Setting `set macthinstrokes` doesn't have any effect

從 MacVim/MMCoreTextView.m 中連結的 755-758 行附近開始，並將其對 Core Text 的處理與連結的 iTermGraphicsUtilities.m 程式碼進行比較。使用 gvim --clean 和 :set macthinstrokes 重現此行為，然後確認細筆畫設定會如預期變更算繪的字型。

It looks like there has been regression and the set macthinstrokes option stopped working at some point

Describe the bug
set macthinstrokes doesn't change the way the font is rendered

To Reproduce

1. Run gvim --clean
2. Set the thin strokes option with :set macthinstrokes
3. Observe nothing happens, the font is exactly the same as it was before running the command

Expected behaviour
The font should be slightly thinner

Screenshots
With set macthinstrokes

Without set nomacthinstrokes

Environment:

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Apr  1 2021 08:37:51)
macOS version - x86_64
Included patches: 1-2681
Compiled by GitHub Actions
Huge version with MacVim GUI.  Features included (+) or not (-):
+acl               +file_in_path      -mouse_sysmouse    -tag_old_static
+arabic            +find_in_path      +mouse_urxvt       -tag_any_white
+autocmd           +float             +mouse_xterm       -tcl
+autochdir         +folding           +multi_byte        +termguicolors
-autoservername    -footer            +multi_lang        +terminal
+balloon_eval      +fork()            -mzscheme          +terminfo
+balloon_eval_term +fullscreen        +netbeans_intg     +termresponse
+browse            +gettext           +num64             +textobjects
++builtin_terms    -hangul_input      +odbeditor         +textprop
+byte_offset       +iconv             +packages          +timers
+channel           +insert_expand     +path_extra        +title
+cindent           +ipv6              +perl/dyn          +toolbar
+clientserver      +job               +persistent_undo   +transparency
+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_gui    +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
-farsi             +mouse_sgr         +tag_binary
   system vimrc file: "$VIM/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
  system gvimrc file: "$VIM/gvimrc"
    user gvimrc file: "$HOME/.gvimrc"
2nd user gvimrc file: "~/.vim/gvimrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
    system menu file: "$VIMRUNTIME/menu.vim"
  fall-back for $VIM: "/Applications/MacVim.app/Contents/Resources/vim"
Compilation: clang -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_MACVIM -Wall -Wno-unknown-pragmas -pipe -DMACOS_X -DMACOS_X_DARWIN -g -O2 -arch x86_64 -arch arm64 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -Wall -Wextra -Wshadow -Werror -Wno-error=missing-field-initializers -Wno-error=deprecated-declarations -Wno-error=unused-function
Linking: clang -L. -fstack-protector-strong -L/usr/local/lib -L/usr/local/opt/libyaml/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/opt/readline/lib -L. -fstack-protector-strong -L/usr/local/lib -L/usr/local/opt/libyaml/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/opt/readline/lib -arch x86_64 -arch arm64 -L/usr/local/lib -o Vim -lm -lncurses -liconv /usr/local/lib/libintl.a -framework AppKit -fstack-protector -L/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE

Additional context

MacVim uses exactly the same API as iTerm2

MacVim:
https://github.com/macvim-dev/macvim/blob/ef048edbb7aa6a65d11c7345ea7ca71d9748462a/src/MacVim/MMCoreTextView.m#L755-L758

iTerm2:
https://github.com/gnachman/iTerm2/blob/c52136b7c0bae545436be8d1441449f19e21faa1/sources/iTermGraphicsUtilities.m#L43-L51

In iTerm2 it is working great, so apparently, there is something wrong and that code in MacVim is never reached

Here are the iTerm2 screenshots:

with the thin strokes option

without the thin strokes option