One can do the same without brace levels by using switch case or goto.   -----Ursprüngliche Nachricht----- Von:Breno Guimarães <brenorg_at_[hidden]> Gesendet:Mi 10.12.2025 02:35 Betreff:Re: [std-proposals] [PXXXXR0] Add a New Keyword `undecl` An:Std-Proposals <std-proposals_at_[hidden]>; CC:Sebastian Wittmeier <wittmeier_at_[hidden]>; The paper says that undecl can only be called in the same brace level as the declaration. So I guess this example isn't valid. Em ter., 9 de dez. de 2025, 22:29, Sebastian Wittmeier via Std-Proposals <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> > escreveu: undeclaring a variable is the same as relocating from a variable to nothingness (or to somewhere else).   A variable, which was relocated from, may also not be used any longer afterwards.     One detail may be the difference between position in the program (source code line within the block) and program flow.   int a = -1; for (int i = 0; i < 10; i++) {     if (i == 5)         a++; // can a be used here?     if (i == 4)         undecl a;     if (i == 5)         a++; // and here? }   -----Ursprüngliche Nachricht----- Von:wjf via Std-Proposals <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> > Gesendet:Mi 10.12.2025 02:23 Betreff:[std-proposals] [PXXXXR0] Add a New Keyword `undecl` Anlage:Add_New_Keyword_undecl.pdf An:std-proposals <std-proposals_at_[hidden] <mailto:std-proposals_at_[hidden]> >; CC:wjf <wjf_at_[hidden] <mailto:wjf_at_[hidden]> >; see attachment   <http://thirdqq.qlogo.cn/ek_qqapp/AQNPOicdlIgbG9Ribmfj8EKjTG2hwBlicwibL4stQmE6UNEQ3eh3aQCoFUzN0k1xGg/0> wjf wjf_at_[hidden]   -- Std-Proposals mailing list Std-Proposals_at_[hidden] <mailto:Std-Proposals_at_[hidden]> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals -- Std-Proposals mailing list Std-Proposals_at_[hidden] <mailto:Std-Proposals_at_[hidden]> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals