Clap-generated shell completion failing on macOS /bin/bash with: conditional binary operator expected: syntax error near `IFS'

[gibfahn]

Please complete the following tasks

• [X] I have searched the discussions
• [X] I have searched the open and rejected issues

Rust Version

❯ rustc -V
rustc 1.77.0 (aedd173a2 2024-03-17)

Clap Version

4.5.3

Minimal reproducible code

# Cargo.toml
[package]
name = "my-app"
version = "0.1.0"
edition = "2021"

[dependencies]
clap = { version = "4.5.3", features = [
  "debug",
  "derive",
  "env",
  "string",
  "wrap_help",
] }
clap_complete = "=4.5.1"

// src/main.rs
use clap::{CommandFactory, Parser, ValueHint};
use clap_complete::{generate, Shell};
use std::path::PathBuf;

#[derive(Parser)]
struct Opt {
    #[arg(short, long, value_hint = ValueHint::FilePath)]
    file: Option<PathBuf>,
}

fn main() {
    generate(
        Shell::Bash,
        &mut Opt::command(),
        "my-app",
        &mut std::io::stdout(),
    );
}

Steps to reproduce the bug with the above code

(on a Mac)

cargo run | /bin/bash

Actual Behaviour

Output:

❯ cargo run | /bin/bash
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/my-app`
/bin/bash: line 30: conditional binary operator expected
/bin/bash: line 30: syntax error near `IFS'
/bin/bash: line 30: `                    if [[ -v IFS ]]; then'

Expected Behaviour

Output:

❯ cargo run | /bin/bash
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/my-app`

Additional Context

On clap_complete 4.4.9 this works, on 4.4.10 this fails. I think that this is a regression introduced by https://github.com/clap-rs/clap/pull/5336 . So the issue is probably the same as https://github.com/clap-rs/clap/issues/5190 , which was fixed by https://github.com/clap-rs/clap/pull/5278.

Debug Output

[clap_builder::builder::command]Command::_build: name="my-app"
[clap_builder::builder::command]Command::_propagate:my-app
[clap_builder::builder::command]Command::_check_help_and_version:my-app expand_help_tree=true
[clap_builder::builder::command]Command::long_help_exists
[clap_builder::builder::command]Command::_check_help_and_version: Building default --help
[clap_builder::builder::command]Command::_propagate_global_args:my-app
[clap_builder::builder::debug_asserts]Command::_debug_asserts
[clap_builder::builder::debug_asserts]Arg::_debug_asserts:file
[clap_builder::builder::debug_asserts]Arg::_debug_asserts:help
[clap_builder::builder::debug_asserts]Command::_verify_positionals
[clap_builder::builder::command]Command::_build_bin_names
[ clap_builder::output::usage]Usage::get_required_usage_from: incls=[], matcher=false, incl_last=true
[ clap_builder::output::usage]Usage::get_required_usage_from: unrolled_reqs=[]
[ clap_builder::output::usage]Usage::get_required_usage_from: ret_val=[]

[epage]

This is happening too often and I'm tempted to say bash 4 is unsupported until #3166 is the default completion system since that at least reduces the risk we'll run into issues.

[sudotac]

Sorry for the inconvenience. I thought -v was already supported on bash 4.0, but actually only available on 5.0 or later. I submitted #5444 to fix this. Feel free to use it.

This is happening too often and I'm tempted to say bash 4 is unsupported until https://github.com/clap-rs/clap/issues/3166 is the default completion system since that at least reduces the risk we'll run into issues.

I agree with it. This time it's easy to fix that, but caring about unsupported features on (very) older versions anytime is generally a hard work.

(By the way, I'm personally looking forward to native completion system!)

[gibfahn]

Thanks for fixing this!