Issue #21709 has been updated by naruse (Yui NARUSE). ```ruby re = /#{"\\p{In_Arabic}".encode("US-ASCII")}\u1234/ # encoding mismatch in dynamic regexp : US-ASCII and UTF-8 ``` This behavior looks a bug. ---------------------------------------- Bug #21709: Regexp interpolation is inconsistent with String interpolation https://bugs.ruby-lang.org/issues/21709#change-115590 * Author: thyresias (Thierry Lambert) * Status: Open * ruby -v: ruby 3.4.7 (2025-10-08 revision 7a5688e2a2) +PRISM [x64-mingw-ucrt] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- ```ruby %w(foo être).each do |s| puts "string: #{s.inspect} -> #{s.encoding}" puts "escaped: #{Regexp.escape(s).inspect} -> #{Regexp.escape(s).encoding}" end ``` Output: ``` string: "foo" -> UTF-8 escaped: "foo" -> US-ASCII string: "être" -> UTF-8 escaped: "être" -> UTF-8 ``` The result should always match the encoding of the argument. -- https://bugs.ruby-lang.org/