Invalid escape sequences in regexes when installing gedit

[Erik Roland van der Meer]

On a clean install of the 24.04 beta, if you do a "sudo apt install gedit", you get the following messages at the end of the install:

/usr/lib/x86_64-linux-gnu/gedit/plugins/externaltools/library.py:212: SyntaxWarning: invalid escape sequence '\-'
  RE_KEY = re.compile('^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
/usr/lib/x86_64-linux-gnu/gedit/plugins/snippets/substitutionparser.py:162: SyntaxWarning: invalid escape sequence '\s'
  match = re.match('\\\\?%s\s*' % self.REG_GROUP, tokens)

So there are 2 issues with regexes.

Bug #2055010 reports the first of these, but not the second, and it also reports a different issue as "the huger problem" (one that I can't reproduce). I hope I'm making the right call in opening a new bug report specifically for these regex issues.

Some more details:
- on the clean install, I did apply all available updates before trying to install gedit
- you can also reproduce this issue from the live ("try ubuntu") environment

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: gedit 46.2-1build1
ProcVersionSignature: Ubuntu 6.8.0-22.22-generic 6.8.1
Uname: Linux 6.8.0-22-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.28.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.496
CloudArchitecture: x86_64
CloudID: nocloud
CloudName: unknown
CloudPlatform: nocloud
CloudSubPlatform: seed-dir (/var/lib/cloud/seed/nocloud)
CurrentDesktop: ubuntu:GNOME
Date: Sat Apr 13 08:41:26 2024
LiveMediaBuild: Ubuntu 24.04 LTS "Noble Numbat" - Beta amd64 (20240410.2)
ProcEnviron:
 LANG=C.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: gedit
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[fprietog (fprietog)]

It can also be reproduced reinstalling gedit (in this example in aarch64 architecture):

# apt install --reinstall gedit
Leyendo lista de paquetes... Hecho
Creando árbol de dependencias... Hecho
Leyendo la información de estado... Hecho
0 actualizados, 0 nuevos se instalarán, 1 reinstalados, 0 para eliminar y 0 no actualizados.
Se necesita descargar 353 kB de archivos.
Se utilizarán 0 B de espacio de disco adicional después de esta operación.
Des:1 http://ports.ubuntu.com/ubuntu-ports noble/universe arm64 gedit arm64 46.2-2 [353 kB]
Descargados 353 kB en 0s (1.178 kB/s)
(Leyendo la base de datos ... 221724 ficheros o directorios instalados actualmente.)
Preparando para desempaquetar .../gedit_46.2-2_arm64.deb ...
Desempaquetando gedit (46.2-2) sobre (46.2-2) ...
Configurando gedit (46.2-2) ...
/usr/lib/aarch64-linux-gnu/gedit/plugins/externaltools/library.py:212: SyntaxWarning: invalid escape sequence '\-'
  RE_KEY = re.compile('^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
/usr/lib/aarch64-linux-gnu/gedit/plugins/snippets/substitutionparser.py:162: SyntaxWarning: invalid escape sequence '\s'
  match = re.match('\\\\?%s\s*' % self.REG_GROUP, tokens)

[michaelly (michaellaunay)]

To get gedit working on Ubuntu 24.04.01 you must change string to raw :

```bash
michaellaunay@Caravale:~$ sudo dpkg-reconfigure gedit
​/usr/lib/x86_64-linux-gnu/gedit/plugins/externaltools/library.py:212: SyntaxWarning: invalid escape sequence '\-' and'\['
  RE_KEY = re.compile('^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
​/usr/lib/x86_64-linux-gnu/gedit/plugins/snippets/substitutionparser.py:162: SyntaxWarning: invalid escape sequence '\s'
  match = re.match('\\?%s\s*' % self.REG_GROUP, tokens)
```

The "SyntaxWarning" warnings are due to invalid escape sequences in the strings within the Python scripts. These warnings appear when an escape sequence like '\-' or `\[` or `\s` is used without the string being marked as a raw string.

To fix these warnings, the affected strings need to be converted into raw strings by adding an `r` before the quotation marks. Here’s how to correct the two problematic lines in the mentioned Python files:

1. File `library.py`, line 212:

   Before the correction:

```Python
   RE_KEY = re.compile('^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
```

   After the correction:
```Python
   RE_KEY = re.compile(r'^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
```

2. File `substitutionparser.py`, line 162:

   Before the correction:
```Python
   match = re.match('\\?%s\s*' % self.REG_GROUP, tokens)
```

   After the correction:
```python
   match = re.match(r'\\?%s\s*' % self.REG_GROUP, tokens)
```

I manually edited these files to apply the corrections.

[michaelly (michaellaunay)]

Here’s how to reproduce
```bash
michaellaunay@Caravale:~$ sudo apt update && sudo apt dist-upgrade
michaellaunay@Caravale:~$ sudo apt install gedit
...
Paramétrage de gedit (46.2-2) ...
/usr/lib/x86_64-linux-gnu/gedit/plugins/externaltools/library.py:212: SyntaxWarning: invalid escape sequence '\-'
  RE_KEY = re.compile('^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
/usr/lib/x86_64-linux-gnu/gedit/plugins/snippets/substitutionparser.py:162: SyntaxWarning: invalid escape sequence '\s'
  match = re.match('\\\\?%s\s*' % self.REG_GROUP, tokens)
```
Attached is the patch that applies the corrections described in my previous comment

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "This patch fixes invalid escape sequence warnings in library.py and substitutionparser.py by converting the affected strings to raw strings." seems to be a patch. If it isn't, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are a member of the ~ubuntu-reviewers, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issues please contact him.]

[fprietog (fprietog)]

Same problem happen in Ubuntu 24.10 Oracular upgrade:

Configurando python3 (3.12.6-0ubuntu1) ...
running python rtupdate hooks for python3.12...
/usr/lib/x86_64-linux-gnu/gedit/plugins/externaltools/library.py:212: SyntaxWarning: invalid escape sequence '\-'
  RE_KEY = re.compile('^([a-zA-Z_][a-zA-Z0-9_.\-]*)(\[([a-zA-Z_@]+)\])?$')
/usr/lib/x86_64-linux-gnu/gedit/plugins/snippets/substitutionparser.py:162: SyntaxWarning: invalid escape sequence '\s'
  match = re.match('\\\\?%s\s*' % self.REG_GROUP, tokens)