13 Templates [temp]

The template parameters of a template are specified in the angle bracket enclosed list that immediately follows the keyword template.

A primary template declaration is one in which the name of the template is not followed by a template-argument-list.

The template argument list of a primary template is the template argument list of its template-head ([temp.arg]).

A template declaration in which the name of the template is followed by a template-argument-list is a partial specialization ([temp.spec.partial]) of the template named in the declaration, which shall be a class or variable template.

A separately instantiated construct of a templated function F is a

• (3.1)
  default argument,
• (3.2)
  noexcept-specifier, or
• (3.3)
  function-contract-specifier

of F.

For purposes of name lookup and instantiation, separately instantiated constructs, type-constraints, and requires-clauses ([temp.pre]) are considered definitions; each separately instantiated construct, type-constraint, or requires-clause is a separate definition which is unrelated to the templated function definition or to any other separately instantiated constructs, type-constraints, or requires-clauses.

For the purpose of instantiation, the substatements of a constexpr if statement ([stmt.if]) are considered definitions.

For the purpose of name lookup and instantiation, the compound-statement of an expansion-statement is considered a template definition.

Because an alias-declaration cannot declare a template-id, it is not possible to partially or explicitly specialize an alias template.