Auto merge of #147003 - matthiaskrgr:rollup-b5z9uiz, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - rust-lang/rust#146556 (Fix duration_since panic on unix when std is built with integer overflow checks)
 - rust-lang/rust#146679 (Clarify Display for error should not include source)
 - rust-lang/rust#146753 (Improve the pretty print of UnstableFeature clause)
 - rust-lang/rust#146894 (Improve derive suggestion of const param)
 - rust-lang/rust#146950 (core: simplify `CStr::default()`)
 - rust-lang/rust#146958 (Fix infinite recursion in Path::eq with String)
 - rust-lang/rust#146971 (fix ICE in writeback due to bound regions)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 2 insertions, 5 deletions

diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs
index b0c8c4b1ca4..3e78d680ea6 100644
--- a/library/alloc/src/ffi/c_str.rs
+++ b/library/alloc/src/ffi/c_str.rs
@@ -970,17 +970,14 @@ impl Default for Rc<CStr> {
     /// This may or may not share an allocation with other Rcs on the same thread.
     #[inline]
     fn default() -> Self {
-        let rc = Rc::<[u8]>::from(*b"\0");
-        // `[u8]` has the same layout as `CStr`, and it is `NUL` terminated.
-        unsafe { Rc::from_raw(Rc::into_raw(rc) as *const CStr) }
+        Rc::from(c"")
     }
 }
 
 #[stable(feature = "default_box_extra", since = "1.17.0")]
 impl Default for Box<CStr> {
     fn default() -> Box<CStr> {
-        let boxed: Box<[u8]> = Box::from([0]);
-        unsafe { Box::from_raw(Box::into_raw(boxed) as *mut CStr) }
+        Box::from(c"")
     }
 }