From aa537824c40437d11d32c66fe16d4764b072c094 Mon Sep 17 00:00:00 2001
From: joboet <jonasboettiger@icloud.com>
Date: Wed, 24 Sep 2025 00:50:36 +0200
Subject: [PATCH 1/2] core: simplify `CStr::default()`

Just use a `CStr`-literal...
---
 library/core/src/ffi/c_str.rs | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index d0b53e3a237f6..09d9b160700ca 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -179,9 +179,7 @@ impl fmt::Debug for CStr {
 impl Default for &CStr {
     #[inline]
     fn default() -> Self {
-        const SLICE: &[c_char] = &[0];
-        // SAFETY: `SLICE` is indeed pointing to a valid nul-terminated string.
-        unsafe { CStr::from_ptr(SLICE.as_ptr()) }
+        c""
     }
 }
 

From a875f7779e3c3b9023bff24b6beca08e7be0e0e8 Mon Sep 17 00:00:00 2001
From: joboet <jonasboettiger@icloud.com>
Date: Wed, 24 Sep 2025 14:13:34 +0200
Subject: [PATCH 2/2] alloc: simplify `Default` for `Box<CStr>` and `Rc<CStr>`

---
 library/alloc/src/ffi/c_str.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs
index b0c8c4b1ca4a7..3e78d680ea68a 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"")
     }
 }