3 files changed, 10 insertions, 7 deletions
diff --git a/library/std/src/io/error/repr_bitpacked.rs b/library/std/src/io/error/repr_bitpacked.rs
index 358148405..f94f88bac 100644
--- a/library/std/src/io/error/repr_bitpacked.rs
+++ b/library/std/src/io/error/repr_bitpacked.rs
@@ -102,7 +102,7 @@
 //! to use a pointer type to store something that may hold an integer, some of
 //! the time.
 
-use super::{Custom, ErrorData, ErrorKind, SimpleMessage};
+use super::{Custom, ErrorData, ErrorKind, RawOsError, SimpleMessage};
 use alloc::boxed::Box;
 use core::marker::PhantomData;
 use core::mem::{align_of, size_of};
@@ -172,7 +172,7 @@ impl Repr {
     }
 
     #[inline]
-    pub(super) fn new_os(code: i32) -> Self {
+    pub(super) fn new_os(code: RawOsError) -> Self {
         let utagged = ((code as usize) << 32) | TAG_OS;
         // Safety: `TAG_OS` is not zero, so the result of the `|` is not 0.
         let res = Self(unsafe { NonNull::new_unchecked(ptr::invalid_mut(utagged)) }, PhantomData);
@@ -250,7 +250,7 @@ where
     let bits = ptr.as_ptr().addr();
     match bits & TAG_MASK {
         TAG_OS => {
-            let code = ((bits as i64) >> 32) as i32;
+            let code = ((bits as i64) >> 32) as RawOsError;
             ErrorData::Os(code)
         }
         TAG_SIMPLE => {
@@ -374,6 +374,9 @@ static_assert!((TAG_MASK + 1).is_power_of_two());
 static_assert!(align_of::<SimpleMessage>() >= TAG_MASK + 1);
 static_assert!(align_of::<Custom>() >= TAG_MASK + 1);
 
+// `RawOsError` must be an alias for `i32`.
+const _: fn(RawOsError) -> i32 = |os| os;
+
 static_assert!(@usize_eq: TAG_MASK & TAG_SIMPLE_MESSAGE, TAG_SIMPLE_MESSAGE);
 static_assert!(@usize_eq: TAG_MASK & TAG_CUSTOM, TAG_CUSTOM);
 static_assert!(@usize_eq: TAG_MASK & TAG_OS, TAG_OS);
diff --git a/library/std/src/io/error/repr_unpacked.rs b/library/std/src/io/error/repr_unpacked.rs
index d6ad55b99..093fde337 100644
--- a/library/std/src/io/error/repr_unpacked.rs
+++ b/library/std/src/io/error/repr_unpacked.rs
@@ -2,7 +2,7 @@
 //! non-64bit targets, where the packed 64 bit representation wouldn't work, and
 //! would have no benefit.
 
-use super::{Custom, ErrorData, ErrorKind, SimpleMessage};
+use super::{Custom, ErrorData, ErrorKind, RawOsError, SimpleMessage};
 use alloc::boxed::Box;
 
 type Inner = ErrorData<Box<Custom>>;
@@ -18,7 +18,7 @@ impl Repr {
         Self(Inner::Custom(b))
     }
     #[inline]
-    pub(super) fn new_os(code: i32) -> Self {
+    pub(super) fn new_os(code: RawOsError) -> Self {
         Self(Inner::Os(code))
     }
     #[inline]
diff --git a/library/std/src/io/error/tests.rs b/library/std/src/io/error/tests.rs
index 16c634e9a..36d52aef0 100644
--- a/library/std/src/io/error/tests.rs
+++ b/library/std/src/io/error/tests.rs
@@ -71,7 +71,7 @@ fn test_const() {
 
 #[test]
 fn test_os_packing() {
-    for code in -20i32..20i32 {
+    for code in -20..20 {
         let e = Error::from_raw_os_error(code);
         assert_eq!(e.raw_os_error(), Some(code));
         assert_matches!(
@@ -190,5 +190,5 @@ fn test_std_io_error_downcast() {
     let io_error = io_error.downcast::<E>().unwrap_err();
 
     assert_eq!(SIMPLE_MESSAGE.kind, io_error.kind());
-    assert_eq!(SIMPLE_MESSAGE.message, &*format!("{io_error}"));
+    assert_eq!(SIMPLE_MESSAGE.message, format!("{io_error}"));
 }