bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Markus Triska]

To reproduce this issue, please start Emacs with:

    $ emacs -Q

and then insert the following text in the *scratch* buffer:

    Ϊ́"

The expected appearance is: the letter Ι combined with diaeresis and
acute accent, followed by double quote.

Instead, I see: the letter I combined with diaeresis, followed by
double quote combined with acute accent.

All the best,
Markus

In GNU Emacs 30.0.50 (build 1, x86_64-apple-darwin18.2.0, X toolkit,
 cairo version 1.17.6, Xaw scroll bars) of 2023-09-11 built on
 mac
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description:  Mac OS X 10.14.2

Configured using:
 'configure --prefix=/opt/local --disable-silent-rules --without-ns
 --without-dbus --without-gconf --without-libotf --without-m17n-flt
 --with-libgmp --with-gnutls --with-json --with-xml2 --with-modules
 --with-sqlite3 --with-webp --infodir /opt/local/share/info/emacs
 --with-x-toolkit=lucid --without-xaw3d --without-imagemagick --with-xpm
 --with-jpeg --with-tiff --with-gif --with-png --with-lcms2
 --without-rsvg --with-xft --with-native-compilation=aot
 --with-tree-sitter 'CFLAGS=-pipe -Os -Wno-attributes
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk -arch
 x86_64' 'CPPFLAGS=-I/opt/local/include
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk'
 'LDFLAGS=-L/opt/local/lib -Wl,-headerpad_max_install_names -lfreetype
 -lfontconfig -Wl,-rpath /opt/local/lib/gcc12 -Wl,-no_pie
 -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk
 -arch x86_64''

Configured features:
ACL CAIRO FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON
LCMS2 LIBXML2 MODULES NATIVE_COMP NOTIFY KQUEUE PDUMPER PNG SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM XINPUT2
XPM LUCID ZLIB

Important settings:
  value of $LC_CTYPE: UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Eli Zaretskii]

> From: Markus Triska <triska@metalevel.at>
> Date: Wed, 25 Oct 2023 00:22:38 +0200
> 
> To reproduce this issue, please start Emacs with:
> 
>     $ emacs -Q
> 
> and then insert the following text in the *scratch* buffer:
> 
>     Ϊ́"
> 
> The expected appearance is: the letter Ι combined with diaeresis and
> acute accent, followed by double quote.
> 
> Instead, I see: the letter I combined with diaeresis, followed by
> double quote combined with acute accent.

Try another font.  On my system, the display is like you expect.

If you go to the letter I and type "C-u C-x =", what does Emacs say in
the *Help* buffer?

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Markus Triska]

Eli Zaretskii <eliz@gnu.org> writes:

> Try another font.  On my system, the display is like you expect.
>
> If you go to the letter I and type "C-u C-x =", what does Emacs say in
> the *Help* buffer?

Please find the buffer content below.

Personally, I found that the DejaVu Sans Mono font works very well for
many use cases, and I would like to keep using it. Is there any way to
make it render this as intended?

Thank you and all the best,
Markus


             position: 295 of 324 (91%), column: 0
            character: Ι (displayed as Ι) (codepoint 921, #o1631, #x399)
              charset: unicode-bmp (Unicode Basic Multilingual Plane (U+0000..U+FFFF))
code point in charset: 0x0399
               script: greek
               syntax: w 	which means: word
             category: .:Base, G:2-byte Greek, L:Strong L2R, c:Chinese, g:Greek, h:Korean, j:Japanese
             to input: type "C-x 8 RET 399" or "C-x 8 RET GREEK CAPITAL LETTER IOTA"
          buffer code: #xCE #x99
            file code: #xCE #x99 (encoded by coding system utf-8-unix)
              display: composed to form "Ϊ́" (see below)

Composed with the following character(s) "̈́" using this font:
  ftcrhb:-PfEd-DejaVu Sans Mono-regular-normal-normal-*-20-*-*-*-m-0-iso10646-1
by these glyphs:
  [0 2 921 760 12 1 11 18 0 nil]
  [0 2 776 649 12 4 10 16 -12 [0 0 0]]
with these character(s):
  ̈ (#x308) COMBINING DIAERESIS
  ́ (#x301) COMBINING ACUTE ACCENT

Character code properties: customize what to show
  name: GREEK CAPITAL LETTER IOTA
  general-category: Lu (Letter, Uppercase)
  decomposition: (921) ('Ι')

There are text properties here:
  fontified            t

[back]

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Eli Zaretskii]

> From: Markus Triska <triska@metalevel.at>
> Cc: 66737@debbugs.gnu.org
> Date: Thu, 26 Oct 2023 10:27:35 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Try another font.  On my system, the display is like you expect.
> >
> > If you go to the letter I and type "C-u C-x =", what does Emacs say in
> > the *Help* buffer?
> 
> Please find the buffer content below.

This says that Emacs did display the diaeresis, the acute accent, and
Ι as a single grapheme:

>               display: composed to form "Ϊ́" (see below)
> 
> Composed with the following character(s) "̈́" using this font:
>   ftcrhb:-PfEd-DejaVu Sans Mono-regular-normal-normal-*-20-*-*-*-m-0-iso10646-1
> by these glyphs:
>   [0 2 921 760 12 1 11 18 0 nil]
>   [0 2 776 649 12 4 10 16 -12 [0 0 0]]
> with these character(s):
>   ̈ (#x308) COMBINING DIAERESIS
>   ́ (#x301) COMBINING ACUTE ACCENT

So now I don't understand your original report, viz.:

> The expected appearance is: the letter Ι combined with diaeresis and
> acute accent, followed by double quote.
> 
> Instead, I see: the letter I combined with diaeresis, followed by
> double quote combined with acute accent.

How do you see that the acute accent is combined with the double
quote?  Emacs, above, says it's combined with Ι and the diaeresis, not
with the double quote.

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Markus Triska]

Eli Zaretskii <eliz@gnu.org> writes:

> How do you see that the acute accent is combined with the double
> quote?  Emacs, above, says it's combined with Ι and the diaeresis, not
> with the double quote.

Yes, that's correct: What Emacs says is not what I see, I see the acute
accent combined with the double quote, here is a screenshot:

    https://www.metalevel.at/ei/issue66737.png

All the best,
Markus

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Eli Zaretskii]

> From: Markus Triska <triska@metalevel.at>
> Cc: 66737@debbugs.gnu.org
> Date: Thu, 26 Oct 2023 11:06:50 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > How do you see that the acute accent is combined with the double
> > quote?  Emacs, above, says it's combined with Ι and the diaeresis, not
> > with the double quote.
> 
> Yes, that's correct: What Emacs says is not what I see, I see the acute
> accent combined with the double quote, here is a screenshot:
> 
>     https://www.metalevel.at/ei/issue66737.png

Then that's a problem with this font.  I see the same here when I use
DejaVu Sans Mono as the default font.  I think HarfBuzz developers
said several times that DejaVu Sans Mono is a problematic font.

I don't think this is an Emacs problem.

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Eli Zaretskii]

> Cc: 66737@debbugs.gnu.org
> Date: Thu, 26 Oct 2023 12:40:09 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > From: Markus Triska <triska@metalevel.at>
> > Cc: 66737@debbugs.gnu.org
> > Date: Thu, 26 Oct 2023 11:06:50 +0200
> > 
> > Eli Zaretskii <eliz@gnu.org> writes:
> > 
> > > How do you see that the acute accent is combined with the double
> > > quote?  Emacs, above, says it's combined with Ι and the diaeresis, not
> > > with the double quote.
> > 
> > Yes, that's correct: What Emacs says is not what I see, I see the acute
> > accent combined with the double quote, here is a screenshot:
> > 
> >     https://www.metalevel.at/ei/issue66737.png
> 
> Then that's a problem with this font.  I see the same here when I use
> DejaVu Sans Mono as the default font.  I think HarfBuzz developers
> said several times that DejaVu Sans Mono is a problematic font.
> 
> I don't think this is an Emacs problem.

No further comments, so I'm now closing this bug.

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Markus Triska]

Eli Zaretskii <eliz@gnu.org> writes:

> No further comments, so I'm now closing this bug.

For me, the issue persists. Is there nothing that Emacs can or should do
about this? If so, then please ignore this issue.

Thank you and all the best,
Markus

bug#66737: 30.0.50; Unexpected combination of double quote and acute accent

[Eli Zaretskii]

> From: Markus Triska <triska@metalevel.at>
> Cc: 66737-done@debbugs.gnu.org
> Date: Sat, 04 Nov 2023 10:17:41 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > No further comments, so I'm now closing this bug.
> 
> For me, the issue persists. Is there nothing that Emacs can or should do
> about this? If so, then please ignore this issue.

It seems to be a problem with the font, so Emacs cannot do anything
about it, AFAIU.