Use min args in clap derive to ensure a command is provided

src/main.rs

@@ -1,61 +1,38 @@
 use clap::Parser;
 use eyre::Result;
-use std::{path::PathBuf, str::FromStr};
+use std::path::PathBuf;
 
 /// A command runner that optionally logs the I/O streams to files.
 #[derive(Debug, Parser, PartialEq)]
 #[command(version)]
 struct Cli {
     /// The file to log stdin to.
     #[clap(short, long, env)]
-    in_file: Option<String>,
+    in_file: Option<PathBuf>,
 
     /// The file to log stdout to.
     #[clap(short, long, env)]
-    out_file: Option<String>,
+    out_file: Option<PathBuf>,
 
     /// The file to log stderr to.
     #[clap(short, long, env)]
-    err_file: Option<String>,
+    err_file: Option<PathBuf>,
 
     /// The command to run and its arguments. A command must be specified, arguments are space delimited.
-    #[clap(last = true)]
+    #[clap(last = true, required = true, num_args = 1..)]
     exec: Vec<String>,
 }
 
 fn main() -> Result<()> {
     let cli = Cli::parse();
 
     let exec = cli.exec.iter().map(String::as_str).collect::<Vec<&str>>();
-    if exec.is_empty() {
-        use clap::CommandFactory;
-        eprintln!("EXEC must have at least one argument.");
-        eprintln!("{}", Cli::command().render_long_help());
-        std::process::exit(1);
-    }
-
-    let in_file = cli
-        .in_file
-        .as_ref()
-        .map(|s| PathBuf::from_str(s))
-        .transpose()?;
-    let out_file = cli
-        .out_file
-        .as_ref()
-        .map(|s| PathBuf::from_str(s))
-        .transpose()?;
-    let err_file = cli
-        .err_file
-        .as_ref()
-        .map(|s| PathBuf::from_str(s))
-        .transpose()?;
-
     let code = runner::run(
         exec[0],
         &exec[1..],
-        in_file.as_deref(),
-        out_file.as_deref(),
-        err_file.as_deref(),
+        cli.in_file.as_deref(),
+        cli.out_file.as_deref(),
+        cli.err_file.as_deref(),
     )?;
 
     std::process::exit(code);