[PATCH v2 0/2] rust: minor idiomatic fixes to doctest generator

[PATCH v2 0/2] rust: minor idiomatic fixes to doctest generator

[Tamir Duberstein]

Please see individual commit messages.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
Changes in v2:
- rustfmt.
- Alice's RB.
- Add second patch to emit information in panic rather than separately
  to stderr.
- Link to v1: https://lore.kernel.org/r/20250527-idiomatic-match-slice-v1-1-34b0b1d1d58c@gmail.com

---
Tamir Duberstein (2):
      rust: replace length checks with match
      rust: emit path candidates in panic message

 scripts/rustdoc_test_gen.rs | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)
---
base-commit: 1ce98bb2bb30713ec4374ef11ead0d7d3e856766
change-id: 20250527-idiomatic-match-slice-26a79d100e4d

Best regards,
-- 
Tamir Duberstein <tamird@gmail.com>

[PATCH v2 1/2] rust: replace length checks with match

[Tamir Duberstein]

Use a match expression with slice patterns instead of length checks and
indexing. The result is more idiomatic, which is a better example for
future Rust code authors.

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 scripts/rustdoc_test_gen.rs | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/scripts/rustdoc_test_gen.rs b/scripts/rustdoc_test_gen.rs
index 1ca253594d38..d796481f4359 100644
--- a/scripts/rustdoc_test_gen.rs
+++ b/scripts/rustdoc_test_gen.rs
@@ -85,24 +85,23 @@ fn find_candidates(
         }
     }
 
-    assert!(
-        valid_paths.len() > 0,
-        "No path candidates found for `{file}`. This is likely a bug in the build system, or some \
-        files went away while compiling."
-    );
-
-    if valid_paths.len() > 1 {
-        eprintln!("Several path candidates found:");
-        for path in valid_paths {
-            eprintln!("    {path:?}");
+    match valid_paths.as_slice() {
+        [] => panic!(
+            "No path candidates found for `{file}`. This is likely a bug in the build system, or \
+            some files went away while compiling."
+        ),
+        [valid_path] => valid_path.to_str().unwrap(),
+        valid_paths => {
+            eprintln!("Several path candidates found:");
+            for path in valid_paths {
+                eprintln!("    {path:?}");
+            }
+            panic!(
+                "Several path candidates found for `{file}`, please resolve the ambiguity by \
+                renaming a file or folder."
+            );
         }
-        panic!(
-            "Several path candidates found for `{file}`, please resolve the ambiguity by renaming \
-            a file or folder."
-        );
     }
-
-    valid_paths[0].to_str().unwrap()
 }
 
 fn main() {

-- 
2.49.0

[PATCH v2 2/2] rust: emit path candidates in panic message

[Tamir Duberstein]

Include all information in the panic message rather than emit fragments
to stderr.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>
---
 scripts/rustdoc_test_gen.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/scripts/rustdoc_test_gen.rs b/scripts/rustdoc_test_gen.rs
index d796481f4359..f95129b03cd8 100644
--- a/scripts/rustdoc_test_gen.rs
+++ b/scripts/rustdoc_test_gen.rs
@@ -92,13 +92,15 @@ fn find_candidates(
         ),
         [valid_path] => valid_path.to_str().unwrap(),
         valid_paths => {
-            eprintln!("Several path candidates found:");
+            use std::fmt::Write;
+
+            let mut candidates = String::new();
             for path in valid_paths {
-                eprintln!("    {path:?}");
+                write!(&mut candidates, "    {path:?}").unwrap();
             }
             panic!(
                 "Several path candidates found for `{file}`, please resolve the ambiguity by \
-                renaming a file or folder."
+                renaming a file or folder. Candidates:\n{candidates}",
             );
         }
     }

-- 
2.49.0

Re: [PATCH v2 2/2] rust: emit path candidates in panic message

[Miguel Ojeda]

On Thu, May 29, 2025 at 3:15 PM Tamir Duberstein <tamird@gmail.com> wrote:
>
> Include all information in the panic message rather than emit fragments
> to stderr.

Could we explain the "why" as well in the message? (i.e. not just the "what")

Thanks!

Cheers,
Miguel

Re: [PATCH v2 2/2] rust: emit path candidates in panic message

[Tamir Duberstein]

On Thu, May 29, 2025 at 9:21 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Thu, May 29, 2025 at 3:15 PM Tamir Duberstein <tamird@gmail.com> wrote:
> >
> > Include all information in the panic message rather than emit fragments
> > to stderr.
>
> Could we explain the "why" as well in the message? (i.e. not just the "what")

Sure, that would be:

Include all information in the panic message rather than emit fragments
to stderr to avoid possible interleaving with other output.

Let me know if I should send another spin for this, or if this is ok
to do on apply.

Re: [PATCH v2 2/2] rust: emit path candidates in panic message

[Miguel Ojeda]

On Thu, May 29, 2025 at 4:38 PM Tamir Duberstein <tamird@gmail.com> wrote:
>
> Sure, that would be:
>
> Include all information in the panic message rather than emit fragments
> to stderr to avoid possible interleaving with other output.
>
> Let me know if I should send another spin for this, or if this is ok
> to do on apply.

Thanks! No worries, I can do that on apply.

Cheers,
Miguel

Re: [PATCH v2 2/2] rust: emit path candidates in panic message

[Miguel Ojeda]

On Thu, May 29, 2025 at 3:15 PM Tamir Duberstein <tamird@gmail.com> wrote:
>
> +                write!(&mut candidates, "    {path:?}").unwrap();

I assume this was supposed to be `writeln!`; otherwise, we lose the
newlines and the indent does not make much sense.

I will fix it when applying.

Cheers,
Miguel

Re: [PATCH v2 0/2] rust: minor idiomatic fixes to doctest generator

[Miguel Ojeda]

On Thu, May 29, 2025 at 3:15 PM Tamir Duberstein <tamird@gmail.com> wrote:
>
> Please see individual commit messages.
>
> Signed-off-by: Tamir Duberstein <tamird@gmail.com>

Applied to `rust-next` -- thanks everyone!

    [ Reworded title. - Miguel ]

    [ Kept newlines using `writeln!`. Used new message from Tamir. Reworded
      title. - Miguel ]

Cheers,
Miguel

Re: [PATCH v2 2/2] rust: emit path candidates in panic message

[Tamir Duberstein]

On Sun, Jul 20, 2025 at 6:20 PM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Thu, May 29, 2025 at 3:15 PM Tamir Duberstein <tamird@gmail.com> wrote:
> >
> > +                write!(&mut candidates, "    {path:?}").unwrap();
>
> I assume this was supposed to be `writeln!`; otherwise, we lose the
> newlines and the indent does not make much sense.

Duh, yes, that's right.

> I will fix it when applying.

Thank you!