[Bug 2137532] Re: tr handles UTF-8 wrong

[Sylvestre Ledru]

The Euro symbol (€) is encoded as the 3 bytes e2 82 ac in UTF-8. 
The current tr implementation treats each byte separately, so:

1. When we do tr € E, it's actually mapping:
  - byte e2 → E
  - byte 82 → E
  - byte ac → E

So the 3-byte Euro symbol becomes 3 Es → EEE

2. When we do tr E €, it's trying to map:
  - byte E (0x45) → byte e2 (first byte of Euro)

But this creates invalid UTF-8, hence the replacement character �.

so, it is the expected behavior.
GNU coreutils is doing the same


$ echo € | gnutr € E
EEE

$ echo E | gnutr E €
�

** Changed in: rust-coreutils (Ubuntu)
       Status: New => Invalid

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https://bugs.launchpad.net/bugs/2137532

Title:
  tr handles UTF-8 wrong

Status in rust-coreutils package in Ubuntu:
  Invalid

Bug description:
  ```
  medo at dev:~$ env | grep ^LANG
  LANG=de_DE.UTF-8
  medo at dev:~$ echo € | tr € E
  EEE
  medo at dev:~$ echo E | tr E €
  �
  ```

  should be
  ```
  medo at dev:~$ env | grep ^LANG
  LANG=de_DE.UTF-8
  medo at dev:~$ echo € | tr € E
  E
  medo at dev:~$ echo E | tr E €
  €
  ```

  ProblemType: Bug
  DistroRelease: Ubuntu 25.10
  Package: coreutils-from-uutils 0.0.0~ubuntu24
  ProcVersionSignature: Ubuntu 6.17.0-8.8-generic 6.17.2
  Uname: Linux 6.17.0-8-generic x86_64
  ApportVersion: 2.33.1-0ubuntu3
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CloudArchitecture: x86_64
  CloudBuildName: minimal
  CloudID: nocloud
  CloudName: unknown
  CloudPlatform: nocloud
  CloudSerial: 20251210
  CloudSubPlatform: seed-dir (dmi,/dev/sr0)
  Date: Tue Jan  6 09:40:25 2026
  PackageArchitecture: all
  ProcEnviron:
   LANG=de_DE.UTF-8
   PATH=(custom, no user)
   SHELL=/bin/bash
   TERM=xterm-kitty
   XDG_RUNTIME_DIR=<set>
  SourcePackage: coreutils-from
  UpgradeStatus: No upgrade log present (probably fresh install)

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