Rollup merge of #123976 - ChrisDenton:no-libc-in-std-doc-tests, r=Mark-Simulacrum

Use fake libc in core test

The war on libc continues.

Some platforms may not need to link to the libc crate (and it's possible some may not even have a libc), therefore we shouldn't require it for tests. This creates dummy `malloc` and `free` implementations for use in the pointer docs, but, keeps the public documentation looking the same as before.

1 files changed, 6 insertions, 2 deletions

diff --git a/library/core/src/primitive_docs.rs b/library/core/src/primitive_docs.rs
index e8e23f2a7ec..bda1ee6f457 100644
--- a/library/core/src/primitive_docs.rs
+++ b/library/core/src/primitive_docs.rs
@@ -537,7 +537,11 @@ impl () {}
 /// ## 4. Get it from C.
 ///
 /// ```
-/// # #![feature(rustc_private)]
+/// # mod libc {
+/// # pub unsafe fn malloc(_size: usize) -> *mut core::ffi::c_void { core::ptr::NonNull::dangling().as_ptr() }
+/// # pub unsafe fn free(_ptr: *mut core::ffi::c_void) {}
+/// # }
+/// # #[cfg(any())]
 /// #[allow(unused_extern_crates)]
 /// extern crate libc;
 ///
@@ -548,7 +552,7 @@ impl () {}
 ///     if my_num.is_null() {
 ///         panic!("failed to allocate memory");
 ///     }
-///     libc::free(my_num as *mut libc::c_void);
+///     libc::free(my_num as *mut core::ffi::c_void);
 /// }
 /// ```
 ///