Subject: bug#71784: 31.0.50; Inconsistent fontification for field_identifier in c++-ts-mode

From: Ergus <[email-masked]>
Date: Wed, 26 Jun 2024 16:13:47 +0200

Hi:

Using the c++-ts-mode I found that there is some inconsistent
fontification for the `fields_identifier`:

See the fontification in this example with `emacs -Q`.

```test.cpp

std::string key;
bool inserted;

struct name_t {
	std::string key;
	bool inserted;
};

name_t keys = {"aaa", true};

keys.inserted = false;
bool a = keys.inserted;
```

1. The `keys.inserted` values are shown differently before or after the
= (the inserted word is fontified is some cases, but not in all)

2. The variable names are fontified differently outside or
inside the struct.

3. The escape sequence (\t) is fontified differently to the rest of the
text inside the string. I don't know if that is intentional or not. If
it is intentional, just ignore this comment.

The inconsistencies 1 and 2 are not only different to c++-mode but they
are semantically incorrect.

Best,
Ergus

In GNU Emacs 31.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version
 3.24.42, cairo version 1.18.0) of 2024-06-26 built on RTX
Repository revision: d800d6b3bdaa927e031e003e761e623147e812e6
Repository branch: project
System Description: Arch Linux

Configured using:
 'configure --prefix=/home/ergo/.local/ --with-mailutils --with-pgtk
 --with-modules --with-cairo --with-harfbuzz
 --with-native-compilation=aot
 '--program-transform-name=s/^ctags$/ctags.emacs/''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PGTK
PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
TREE_SITTER WEBP XIM GTK3 ZLIB

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

Major mode: C++//

Minor modes in effect:
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  windmove-mode: t
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  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  size-indication-mode: t
  column-number-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
/mnt/casa/gits/emacs_clones/cuda-mode/cuda-mode hides /home/ergo/.config/emacs/elpa/cuda-mode-20201013.2230/cuda-mode
/mnt/casa/gits/emacs_clones/gtags-mode/gtags-mode hides /home/ergo/.config/emacs/elpa/gtags-mode-1.6/gtags-mode
/home/ergo/.config/emacs/elpa/transient-20240626.947/transient hides /home/ergo/.local/share/emacs/31.0.50/lisp/transient

Features:
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Memory information:
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 (strings 32 58441 11185) (string-bytes 1 2123450) (vectors 16 22552)
 (vector-slots 8 264028 8898) (floats 8 109 235) (intervals 56 1774 0)
 (buffers 992 15))