Re: [PATCH] rust: disallow use of `CStr::as_ptr`

[kernel test robot <lkp@intel.com>]

Hi Gary,

kernel test robot noticed the following build warnings:

[auto build test WARNING on rust/rust-next]
[also build test WARNING on next-20260121]
[cannot apply to linus/master v6.16-rc1]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Gary-Guo/rust-disallow-use-of-CStr-as_ptr/20260122-014335
base:   https://github.com/Rust-for-Linux/linux rust-next
patch link:    https://lore.kernel.org/r/20260121165835.4097975-1-gary%40kernel.org
patch subject: [PATCH] rust: disallow use of `CStr::as_ptr`
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20260122/202601221157.89t3Sqbl-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260122/202601221157.89t3Sqbl-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601221157.89t3Sqbl-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> warning: use of a disallowed method `core::ffi::CStr::as_ptr`
   --> rust/kernel/task.rs:422:54
   |
   422 |         unsafe { crate::bindings::__might_sleep(file.as_ptr().cast(), loc.line() as i32) }
   |                                                      ^^^^^^ help: Kernel's `char` is always unsigned. Use `as_char_ptr` instead.: `kernel::prelude::CStrExt::as_char_ptr`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#disallowed_methods
   = note: `-W clippy::disallowed-methods` implied by `-W clippy::all`
   = help: to override `-W clippy::all` add `#[allow(clippy::disallowed_methods)]`

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