Issue #20033 has been updated by Eregon (Benoit Daloze). +1, it should only be static regexp literals which assign variables (= without `#{}`), that's much simpler for everyone to understand. The current situation feels like mixing parsing and compilation/optimization in the parser. ---------------------------------------- Bug #20033: `/#{''}(?<lvar>)/ =~ s` looks like a dynamic regexp match but assigns to local variable https://bugs.ruby-lang.org/issues/20033#change-105498 * Author: tompng (tomoya ishida) * Status: Open * Priority: Normal * ruby -v: ruby 3.3.0dev (2023-11-30T16:23:25Z master d048bae96b) [x86_64-linux] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- I expect all of these code not to assign to lvar because all regexp looks like embedded dynamic regexp. ~~~ruby /#{''}(?<lvar>)/ =~ '' # assings to lvar /#{"#{''}"}(?<lvar>)/ =~ '' # does not assign to lvar /#{<<A}(?<lvar>)/ =~ '' # assigns to lvar string A /#{<<A}(?<lvar>)/ =~ '' # does not assign to lvar #{'string'} A ~~~ I think `/#{'a'}/` can be a DREGX because for string, `"#{'a'}#{'b'}"` is DSTR `(DSTR@1:0-1:14 "ab" nil nil)`. -- https://bugs.ruby-lang.org/