Auto merge of #140360 - matthiaskrgr:rollup-savbr84, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #137439 (Stabilise `std::ffi::c_str`)
 - #137714 (Update safety documentation for `CString::from_ptr` and `str::from_boxed_utf8_unchecked`)
 - #139031 (Use char::is_whitespace directly in str::trim*)
 - #139090 (fix docs for `Peekable::next_if{_eq}`)
 - #140297 (Update example to use CStr::to_string_lossy)
 - #140330 (Clarified bootstrap optimization "true" argument)
 - #140339 (session: Cleanup `CanonicalizedPath::new`)
 - #140346 (rustc_span: Some hygiene cleanups)

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

3 files changed, 15 insertions, 4 deletions

diff --git a/library/alloc/src/ffi/c_str.rs b/library/alloc/src/ffi/c_str.rs
index d5b19470e31..8b448a18402 100644
--- a/library/alloc/src/ffi/c_str.rs
+++ b/library/alloc/src/ffi/c_str.rs
@@ -351,9 +351,14 @@ impl CString {
     /// # Safety
     ///
     /// This should only ever be called with a pointer that was earlier
-    /// obtained by calling [`CString::into_raw`]. Other usage (e.g., trying to take
-    /// ownership of a string that was allocated by foreign code) is likely to lead
-    /// to undefined behavior or allocator corruption.
+    /// obtained by calling [`CString::into_raw`], and the memory it points to must not be accessed
+    /// through any other pointer during the lifetime of reconstructed `CString`.
+    /// Other usage (e.g., trying to take ownership of a string that was allocated by foreign code)
+    /// is likely to lead to undefined behavior or allocator corruption.
+    ///
+    /// This function does not validate ownership of the raw pointer's memory.
+    /// A double-free may occur if the function is called twice on the same raw pointer.
+    /// Additionally, the caller must ensure the pointer is not dangling.
     ///
     /// It should be noted that the length isn't just "recomputed," but that
     /// the recomputed length must match the original length from the
@@ -818,6 +823,7 @@ impl From<Vec<NonZero<u8>>> for CString {
     }
 }
 
+#[stable(feature = "c_string_from_str", since = "1.85.0")]
 impl FromStr for CString {
     type Err = NulError;
 
@@ -830,6 +836,7 @@ impl FromStr for CString {
     }
 }
 
+#[stable(feature = "c_string_from_str", since = "1.85.0")]
 impl TryFrom<CString> for String {
     type Error = IntoStringError;
 
diff --git a/library/alloc/src/ffi/mod.rs b/library/alloc/src/ffi/mod.rs
index 695d7ad07cf..05a2763a225 100644
--- a/library/alloc/src/ffi/mod.rs
+++ b/library/alloc/src/ffi/mod.rs
@@ -87,5 +87,5 @@ pub use self::c_str::CString;
 #[stable(feature = "alloc_c_string", since = "1.64.0")]
 pub use self::c_str::{FromVecWithNulError, IntoStringError, NulError};
 
-#[unstable(feature = "c_str_module", issue = "112134")]
+#[stable(feature = "c_str_module", since = "CURRENT_RUSTC_VERSION")]
 pub mod c_str;
diff --git a/library/alloc/src/str.rs b/library/alloc/src/str.rs
index 0664f2c3cf2..24c5d4c92f7 100644
--- a/library/alloc/src/str.rs
+++ b/library/alloc/src/str.rs
@@ -603,6 +603,10 @@ impl str {
 /// Converts a boxed slice of bytes to a boxed string slice without checking
 /// that the string contains valid UTF-8.
 ///
+/// # Safety
+///
+/// * The provided bytes must contain a valid UTF-8 sequence.
+///
 /// # Examples
 ///
 /// ```