[Pkg-fonts-devel] Bug#974537: fonts-noto-core: Fallback font selection changed and incorrect glyph displayed

[astian]

Package: fonts-noto-core
Version: 20201109-1
Severity: normal

Dear Maintainer,

With version 20200323-1, when attempting to render code points such as
0x3001 and 0x3002, fontconfig would choose "Noto Sans CJK JP" [0] as
fallback for "Monospace".  This was expected behaviour, I want to see
Japanese punctuation glyphs.
  0: /usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc

Binary packages for version 20200323-1 seem to be gone from the archive
but version 20181227-1 also shows the wanted behaviour.

After updating to version 20201027-3 and later also 20201109-1,
fontconfig chooses "Noto Sans Mongolian" [1].  This results in
unintended glyphs.
  1: /usr/share/fonts/truetype/noto/NotoSansMongolian-Regular.ttf

STR:

  a) Run:
       $ LANG=en_US.UTF-8 pango-view --font monospace -t $'\u3001'
     Or even:
       $ LANG=en_US.UTF-8 pango-view -t $'\u3001'

  b) Run:
       $ fc-match --sort monospace family style file | grep -i -e cjk -e mongo
     Or even:
       $ fc-match --sort : family style file | grep -i -e cjk -e mongo

Expected behaviour:

  a) The pango-view window shows the Japanese comma glyph (see for
     example "Noto Sans CJK JP" in fontforge).

  b) A Japanese font is preferred:
       Noto Sans CJK JP:style=Regular:file=/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc
       Noto Sans Mongolian:style=Regular:file=/usr/share/fonts/truetype/noto/NotoSansMongolian-Regular.ttf

Actual behaviour:

  a) The pango-view window shows a different glyph (from "Noto Sans
     Mongolian").

  b) A Mongolian font is preferred:
       Noto Sans Mongolian:style=Regular:file=/usr/share/fonts/truetype/noto/NotoSansMongolian-Regular.ttf
       Noto Sans CJK JP:style=Regular:file=/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc

This looks like a regression and it is one for me, but I guess it could
also be a configuration issue involving fontconfig.  I have no custom
fontconfig configuration, though, so if somehow this is not considered a
regression, perhaps you could recommend a configuration that would
restore the previous behaviour for me?

Thanks.

-- Package-specific info:
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name               Version       Architecture Description
+++-==================-=============-============-=====================================================
ii  fontconfig         2.13.1-4.2    amd64        generic font configuration library - support binaries
ii  libfreetype6:amd64 2.10.2+dfsg-4 amd64        FreeType 2 font engine, shared library files
ii  libxft2:amd64      2.3.2-2       amd64        FreeType-based font drawing library for X

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable-debug
  APT policy: (500, 'unstable-debug'), (500, 'unstable'), (500, 'testing'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.19.0-10-amd64 (SMP w/4 CPU threads)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB:en
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

-- no debconf information