`Cargo check` ignores `g:rust_cargo_check_all_features`

Read the argument construction in autoload/cargo.vim and compare it with the checker logic in syntax_checkers/rust/cargo.vim, linked in the issue. Check how :Cargo check handles g:rust_cargo_check_all_features; done means the command includes --all-features when the variable is enabled, matching the reported expected behavior.

When we add g:rust_cargo_check_all_features = 1 to .vimrc, Cargo check don't pass all-features

Here is how Cargo check computes a cargo argument:

https://github.com/rust-lang/rust.vim/blob/4aa69b84c8a58fcec6b6dad6fe244b916b1cf830/autoload/cargo.vim#L5-L19

And here is how we build the internal checker:
https://github.com/rust-lang/rust.vim/blob/4aa69b84c8a58fcec6b6dad6fe244b916b1cf830/syntax_checkers/rust/cargo.vim#L53-L64

Seems we are missing these global vars check in autoload/cargo.vim. Maybe its a feature, and not a bug.

rust.vim version

https://github.com/rust-lang/rust.vim/commit/4aa69b84c8a58fcec6b6dad6fe244b916b1cf830

Steps to reproduce

1. Add let g:rust_cargo_check_all_features = 1 to $MYVIMRC and source it, if applicable
2. Run :Cargo check

Expected vs. actual behavior

The cargo command should be cargo check --all-features, but it is just cargo check

Debug info

rust.vim Global Variables:

let g:ftplugin_rust_source_path = v:null
let g:loaded_syntastic_rust_cargo_checker = v:null
let g:loaded_syntastic_rust_filetype = v:null
let g:loaded_syntastic_rust_rustc_checker = v:null
let g:rust_bang_comment_leader = v:null
let g:rust_cargo_avoid_whole_workspace = v:null
let g:rust_clip_command = v:null
let g:rust_conceal = v:null
let g:rust_conceal_mod_path = v:null
let g:rust_conceal_pub = v:null
let g:rust_fold = v:null
let g:rust_last_args = v:null
let b:rust_last_args = []
let g:rust_last_rustc_args = v:null
let b:rust_last_rustc_args = []
let g:rust_original_delimitMate_excluded_regions = v:null
let g:rust_playpen_url = v:null
let g:rust_prev_delimitMate_quotes = v:null
let g:rust_recent_nearest_cargo_tol = v:null
let g:rust_recent_root_cargo_toml = v:null
let g:rust_recommended_style = v:null
let g:rust_set_conceallevel = v:null
let g:rust_set_conceallevel=1 = v:null
let g:rust_set_foldmethod = v:null
let g:rust_set_foldmethod=1 = v:null
let g:rust_shortener_url = v:null
let g:rustc_makeprg_no_percent = v:null
let g:rustc_path = v:null
let g:rustfmt_autosave = 1
let g:rustfmt_autosave_if_config_present = v:null
let g:rustfmt_command = 'rustfmt'
let g:rustfmt_emit_files = 1
let g:rustfmt_fail_silently = 0
let g:rustfmt_options = ''
let g:syntastic_extra_filetypes = ['rust']
let g:syntastic_rust_cargo_fname = v:null
rustfmt 1.4.38-nightly (e95b10b 2022-03-13)

rustc 1.61.0-nightly (e95b10ba4 2022-03-13)

cargo 1.61.0-nightly (65c8266 2022-03-09)



VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Feb 24 2022 18:41:57)
Included patches: 1-4464
Compiled by Arch Linux
Huge version without GUI.  Features included (+) or not (-):
+acl               +channel           +cscope            +ex_extra          -hangul_input      +linebreak         +mouse_dec         -mzscheme          +profile           -sodium            +tcl/dyn           +user_commands     +wildmenu
+arabic            +cindent           +cursorbind        +extra_search      +iconv             +lispindent        +mouse_gpm         +netbeans_intg     -python            -sound             +termguicolors     +vartabs           +windows
+autocmd           -clientserver      +cursorshape       -farsi             +insert_expand     +listcmds          -mouse_jsbterm     +num64             +python3/dyn       +spell             +terminal          +vertsplit         +writebackup
+autochdir         -clipboard         +dialog_con        +file_in_path      +ipv6              +localmap          +mouse_netterm     +packages          +quickfix          +startuptime       +terminfo          +vim9script        -X11
-autoservername    +cmdline_compl     +diff              +find_in_path      +job               +lua/dyn           +mouse_sgr         +path_extra        +reltime           +statusline        +termresponse      +viminfo           -xfontset
-balloon_eval      +cmdline_hist      +digraphs          +float             +jumplist          +menu              -mouse_sysmouse    +perl/dyn          +rightleft         -sun_workshop      +textobjects       +virtualedit       -xim
+balloon_eval_term +cmdline_info      -dnd               +folding           +keymap            +mksession         +mouse_urxvt       +persistent_undo   +ruby/dyn          +syntax            +textprop          +visual            -xpm
-browse            +comments          -ebcdic            -footer            +lambda            +modify_fname      +mouse_xterm       +popupwin          +scrollbind        +tag_binary        +timers            +visualextra       -xsmp
++builtin_terms    +conceal           +emacs_tags        +fork()            +langmap           +mouse             +multi_byte        +postscript        +signs             -tag_old_static    +title             +vreplace          -xterm_clipboard
+byte_offset       +cryptv            +eval              +gettext           +libcall           -mouseshape        +multi_lang        +printer           +smartindent       -tag_any_white     -toolbar           +wildignore        -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 -fexceptions -Wformat -Werror=format-security -fstack-clash-protection -fcf-protection -flto -D_REENTRANT -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 -flto -L/usr/local/lib -o vim -lm -ltinfo -lelf -lacl -lattr -lgpm -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 -lut
il -lc -L/usr/lib -ltclstub8.6 -ldl -lz -lpthread -lm