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std::execution:: just_error

From cppreference.net
Defined in header <execution>
inline constexpr just_error_t just_error { } ;
struct just_error_t { /*unspecified*/ } ;
(since C++26)
(customization point object)
Call signature
execution :: sender auto just_error ( auto && error ) ;
(since C++26)

A sender factory that returns a sender which completes immediately by calling the receiver’s set_error() .

Let e be a subexpression represented by an input error which will be injected and returned by the receiver. The expression just_error ( e ) is expression-equivalent to /*make-sender*/ ( just_error, /*product-type*/ ( e ) )

Customization point objects

The name execution::just_error denotes a customization point object , which is a const function object of a literal semiregular class type. The cv-unqualified version of its type is a tag type denoted as execution::just_error_t . See CustomizationPointObject for details.

Notes

If the provided error is an lvalue reference, a copy is made inside the returned sender and a non-const lvalue reference to the copy is sent to the receiver’s set_error . If the provided value is an rvalue reference, it is moved into the returned sender and an rvalue reference to it is sent to the receiver’s set_error .

Example