tmp/tmpd5bw3ykt/{from.md → to.md}
RENAMED
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### The `constexpr` and `consteval` specifiers <a id="dcl.constexpr">[[dcl.constexpr]]</a>
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The `constexpr` specifier shall be applied only to the definition of a
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variable or variable template
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function template. The `consteval`
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-
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implicitly an inline function or variable [[dcl.inline]]. If any
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declaration of a function or function template has a `constexpr` or
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`consteval` specifier, then all its declarations shall contain the same
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specifier.
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— *end example*]
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A `constexpr` or `consteval` specifier used in the declaration of a
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function declares that function to be a *constexpr function*.
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[*Note 3*: A function
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A destructor, an allocation function, or a deallocation function shall
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not be declared with the `consteval` specifier.
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A function is *constexpr-suitable* if
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- it is not a coroutine [[dcl.fct.def.coroutine]], and
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- if the function is a constructor or destructor, its class does not
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have any virtual base classes.
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Except for instantiated constexpr functions, non-templated constexpr
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functions shall be constexpr-suitable.
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[*Example 2*:
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— *end example*]
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A `constexpr` specifier used in an object declaration declares the
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object as const. Such an object shall have literal type and shall be
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initialized.
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full-expression of the initialization shall be a constant expression
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[[expr.const]]. A `constexpr` variable that is an object, as well as any
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temporary to which a `constexpr` reference is bound, shall have constant
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destruction.
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[*Example 4*:
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struct pixel {
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int x, y;
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};
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constexpr pixel ur = { 1294, 1024 }; // OK
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constexpr pixel origin; // error: initializer missing
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```
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— *end example*]
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### The `constexpr` and `consteval` specifiers <a id="dcl.constexpr">[[dcl.constexpr]]</a>
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The `constexpr` specifier shall be applied only to the definition of a
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variable or variable template, a structured binding declaration, or the
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declaration of a function or function template. The `consteval`
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specifier shall be applied only to the declaration of a function or
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function template. A function or static data member declared with the
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`constexpr` or `consteval` specifier on its first declaration is
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implicitly an inline function or variable [[dcl.inline]]. If any
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declaration of a function or function template has a `constexpr` or
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`consteval` specifier, then all its declarations shall contain the same
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specifier.
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— *end example*]
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A `constexpr` or `consteval` specifier used in the declaration of a
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function declares that function to be a *constexpr function*.
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[*Note 3*: A function declared with the `consteval` specifier is an
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immediate function [[expr.const]]. — *end note*]
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A destructor, an allocation function, or a deallocation function shall
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not be declared with the `consteval` specifier.
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A function is *constexpr-suitable* if it is not a coroutine
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[[dcl.fct.def.coroutine]].
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Except for instantiated constexpr functions, non-templated constexpr
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functions shall be constexpr-suitable.
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[*Example 2*:
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— *end example*]
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A `constexpr` specifier used in an object declaration declares the
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object as const. Such an object shall have literal type and shall be
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initialized. A `constexpr` variable shall be constant-initializable
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[[expr.const]]. A `constexpr` variable that is an object, as well as any
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temporary to which a `constexpr` reference is bound, shall have constant
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destruction.
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[*Example 4*:
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struct pixel {
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int x, y;
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};
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constexpr pixel ur = { 1294, 1024 }; // OK
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constexpr pixel origin; // error: initializer missing
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namespace N {
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void f() {
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int x;
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constexpr int& ar = x; // OK
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static constexpr int& sr = x; // error: x is not constexpr-representable
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// at the point indicated below
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}
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// immediate scope here is that of N
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}
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```
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— *end example*]
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