gtksourceview3 was superseded by gtksourceview4 in 2018. Both libraries
provide a GTK 3 widget to display source code with syntax highlighting,
for use in text editors and similar applications.

gtksourceview4 has itself been superseded by gtksourceview5 (ITP: #996609), which is for GTK 4 applications.

Applications that use gtksourceview3 should switch to gtksourceview4.
Even if the application is going to be ported to GTK 4 and gtksourceview5,
it is probably a good idea to move to gtksourceview4 first.

Upstream porting guide: https://developer-old.gnome.org/gtksourceview/4.2/porting-guide-3-to-4.html

Mass-filed bugs for this will be usertagged to appear in https://udd.debian.org/cgi-bin/bts-usertags.cgi?user=pkg-gnome-maintainers%40lists.alioth.debian.org&tag=gtksourceview3
and will be marked as blocking #996689. I intend to open bugs at a non-RC severity, but they might be escalated to a RC severity later.

For packages that provide a shared library, such as libgtksourceviewmm,
this change will probably result in a transition (assuming the package
is not removed altogether).

dak says the following packages are affected:

smcv@coccia ~ % dak rm -R -n gtksourceview3

...

# Broken Depends:
almanah: almanah
anjuta: anjuta
autokey: autokey-gtk
coq: coqide [amd64 arm64 armhf i386 ppc64el]
denemo: denemo
desktopfolder: desktopfolder
formiko: formiko
frama-c: frama-c-base
giggle: giggle
gitg: gitg
gnusim8085: gnusim8085
gobby: gobby
gretl: gretl
gtk-d: libgtkdsv-3-0 [amd64 arm64 armel armhf i386 s390x]
libgtkdsv-3-dev [amd64 arm64 armel armhf i386 s390x]
gummi: gummi
java-gnome: libjava-gnome-jni
lablgtk3: liblablgtksourceview3-ocaml
liblablgtksourceview3-ocaml-dev
laby: laby [amd64 arm64 armhf i386 ppc64el s390x]
latexila: latexila
libgtksourceviewmm: libgtksourceviewmm-3.0-0v5
libgtksourceviewmm-3.0-dev
mate-applets: mate-applets
meld: meld
mousepad: mousepad
oregano: oregano
pluma: gir1.2-pluma-1.0
pluma
pspp: pspp
pychess: pychess
pycode-browser: pycode-browser
rednotebook: rednotebook
reportbug: reportbug-gtk
rmlint: rmlint-gui
sequeler: sequeler
snapper-gui: snapper-gui
sugar: python3-jarabe
sugar-pippy-activity: sugar-pippy-activity
why3: why3
xpad: xpad

# Broken Build-Depends:
almanah: libgtksourceview-3.0-dev
anjuta: libgtksourceview-3.0-dev (>= 3.0.0)
denemo: libgtksourceview-3.0-dev
desktopfolder: libgtksourceview-3.0-dev
giggle: libgtksourceview-3.0-dev
gitg: libgtksourceview-3.0-dev (>= 3.10)
gnusim8085: libgtksourceview-3.0-dev (>= 3.10.0)
gobby: libgtksourceview-3.0-dev
gretl: libgtksourceview-3.0-dev
gtk-d: libgtksourceview-3.0-dev
gummi: libgtksourceview-3.0-dev
java-gnome: libgtksourceview-3.0-dev (>= 3.0)
lablgtk3: libgtksourceview-3.0-dev
latexila: libgtksourceview-3.0-dev (>= 3.18)
libgtksourceviewmm: libgtksourceview-3.0-dev (>= 3.18.0)
mate-applets: libgtksourceview-3.0-dev
mousepad: libgtksourceview-3.0-dev
oregano: libgtksourceview-3.0-dev
pluma: libgtksourceview-3.0-dev
pspp: libgtksourceview-3.0-dev (>= 3.22)
pychess: gir1.2-gtksource-3.0
ruby-gnome: libgtksourceview-3.0-dev
sequeler: libgtksourceview-3.0-dev
xpad: libgtksourceview-3.0-dev (>= 3.22)

smcv

Angel Abad <angel@debian.org>
almanah

Anthony Fok <foka@debian.org>
autokey (U)
denemo (U)

Balint Reczey <rbalint@ubuntu.com>
meld

Ben Pfaff <blp@cs.stanford.edu>
pspp (U)

Benjamin Barenblat <bbaren@debian.org>
coq (U)

Carlos Maddela <e7appew@gmail.com>
rmlint

David Mohammed <fossfreedom@ubuntu.com>
desktopfolder

Debian Electronics Team <pkg-electronics-devel@alioth-lists.debian.net>
gnusim8085

Debian Electronics Team <pkg-electronics-devel@lists.alioth.debian.org>
oregano

Debian GNOME Maintainers <pkg-gnome-maintainers@lists.alioth.debian.org>
anjuta
gitg
gtk-d
libgtksourceviewmm
meld (U)

Debian Java Maintainers <pkg-java-maintainers@lists.alioth.debian.org>
java-gnome

Debian OCaml Maintainers <debian-ocaml-maint@lists.debian.org>
coq
frama-c
lablgtk3
laby
why3

Debian Python Team <team+python@tracker.debian.org>
autokey

Debian QA Group <packages@qa.debian.org>
giggle

Debian Ruby Extras Maintainers <pkg-ruby-extras-maintainers@lists.alioth.debian.org>
ruby-gnome

Debian Science Maintainers <debian-science-maintainers@lists.alioth.debian.org>
gummi

Debian Science Team <debian-science-maintainers@lists.alioth.debian.org>
pspp

Debian Sugar Team <pkg-sugar-devel@lists.alioth.debian.org>
sugar
sugar-pippy-activity

Debian Xfce Maintainers <debian-xfce@lists.debian.org>
mousepad

Debian+Ubuntu MATE Packaging Team <debian-mate@lists.debian.org>
mate-applets
pluma

Dirk Eddelbuettel <edd@debian.org>
gretl

Dmitry Smirnov <onlyjob@debian.org>
giggle

Dr. Tobias Quathamer <toddy@debian.org>
denemo

Emilio Pozuelo Monfort <pochu@debian.org>
meld (U)

Enrico Tassi <gareuselesinge@debian.org>
coq (U)

Friedrich Beckmann <friedrich.beckmann@gmx.de>
pspp
pspp (U)

Georges Khaznadar <georgesk@debian.org>
pycode-browser

Guilhem Bonnefille <guilhem.bonnefille@gmail.com>
giggle (U)

Guillaume Mazoyer <respawneral@gmail.com>
java-gnome (U)

HIGUCHI Daisuke (VDR dai) <dai@debian.org>
ruby-gnome (U)

Hugo Lefeuvre <hle@debian.org>
gummi (U)

JCF Ploemen (jcfp) <linux@jcf.pm>
xpad

Jendrik Seipp <jendrikseipp@gmail.com>
rednotebook

Jeremy Bicha <jbicha@debian.org>
anjuta (U)
gitg (U)
gtk-d (U)
libgtksourceviewmm (U)
meld (U)

John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
mate-applets (U)
pluma (U)

Jonas Smedegaard <dr@jones.dk>
sugar (U)
sugar-pippy-activity (U)

Josselin Mouette <joss@debian.org>
libgtksourceviewmm (U)

Laurent Bigonville <bigon@debian.org>
gitg (U)

Luke Faraone <lfaraone@debian.org>
autokey
autokey (U)

Manu Mahajan <manu@codepencil.com>
java-gnome (U)

Martin Wimpress <code@flexion.org>
mate-applets (U)

Matthias Klumpp <mak@debian.org>
gtk-d (U)

Mehdi Dogguy <mehdi@debian.org>
frama-c (U)
laby (U)

Michael Biebl <biebl@debian.org>
libgtksourceviewmm (U)

Michael Schutte <m.schutte.jr@gmail.com>
ruby-gnome (U)

Mike Gabriel <sunweaver@debian.org>
mate-applets (U)
pluma (U)

Nis Martensen <nis.martensen@web.de>
reportbug (U)

Ondřej Tůma <mcbig@zeropage.cz>
formiko

Onkar Shinde <onkarshinde@gmail.com>
gnusim8085 (U)

Onkar Shinde <onkarshinde@ubuntu.com>
java-gnome (U)

Paul van Tilburg <paulvt@debian.org>
ruby-gnome (U)

Phil Wyett <philip.wyett@kathenas.org>
rednotebook

Philipp Kern <pkern@debian.org>
gobby

Python Applications Packaging Team <python-apps-team@lists.alioth.debian.org>
autokey (U)

Ralf Treinen <treinen@debian.org>
coq (U)
frama-c (U)
lablgtk3 (U)
why3 (U)

Reportbug Maintainers <debian-reportbug@lists.debian.org>
reportbug

Ritesh Raj Sarraf <rrs@debian.org>
snapper-gui

Ruben Undheim <rubund@debian.org>
oregano (U)

Samuel Mimram <smimram@debian.org>
coq (U)

Sandro Tosi <morph@debian.org>
reportbug (U)

Santiago Ruano Rincón <santiago@debian.org>
sugar (U)

Stefano Karapetsas <stefano@karapetsas.com>
mate-applets (U)
pluma (U)

Stéphane Glondu <glondu@debian.org>
coq (U)

Tanguy Ortolo <tanguy+debian@ortolo.eu>
latexila

Vangelis Mouhtsis <vangelis@gnugr.org>
mate-applets (U)
pluma (U)

Varun Hiremath <varun@debian.org>
pychess

Yangfl <mmyangfl@gmail.com>
sequeler

Yves-Alexis Perez <corsac@debian.org>
mousepad (U)

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