init: allow nonstandard_style for generated accessor/value

[Mirko-A]

Allows nonstandard_style lint on accessors/values generated as local variables in init!.

Since the same warning will be reported by the compiler on the struct field, having the extra warning for the generated accessor/value is unnecessary and confusing.

Reported-by: Gary Guo gary@garyguo.net
Link: #125
Closes: https://lore.kernel.org/rust-for-linux/DGTBJBIVFZ2K.2F1ZEFGY0G7NK@garyguo.net/
Fixes: f1b0c3c ("internal: init: remove #[disable_initialized_field_access]")

[Mirko-A]

Tested with the following changes:

diff --git a/examples/big_struct_in_place.rs b/examples/big_struct_in_place.rs
index 80f89b5..5525cae 100644
--- a/examples/big_struct_in_place.rs
+++ b/examples/big_struct_in_place.rs
@@ -13,8 +13,8 @@ pub struct BigStruct {
     a: u64,
     b: u64,
     c: u64,
-    d: u64,
-    managed_buf: ManagedBuf,
+    NONSTANDARD_D: u64,
+    MANAGED_BUF: ManagedBuf,
 }

 #[derive(Debug)]
@@ -37,8 +37,8 @@ fn main() {
             a: 7,
             b: 186,
             c: 7789,
-            d: 34,
-            managed_buf <- ManagedBuf::new(),
+            NONSTANDARD_D: 34,
+            MANAGED_BUF <- ManagedBuf::new(),
         }))
         .unwrap();
         println!("{}", core::mem::size_of_val(&*buf));

Output before the patch:

$ cargo run --example big_struct_in_place
[...]
error: structure field `NONSTANDARD_D` should have a snake case name
  --> examples/big_struct_in_place.rs:16:5
   |
16 |     NONSTANDARD_D: u64,
   |     ^^^^^^^^^^^^^ help: convert the identifier to snake case: `nonstandard_d`
   |
   = note: `-D non-snake-case` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(non_snake_case)]`

error: structure field `MANAGED_BUF` should have a snake case name
  --> examples/big_struct_in_place.rs:17:5
   |
17 |     MANAGED_BUF: ManagedBuf,
   |     ^^^^^^^^^^^ help: convert the identifier to snake case: `managed_buf`

error: variable `NONSTANDARD_D` should have a snake case name
  --> examples/big_struct_in_place.rs:40:28
   |
40 |             NONSTANDARD_D: 34,
   |                            ^^ help: convert the identifier to snake case: `nonstandard_d`

error: variable `NONSTANDARD_D` should have a snake case name
  --> examples/big_struct_in_place.rs:40:13
   |
40 |             NONSTANDARD_D: 34,
   |             ^^^^^^^^^^^^^ help: convert the identifier to snake case: `nonstandard_d`

error: variable `MANAGED_BUF` should have a snake case name
  --> examples/big_struct_in_place.rs:41:13
   |
41 |             MANAGED_BUF <- ManagedBuf::new(),
   |             ^^^^^^^^^^^ help: convert the identifier to snake case: `managed_buf`

error: could not compile `pin-init` (example "big_struct_in_place") due to 5 previous errors

Output after the patch:

$ cargo run --example big_struct_in_place
[...]
error: structure field `NONSTANDARD_D` should have a snake case name
  --> examples/big_struct_in_place.rs:16:5
   |
16 |     NONSTANDARD_D: u64,
   |     ^^^^^^^^^^^^^ help: convert the identifier to snake case: `nonstandard_d`
   |
   = note: `-D non-snake-case` implied by `-D warnings`
   = help: to override `-D warnings` add `#[allow(non_snake_case)]`

error: structure field `MANAGED_BUF` should have a snake case name
  --> examples/big_struct_in_place.rs:17:5
   |
17 |     MANAGED_BUF: ManagedBuf,
   |     ^^^^^^^^^^^ help: convert the identifier to snake case: `managed_buf`

error: could not compile `pin-init` (example "big_struct_in_place") due to 2 previous errors

I am still quite new to the process of contributing to Rust-For-Linux. Please let me know if I've made any mistakes or if I've missed something.

[nbdd0121]

Please add a test for this

[Mirko-A]

Does something like this look okay?

[nbdd0121]

I think what you want is not a compile_fail test, but rather than the code (with allow on the struct definition side), compiles to completion without warnings? So this should just be a test in src/tests.

[Mirko-A]

Right, that sounds like a better approach.

I've amended the existing test commit to keep the branch clean, hopefully that's okay: 2d194be

So this should just be a test in src/tests.

I put the test under the existing tests directory in the crate root, I hope that's what you meant. If you specifically wanted a new directory in src, I'm happy to move it.

[Mirko-A]

Two more things:

1. The CI failure seems unrelated, running rustup run 1.78 cargo check on main produces the same error for me.
2. Would you like me to add a changelog entry for this fix?

[nbdd0121]

main works fine for me. Did you not add RUSTC_BOOTSTRAP=1? Please do add a changelog entry.

[nbdd0121]

Suggested change

	used for structs with non-snake-case field names. Warnings are still reported on the
	struct definition, as expected.
	used for structs with non-snake-case field names. Warnings on the
	struct definition are unaffected.

[Mirko-A]

d4e1179

[nbdd0121]

Can you add a test case with pin_init!() macro and a struct with #[pin_data]?

[Mirko-A]

Ah, there are nonstandard_style warnings in pin_init! too. I tried adding such test case but it doesn't pass with the current set of changes.

Would you like me to address that in this pull request as well, or keep this one focused on init!?

[nbdd0121]

Please address both, thanks!

[Mirko-A]

Sorry for the delay - I just pushed a few more commits. Hopefully that covers everything now.

I kept the new commits separate, so that it is easier to see the diffs. Please let me know if you want them squashed.