Function resolve_at_file

src/tool_command/args.rs:720–735

Read a value from disk when it starts with `@`. The leading `@` is stripped; the rest is treated as a path (relative to cwd). Plain values pass through unchanged. To pass a literal `@` as the first character, use `--args` instead.

(raw: &str, read_stdin: &mut impl FnMut() -> Result<String>)

/// pass through unchanged. To pass a literal `@` as the first character, use
/// `--args` instead.
fn resolve_at_file(raw: &str, read_stdin: &mut impl FnMut() -> Result<String>) -> Result<String> {
    if let Some(path) = raw.strip_prefix('@') {
        if path == "-" {
            return read_stdin();
        }
        let buf = PathBuf::from(path);
        std::fs::read_to_string(&buf).map_err(|e| TraceDecayError::Config {
            message: format!(
                "failed to read @{path}: {e} — the path is resolved relative to the current \
                 directory; for a literal value that begins with `@`, use --args instead"
            ),
        })
    } else {
        Ok(raw.to_string())
    }
}