Merging upstream version 1.73.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

2 files changed, 21 insertions, 22 deletions

diff --git a/library/core/src/ffi/c_str.rs b/library/core/src/ffi/c_str.rs
index 39f795c1f..163a65c90 100644
--- a/library/core/src/ffi/c_str.rs
+++ b/library/core/src/ffi/c_str.rs
@@ -20,10 +20,10 @@ use crate::str;
 /// in each pair are borrowed references; the latter are owned
 /// strings.
 ///
-/// Note that this structure is **not** `repr(C)` and is not recommended to be
-/// placed in the signatures of FFI functions. Instead, safe wrappers of FFI
-/// functions may leverage the unsafe [`CStr::from_ptr`] constructor to provide
-/// a safe interface to other consumers.
+/// Note that this structure does **not** have a guaranteed layout (the `repr(transparent)`
+/// notwithstanding) and is not recommended to be placed in the signatures of FFI functions.
+/// Instead, safe wrappers of FFI functions may leverage the unsafe [`CStr::from_ptr`] constructor
+/// to provide a safe interface to other consumers.
 ///
 /// [`CString`]: ../../std/ffi/struct.CString.html
 /// [`String`]: ../../std/string/struct.String.html
@@ -82,12 +82,12 @@ use crate::str;
 #[stable(feature = "core_c_str", since = "1.64.0")]
 #[rustc_has_incoherent_inherent_impls]
 #[lang = "CStr"]
-// FIXME:
 // `fn from` in `impl From<&CStr> for Box<CStr>` current implementation relies
 // on `CStr` being layout-compatible with `[u8]`.
-// When attribute privacy is implemented, `CStr` should be annotated as `#[repr(transparent)]`.
-// Anyway, `CStr` representation and layout are considered implementation detail, are
-// not documented and must not be relied upon.
+// However, `CStr` layout is considered an implementation detail and must not be relied upon. We
+// want `repr(transparent)` but we don't want it to show up in rustdoc, so we hide it under
+// `cfg(doc)`. This is an ad-hoc implementation of attribute privacy.
+#[cfg_attr(not(doc), repr(transparent))]
 pub struct CStr {
     // FIXME: this should not be represented with a DST slice but rather with
     //        just a raw `c_char` along with some form of marker to make
@@ -197,8 +197,8 @@ impl CStr {
     ///
     /// This function will wrap the provided `ptr` with a `CStr` wrapper, which
     /// allows inspection and interoperation of non-owned C strings. The total
-    /// size of the raw C string must be smaller than `isize::MAX` **bytes**
-    /// in memory due to calling the `slice::from_raw_parts` function.
+    /// size of the terminated buffer must be smaller than [`isize::MAX`] **bytes**
+    /// in memory (a restriction from [`slice::from_raw_parts`]).
     ///
     /// # Safety
     ///
@@ -253,10 +253,10 @@ impl CStr {
     /// ```
     ///
     /// [valid]: core::ptr#safety
-    #[inline]
+    #[inline] // inline is necessary for codegen to see strlen.
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "101719")]
+    #[rustc_const_unstable(feature = "const_cstr_from_ptr", issue = "113219")]
     pub const unsafe fn from_ptr<'a>(ptr: *const c_char) -> &'a CStr {
         // SAFETY: The caller has provided a pointer that points to a valid C
         // string with a NUL terminator of size less than `isize::MAX`, whose
@@ -280,6 +280,8 @@ impl CStr {
                 len
             }
 
+            // `inline` is necessary for codegen to see strlen.
+            #[inline]
             fn strlen_rt(s: *const c_char) -> usize {
                 extern "C" {
                     /// Provided by libc or compiler_builtins.
@@ -295,11 +297,11 @@ impl CStr {
         }
     }
 
-    /// Creates a C string wrapper from a byte slice.
+    /// Creates a C string wrapper from a byte slice with any number of nuls.
     ///
     /// This method will create a `CStr` from any byte slice that contains at
-    /// least one nul byte. The caller does not need to know or specify where
-    /// the nul byte is located.
+    /// least one nul byte. Unlike with [`CStr::from_bytes_with_nul`], the caller
+    /// does not need to know where the nul byte is located.
     ///
     /// If the first byte is a nul character, this method will return an
     /// empty `CStr`. If multiple nul characters are present, the `CStr` will
@@ -341,7 +343,8 @@ impl CStr {
         }
     }
 
-    /// Creates a C string wrapper from a byte slice.
+    /// Creates a C string wrapper from a byte slice with exactly one nul
+    /// terminator.
     ///
     /// This function will cast the provided `bytes` to a `CStr`
     /// wrapper after ensuring that the byte slice is nul-terminated
diff --git a/library/core/src/ffi/mod.rs b/library/core/src/ffi/mod.rs
index 0488c8076..b2c9a0800 100644
--- a/library/core/src/ffi/mod.rs
+++ b/library/core/src/ffi/mod.rs
@@ -52,11 +52,6 @@ macro_rules! type_alias {
 }
 
 type_alias! { "c_char.md", c_char = c_char_definition::c_char, NonZero_c_char = c_char_definition::NonZero_c_char;
-// Make this type alias appear cfg-dependent so that Clippy does not suggest
-// replacing `0 as c_char` with `0_i8`/`0_u8`. This #[cfg(all())] can be removed
-// after the false positive in https://github.com/rust-lang/rust-clippy/issues/8093
-// is fixed.
-#[cfg(all())]
 #[doc(cfg(all()))] }
 
 type_alias! { "c_schar.md", c_schar = i8, NonZero_c_schar = NonZeroI8; }
@@ -115,7 +110,8 @@ mod c_char_definition {
                     target_arch = "powerpc64",
                     target_arch = "s390x",
                     target_arch = "riscv64",
-                    target_arch = "riscv32"
+                    target_arch = "riscv32",
+                    target_arch = "csky"
                 )
             ),
             all(target_os = "android", any(target_arch = "aarch64", target_arch = "arm")),