Re: [PATCH 1/1] Use new `--output-format=doctest` rustdoc command line flag to improve doctest handling

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

Hi Guillaume,

kernel test robot noticed the following build errors:

[auto build test ERROR on rust/rust-next]
[also build test ERROR on shuah-kselftest/kunit shuah-kselftest/kunit-fixes linus/master v6.16-rc2 next-20250617]
[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/Guillaume-Gomez/Use-new-output-format-doctest-rustdoc-command-line-flag-to-improve-doctest-handling/20250617-220502
base:   https://github.com/Rust-for-Linux/linux rust-next
patch link:    https://lore.kernel.org/r/20250617140032.1133337-2-guillaume1.gomez%40gmail.com
patch subject: [PATCH 1/1] Use new `--output-format=doctest` rustdoc command line flag to improve doctest handling
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20250618/202506181334.f0STx6ta-lkp@intel.com/config)
compiler: clang version 18.1.8 (https://github.com/llvm/llvm-project 3b5b5c1ec4a3095ab096dd780e84d7ab81f3d7ff)
rustc: rustc 1.78.0 (9b00956e5 2024-04-29)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250618/202506181334.f0STx6ta-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/202506181334.f0STx6ta-lkp@intel.com/

All errors (new ones prefixed by >>):

   PATH=/opt/cross/clang-18/bin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
   INFO PATH=/opt/cross/rustc-1.78.0-bindgen-0.65.1/cargo/bin:/opt/cross/clang-18/bin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
   /usr/bin/timeout -k 100 12h /usr/bin/make KCFLAGS= -Wno-error=return-type -Wreturn-type -funsigned-char -Wundef W=1 --keep-going LLVM=1 -j32 -C source O=/kbuild/obj/consumer/x86_64-rhel-9.4-rust ARCH=x86_64 SHELL=/bin/bash rustfmtcheck
   make: Entering directory '/kbuild/src/consumer'
   make[1]: Entering directory '/kbuild/obj/consumer/x86_64-rhel-9.4-rust'
>> Diff in scripts/rustdoc_test_builder.rs at line 16:
    //! the `gen` script (done there since we need to be aware of all the tests in a given file).
    
    use std::collections::HashMap;
   -use std::io::Read;
    use std::fs::create_dir_all;
   +use std::io::Read;
    
    use json::JsonValue;
    
   Diff in scripts/rustdoc_test_builder.rs at line 25:
    
    fn generate_doctest(file: &str, line: i32, doctest_code: &HashMap<String, JsonValue>) -> bool {
        // FIXME: Once let chain feature is stable, please use it instead.
   -    let Some(JsonValue::Object(wrapper)) = doctest_code.get("wrapper") else { return false };
   -    let Some(JsonValue::String(before)) = wrapper.get("before") else { return false };
   -    let Some(JsonValue::String(after)) = wrapper.get("after") else { return false };
   -    let Some(JsonValue::String(code)) = doctest_code.get("code") else { return false };
   -    let Some(JsonValue::String(crate_level_code)) = doctest_code.get("crate_level") else { return false };
   +    let Some(JsonValue::Object(wrapper)) = doctest_code.get("wrapper") else {
   +        return false;
   +    };
   +    let Some(JsonValue::String(before)) = wrapper.get("before") else {
   +        return false;
   +    };
   +    let Some(JsonValue::String(after)) = wrapper.get("after") else {
   +        return false;
   +    };
   +    let Some(JsonValue::String(code)) = doctest_code.get("code") else {
   +        return false;
   +    };
   +    let Some(JsonValue::String(crate_level_code)) = doctest_code.get("crate_level") else {
   +        return false;
   +    };
    
        // For tests that get generated with `Result`, `rustdoc` generates an `unwrap()` on
        // the return value to check there were no returned errors. Instead, we use our assert macro
   make[1]: Leaving directory '/kbuild/obj/consumer/x86_64-rhel-9.4-rust'
   make[2]: *** [Makefile:1825: rustfmt] Error 123
   make[2]: Target 'rustfmtcheck' not remade because of errors.
   make[1]: *** [Makefile:248: __sub-make] Error 2
   make[1]: Target 'rustfmtcheck' not remade because of errors.
   make: *** [Makefile:248: __sub-make] Error 2
   make: Target 'rustfmtcheck' not remade because of errors.
   make: Leaving directory '/kbuild/src/consumer'

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