nix-super/src/libutil/variant-wrapper.hh

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#pragma once
///@file
// not used, but will be used by callers
#include <variant>
/**
* Force the default versions of all constructors (copy, move, copy
* assignment).
*/
#define FORCE_DEFAULT_CONSTRUCTORS(CLASS_NAME) \
CLASS_NAME(const CLASS_NAME &) = default; \
CLASS_NAME(CLASS_NAME &) = default; \
CLASS_NAME(CLASS_NAME &&) = default; \
\
CLASS_NAME & operator =(const CLASS_NAME &) = default; \
CLASS_NAME & operator =(CLASS_NAME &) = default;
/**
* Make a wrapper constructor. All args are forwarded to the
* construction of the "raw" field. (Which we assume is the only one.)
*
* The moral equivalent of `using Raw::Raw;`
*/
#define MAKE_WRAPPER_CONSTRUCTOR(CLASS_NAME) \
FORCE_DEFAULT_CONSTRUCTORS(CLASS_NAME) \
\
CLASS_NAME(auto &&... arg) \
: raw(std::forward<decltype(arg)>(arg)...) \
{ }