Use generic NonZero internally.

compiler/rustc_session/src/config.rs

@@ -3226,7 +3226,7 @@ pub(crate) mod dep_tracking {
     };
     use std::collections::BTreeMap;
     use std::hash::{DefaultHasher, Hash};
-    use std::num::NonZeroUsize;
+    use std::num::NonZero;
     use std::path::PathBuf;
 
     pub trait DepTrackingHash {
@@ -3268,7 +3268,7 @@ pub(crate) mod dep_tracking {
     impl_dep_tracking_hash_via_hash!(
         bool,
         usize,
-        NonZeroUsize,
+        NonZero<usize>,
         u64,
         Hash64,
         String,

compiler/rustc_session/src/errors.rs

@@ -1,4 +1,4 @@
-use std::num::NonZeroU32;
+use std::num::NonZero;
 
 use rustc_ast::token;
 use rustc_ast::util::literal::LitError;
@@ -26,7 +26,7 @@ impl<'a> IntoDiagnostic<'a> for FeatureGateError {
 #[derive(Subdiagnostic)]
 #[note(session_feature_diagnostic_for_issue)]
 pub struct FeatureDiagnosticForIssue {
-    pub n: NonZeroU32,
+    pub n: NonZero<u32>,
 }
 
 #[derive(Subdiagnostic)]

compiler/rustc_session/src/lib.rs

@@ -1,3 +1,4 @@
+#![feature(generic_nonzero)]
 #![feature(let_chains)]
 #![feature(lazy_cell)]
 #![feature(option_get_or_insert_default)]

compiler/rustc_session/src/options.rs

@@ -21,7 +21,7 @@ use rustc_span::SourceFileHashAlgorithm;
 use std::collections::BTreeMap;
 
 use std::hash::{DefaultHasher, Hasher};
-use std::num::{IntErrorKind, NonZeroUsize};
+use std::num::{IntErrorKind, NonZero};
 use std::path::PathBuf;
 use std::str;
 
@@ -617,7 +617,7 @@ mod parse {
     pub(crate) fn parse_threads(slot: &mut usize, v: Option<&str>) -> bool {
         match v.and_then(|s| s.parse().ok()) {
             Some(0) => {
-                *slot = std::thread::available_parallelism().map_or(1, std::num::NonZeroUsize::get);
+                *slot = std::thread::available_parallelism().map_or(1, NonZero::<usize>::get);
                 true
             }
             Some(i) => {
@@ -991,7 +991,10 @@ mod parse {
         true
     }
 
-    pub(crate) fn parse_treat_err_as_bug(slot: &mut Option<NonZeroUsize>, v: Option<&str>) -> bool {
+    pub(crate) fn parse_treat_err_as_bug(
+        slot: &mut Option<NonZero<usize>>,
+        v: Option<&str>,
+    ) -> bool {
         match v {
             Some(s) => match s.parse() {
                 Ok(val) => {
@@ -1004,7 +1007,7 @@ mod parse {
                 }
             },
             None => {
-                *slot = NonZeroUsize::new(1);
+                *slot = NonZero::<usize>::new(1);
                 true
             }
         }
@@ -1950,7 +1953,7 @@ written to standard error output)"),
         "translate remapped paths into local paths when possible (default: yes)"),
     trap_unreachable: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "generate trap instructions for unreachable intrinsics (default: use target setting, usually yes)"),
-    treat_err_as_bug: Option<NonZeroUsize> = (None, parse_treat_err_as_bug, [TRACKED],
+    treat_err_as_bug: Option<NonZero<usize>> = (None, parse_treat_err_as_bug, [TRACKED],
         "treat the `val`th error that occurs as bug (default if not specified: 0 - don't treat errors as bugs. \
         default if specified without a value: 1 - treat the first error as bug)"),
     trim_diagnostic_paths: bool = (true, parse_bool, [UNTRACKED],