tmp/tmp0f4nw290/{from.md → to.md}
RENAMED
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@@ -8,21 +8,23 @@ arguments of the class template specialization with the template
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argument lists of the partial specializations.
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- If exactly one matching specialization is found, the instantiation is
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generated from that specialization.
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- If more than one matching specialization is found, the partial order
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rules
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specializations is more specialized than the others. If none of the
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specializations is more specialized than all of the other matching
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specializations, then the use of the class template is ambiguous and
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the program is ill-formed.
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- If no matches are found, the instantiation is generated from the
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primary template.
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A partial specialization matches a given actual template argument list
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if the template arguments of the partial specialization can be deduced
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from the actual template argument list
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[*Example 1*:
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``` cpp
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template<class T1, class T2, int I> class A { }; // #1
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@@ -38,15 +40,31 @@ A<int, char*, 1> a4; // uses #5, T1 is int, T2 is char, I is 1
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A<int*, int*, 2> a5; // ambiguous: matches #3 and #5
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```
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— *end example*]
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If the template arguments of a partial specialization cannot be deduced
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because of the structure of its *template-parameter-list* and the
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*template-id*, the program is ill-formed.
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-
[*Example
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``` cpp
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template <int I, int J> struct A {};
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template <int I> struct A<I+5, I*2> {}; // error
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argument lists of the partial specializations.
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- If exactly one matching specialization is found, the instantiation is
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generated from that specialization.
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- If more than one matching specialization is found, the partial order
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+
rules [[temp.class.order]] are used to determine whether one of the
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specializations is more specialized than the others. If none of the
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specializations is more specialized than all of the other matching
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specializations, then the use of the class template is ambiguous and
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the program is ill-formed.
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- If no matches are found, the instantiation is generated from the
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primary template.
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A partial specialization matches a given actual template argument list
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if the template arguments of the partial specialization can be deduced
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from the actual template argument list [[temp.deduct]], and the deduced
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template arguments satisfy the associated constraints of the partial
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specialization, if any [[temp.constr.decl]].
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[*Example 1*:
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``` cpp
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template<class T1, class T2, int I> class A { }; // #1
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A<int*, int*, 2> a5; // ambiguous: matches #3 and #5
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```
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— *end example*]
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[*Example 2*:
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``` cpp
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template<typename T> concept C = requires (T t) { t.f(); };
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template<typename T> struct S { }; // #1
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template<C T> struct S<T> { }; // #2
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struct Arg { void f(); };
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S<int> s1; // uses #1; the constraints of #2 are not satisfied
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S<Arg> s2; // uses #2; both constraints are satisfied but #2 is more specialized
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```
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+
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— *end example*]
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If the template arguments of a partial specialization cannot be deduced
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because of the structure of its *template-parameter-list* and the
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*template-id*, the program is ill-formed.
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[*Example 3*:
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``` cpp
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template <int I, int J> struct A {};
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template <int I> struct A<I+5, I*2> {}; // error
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