process/renice: cross-platform clippy fix

Author: jgarzik

process/renice.rs

@@ -79,12 +79,13 @@ fn lookup_uid(username: &str) -> Result<u32, &'static str> {
     Ok(passwd.pw_uid)
 }
 
+#[allow(clippy::unnecessary_cast)] // PRIO_* types differ: i32 on macOS, u32 on Linux
 fn parse_id(which: u32, input: &str) -> Result<u32, &'static str> {
     match input.parse::<u32>() {
         Ok(0) => Err("Invalid ID"),
         Ok(n) => Ok(n),
         Err(e) => {
-            if which != libc::PRIO_USER {
+            if which != libc::PRIO_USER as u32 {
                 eprintln!("{}", e);
                 Err("Invalid ID")
             } else {
@@ -108,13 +109,15 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let args = Args::parse();
 
     // which class of priority to modify
+    // Cast to u32 for cross-platform compatibility (i32 on macOS, u32 on Linux)
+    #[allow(clippy::unnecessary_cast)]
     let which: u32 = {
         if args.pgrp {
-            libc::PRIO_PGRP
+            libc::PRIO_PGRP as u32
         } else if args.user {
-            libc::PRIO_USER
+            libc::PRIO_USER as u32
         } else {
-            libc::PRIO_PROCESS
+            libc::PRIO_PROCESS as u32
         }
     };