[rust-server] Fix clippy warnings

[siketyan]

This pull request fixes these clippy warnings:

• clippy::disallowed_names (renamed from clippy::blacklisted_name)
• clippy::single_match (dismissed because it occurs in some cases)
• clippy::explicit_auto_deref
• clippy::needless_borrow
• clippy::suspicious_to_owned

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@frol @farcaller @richardwhiuk @paladinzh @jacob-pro

[siketyan]

I have just published a built Docker image on rev 5de15fb (only for Arm64, sorry!).
Please take a look if you want to test the new behaviour of rust-server generator.
Thank you!

https://github.com/yumemi-inc/openapi-generator/pkgs/container/openapi-generator/48974185?tag=v6.3.0-SNAPSHOT

[wing328]

when testing it locally, I got the following errors in the rust-server sample:

error: unknown lint: `clippy::disallowed_names`
 --> output/petstore-with-fake-endpoints-models-for-testing/src/lib.rs:3:48
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::disallowed_names)]
  |                                                ^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::disallowed_types`

error: unknown lint: `clippy::disallowed_names`
 --> output/no-example-v3/src/lib.rs:3:48
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::disallowed_names)]
  |                                                ^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::disallowed_types`

error: unknown lint: `clippy::disallowed_names`
 --> output/rust-server-test/src/lib.rs:3:48
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::disallowed_names)]
  |                                                ^^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `clippy::disallowed_types`

error: could not compile `no-example-v3` due to 2 previous errors
warning: build failed, waiting for other jobs to finish...
error: could not compile `multipart-v3` due to 2 previous errors
error: could not compile `rust-server-test` due to 2 previous errors
error: use of a blacklisted/placeholder name `foo`
    --> output/petstore-with-fake-endpoints-models-for-testing/src/models.rs:3101:36
     |
3101 |             self.foo.as_ref().map(|foo| {
     |                                    ^^^
     |
     = note: `-D clippy::blacklisted-name` implied by `-D warnings`
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name

error: use of a blacklisted/placeholder name `baz`
    --> output/petstore-with-fake-endpoints-models-for-testing/src/models.rs:5081:36
     |
5081 |             self.baz.as_ref().map(|baz| {
     |                                    ^^^
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#blacklisted_name

error: could not compile `petstore-with-fake-endpoints-models-for-testing` due to 4 previous errors
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  12:34 min
[INFO] Finished at: 2022-11-07T21:56:55+08:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (clippy) on project RustServerTests: Command execution failed.: Process exited with an error: 101 (Exit value: 101) -> [Help 1]

can you please take a look when you've time?

[siketyan]

@wing328
It is a version mismatch of clippy.
As described in the description, clippy renamed the lint recently.
In fact, I have tested it works on my local environment.

I think there is no way to support both version of clippy for allowing or denying lints, so we need to decide to support the latest only or keep the current behaviour.

How do you think about that?

[jacob-pro]

@wing328 I think we need to consider pinning the project to fixed version of clippy and Rust in general. Otherwise what will happen is our CI checks may fail in future even though the code hasn't changed. I mentioned this before here:
#13473 (comment)

We need to define a MSRV and have the CI install this fixed version

[siketyan]

I apologise I missed your comments in the previous pull request.

I agree that we should set MSRV for supporting and testing. Since clippy is intended to use in project-local, there is no backward compatibility as shown as the testing result now. To keep the MSRV older (it means the warnings are continuously shown in later toolchains), or to keep later (older toolchains will not be supported) is an important decision I think.

[wing328]

I think we need to consider pinning the project to fixed version of clippy and Rust in general.

the suggestion sounds good.

[siketyan]

Any updates on this?

We have an additional warnings x37 times since v1.67:

warning: variables can be used directly in the `format!` string
  --> src/client/mod.rs:57:39
   |
57 |     let port = uri.port_u16().map(|x| format!(":{}", x)).unwrap_or_default();
   |                                       ^^^^^^^^^^^^^^^^^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
   = note: `#[warn(clippy::uninlined_format_args)]` on by default
help: change this to
   |
57 -     let port = uri.port_u16().map(|x| format!(":{}", x)).unwrap_or_default();
57 +     let port = uri.port_u16().map(|x| format!(":{x}")).unwrap_or_default();
   |

[wing328]

can you please PM me via slack next week to discuss how to move forward with this?

have a nice weekend.

[wing328]

tests passed via #14758.

we'll merge and see if later someone can contribute a PR or two to improve the CI tests.

[wing328]

and as a workaround, users can enable/disable the warnings: https://doc.rust-lang.org/nightly/clippy/usage.html