tmp/tmpg3tdxomt/{from.md → to.md}
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| 1 |
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## Splice specifiers <a id="basic.splice">[[basic.splice]]</a>
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``` bnf
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splice-specifier:
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'[:' constant-expression ':]'
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```
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``` bnf
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splice-specialization-specifier:
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splice-specifier '<' template-argument-listₒₚₜ '>'
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```
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The *constant-expression* of a *splice-specifier* shall be a converted
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constant expression of type `std::meta::info` [[expr.const]]. A
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*splice-specifier* whose converted *constant-expression* represents a
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construct X is said to *designate* either
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- the underlying entity of X if X is an entity [[basic.pre]], or
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- X otherwise.
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[*Note 1*: A *splice-specifier* is dependent if the converted
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*constant-expression* is value-dependent
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[[temp.dep.splice]]. — *end note*]
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A non-dependent *splice-specifier* of a
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*splice-specialization-specifier* shall designate a template.
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[*Note 2*:
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A `<` following a *splice-specifier* is interpreted as the delimiter of
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a *template-argument-list* when the *splice-specifier* is preceded by
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the keyword `template` or the keyword `typename`, or when it appears in
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a type-only context [[temp.names]].
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[*Example 1*:
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``` cpp
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constexpr int v = 1;
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template<int V> struct TCls {
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static constexpr int s = V + 1;
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};
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using alias = [:^^TCls:]<([:^^v:])>;
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// OK, a splice-specialization-specifier with a parenthesized splice-expression as a template argument
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static_assert(alias::s == 2);
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auto o1 = [:^^TCls:]<([:^^v:])>(); // error: < means less than
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auto o2 = typename [:^^TCls:]<([:^^v:])>(); // OK, o2 is an object of type TCls<1>
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consteval int bad_splice(std::meta::info v) {
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return [:v:]; // error: v is not constant
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}
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```
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— *end example*]
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— *end note*]
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