Allow access to `OsStr` bytes

`OsStr` has historically kept its implementation details private out of
concern for locking us into a specific encoding on Windows.

This is an alternative to #95290 which proposed specifying the encoding on Windows.  Instead, this
only specifies that for cross-platform code, `OsStr`'s encoding is a superset of UTF-8 and defines
rules for safely interacting with it

At minimum, this can greatly simplify the `os_str_bytes` crate and every
arg parser that interacts with `OsStr` directly (which is most of those
that support invalid UTF-8).

1 files changed, 10 insertions, 0 deletions

diff --git a/library/std/src/sys/windows/os_str.rs b/library/std/src/sys/windows/os_str.rs
index 2f2b0e56e08..611f0d040f0 100644
--- a/library/std/src/sys/windows/os_str.rs
+++ b/library/std/src/sys/windows/os_str.rs
@@ -152,6 +152,16 @@ impl Buf {
 
 impl Slice {
     #[inline]
+    pub fn as_os_str_bytes(&self) -> &[u8] {
+        self.inner.as_bytes()
+    }
+
+    #[inline]
+    pub unsafe fn from_os_str_bytes_unchecked(s: &[u8]) -> &Slice {
+        mem::transmute(Wtf8::from_bytes_unchecked(s))
+    }
+
+    #[inline]
     pub fn from_str(s: &str) -> &Slice {
         unsafe { mem::transmute(Wtf8::from_str(s)) }
     }