The act of creating a new definition of a function, class, or member of a
class from a template declaration and one or more template arguments is called
template instantiation. The definition created from a
template instantiation is called a specialization.
A forward declaration of a template instantiation has the form of an explicit template instantiation preceded by the extern keyword.
>>-extern--template--template_declaration----------------------><
The language feature is an orthogonal extension to Standard C++ and C++98 for compatibility with GNU C++.
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