fix: hint shell builtins in command-not-found error

[kimjune01]

Closes #1944.

When fd -x cd (or any shell builtin) fails with "command not found", the error now explains that the command is a shell builtin and shows how to invoke it through a shell:

[fd error]: Command not found: cd. Note: cd is a shell builtin, not a standalone
program. To run shell builtins, invoke a shell explicitly,
e.g. fd -x sh -c 'cd ... "$1"' sh {}

Non-builtins still get the plain "Command not found: foo" message.

The builtin list covers POSIX and common bash builtins that don't have standalone executables. Commands like echo, printf, and test are excluded since they typically exist as /usr/bin/ binaries and work fine with -x.

Changelog entry added.

[wyf027]

CI is failing on a one-line clippy fix (clippy::manual-contains):

fn is_shell_builtin(program: &str) -> bool {
    SHELL_BUILTINS.contains(&program)
}

I've opened #1998 with the same approach plus this fix — happy to close mine if you update this branch instead. Thanks for the original implementation!

[wyf027]

CI note: Ensure 'cargo clippy' has no warnings fails with clippy::manual-contains — SHELL_BUILTINS.contains(&program) instead of .iter().any(|&b| b == program) should fix it (see #1998 for the same change). Happy to close #1998 if you prefer to land this here.

[wyf027]

CI fix for clippy::manual-contains: on @kimjune01's branch, change is_shell_builtin to:

SHELL_BUILTINS.contains(&program)

I pushed the one-line fix to leno23/fd@fix/shell-builtin-hint-1944-clippy (commit 1f27576) — you can cherry-pick onto your PR branch. Happy to close #1998 if this lands here.

[wyf027]

@kimjune01 Clippy fix for is_shell_builtin: use SHELL_BUILTINS.contains(&program) instead of .iter().any(|&b| b == program) (satisfies manual_is_variant_and).

[tavianator]

Does contains() work here?

[tavianator]

I think this should be a HashSet personally

[tavianator]

Thanks for getting the quoting/escaping right here :)

[kimjune01]

Cannot validate on current setup, so drafting. Please close or take it over.