C syntax highlighting: plugin incorrectly highlights reserved keywords inside struct declarations

[alex-tee]

(moved from vim's issues)

Describe the bug
Members inside structs are incorrectly highlighted (vim thinks they are reserved keywords but reserved keywords (to my knowledge) shouldn't be reserved inside structs)

To Reproduce
Detailed steps to reproduce the behavior:

typedef struct MyStruct
{
int a; // this is highlighted normally
int copy; // this is highlighted as a reserved keyword
int delete; // this is highlighted differently as a reserved keyword
} MyStruct;

Expected behavior
Struct members should all be highlighted normally

Screenshots

Environment (please complete the following information):

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled May 28 2021 06:58:52)
Included patches: 1-2891
Compiled by Arch Linux
Huge version without GUI.  Features included (+) or not (-):
+acl               -farsi             +mouse_sgr         +tag_binary
+arabic            +file_in_path      -mouse_sysmouse    -tag_old_static
+autocmd           +find_in_path      +mouse_urxvt       -tag_any_white
+autochdir         +float             +mouse_xterm       +tcl/dyn
-autoservername    +folding           +multi_byte        +termguicolors
-balloon_eval      -footer            +multi_lang        +terminal
+balloon_eval_term +fork()            -mzscheme          +terminfo
-browse            +gettext           +netbeans_intg     +termresponse
++builtin_terms    -hangul_input      +num64             +textobjects
+byte_offset       +iconv             +packages          +textprop
+channel           +insert_expand     +path_extra        +timers
+cindent           +ipv6              +perl/dyn          +title
-clientserver      +job               +persistent_undo   -toolbar
-clipboard         +jumplist          +popupwin          +user_commands
+cmdline_compl     +keymap            +postscript        +vartabs
+cmdline_hist      +lambda            +printer           +vertsplit
+cmdline_info      +langmap           +profile           +virtualedit
+comments          +libcall           +python/dyn        +visual
+conceal           +linebreak         +python3/dyn       +visualextra
+cryptv            +lispindent        +quickfix          +viminfo
+cscope            +listcmds          +reltime           +vreplace
+cursorbind        +localmap          +rightleft         +wildignore
+cursorshape       +lua/dyn           +ruby/dyn          +wildmenu
+dialog_con        +menu              +scrollbind        +windows
+diff              +mksession         +signs             +writebackup
+digraphs          +modify_fname      +smartindent       -X11
-dnd               +mouse             -sound             -xfontset
-ebcdic            -mouseshape        +spell             -xim
+emacs_tags        +mouse_dec         +startuptime       -xpm
+eval              +mouse_gpm         +statusline        -xsmp
+ex_extra          -mouse_jsbterm     -sun_workshop      -xterm_clipboard
+extra_search      +mouse_netterm     +syntax            -xterm_save
   system vimrc file: "/etc/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -march=x86-64 -mtune=generic -O2 -pipe -fno-plt -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 
Linking: gcc -L. -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -fstack-protector-strong -rdynamic -Wl,-export-dynamic -Wl,-E -Wl,-rpath,/usr/lib/perl5/5.34/core_perl/CORE -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -L/usr/local/lib -o vim -lm -ltinfo -lelf -lacl -lattr -lgpm -ldl -Wl,-E -Wl,-rpath,/usr/lib/perl5/5.34/core_perl/CORE -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -fstack-protector-strong -L/usr/local/lib -L/usr/lib/perl5/5.34/core_perl/CORE -lperl -lpthread -ldl -lm -lcrypt -lutil -lc -L/usr/lib -ltclstub8.6 -ldl -lz -lpthread -lm 

• OS: Parabola GNU/Linux (Arch Linux based)
• Terminal: GNOME Terminal

Additional context
I've had this issue for a few years, just never bothered to report it

[alex-tee]

in the example above, "delete" highlighting seems to be an issue on vim side but "copy" highlighting seems to be an issue with this plugin