tmp/tmp311iogms/{from.md → to.md}
RENAMED
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#### Deduced class template specialization types <a id="dcl.type.class.deduct">[[dcl.type.class.deduct]]</a>
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If a placeholder for a deduced class type appears as a *decl-specifier*
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in the *decl-specifier-seq* of an initializing declaration
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A placeholder for a deduced class type can also be used in the
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*type-specifier-seq* in the *new-type-id* or *type-id* of a
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*new-expression*
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[*Example
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``` cpp
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template<class T> struct container {
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container(T t) {}
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template<class Iter> container(Iter beg, Iter end);
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@@ -27,10 +43,10 @@ template<class Iter>
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container(Iter b, Iter e) -> container<typename std::iterator_traits<Iter>::value_type>;
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std::vector<double> v = { ... };
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container c(7); // OK, deduces int for T
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auto d = container(v.begin(), v.end()); // OK, deduces double for T
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container e{5, 6}; // error
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```
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— *end example*]
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#### Deduced class template specialization types <a id="dcl.type.class.deduct">[[dcl.type.class.deduct]]</a>
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If a placeholder for a deduced class type appears as a *decl-specifier*
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in the *decl-specifier-seq* of an initializing declaration [[dcl.init]]
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of a variable, the declared type of the variable shall be cv `T`, where
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`T` is the placeholder.
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[*Example 1*:
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``` cpp
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template <class ...T> struct A {
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A(T...) {}
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};
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A x[29]{}; // error: no declarator operators allowed
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const A& y{}; // error: no declarator operators allowed
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```
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— *end example*]
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The placeholder is replaced by the return type of the function selected
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by overload resolution for class template deduction
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[[over.match.class.deduct]]. If the *decl-specifier-seq* is followed by
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an *init-declarator-list* or *member-declarator-list* containing more
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than one *declarator*, the type that replaces the placeholder shall be
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the same in each deduction.
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A placeholder for a deduced class type can also be used in the
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*type-specifier-seq* in the *new-type-id* or *type-id* of a
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*new-expression* [[expr.new]], as the *simple-type-specifier* in an
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explicit type conversion (functional notation) [[expr.type.conv]], or as
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the *type-specifier* in the *parameter-declaration* of a
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*template-parameter* [[temp.param]]. A placeholder for a deduced class
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type shall not appear in any other context.
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[*Example 2*:
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``` cpp
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template<class T> struct container {
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container(T t) {}
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template<class Iter> container(Iter beg, Iter end);
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container(Iter b, Iter e) -> container<typename std::iterator_traits<Iter>::value_type>;
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std::vector<double> v = { ... };
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container c(7); // OK, deduces int for T
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auto d = container(v.begin(), v.end()); // OK, deduces double for T
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container e{5, 6}; // error: int is not an iterator
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```
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— *end example*]
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