Re: [PATCH 2/3] rust: kunit: use `line!()` inside `kunit_assert!`

[David Gow <david@davidgow.net>]

Le 16/06/2026 à 11:24 PM, Gary Guo a écrit :
> The `diff` parameter is needed currently because doctests want to override
> the line number. Simplify it by changing it to use `line!()`. Have doctests
> override `line!()` macro to achieve the current behavior.
> 
> A few current doctests (or their invoked macros) require `line!()` to
> expand to literal; they're updated to use `::core::line!()` instead.
> 
> Signed-off-by: Gary Guo <gary@garyguo.net>
> ---

Much nicer, thanks!

Reviewed-by: David Gow <david@davidgow.net>

>  rust/kernel/device_id.rs    |  2 +-
>  rust/kernel/kunit.rs        |  8 ++++----
>  rust/kernel/str.rs          |  2 +-
>  rust/macros/kunit.rs        |  4 ++--
>  scripts/rustdoc_test_gen.rs | 16 ++++++++++++----
>  5 files changed, 20 insertions(+), 12 deletions(-)
> 
> diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs
> index 8e9721446014..20e2fe137202 100644
> --- a/rust/kernel/device_id.rs
> +++ b/rust/kernel/device_id.rs
> @@ -195,7 +195,7 @@ macro_rules! module_device_table {
>      ($table_type: literal, $module_table_name:ident, $table_name:ident) => {
>          #[rustfmt::skip]
>          #[export_name =
> -            concat!("__mod_device_table__", line!(),
> +            concat!("__mod_device_table__", ::core::line!(),
>                      "__kmod_", module_path!(),
>                      "__", $table_type,
>                      "__", stringify!($table_name))
> diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> index 157fd0634708..58dfec66b4f6 100644
> --- a/rust/kernel/kunit.rs
> +++ b/rust/kernel/kunit.rs
> @@ -58,7 +58,7 @@ pub fn info(args: fmt::Arguments<'_>) {
>  #[doc(hidden)]
>  #[macro_export]
>  macro_rules! kunit_assert {
> -    ($name:literal, $diff:expr, $condition:expr $(,)?) => {
> +    ($name:literal, $condition:expr $(,)?) => {
>          'out: {
>              // Do nothing if the condition is `true`.
>              if $condition {
> @@ -67,7 +67,7 @@ macro_rules! kunit_assert {
>  
>              // Use `file!()` instead of `::core::file!()` here so it can be overridden.
>              static FILE: &'static $crate::str::CStr = $crate::c_str!(file!());
> -            static LINE: i32 = ::core::line!() as i32 - $diff;
> +            static LINE: i32 = line!() as i32;
>              static CONDITION: &'static $crate::str::CStr = $crate::c_str!(stringify!($condition));
>  
>              // SAFETY: FFI call without safety requirements.
> @@ -165,10 +165,10 @@ unsafe impl Sync for UnaryAssert {}
>  #[doc(hidden)]
>  #[macro_export]
>  macro_rules! kunit_assert_eq {
> -    ($name:literal, $diff:expr, $left:expr, $right:expr $(,)?) => {{
> +    ($name:literal, $left:expr, $right:expr $(,)?) => {{
>          // For the moment, we just forward to the expression assert because, for binary asserts,
>          // KUnit supports only a few types (e.g. integers).
> -        $crate::kunit_assert!($name, $diff, $left == $right);
> +        $crate::kunit_assert!($name, $left == $right);
>      }};
>  }
>  
> diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
> index b3caa9a1c898..644b4279a116 100644
> --- a/rust/kernel/str.rs
> +++ b/rust/kernel/str.rs
> @@ -411,7 +411,7 @@ fn as_ref(&self) -> &BStr {
>  /// const BAD: &CStr = c_str!("literal");
>  ///
>  /// // `c_str!` is still needed for static non-literal C strings.
> -/// const GOOD: &CStr = c_str!(concat!(file!(), ":", line!(), ": My CStr!"));
> +/// const GOOD: &CStr = c_str!(concat!(file!(), ":", ::core::line!(), ": My CStr!"));
>  /// ```
>  #[macro_export]
>  macro_rules! c_str {
> diff --git a/rust/macros/kunit.rs b/rust/macros/kunit.rs
> index 936eff014870..e9152b9d51f9 100644
> --- a/rust/macros/kunit.rs
> +++ b/rust/macros/kunit.rs
> @@ -113,7 +113,7 @@ pub(crate) fn kunit_tests(test_suite: Ident, mut module: ItemMod) -> Result<Toke
>              #[allow(unused)]
>              macro_rules! assert {
>                  ($cond:expr $(,)?) => {{
> -                    kernel::kunit_assert!(#test_str, 0, $cond);
> +                    kernel::kunit_assert!(#test_str, $cond);
>                  }}
>              }
>          });
> @@ -121,7 +121,7 @@ macro_rules! assert {
>              #[allow(unused)]
>              macro_rules! assert_eq {
>                  ($left:expr, $right:expr $(,)?) => {{
> -                    kernel::kunit_assert_eq!(#test_str, 0, $left, $right);
> +                    kernel::kunit_assert_eq!(#test_str, $left, $right);
>                  }}
>              }
>          });
> diff --git a/scripts/rustdoc_test_gen.rs b/scripts/rustdoc_test_gen.rs
> index 37f4877f52e2..acc4debe8592 100644
> --- a/scripts/rustdoc_test_gen.rs
> +++ b/scripts/rustdoc_test_gen.rs
> @@ -169,18 +169,26 @@ fn main() {
>              r#"/// Generated `{name}` KUnit test case from a Rust documentation test.
>  #[no_mangle]
>  pub extern "C" fn {kunit_name}(__kunit_test: *mut ::kernel::bindings::kunit) {{
> -    /// Overrides the usual [`file!`] macro with one that expands to the real path.
> +    // Overrides the usual [`file!`] macro with one that expands to the real path.
>      #[allow(unused)]
>      macro_rules! file {{
>          () => {{ "{real_path}" }}
>      }}
>  
> +    // Overrides the usual [`line!`] macro with one that expands to the real line number.
> +    #[allow(unused)]
> +    macro_rules! line {{
> +        // NOTE: This does not expand to a literal, but a constant expression.
> +        // Therefore code that depends on `line!()` being overrideable needs special adjustment.
> +        () => {{ const {{ ::core::line!() - __DOCTEST_ANCHOR + {line} }} }}
> +    }}
> +
>      /// Overrides the usual [`assert!`] macro with one that calls KUnit instead.
>      #[allow(unused)]
>      macro_rules! assert {{
>          ($cond:expr $(,)?) => {{{{
>              ::kernel::kunit_assert!(
> -                "{kunit_name}", __DOCTEST_ANCHOR - {line}, $cond
> +                "{kunit_name}", $cond
>              );
>          }}}}
>      }}
> @@ -190,7 +198,7 @@ macro_rules! assert {{
>      macro_rules! assert_eq {{
>          ($left:expr, $right:expr $(,)?) => {{{{
>              ::kernel::kunit_assert_eq!(
> -                "{kunit_name}", __DOCTEST_ANCHOR - {line}, $left, $right
> +                "{kunit_name}", $left, $right
>              );
>          }}}}
>      }}
> @@ -212,7 +220,7 @@ macro_rules! assert_eq {{
>  
>      /// The anchor where the test code body starts.
>      #[allow(unused)]
> -    static __DOCTEST_ANCHOR: i32 = ::core::line!() as i32 + {body_offset} + 2;
> +    static __DOCTEST_ANCHOR: u32 = ::core::line!() + {body_offset} + 2;
>      {{
>          #![allow(unreachable_pub, clippy::disallowed_names)]
>          {body}
>