fix: clippy::ptr_cast_constness

https://rust-lang.github.io/rust-clippy/master/index.html#ptr_cast_constness

Part of #12136

src/exec.rs

@@ -415,7 +415,7 @@ fn safe_launch_process(
             // +1 for /bin/sh, +1 for terminating nullptr
             let mut argv2 = [std::ptr::null(); 1 + MAXARGS + 1];
             let bshell = PATH_BSHELL.as_ptr() as *const c_char;
-            argv2[0] = bshell as *mut c_char;
+            argv2[0] = bshell;
             argv2[1..argv.len() + 1].copy_from_slice(argv);
             // The command to call should use the full path,
             // not what we would pass as argv0.

src/fork_exec/spawn.rs

@@ -172,12 +172,12 @@ pub(crate) fn spawn(
         let cmdcstr = unsafe { CStr::from_ptr(cmd) };
         if spawn_err.0 == libc::ENOEXEC && is_thompson_shell_script(cmdcstr) {
             // Create a new argv with /bin/sh prepended.
-            let mut argv2 = vec![PATH_BSHELL.as_ptr() as *mut c_char];
+            let mut argv2: Vec<*mut c_char> = vec![PATH_BSHELL.as_ptr().cast_mut() as *mut c_char];
 
             // The command to call should use the full path,
             // not what we would pass as argv0.
             let cmd2: CString = CString::new(cmdcstr.to_bytes()).unwrap();
-            argv2.push(cmd2.as_ptr() as *mut c_char);
+            argv2.push(cmd2.as_ptr().cast_mut());
             for i in 1.. {
                 let ptr = unsafe { argv.offset(i).read() };
                 if ptr.is_null() {

src/global_safety.rs

@@ -35,7 +35,7 @@ fn clone(&self) -> Self {
 
 impl<T: ?Sized> AtomicRef<T> {
     pub const fn new(value: &'static &'static T) -> Self {
-        Self(AtomicPtr::new(std::ptr::from_ref(value) as *mut &'static T))
+        Self(AtomicPtr::new(std::ptr::from_ref(value).cast_mut()))
     }
 
     pub fn load(&self) -> &'static T {
@@ -43,10 +43,8 @@ pub fn load(&self) -> &'static T {
     }
 
     pub fn store(&self, value: &'static &'static T) {
-        self.0.store(
-            std::ptr::from_ref(value) as *mut &'static T,
-            Ordering::Relaxed,
-        )
+        self.0
+            .store(std::ptr::from_ref(value).cast_mut(), Ordering::Relaxed)
     }
 }
 

src/locale.rs

@@ -81,7 +81,7 @@ unsafe fn lconv_to_locale(lconv: &libc::lconv) -> Locale {
 
     // Up to 4 groups.
     // group_cursor is terminated by either a 0 or CHAR_MAX.
-    let mut group_cursor = lconv.grouping as *const libc::c_char;
+    let mut group_cursor = lconv.grouping.cast_const();
     if group_cursor.is_null() {
         group_cursor = empty.as_ptr();
     }