Return std::process::ExitCode instead of exiting with std::process::exit

rust-lang/rust#77553 still exists on nightly-2025-01-30.

Author: taiki-e

src/cli.rs

@@ -70,7 +70,7 @@ pub(crate) enum DetachPathDeps {
 }
 
 impl Args {
-    pub(crate) fn parse() -> Result<Self> {
+    pub(crate) fn parse() -> Result<Option<Self>> {
         const SUBCMD: &str = "minimal-versions";
 
         // rustc/cargo args must be valid Unicode
@@ -162,11 +162,11 @@ impl Args {
 
                 Short('h') | Long("help") if subcommand.is_none() => {
                     print!("{USAGE}");
-                    std::process::exit(0);
+                    return Ok(None);
                 }
                 Short('V') | Long("version") if subcommand.is_none() => {
                     println!("{} {}", env!("CARGO_PKG_NAME"), env!("CARGO_PKG_VERSION"));
-                    std::process::exit(0);
+                    return Ok(None);
                 }
 
                 // passthrough
@@ -217,15 +217,15 @@ impl Args {
             cargo_args.push(path.clone());
         }
 
-        Ok(Self {
+        Ok(Some(Self {
             no_private,
             direct,
             subcommand,
             manifest_path,
             detach_path_deps,
             cargo_args,
             rest,
-        })
+        }))
     }
 }
 

src/main.rs

@@ -15,26 +15,28 @@ mod manifest;
 mod metadata;
 mod restore;
 
-use std::env;
+use std::{env, process::ExitCode};
 
 use anyhow::Result;
 
 use crate::{cargo::Workspace, cli::Args};
 
-fn main() {
+fn main() -> ExitCode {
     term::init_coloring();
     if let Err(e) = try_main() {
         error!("{e:#}");
     }
     if term::error()
         || term::warn() && env::var_os("CARGO_MINIMAL_VERSIONS_DENY_WARNINGS").is_some()
     {
-        std::process::exit(1)
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
     }
 }
 
 fn try_main() -> Result<()> {
-    let args = Args::parse()?;
+    let Some(args) = Args::parse()? else { return Ok(()) };
     let ws = Workspace::new(args.manifest_path.as_deref(), args.direct)?;
 
     // Remove dev-dependencies from Cargo.toml to prevent the next `cargo update`