Re: [PATCH] rust: print: Fix issue with rust_build_error

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

Hi Joel,

kernel test robot noticed the following build errors:

[auto build test ERROR on rust/rust-next]
[also build test ERROR on linus/master v6.17-rc6 next-20250919]
[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/Joel-Fernandes/rust-print-Fix-issue-with-rust_build_error/20250921-002215
base:   https://github.com/Rust-for-Linux/linux rust-next
patch link:    https://lore.kernel.org/r/20250920161958.2079105-1-joelagnelf%40nvidia.com
patch subject: [PATCH] rust: print: Fix issue with rust_build_error
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20250922/202509220423.4d1foVAO-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/20250922/202509220423.4d1foVAO-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/202509220423.4d1foVAO-lkp@intel.com/

All errors (new ones prefixed by >>):

>> error[E0277]: the `?` operator can only be used in a closure that returns `Result` or `Option` (or another type that implements `FromResidual`)
   --> rust/doctests_kernel_generated.rs:3446:70
   |
   3446 |     pr_info!("The frequency at index 0 is: {:?}n", table.freq(index)?);
   |     -----------------------------------------------------------------^-
   |     |                                                                |
   |     |                                                                cannot use the `?` operator in a closure that returns `()`
   |     this function should return `Result` or `Option` to accept `?`

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