bug#61482: 30.0.50; tree-sitter-c doesn't support _Generic

bug#61482: 30.0.50; tree-sitter-c doesn't support _Generic

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

2011 Standard C has a feature that works like `switch', except it
switches upon the type of an expression at compile time.

This does not seem to be supported at all with c-ts-mode:

{
  const char *typename = _Generic ((expr),
				   const char *:
				     "const char *",
				   int:
				     "int",
				   unsigned long:
				     "unsigned long",
				   default:
				     NULL);
}

here, none of the types are fontified (which fares worse than CC Mode),
nor is _Generic fontified as a keyword.  Indenting anywhere inside the
_Generic expression also results in nothing happening.


In GNU Emacs 30.0.50 (build 72, x86_64-pc-linux-gnu) of 2023-02-13 built
 on trinity
Repository revision: e0b60120a1c3433fe332bff56b5b7483b0424d5c
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101099
System Description: Fedora Linux 37 (Workstation Edition)

Configured using:
 'configure --with-x --with-x-toolkit=no --without-cairo
 --with-dumping=unexec --cache-file=/tmp/ccache'

Configured features:
ACL DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON LCMS2
LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY OLDXMENU PNG RSVG
SECCOMP SOUND SQLITE3 THREADS TIFF TREE_SITTER UNEXEC WEBP X11 XDBE XFT
XIM XINPUT2 XPM ZLIB

Important settings:
  value of $LANG: en_GB.utf8
  value of $XMODIFIERS: @im=none
  locale-coding-system: utf-8-unix

Major mode: C

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-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:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util text-property-search time-date subr-x mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
display-line-numbers c-ts-mode cl-extra help-mode warnings icons
c-ts-common treesit cl-seq cl-loaddefs cl-lib rmc iso-transl tooltip
cconv eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type
elisp-mode mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd
fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow
isearch easymenu timer select scroll-bar mouse jit-lock font-lock syntax
font-core term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting xinput2 x
multi-tty make-network-process emacs)

Memory information:
((conses 16 110475 7691)
 (symbols 48 21846 0)
 (strings 32 31362 1808)
 (string-bytes 1 774600)
 (vectors 16 18868)
 (vector-slots 8 795767 66178)
 (floats 8 67 68)
 (intervals 56 441 2)
 (buffers 984 15))

bug#61482: 30.0.50; tree-sitter-c doesn't support _Generic

[Yuan Fu]

Po Lu <luangruo@yahoo.com> writes:

> 2011 Standard C has a feature that works like `switch', except it
> switches upon the type of an expression at compile time.
>
> This does not seem to be supported at all with c-ts-mode:
>
> {
>   const char *typename = _Generic ((expr),
> 				   const char *:
> 				     "const char *",
> 				   int:
> 				     "int",
> 				   unsigned long:
> 				     "unsigned long",
> 				   default:
> 				     NULL);
> }
>
> here, none of the types are fontified (which fares worse than CC Mode),
> nor is _Generic fontified as a keyword.  Indenting anywhere inside the
> _Generic expression also results in nothing happening.

That’s the same as _Noreturn, tree-sitter-c doesn’t support it now. See
https://github.com/tree-sitter/tree-sitter-c/issues/124, I opened an
issue requesting for _Generic and _Noreturn. But I don’t really know
much about these features, please see if I described it correctly.

Yuan