tmp/tmpbv22m37q/{from.md → to.md}
RENAMED
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| 1 |
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#### Type requirements <a id="expr.prim.req.type">[[expr.prim.req.type]]</a>
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``` bnf
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type-requirement:
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typename nested-name-specifierₒₚₜ type-name ';'
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```
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A *type-requirement* asserts the validity of a type.
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[*Note 1*: The enclosing *requires-expression* will evaluate to `false`
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if substitution of template arguments fails. — *end note*]
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[*Example 1*:
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``` cpp
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template<typename T, typename T::type = 0> struct S;
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template<typename T> using Ref = T&;
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template<typename T> concept C = requires {
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typename T::inner; // required nested member name
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typename S<T>; // required class template specialization
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typename Ref<T>; // required alias template substitution, fails if T is void
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};
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```
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— *end example*]
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A *type-requirement* that names a class template specialization does not
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require that type to be complete [[basic.types]].
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