or function template at namespace scope.
â end note]
[Note 2:
Such a friend function or function template declaration is known as a hidden friend, as it is visible neither to ordinary unqualified lookup ([basic.lookup.unqual]) nor to qualified lookup ([basic.lookup.qual]).
â end note]