std::meta::decay
Defined in header <meta> | ||
|---|---|---|
consteval std::meta::info decay( std::meta::info r ); | (since C++26) |
Performs the type conversions equivalent to the ones performed when passing function arguments by value.
Let T be the type represented by r. Then:
- If
Tis “array of U” or reference to it, equivalent toreturn std::meta::dealias(^^U*);. - Otherwise, if
Tis a function typeFor reference to one, equivalent toreturn std::meta::dealias(^^std::add_pointer_t<F>);. - Otherwise, equivalent to
return std::meta::dealias(^^std::remove_cvref_t<T>);.
In any case, the call to this function is equivalent to return std::meta::dealias(std::decay_t<T>).
Parameters
| r | - | a reflection value |
Return value
A reflection of “decayed” underlying type T.
Exceptions
Throws std::meta::exception if r does not represent a type or type alias.
Example
#include <meta>
static_assert
(""
&& (decay(^^int) == ^^int)
&& (decay(^^int) != ^^float)
&& (decay(^^int&) == ^^int)
&& (decay(^^int&&) == ^^int)
&& (decay(^^const int&) == ^^int)
&& (decay(^^int[2]) == ^^int*)
&& (decay(^^int[4][2]) != ^^int*)
&& (decay(^^int[4][2]) != ^^int**)
&& (decay(^^int[4][2]) == ^^int(*)[2])
&& (decay(^^int(int)) == ^^int(*)(int))
);
int main() {}
See also
| Implicit conversions | array-to-pointer, function-to-pointer, lvalue-to-rvalue conversions |
|
(C++26) | combines meta::remove_cv and meta::remove_reference (function) |
|
(C++26)(C++26)(C++26) | removes const and/or volatile qualifiers from reflected type (function) |
|
(C++26) | removes a reference from reflected type (function) |
|
(C++11) | applies type transformations as when passing a function argument by value (class template) |
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https://en.cppreference.com/cpp/meta/decay
