tmp/tmpcbi8jb19/{from.md → to.md}
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##### Reference binding <a id="over.ics.ref">[[over.ics.ref]]</a>
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When a parameter of
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sequence is a derived-to-base
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[*Example 4*:
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``` cpp
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struct A {};
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struct B : public A {} b;
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int f(A&);
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int f(B&);
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int i = f(b); // calls f(B&), an exact match, rather than f(A&), a conversion
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```
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— *end example*]
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If the parameter binds directly to the result of applying a conversion
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function to the argument expression, the implicit conversion sequence is
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a user-defined conversion sequence [[over.ics.user]] whose second
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standard conversion sequence is
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conversion function returns an entity of a type that is a derived class
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of the parameter type, a derived-to-base conversion.
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When a parameter of reference type is not bound directly to an argument
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expression, the conversion sequence is the one required to convert the
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argument expression to the referenced type according to
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[[over.best.ics]]. Conceptually, this conversion sequence corresponds to
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@@ -35,11 +48,11 @@ the initialization itself and does not constitute a conversion.
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Except for an implicit object parameter, for which see
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[[over.match.funcs]], an implicit conversion sequence cannot be formed
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if it requires binding an lvalue reference other than a reference to a
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non-volatile `const` type to an rvalue or binding an rvalue reference to
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an lvalue
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[*Note 9*: This means, for example, that a candidate function cannot be
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a viable function if it has a non-`const` lvalue reference parameter
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(other than the implicit object parameter) and the corresponding
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argument would require a temporary to be created to initialize the
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##### Reference binding <a id="over.ics.ref">[[over.ics.ref]]</a>
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When a parameter of type “reference to cv `T`” binds directly
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[[dcl.init.ref]] to an argument expression:
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- If the argument expression has a type that is a derived class of the
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parameter type, the implicit conversion sequence is a derived-to-base
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conversion [[over.best.ics]].
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- Otherwise, if the type of the argument is possibly cv-qualified `T`,
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or if `T` is an array type of unknown bound with element type `U` and
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the argument has an array type of known bound whose element type is
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possibly cv-qualified `U`, the implicit conversion sequence is the
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identity conversion.
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- Otherwise, if `T` is a function type, the implicit conversion sequence
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is a function pointer conversion.
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- Otherwise, the implicit conversion sequence is a qualification
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conversion.
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[*Example 4*:
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``` cpp
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struct A {};
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struct B : public A {} b;
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int f(A&);
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int f(B&);
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int i = f(b); // calls f(B&), an exact match, rather than f(A&), a conversion
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+
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void g() noexcept;
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int h(void (&)() noexcept); // #1
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int h(void (&)()); // #2
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int j = h(g); // calls #1, an exact match, rather than #2, a function pointer conversion
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```
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— *end example*]
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If the parameter binds directly to the result of applying a conversion
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function to the argument expression, the implicit conversion sequence is
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a user-defined conversion sequence [[over.ics.user]] whose second
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standard conversion sequence is determined by the above rules.
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When a parameter of reference type is not bound directly to an argument
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expression, the conversion sequence is the one required to convert the
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argument expression to the referenced type according to
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[[over.best.ics]]. Conceptually, this conversion sequence corresponds to
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Except for an implicit object parameter, for which see
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[[over.match.funcs]], an implicit conversion sequence cannot be formed
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if it requires binding an lvalue reference other than a reference to a
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non-volatile `const` type to an rvalue or binding an rvalue reference to
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an lvalue of object type.
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[*Note 9*: This means, for example, that a candidate function cannot be
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a viable function if it has a non-`const` lvalue reference parameter
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(other than the implicit object parameter) and the corresponding
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argument would require a temporary to be created to initialize the
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