Re: [PATCH v4] rust: kernel: introduce `unsafe_precondition_assert!` macro

Re: [PATCH v4] rust: kernel: introduce `unsafe_precondition_assert!` macro

[kernel test robot]

Hi Ritvik,

kernel test robot noticed the following build errors:

[auto build test ERROR on 37816488247ddddbc3de113c78c83572274b1e2e]

url:    https://github.com/intel-lab-lkp/linux/commits/Ritvik-Gupta/rust-kernel-introduce-unsafe_precondition_assert-macro/20250809-032122
base:   37816488247ddddbc3de113c78c83572274b1e2e
patch link:    https://lore.kernel.org/r/20250808192005.209188-1-ritvikfoss%40gmail.com
patch subject: [PATCH v4] rust: kernel: introduce `unsafe_precondition_assert!` macro
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20250812/202508122341.rb7U1Q2P-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/20250812/202508122341.rb7U1Q2P-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/202508122341.rb7U1Q2P-lkp@intel.com/

All errors (new ones prefixed by >>):

>> error[E0423]: cannot initialize a tuple struct which contains private fields
   --> rust/doctests_kernel_generated.rs:8841:5
   |
   8841 |     CpuId(id)
   |     ^^^^^
   |
   note: constructor is not visible here due to private fields
   --> rust/kernel/cpu.rs:47:18
   |
   47   | pub struct CpuId(u32);
   |                  ^^^ private field
   help: you might have meant to use an associated function to build this type
   |
   8841 -     CpuId(id)
   8841 +     CpuId::from_i32_unchecked(_)
   |
   8841 -     CpuId(id)
   8841 +     CpuId::from_u32_unchecked(_)
   |
   8841 -     CpuId(id)
   8841 +     CpuId::current()
   |

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v4] rust: kernel: introduce `unsafe_precondition_assert!` macro

[Ritvik Gupta]

If someone's referring to it in the future, this was doctest issue.

It’s actually the second time I’ve hit it.
On my end, this error wasn't occurring when compiling the kernel.

What I was missing:
1. Enable `Kernel Hacking > Kernel Testing and Coverage > KUnit`
2. Enable Doctest in `Rust hacking > Doctests for the 'kernel' crate`

I can now reproduce capture the issue locally.
Won't happen again :)