library: Move CStr to libcore, and CString to liballoc

Cargo.lock

@@ -731,9 +731,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.70"
+version = "0.1.71"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "80873f979f0a344a4ade87c2f70d9ccf5720b83b10c97ec7cd745895d021e85a"
+checksum = "163437f05ca8f29d7e9128ea728dedf5eb620e445fbca273641d3a3050305f23"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",

compiler/rustc_hir/src/lang_items.rs

@@ -326,6 +326,8 @@ language_item_table! {
     Range,                   sym::Range,               range_struct,               Target::Struct,         GenericRequirement::None;
     RangeToInclusive,        sym::RangeToInclusive,    range_to_inclusive_struct,  Target::Struct,         GenericRequirement::None;
     RangeTo,                 sym::RangeTo,             range_to_struct,            Target::Struct,         GenericRequirement::None;
+
+    CStr,                    sym::CStr,                c_str,                      Target::Struct,         GenericRequirement::None;
 }
 
 pub enum GenericRequirement {

compiler/rustc_metadata/src/creader.rs

@@ -417,6 +417,7 @@ impl<'a> CrateLoader<'a> {
 
         let crate_metadata = CrateMetadata::new(
             self.sess,
+            &self.cstore,
             metadata,
             crate_root,
             raw_proc_macros,

compiler/rustc_metadata/src/rmeta/decoder.rs

@@ -1,6 +1,6 @@
 // Decoding metadata from a single crate's metadata
 
-use crate::creader::CrateMetadataRef;
+use crate::creader::{CStore, CrateMetadataRef};
 use crate::rmeta::table::{FixedSizeEncoding, Table};
 use crate::rmeta::*;
 
@@ -1737,6 +1737,7 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
 impl CrateMetadata {
     crate fn new(
         sess: &Session,
+        cstore: &CStore,
         blob: MetadataBlob,
         root: CrateRoot<'static>,
         raw_proc_macros: Option<&'static [ProcMacro]>,
@@ -1752,11 +1753,6 @@ impl CrateMetadata {
             .decode((&blob, sess))
             .map(|trait_impls| (trait_impls.trait_id, trait_impls.impls))
             .collect();
-        let incoherent_impls = root
-            .incoherent_impls
-            .decode((&blob, sess))
-            .map(|incoherent_impls| (incoherent_impls.self_ty, incoherent_impls.impls))
-            .collect();
         let alloc_decoding_state =
             AllocDecodingState::new(root.interpret_alloc_index.decode(&blob).collect());
         let dependencies = Lock::new(cnum_map.iter().cloned().collect());
@@ -1765,11 +1761,11 @@ impl CrateMetadata {
         // that does not copy any data. It just does some data verification.
         let def_path_hash_map = root.def_path_hash_map.decode(&blob);
 
-        CrateMetadata {
+        let mut cdata = CrateMetadata {
             blob,
             root,
             trait_impls,
-            incoherent_impls,
+            incoherent_impls: Default::default(),
             raw_proc_macros,
             source_map_import_info: OnceCell::new(),
             def_path_hash_map,
@@ -1786,7 +1782,17 @@ impl CrateMetadata {
             hygiene_context: Default::default(),
             def_key_cache: Default::default(),
             def_path_hash_cache: Default::default(),
-        }
+        };
+
+        // Need `CrateMetadataRef` to decode `DefId`s in simplified types.
+        cdata.incoherent_impls = cdata
+            .root
+            .incoherent_impls
+            .decode(CrateMetadataRef { cdata: &cdata, cstore })
+            .map(|incoherent_impls| (incoherent_impls.self_ty, incoherent_impls.impls))
+            .collect();
+
+        cdata
     }
 
     crate fn dependencies(&self) -> LockGuard<'_, Vec<CrateNum>> {

compiler/rustc_typeck/src/check/method/probe.rs

@@ -644,7 +644,11 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 self.assemble_inherent_impl_candidates_for_type(p.def_id());
             }
             ty::Adt(def, _) => {
-                self.assemble_inherent_impl_candidates_for_type(def.did());
+                let def_id = def.did();
+                self.assemble_inherent_impl_candidates_for_type(def_id);
+                if Some(def_id) == self.tcx.lang_items().c_str() {
+                    self.assemble_inherent_candidates_for_incoherent_ty(raw_self_ty);
+                }
             }
             ty::Foreign(did) => {
                 self.assemble_inherent_impl_candidates_for_type(did);

compiler/rustc_typeck/src/coherence/inherent_impls.rs

@@ -55,7 +55,12 @@ impl<'tcx> ItemLikeVisitor<'_> for InherentCollect<'tcx> {
         let self_ty = self.tcx.type_of(item.def_id);
         match *self_ty.kind() {
             ty::Adt(def, _) => {
-                self.check_def_id(item, def.did());
+                let def_id = def.did();
+                if !def_id.is_local() && Some(def_id) == self.tcx.lang_items().c_str() {
+                    self.check_primitive_impl(item.def_id, self_ty, items, ty.span)
+                } else {
+                    self.check_def_id(item, def_id);
+                }
             }
             ty::Foreign(did) => {
                 self.check_def_id(item, did);

library/std/src/ffi/c_str/tests.rs → library/alloc/src/ffi/c_str/tests.rs

@@ -1,10 +1,12 @@
 use super::*;
-use crate::borrow::Cow::{Borrowed, Owned};
-use crate::collections::hash_map::DefaultHasher;
-use crate::hash::{Hash, Hasher};
-use crate::os::raw::c_char;
 use crate::rc::Rc;
 use crate::sync::Arc;
+use core::assert_matches::assert_matches;
+use core::ffi::FromBytesUntilNulError;
+use core::hash::{Hash, Hasher};
+
+#[allow(deprecated)]
+use core::hash::SipHasher13 as DefaultHasher;
 
 #[test]
 fn c_to_rust() {
@@ -47,22 +49,6 @@ fn borrowed() {
     }
 }
 
-#[test]
-fn to_str() {
-    let data = b"123\xE2\x80\xA6\0";
-    let ptr = data.as_ptr() as *const c_char;
-    unsafe {
-        assert_eq!(CStr::from_ptr(ptr).to_str(), Ok("123…"));
-        assert_eq!(CStr::from_ptr(ptr).to_string_lossy(), Borrowed("123…"));
-    }
-    let data = b"123\xE2\0";
-    let ptr = data.as_ptr() as *const c_char;
-    unsafe {
-        assert!(CStr::from_ptr(ptr).to_str().is_err());
-        assert_eq!(CStr::from_ptr(ptr).to_string_lossy(), Owned::<str>(format!("123\u{FFFD}")));
-    }
-}
-
 #[test]
 fn to_owned() {
     let data = b"123\0";
@@ -78,9 +64,11 @@ fn equal_hash() {
     let ptr = data.as_ptr() as *const c_char;
     let cstr: &'static CStr = unsafe { CStr::from_ptr(ptr) };
 
+    #[allow(deprecated)]
     let mut s = DefaultHasher::new();
     cstr.hash(&mut s);
     let cstr_hash = s.finish();
+    #[allow(deprecated)]
     let mut s = DefaultHasher::new();
     CString::new(&data[..data.len() - 1]).unwrap().hash(&mut s);
     let cstring_hash = s.finish();
@@ -122,11 +110,11 @@ fn cstr_from_bytes_until_nul() {
     // Test an empty slice. This should fail because it
     // does not contain a nul byte.
     let b = b"";
-    assert_eq!(CStr::from_bytes_until_nul(&b[..]), Err(FromBytesUntilNulError(())));
+    assert_matches!(CStr::from_bytes_until_nul(&b[..]), Err(FromBytesUntilNulError { .. }));
 
     // Test a non-empty slice, that does not contain a nul byte.
     let b = b"hello";
-    assert_eq!(CStr::from_bytes_until_nul(&b[..]), Err(FromBytesUntilNulError(())));
+    assert_matches!(CStr::from_bytes_until_nul(&b[..]), Err(FromBytesUntilNulError { .. }));
 
     // Test an empty nul-terminated string
     let b = b"\0";

library/alloc/src/ffi/mod.rs

@@ -0,0 +1,91 @@
+//! Utilities related to FFI bindings.
+//!
+//! This module provides utilities to handle data across non-Rust
+//! interfaces, like other programming languages and the underlying
+//! operating system. It is mainly of use for FFI (Foreign Function
+//! Interface) bindings and code that needs to exchange C-like strings
+//! with other languages.
+//!
+//! # Overview
+//!
+//! Rust represents owned strings with the [`String`] type, and
+//! borrowed slices of strings with the [`str`] primitive. Both are
+//! always in UTF-8 encoding, and may contain nul bytes in the middle,
+//! i.e., if you look at the bytes that make up the string, there may
+//! be a `\0` among them. Both `String` and `str` store their length
+//! explicitly; there are no nul terminators at the end of strings
+//! like in C.
+//!
+//! C strings are different from Rust strings:
+//!
+//! * **Encodings** - Rust strings are UTF-8, but C strings may use
+//! other encodings. If you are using a string from C, you should
+//! check its encoding explicitly, rather than just assuming that it
+//! is UTF-8 like you can do in Rust.
+//!
+//! * **Character size** - C strings may use `char` or `wchar_t`-sized
+//! characters; please **note** that C's `char` is different from Rust's.
+//! The C standard leaves the actual sizes of those types open to
+//! interpretation, but defines different APIs for strings made up of
+//! each character type. Rust strings are always UTF-8, so different
+//! Unicode characters will be encoded in a variable number of bytes
+//! each. The Rust type [`char`] represents a '[Unicode scalar
+//! value]', which is similar to, but not the same as, a '[Unicode
+//! code point]'.
+//!
+//! * **Nul terminators and implicit string lengths** - Often, C
+//! strings are nul-terminated, i.e., they have a `\0` character at the
+//! end. The length of a string buffer is not stored, but has to be
+//! calculated; to compute the length of a string, C code must
+//! manually call a function like `strlen()` for `char`-based strings,
+//! or `wcslen()` for `wchar_t`-based ones. Those functions return
+//! the number of characters in the string excluding the nul
+//! terminator, so the buffer length is really `len+1` characters.
+//! Rust strings don't have a nul terminator; their length is always
+//! stored and does not need to be calculated. While in Rust
+//! accessing a string's length is an *O*(1) operation (because the
+//! length is stored); in C it is an *O*(*n*) operation because the
+//! length needs to be computed by scanning the string for the nul
+//! terminator.
+//!
+//! * **Internal nul characters** - When C strings have a nul
+//! terminator character, this usually means that they cannot have nul
+//! characters in the middle — a nul character would essentially
+//! truncate the string. Rust strings *can* have nul characters in
+//! the middle, because nul does not have to mark the end of the
+//! string in Rust.
+//!
+//! # Representations of non-Rust strings
+//!
+//! [`CString`] and [`CStr`] are useful when you need to transfer
+//! UTF-8 strings to and from languages with a C ABI, like Python.
+//!
+//! * **From Rust to C:** [`CString`] represents an owned, C-friendly
+//! string: it is nul-terminated, and has no internal nul characters.
+//! Rust code can create a [`CString`] out of a normal string (provided
+//! that the string doesn't have nul characters in the middle), and
+//! then use a variety of methods to obtain a raw <code>\*mut [u8]</code> that can
+//! then be passed as an argument to functions which use the C
+//! conventions for strings.
+//!
+//! * **From C to Rust:** [`CStr`] represents a borrowed C string; it
+//! is what you would use to wrap a raw <code>\*const [u8]</code> that you got from
+//! a C function. A [`CStr`] is guaranteed to be a nul-terminated array
+//! of bytes. Once you have a [`CStr`], you can convert it to a Rust
+//! <code>&[str]</code> if it's valid UTF-8, or lossily convert it by adding
+//! replacement characters.
+//!
+//! [`String`]: crate::string::String
+//! [`CStr`]: core::ffi::CStr
+
+#![unstable(feature = "alloc_ffi", issue = "94079")]
+
+#[cfg(bootstrap)]
+#[unstable(feature = "cstr_internals", issue = "none")]
+pub use self::c_str::CStrExt;
+#[unstable(feature = "alloc_c_string", issue = "94079")]
+pub use self::c_str::FromVecWithNulError;
+#[unstable(feature = "alloc_c_string", issue = "94079")]
+pub use self::c_str::{CString, IntoStringError, NulError};
+
+mod c_str;

library/alloc/src/lib.rs

@@ -86,11 +86,13 @@
 #![allow(explicit_outlives_requirements)]
 //
 // Library features:
+#![cfg_attr(not(no_global_oom_handling), feature(alloc_c_string))]
 #![feature(alloc_layout_extra)]
 #![feature(allocator_api)]
 #![feature(array_chunks)]
 #![feature(array_methods)]
 #![feature(array_windows)]
+#![feature(assert_matches)]
 #![feature(async_iterator)]
 #![feature(coerce_unsized)]
 #![cfg_attr(not(no_global_oom_handling), feature(const_alloc_error))]
@@ -104,9 +106,12 @@
 #![feature(const_maybe_uninit_write)]
 #![feature(const_maybe_uninit_as_mut_ptr)]
 #![feature(const_refs_to_cell)]
+#![feature(core_c_str)]
 #![feature(core_intrinsics)]
+#![feature(core_ffi_c)]
 #![feature(const_eval_select)]
 #![feature(const_pin)]
+#![feature(cstr_from_bytes_until_nul)]
 #![feature(dispatch_from_dyn)]
 #![feature(exact_size_is_empty)]
 #![feature(extend_one)]
@@ -152,6 +157,7 @@
 #![feature(exclusive_range_pattern)]
 #![feature(fundamental)]
 #![cfg_attr(not(test), feature(generator_trait))]
+#![feature(hashmap_internals)]
 #![feature(lang_items)]
 #![feature(let_else)]
 #![feature(min_specialization)]
@@ -160,6 +166,7 @@
 #![feature(nll)] // Not necessary, but here to test the `nll` feature.
 #![feature(rustc_allow_const_fn_unstable)]
 #![feature(rustc_attrs)]
+#![feature(slice_internals)]
 #![feature(staged_api)]
 #![cfg_attr(test, feature(test))]
 #![feature(unboxed_closures)]
@@ -205,6 +212,8 @@ mod boxed {
 }
 pub mod borrow;
 pub mod collections;
+#[cfg(not(no_global_oom_handling))]
+pub mod ffi;
 pub mod fmt;
 pub mod rc;
 pub mod slice;

library/alloc/src/slice.rs

@@ -153,7 +153,7 @@ pub use hack::to_vec;
 // functions are actually methods that are in `impl [T]` but not in
 // `core::slice::SliceExt` - we need to supply these functions for the
 // `test_permutations` test
-mod hack {
+pub(crate) mod hack {
     use core::alloc::Allocator;
 
     use crate::boxed::Box;

library/alloc/tests/c_str.rs

@@ -0,0 +1,18 @@
+use std::borrow::Cow::{Borrowed, Owned};
+use std::ffi::{c_char, CStr};
+
+#[test]
+fn to_str() {
+    let data = b"123\xE2\x80\xA6\0";
+    let ptr = data.as_ptr() as *const c_char;
+    unsafe {
+        assert_eq!(CStr::from_ptr(ptr).to_str(), Ok("123…"));
+        assert_eq!(CStr::from_ptr(ptr).to_string_lossy(), Borrowed("123…"));
+    }
+    let data = b"123\xE2\0";
+    let ptr = data.as_ptr() as *const c_char;
+    unsafe {
+        assert!(CStr::from_ptr(ptr).to_str().is_err());
+        assert_eq!(CStr::from_ptr(ptr).to_string_lossy(), Owned::<str>(format!("123\u{FFFD}")));
+    }
+}

library/alloc/tests/lib.rs

@@ -12,6 +12,8 @@
 #![feature(const_nonnull_slice_from_raw_parts)]
 #![feature(const_ptr_write)]
 #![feature(const_try)]
+#![feature(core_c_str)]
+#![feature(core_ffi_c)]
 #![feature(core_intrinsics)]
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
@@ -49,6 +51,7 @@ mod binary_heap;
 mod borrow;
 mod boxed;
 mod btree_set_hash;
+mod c_str;
 mod const_fns;
 mod cow_str;
 mod fmt;

library/core/src/ffi/mod.rs

@@ -14,6 +14,11 @@ use crate::marker::PhantomData;
 use crate::num::*;
 use crate::ops::{Deref, DerefMut};
 
+#[unstable(feature = "core_c_str", issue = "94079")]
+pub use self::c_str::{CStr, FromBytesUntilNulError, FromBytesWithNulError};
+
+mod c_str;
+
 macro_rules! type_alias_no_nz {
     {
       $Docfile:tt, $Alias:ident = $Real:ty;

library/core/src/lib.rs

@@ -20,7 +20,7 @@
 // FIXME: Fill me in with more detail when the interface settles
 //! This library is built on the assumption of a few existing symbols:
 //!
-//! * `memcpy`, `memcmp`, `memset` - These are core memory routines which are
+//! * `memcpy`, `memcmp`, `memset`, `strlen` - These are core memory routines which are
 //!   often generated by LLVM. Additionally, this library can make explicit
 //!   calls to these functions. Their signatures are the same as found in C.
 //!   These functions are often provided by the system libc, but can also be

library/std/Cargo.toml

@@ -16,7 +16,7 @@ panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
 core = { path = "../core" }
 libc = { version = "0.2.116", default-features = false, features = ['rustc-dep-of-std'] }
-compiler_builtins = { version = "0.1.69" }
+compiler_builtins = { version = "0.1.71" }
 profiler_builtins = { path = "../profiler_builtins", optional = true }
 unwind = { path = "../unwind" }
 hashbrown = { version = "0.12", default-features = false, features = ['rustc-dep-of-std'] }

library/std/src/error.rs

@@ -26,6 +26,7 @@ use crate::borrow::Cow;
 use crate::cell;
 use crate::char;
 use crate::fmt::{self, Debug, Display, Write};
+use crate::io;
 use crate::mem::transmute;
 use crate::num;
 use crate::str;
@@ -612,6 +613,48 @@ impl Error for alloc::collections::TryReserveError {}
 #[unstable(feature = "duration_checked_float", issue = "83400")]
 impl Error for time::FromFloatSecsError {}
 
+#[stable(feature = "rust1", since = "1.0.0")]
+impl Error for alloc::ffi::NulError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        "nul byte found in data"
+    }
+}
+
+#[stable(feature = "rust1", since = "1.0.0")]
+impl From<alloc::ffi::NulError> for io::Error {
+    /// Converts a [`alloc::ffi::NulError`] into a [`io::Error`].
+    fn from(_: alloc::ffi::NulError) -> io::Error {
+        io::const_io_error!(io::ErrorKind::InvalidInput, "data provided contains a nul byte")
+    }
+}
+
+#[stable(feature = "frombyteswithnulerror_impls", since = "1.17.0")]
+impl Error for core::ffi::FromBytesWithNulError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        self.__description()
+    }
+}
+
+#[unstable(feature = "cstr_from_bytes_until_nul", issue = "95027")]
+impl Error for core::ffi::FromBytesUntilNulError {}
+
+#[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
+impl Error for alloc::ffi::FromVecWithNulError {}
+
+#[stable(feature = "cstring_into", since = "1.7.0")]
+impl Error for alloc::ffi::IntoStringError {
+    #[allow(deprecated)]
+    fn description(&self) -> &str {
+        "C string contained non-utf8 bytes"
+    }
+
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        Some(self.__source())
+    }
+}
+
 // Copied from `any.rs`.
 impl dyn Error + 'static {
     /// Returns `true` if the inner type is the same as `T`.

library/std/src/ffi/mod.rs

@@ -146,12 +146,24 @@
 
 #![stable(feature = "rust1", since = "1.0.0")]
 
-#[stable(feature = "cstr_from_bytes", since = "1.10.0")]
-pub use self::c_str::FromBytesWithNulError;
+/// See [alloc::ffi::FromVecWithNulError].
 #[stable(feature = "cstring_from_vec_with_nul", since = "1.58.0")]
-pub use self::c_str::FromVecWithNulError;
+pub type FromVecWithNulError = alloc::ffi::FromVecWithNulError;
+/// See [alloc::ffi::CString].
+#[stable(feature = "rust1", since = "1.0.0")]
+pub type CString = alloc::ffi::CString;
+/// See [alloc::ffi::IntoStringError].
+#[stable(feature = "rust1", since = "1.0.0")]
+pub type IntoStringError = alloc::ffi::IntoStringError;
+/// See [alloc::ffi::NulError].
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use self::c_str::{CStr, CString, IntoStringError, NulError};
+pub type NulError = alloc::ffi::NulError;
+/// See [core::ffi::CStr].
+#[stable(feature = "rust1", since = "1.0.0")]
+pub type CStr = core::ffi::CStr;
+/// See [core::ffi::FromBytesWithNulError].
+#[stable(feature = "cstr_from_bytes", since = "1.10.0")]
+pub type FromBytesWithNulError = core::ffi::FromBytesWithNulError;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use self::os_str::{OsStr, OsString};
@@ -176,5 +188,4 @@ pub use core::ffi::{c_ptrdiff_t, c_size_t, c_ssize_t};
 )]
 pub use core::ffi::{VaList, VaListImpl};
 
-mod c_str;
 mod os_str;

library/std/src/lib.rs

@@ -260,7 +260,10 @@
 #![feature(atomic_mut_ptr)]
 #![feature(char_error_internals)]
 #![feature(char_internals)]
+#![feature(core_c_str)]
 #![feature(core_intrinsics)]
+#![feature(cstr_from_bytes_until_nul)]
+#![feature(cstr_internals)]
 #![feature(duration_checked_float)]
 #![feature(duration_constants)]
 #![feature(exact_size_is_empty)]
@@ -286,6 +289,7 @@
 //
 // Library features (alloc):
 #![feature(alloc_layout_extra)]
+#![feature(alloc_c_string)]
 #![feature(allocator_api)]
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]

library/std/src/prelude/v1.rs

@@ -95,3 +95,7 @@ pub use crate::string::{String, ToString};
 #[stable(feature = "rust1", since = "1.0.0")]
 #[doc(no_inline)]
 pub use crate::vec::Vec;
+
+#[cfg(bootstrap)]
+#[unstable(feature = "cstr_internals", issue = "none")]
+pub use alloc::ffi::CStrExt;

library/std/src/sys/hermit/mod.rs

@@ -71,16 +71,6 @@ pub fn unsupported_err() -> crate::io::Error {
     )
 }
 
-pub unsafe fn strlen(start: *const c_char) -> usize {
-    let mut str = start;
-
-    while *str != 0 {
-        str = str.offset(1);
-    }
-
-    (str as usize) - (start as usize)
-}
-
 #[no_mangle]
 pub extern "C" fn floor(x: f64) -> f64 {
     unsafe { intrinsics::floorf64(x) }

library/std/src/sys/sgx/mod.rs

@@ -5,7 +5,6 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 
 use crate::io::ErrorKind;
-use crate::os::raw::c_char;
 use crate::sync::atomic::{AtomicBool, Ordering};
 
 pub mod abi;
@@ -130,15 +129,6 @@ pub fn decode_error_kind(code: i32) -> ErrorKind {
     }
 }
 
-pub unsafe fn strlen(mut s: *const c_char) -> usize {
-    let mut n = 0;
-    while unsafe { *s } != 0 {
-        n += 1;
-        s = unsafe { s.offset(1) };
-    }
-    return n;
-}
-
 pub fn abort_internal() -> ! {
     abi::usercalls::exit(true)
 }

library/std/src/sys/solid/mod.rs

@@ -99,5 +99,3 @@ pub fn hashmap_random_keys() -> (u64, u64) {
         (x1, x2)
     }
 }
-
-pub use libc::strlen;

library/std/src/sys/unix/mod.rs

@@ -3,7 +3,6 @@
 use crate::io::ErrorKind;
 
 pub use self::rand::hashmap_random_keys;
-pub use libc::strlen;
 
 #[cfg(not(target_os = "espidf"))]
 #[macro_use]

library/std/src/sys/unsupported/common.rs

@@ -4,10 +4,6 @@ pub mod memchr {
     pub use core::slice::memchr::{memchr, memrchr};
 }
 
-// This is not necessarily correct. May want to consider making it part of the
-// spec definition?
-use crate::os::raw::c_char;
-
 // SAFETY: must be called only once during runtime initialization.
 // NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
@@ -38,15 +34,3 @@ pub fn abort_internal() -> ! {
 pub fn hashmap_random_keys() -> (u64, u64) {
     (1, 2)
 }
-
-pub unsafe fn strlen(mut s: *const c_char) -> usize {
-    // SAFETY: The caller must guarantee `s` points to a valid 0-terminated string.
-    unsafe {
-        let mut n = 0;
-        while *s != 0 {
-            n += 1;
-            s = s.offset(1);
-        }
-        n
-    }
-}

library/std/src/sys/windows/mod.rs

@@ -7,7 +7,6 @@ use crate::path::PathBuf;
 use crate::time::Duration;
 
 pub use self::rand::hashmap_random_keys;
-pub use libc::strlen;
 
 #[macro_use]
 pub mod compat;

src/tools/clippy/clippy_utils/src/paths.rs

@@ -23,7 +23,7 @@ pub const BTREEMAP_ENTRY: [&str; 6] = ["alloc", "collections", "btree", "map", "
 pub const BTREEMAP_INSERT: [&str; 6] = ["alloc", "collections", "btree", "map", "BTreeMap", "insert"];
 pub const CLONE_TRAIT_METHOD: [&str; 4] = ["core", "clone", "Clone", "clone"];
 pub const COW: [&str; 3] = ["alloc", "borrow", "Cow"];
-pub const CSTRING_AS_C_STR: [&str; 5] = ["std", "ffi", "c_str", "CString", "as_c_str"];
+pub const CSTRING_AS_C_STR: [&str; 5] = ["alloc", "ffi", "c_str", "CString", "as_c_str"];
 pub const DEFAULT_TRAIT_METHOD: [&str; 4] = ["core", "default", "Default", "default"];
 pub const DEREF_MUT_TRAIT_METHOD: [&str; 5] = ["core", "ops", "deref", "DerefMut", "deref_mut"];
 /// Preferably use the diagnostic item `sym::deref_method` where possible