ALE tells ShellCheck to treat files with the ".bash" extension as sh files when vim-polyglot is enabled

[openjck]

Information

VIM version

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Nov 08 2021 14:19:29)
Included patches: 1-2434, 3402-3403, 3409, 3428, 3487, 3564, 3581-3582

Operating System: Ubuntu 21.04

What went wrong

When ALE and vim-polyglot are both enabled, ALE tells ShellCheck that files ending with a .bash extension are of type sh.

Reproducing the bug

Steps to reproduce

1. Install ShellCheck
2. mv ~/.vim ~/.vim.bak.ale-issue-3988.$(date '+%s')
3. git clone --depth 1 https://github.com/dense-analysis/ale.git ~/.vim/pack/plugins/start/ale
4. git clone --depth 1 https://github.com/sheerun/vim-polyglot ~/.vim/pack/plugins/start/vim-polyglot
5. vim example.bash
6. Enter the following contents:

function example() {
  echo 'example'
}

Actual results

:ALEInfo reports that option -s sh is passed to ShellCheck. ShellCheck reports the following error, which only applies to POSIX sh:

SC2112: 'function' keyword is non-standard. Delete it.

Expected results

:ALEInfo reports that option -s bash is passed to ShellCheck and ShellCheck reports no errors.

:ALEInfo

 Current Filetype: sh
Available Linters: ['bashate', 'cspell', 'language_server', 'shell', 'shellcheck']
  Enabled Linters: ['bashate', 'cspell', 'language_server', 'shell', 'shellcheck']
  Ignored Linters: []
 Suggested Fixers: 
  'remove_trailing_lines' - Remove all blank lines at the end of a file.
  'shfmt' - Fix sh files with shfmt.
  'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
 Linter Variables:

let g:ale_sh_bashate_executable = 'bashate'
let g:ale_sh_bashate_options = ''
let g:ale_sh_language_server_executable = 'bash-language-server'
let g:ale_sh_language_server_use_global = 0
let g:ale_sh_shell_default_shell = 'bash'
let g:ale_sh_shellcheck_change_directory = 1
let g:ale_sh_shellcheck_dialect = 'auto'
let g:ale_sh_shellcheck_exclusions = ''
let g:ale_sh_shellcheck_executable = 'shellcheck'
let g:ale_sh_shellcheck_options = ''
 Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = 0
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = v:null
let g:ale_disable_lsp = 0
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = 0
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 1
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'normal'
let g:ale_linter_aliases = {}
let g:ale_linters = {}
let g:ale_linters_explicit = 0
let g:ale_linters_ignore = {}
let g:ale_list_vertical = 0
let g:ale_list_window_size = 10
let g:ale_loclist_msg_format = '%code: %%s'
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = -1
let g:ale_maximum_file_size = v:null
let g:ale_open_list = 0
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_root = {}
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = 0
let g:ale_sign_error = '>>'
let g:ale_sign_info = '--'
let g:ale_sign_offset = 1000000
let g:ale_sign_style_error = '>>'
let g:ale_sign_style_warning = '--'
let g:ale_sign_warning = '--'
let g:ale_sign_highlight_linenrs = 0
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
  Command History:

(executable check - failure) bashate
(executable check - failure) cspell
(executable check - success) sh
(finished - exit code 0) ['/bin/bash', '-c', 'sh -n ''/tmp/vZUaM5c/1/example.bash''']

<<<NO OUTPUT RETURNED>>>

(executable check - success) shellcheck
(finished - exit code 0) ['/bin/bash', '-c', 'cd ''/home/john'' && ''shellcheck'' --version']

<<<OUTPUT STARTS>>>
ShellCheck - shell script analysis tool
version: 0.7.1
license: GNU General Public License, version 3
website: https://www.shellcheck.net
<<<OUTPUT ENDS>>>

(finished - exit code 0) ['/bin/bash', '-c', 'cd ''/home/john'' && ''shellcheck'' -s sh -x -f gcc - < ''/tmp/vZUaM5c/2/example.bash''']

<<<NO OUTPUT RETURNED>>>

(executable check - failure) bashate
(executable check - failure) cspell
(finished - exit code 2) ['/bin/bash', '-c', 'sh -n ''/tmp/vZUaM5c/3/example.bash''']

<<<OUTPUT STARTS>>>
/tmp/vZUaM5c/3/example.bash: 1: Syntax error: "(" unexpected
<<<OUTPUT ENDS>>>

(finished - exit code 1) ['/bin/bash', '-c', 'cd ''/home/john'' && ''shellcheck'' -s sh -x -f gcc - < ''/tmp/vZUaM5c/4/example.bash''']

<<<OUTPUT STARTS>>>
-:1:1: note: The mentioned syntax error was in this function. [SC1009]
-:1:20: error: Couldn't parse this brace group. Fix to allow more checks. [SC1073]
-:2:1: error: You need at least one command here. Use 'true;' as a no-op. [SC1055]
-:2:2: error: Unexpected keyword/token. Fix any mentioned problems and try again. [SC1072]
<<<OUTPUT ENDS>>>

(executable check - failure) bashate
(executable check - failure) cspell
(finished - exit code 2) ['/bin/bash', '-c', 'sh -n ''/tmp/vZUaM5c/5/example.bash''']

<<<OUTPUT STARTS>>>
/tmp/vZUaM5c/5/example.bash: 1: Syntax error: "(" unexpected
<<<OUTPUT ENDS>>>

(finished - exit code 1) ['/bin/bash', '-c', 'cd ''/home/john'' && ''shellcheck'' -s sh -x -f gcc - < ''/tmp/vZUaM5c/6/example.bash''']

<<<OUTPUT STARTS>>>
-:1:1: warning: 'function' keyword is non-standard. Delete it. [SC2112]
<<<OUTPUT ENDS>>>

Other notes

This works as expected if vim-polyglot is not enabled when Vim starts up, e.g., if the steps above are repeated and step 4 is skipped.

[hsanson]

ALE determines the shell dialect in this order:

1. Check for shellcheck directive (see https://github.com/koalaman/shellcheck/wiki/Directive#shell)
2. Check for shebang #! line at the start of the script.
3. Check vim's local buffer variables (e.g. b:is_bash, b:is_sh, and b:is_kornshell). Set by vim ftdetect.
4. Check vim's global variables (e.g. g:is_bash, g:is_sh, and g:is_kornshell). Set by users to override vim ftdetect.
5. Check the filetype.

In your example 1 and 2 do not apply. For 3 I could test that b:is_bash is properly set when vim-polyglot is not installed but not defined if vim-polyglot is installed. Somehow vim-polyglot is messing with vim's default auto-detect logic and undefining these buffer variables.

You can test this by running ":echo b:is_bash" with the vim-polyglot plugin installed and when not installed.

Simple solution is to add a shellcheck directive to the script so ALE properly detects it as bash. Also would be good idea to report an issue in vim-polyglot to investigate the problem on their side.