Issue #16927 has been updated by naruse (Yui NARUSE). As nobu says, since String#tr is for codepoints, so this proposal is rejected. Maybe though a dedicated method for this use case can be reasonable, the current use case is not enough to design it. ---------------------------------------- Bug #16927: String#tr won't return the expected result for some sign with diacritics https://bugs.ruby-lang.org/issues/16927#change-104878 * Author: psychoslave (mathieu lovato stumpf guntz) * Status: Open * Priority: Normal * ruby -v: ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-linux] * Backport: 2.5: UNKNOWN, 2.6: UNKNOWN, 2.7: UNKNOWN ---------------------------------------- # Context Not much interest for the bug here, but I always appreciate to be given more context. So, as part of a larger project, I needed to utter every number from zero to 255 with a single syllable written as a consonant-vowel-consonant (CVC) in IPA. To avoid ambiguity, the nomenclature should not collide with existing numerical terms like "six" and "ten" in any language for which the documentation was found. As it was not enough nerdy, I came with the idea to mark with diacritics primes and congruence with 2, 8, 12, 16 (optionally and without intended phonological alteration though). If you are curious about it, you can look at [the algorithm](https://gitlab.com/psychoslave/isotopy/-/blob/master/tool/combinations/trigr...) I used to build the nomenclature matching [the specification](https://gitlab.com/psychoslave/isotopy/-/issues/4). # Code to reproduce the bug ``` ruby #!/bin/env ruby translated = 'aeiou'.tr('aeiou', 'ą̂ę̂į̂ǫ̂ų̂') substitued = 'aeiou'.sub(/aeiou/, 'ą̂ę̂į̂ǫ̂ų̂') puts `ruby -v`, translated == substitued, translated, substitued # Actual result ``` On my box, this outputs: ``` ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-linux] false ą̂ę̂į ą̂ę̂į̂ǫ̂ų̂ ``` # Expected result `tr` should return a congruent result: either it should fail for all signs with similar diacritics, or (preferably) return the specified Unicode glyph. That is, in the code above, `translated == substitued` should be `true`. # Remarks I am not a Unicode Guru: maybe the missing signs generating the difference comes from the way they are encoded. I am aware that some glyphs come in duplicates: as solo code points vs. combined code point sequences. However I'm cannot tell if the above code uses a mixture of both. -- https://bugs.ruby-lang.org/