tmp/tmp11n_0y4v/{from.md → to.md}
RENAMED
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## Deduction guides <a id="temp.deduct.guide">[[temp.deduct.guide]]</a>
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Deduction guides are used when a *template-name* appears as a type
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specifier for a deduced class type
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-
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-
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-
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``` bnf
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deduction-guide:
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-
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```
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[*Example 1*:
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``` cpp
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@@ -29,183 +29,14 @@ S x{A()}; // x is of type S<short, int>
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```
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— *end example*]
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The same restrictions apply to the *parameter-declaration-clause* of a
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-
deduction guide as in a function declaration
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*simple-template-id* shall name a class template specialization. The
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| 36 |
*template-name* shall be the same *identifier* as the *template-name* of
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the *simple-template-id*. A *deduction-guide* shall be declared in the
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same scope as the corresponding class template and, for a member class
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template, with the same access. Two deduction guide declarations in the
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same translation unit for the same class template shall not have
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equivalent *parameter-declaration-clause*s.
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<!-- Link reference definitions -->
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[basic.def]: basic.md#basic.def
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[basic.def.odr]: basic.md#basic.def.odr
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[basic.link]: basic.md#basic.link
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[basic.lookup]: basic.md#basic.lookup
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[basic.lookup.argdep]: basic.md#basic.lookup.argdep
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| 49 |
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[basic.lookup.classref]: basic.md#basic.lookup.classref
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[basic.lookup.qual]: basic.md#basic.lookup.qual
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[basic.lookup.unqual]: basic.md#basic.lookup.unqual
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[basic.scope]: basic.md#basic.scope
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[basic.scope.hiding]: basic.md#basic.scope.hiding
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| 54 |
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[basic.stc.dynamic.deallocation]: basic.md#basic.stc.dynamic.deallocation
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[basic.types]: basic.md#basic.types
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[class]: class.md#class
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| 57 |
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[class.abstract]: class.md#class.abstract
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[class.access]: class.md#class.access
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[class.base.init]: special.md#class.base.init
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[class.derived]: class.md#class.derived
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[class.dtor]: special.md#class.dtor
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[class.friend]: class.md#class.friend
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| 63 |
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[class.local]: class.md#class.local
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[class.mem]: class.md#class.mem
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[class.member.lookup]: class.md#class.member.lookup
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[class.qual]: basic.md#class.qual
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[class.temporary]: special.md#class.temporary
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| 68 |
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[conv]: conv.md#conv
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[conv.array]: conv.md#conv.array
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[conv.fctptr]: conv.md#conv.fctptr
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[conv.func]: conv.md#conv.func
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[conv.qual]: conv.md#conv.qual
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| 73 |
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[dcl.align]: dcl.md#dcl.align
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[dcl.attr.grammar]: dcl.md#dcl.attr.grammar
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[dcl.dcl]: dcl.md#dcl.dcl
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[dcl.enum]: dcl.md#dcl.enum
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[dcl.fct]: dcl.md#dcl.fct
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| 78 |
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[dcl.fct.def.general]: dcl.md#dcl.fct.def.general
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[dcl.fct.default]: dcl.md#dcl.fct.default
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| 80 |
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[dcl.init]: dcl.md#dcl.init
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| 81 |
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[dcl.init.list]: dcl.md#dcl.init.list
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| 82 |
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[dcl.meaning]: dcl.md#dcl.meaning
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| 83 |
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[dcl.spec.auto]: dcl.md#dcl.spec.auto
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| 84 |
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[dcl.struct.bind]: dcl.md#dcl.struct.bind
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| 85 |
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[dcl.type.auto.deduct]: dcl.md#dcl.type.auto.deduct
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[dcl.type.class.deduct]: dcl.md#dcl.type.class.deduct
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[dcl.type.elab]: dcl.md#dcl.type.elab
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| 88 |
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[except.spec]: except.md#except.spec
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| 89 |
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[expr.const]: expr.md#expr.const
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[expr.new]: expr.md#expr.new
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[expr.prim.fold]: expr.md#expr.prim.fold
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[expr.prim.lambda]: expr.md#expr.prim.lambda
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[expr.prim.lambda.closure]: expr.md#expr.prim.lambda.closure
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[expr.ref]: expr.md#expr.ref
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[expr.sizeof]: expr.md#expr.sizeof
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[expr.typeid]: expr.md#expr.typeid
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[implimits]: limits.md#implimits
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[intro.defs]: intro.md#intro.defs
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[intro.object]: intro.md#intro.object
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[lex.string]: lex.md#lex.string
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[namespace.def]: dcl.md#namespace.def
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[namespace.memdef]: dcl.md#namespace.memdef
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[namespace.udecl]: dcl.md#namespace.udecl
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[over.ics.rank]: over.md#over.ics.rank
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[over.match]: over.md#over.match
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[over.match.best]: over.md#over.match.best
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[over.match.class.deduct]: over.md#over.match.class.deduct
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[over.match.conv]: over.md#over.match.conv
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[over.match.ref]: over.md#over.match.ref
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[over.over]: over.md#over.over
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[special]: special.md#special
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[stmt.if]: stmt.md#stmt.if
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[support.types]: language.md#support.types
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[tab:fold.empty]: #tab:fold.empty
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[temp]: #temp
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[temp.alias]: #temp.alias
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[temp.arg]: #temp.arg
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[temp.arg.explicit]: #temp.arg.explicit
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[temp.arg.nontype]: #temp.arg.nontype
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[temp.arg.template]: #temp.arg.template
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[temp.arg.type]: #temp.arg.type
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[temp.class]: #temp.class
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[temp.class.order]: #temp.class.order
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[temp.class.spec]: #temp.class.spec
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[temp.class.spec.match]: #temp.class.spec.match
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[temp.class.spec.mfunc]: #temp.class.spec.mfunc
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[temp.decls]: #temp.decls
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[temp.deduct]: #temp.deduct
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[temp.deduct.call]: #temp.deduct.call
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[temp.deduct.conv]: #temp.deduct.conv
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[temp.deduct.decl]: #temp.deduct.decl
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[temp.deduct.funcaddr]: #temp.deduct.funcaddr
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[temp.deduct.guide]: #temp.deduct.guide
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[temp.deduct.partial]: #temp.deduct.partial
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[temp.deduct.type]: #temp.deduct.type
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[temp.dep]: #temp.dep
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[temp.dep.candidate]: #temp.dep.candidate
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[temp.dep.constexpr]: #temp.dep.constexpr
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[temp.dep.expr]: #temp.dep.expr
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[temp.dep.res]: #temp.dep.res
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[temp.dep.temp]: #temp.dep.temp
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[temp.dep.type]: #temp.dep.type
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[temp.expl.spec]: #temp.expl.spec
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[temp.explicit]: #temp.explicit
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[temp.fct]: #temp.fct
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[temp.fct.spec]: #temp.fct.spec
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[temp.friend]: #temp.friend
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[temp.func.order]: #temp.func.order
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[temp.inject]: #temp.inject
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[temp.inst]: #temp.inst
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[temp.local]: #temp.local
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[temp.mem]: #temp.mem
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[temp.mem.class]: #temp.mem.class
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[temp.mem.enum]: #temp.mem.enum
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[temp.mem.func]: #temp.mem.func
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[temp.names]: #temp.names
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[temp.nondep]: #temp.nondep
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[temp.over]: #temp.over
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[temp.over.link]: #temp.over.link
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[temp.param]: #temp.param
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[temp.point]: #temp.point
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[temp.res]: #temp.res
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[temp.spec]: #temp.spec
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[temp.static]: #temp.static
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[temp.type]: #temp.type
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[temp.variadic]: #temp.variadic
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[^1]: Since template *template-parameter*s and template
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*template-argument*s are treated as types for descriptive purposes,
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the terms *non-type parameter* and *non-type argument* are used to
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refer to non-type, non-template parameters and arguments.
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[^2]: A `>` that encloses the *type-id* of a `dynamic_cast`,
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`static_cast`, `reinterpret_cast` or `const_cast`, or which encloses
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| 175 |
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the *template-argument*s of a subsequent *template-id*, is
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considered nested for the purpose of this description.
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[^3]: There is no such ambiguity in a default *template-argument*
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because the form of the *template-parameter* determines the
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allowable forms of the *template-argument*.
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[^4]: There is no way in which they could be used.
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[^5]: That is, declarations of non-template functions do not merely
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guide overload resolution of function template specializations with
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| 186 |
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the same name. If such a non-template function is odr-used (
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[[basic.def.odr]]) in a program, it must be defined; it will not be
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implicitly instantiated using the function template definition.
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[^6]: Friend declarations do not introduce new names into any scope,
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either when the template is declared or when it is instantiated.
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[^7]: Default arguments are not considered to be arguments in this
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context; they only become arguments after a function has been
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selected.
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-
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[^8]: Although the *template-argument* corresponding to a
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*template-parameter* of type `bool` may be deduced from an array
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| 199 |
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bound, the resulting value will always be `true` because the array
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bound will be nonzero.
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[^9]: The parameters of function template specializations contain no
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template parameter types. The set of conversions allowed on deduced
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| 204 |
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arguments is limited, because the argument deduction process
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produces function templates with parameters that either match the
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| 206 |
-
call arguments exactly or differ only in ways that can be bridged by
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| 207 |
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the allowed limited conversions. Non-deduced arguments allow the
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full range of conversions. Note also that [[over.match.best]]
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specifies that a non-template function will be given preference over
|
| 210 |
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a template specialization if the two functions are otherwise equally
|
| 211 |
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good candidates for an overload match.
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+
#### Deduction guides <a id="temp.deduct.guide">[[temp.deduct.guide]]</a>
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Deduction guides are used when a *template-name* appears as a type
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| 4 |
+
specifier for a deduced class type [[dcl.type.class.deduct]]. Deduction
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| 5 |
+
guides are not found by name lookup. Instead, when performing class
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| 6 |
+
template argument deduction [[over.match.class.deduct]], any deduction
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guides declared for the class template are considered.
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``` bnf
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| 10 |
deduction-guide:
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+
explicit-specifierₒₚₜ template-name '(' parameter-declaration-clause ')' '->' simple-template-id ';'
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```
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[*Example 1*:
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``` cpp
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```
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— *end example*]
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The same restrictions apply to the *parameter-declaration-clause* of a
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+
deduction guide as in a function declaration [[dcl.fct]]. The
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*simple-template-id* shall name a class template specialization. The
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*template-name* shall be the same *identifier* as the *template-name* of
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the *simple-template-id*. A *deduction-guide* shall be declared in the
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same scope as the corresponding class template and, for a member class
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template, with the same access. Two deduction guide declarations in the
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same translation unit for the same class template shall not have
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equivalent *parameter-declaration-clause*s.
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