Switch from #[no_mangle] to #[unsafe(no_mangle)]

This is in preparation for switching to the 2024 edition.

Author: nicholasbishop

README.md

@@ -69,7 +69,7 @@ Now, add your function signature:
 ```rust
 use core::ffi::{c_char, c_int};
 
-#[no_mangle]
+#[unsafe(no_mangle)]
 unsafe extern "C" fn c_library_print(str: *const c_char, args: ...) -> c_int {
     todo!()
 }
@@ -78,13 +78,13 @@ unsafe extern "C" fn c_library_print(str: *const c_char, args: ...) -> c_int {
 Think about what you're doing:
 
 - If you're implenting `printf` *because you don't have one*, you'll want to
-  call it `printf` and add `#[no_mangle]`.
+  call it `printf` and add `#[unsafe(no_mangle)]`.
 - Likewise, if you're creating a custom log function for a C library and it
-  expects to call a globally-defined function, keep `#[no_mangle]` and
+  expects to call a globally-defined function, keep `#[unsafe(no_mangle)]` and
   rename the function to what it expects.
 - On the other hand, if your C library expects you to call a function to
   register a callback ([example 1][sigrok-log], [example 2][libusb-log]),
-  remove `#[no_mangle]`.
+  remove `#[unsafe(no_mangle)]`.
 
 Now, add your logic:
 

src/lib.rs

@@ -65,7 +65,7 @@
 //! # #![feature(c_variadic)]
 //! use core::ffi::{c_char, c_int};
 //!
-//! #[no_mangle]
+//! #[unsafe(no_mangle)]
 //! unsafe extern "C" fn c_library_print(str: *const c_char, args: ...) -> c_int {
 //!     todo!()
 //! }
@@ -74,20 +74,20 @@
 //! Think about what you're doing:
 //!
 //! - If you're implenting `printf` *because you don't have one*, you'll want to
-//!   call it `printf` and add `#[no_mangle]`.
+//!   call it `printf` and add `#[unsafe(no_mangle)]`.
 //! - Likewise, if you're creating a custom log function for a C library and it
-//!   expects to call a globally-defined function, keep `#[no_mangle]` and
+//!   expects to call a globally-defined function, keep `#[unsafe(no_mangle)]` and
 //!   rename the function to what it expects.
 //! - On the other hand, if your C library expects you to call a function to
 //!   register a callback ([example 1][sigrok-log], [example 2][libusb-log]),
-//!   remove `#[no_mangle]`.
+//!   remove `#[unsafe(no_mangle)]`.
 //!
 //! Now, add your logic:
 //!
 //! ```rust
 //! # #![feature(c_variadic)]
 //! # use core::ffi::{c_char, c_int};
-//! # #[no_mangle]
+//! # #[unsafe(no_mangle)]
 //! # unsafe extern "C" fn c_library_print(str: *const c_char, args: ...) -> c_int {
 //! use printf_compat::{format, output};
 //! let mut s = String::new();

src/output.rs

@@ -323,7 +323,7 @@ pub unsafe fn display<'a>(format: *const c_char, va_list: VaList<'a>) -> VaListD
 ///
 /// use core::ffi::{c_char, c_int};
 ///
-/// #[no_mangle]
+/// #[unsafe(no_mangle)]
 /// unsafe extern "C" fn c_library_print(str: *const c_char, args: ...) -> c_int {
 ///     let format = unsafe { printf_compat::output::display(str, args) };
 ///     println!("{}", format);