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std:: unstoppable_token

From cppreference.net
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定义于头文件 <stop_token>
template < class Token >

concept unstoppable_token =
std :: stoppable_token < Token > &&
requires ( const Token tok ) {
requires std:: bool_constant < ( ! tok. stop_possible ( ) ) > :: value ;

} ;
(C++26 起)

概念 unstoppable_token<Token> 对 stoppable_token 提出了额外要求，即该类型不允许停止操作。这意味着表达式 tok. stop_possible ( ) 必须能在常量表达式中使用，且返回 false 。