The "shell" directive has no effect in a shell script file

[Sylvain Prat]

Code editor

Sublime Text

Platform

Windows, Linux

Version

5.0.0

What steps will reproduce the bug?

The following script raises a shellcheck warning on the "set" line:

#!/bin/sh
# shellcheck shell=ash
set -euxo pipefail

However it should not because I explicitly defined the shell to eliminate the warning.

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior?

I would expect the shell directive to be taken into account, so no warning should appear on the "set" line

What do you see instead?

The shell directive is ignored

Additional information

I suspect that the problem is caused by the LSP language server passing the --shell option to the command-line which have the priority over the shell directive defined in my script file. But, AFAIK, there's no way to change/remove the value of the --shell option, right?

[Sylvain Prat]

After diving a bit into the code, i can see that the shell directive is not used in the guessShellDialect method which is used to derive the shell that will be passed to the --shell option in the command-line. The method use either the file extension or parses the shebang to derive the shell, that's all.

I must admit that I don't understand why the language server need to detect the shell dialect instead of letting shellcheck do its job. There is a comment that attempt to give a rationale:

// NOTE: that ShellCheck actually does shebang parsing, but we manually
// do it here in order to fallback to bash for files without a shebang.
// This enables parsing files with a bash syntax, but could yield false positives.

However I don't understand the argument here: if the user want his shell script to be interpreted as a bash script, he can either add a shebang or use a shellcheck directive, right?

[Kenneth Skovhus]

PR are more than welcome here. The current behaviour is not perfect, but does enable people to use ShellCheck for bash-like without adding directives. We can either include parsing directives when guessing the dialect OR simply remove the feature to enable parsing files with a bash syntax.

Also the support for enabling parsing files with a bash syntax was added before the directive parser (PR).