Use generic NonZero everywhere else.

library/proc_macro/src/bridge/symbol.rs

@@ -136,7 +136,7 @@ fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
         arena: arena::Arena::new(),
         names: fxhash::FxHashMap::default(),
         strings: Vec::new(),
-        // Start with a base of 1 to make sure that `NonZeroU32` works.
+        // Start with a base of 1 to make sure that `NonZero<u32>` works.
         sym_base: NonZero::new(1).unwrap(),
     });
 }

library/test/src/helpers/concurrency.rs

@@ -1,10 +1,10 @@
 //! Helper module which helps to determine amount of threads to be used
 //! during tests execution.
-use std::{env, num::NonZeroUsize, thread};
+use std::{env, num::NonZero, thread};
 
 pub fn get_concurrency() -> usize {
     if let Ok(value) = env::var("RUST_TEST_THREADS") {
-        match value.parse::<NonZeroUsize>().ok() {
+        match value.parse::<NonZero<usize>>().ok() {
             Some(n) => n.get(),
             _ => panic!("RUST_TEST_THREADS is `{value}`, should be a positive integer."),
         }

library/test/src/lib.rs

@@ -17,6 +17,7 @@
 #![unstable(feature = "test", issue = "50297")]
 #![doc(test(attr(deny(warnings))))]
 #![doc(rust_logo)]
+#![feature(generic_nonzero)]
 #![feature(rustdoc_internals)]
 #![feature(internal_output_capture)]
 #![feature(staged_api)]