[rust-server] Resolve clippy warnings

[siketyan]

This pull request edits rust-server template to resolve all of clippy warnings I confirmed. At the latest master branch, clippy is failing because it is affected by -Dwarnings flags implied in .cargo/config that is also generated by rust-server variant themselves.

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Would you please review this PR?
@frol @farcaller @richardwhiuk @paladinzh

[wing328]

cc @jacob-pro who has recently done some works on the Rust generators.

[jacob-pro]

This looks good - I was planning to do a similar cleanup for Rust client at some point.

The only thing I think needs to be added is some way of testing so that this doesn't happen again in future.

I'm not sure where the build is configured though for Rust - do you know @wing328 ?

In my projects I usually add something like this to the build step:

cargo clippy --all-features --workspace -- -D warnings

[wing328]

Rust clients, servers are tested in Travis: https://github.com/OpenAPITools/openapi-generator/blob/master/pom.xml#L1143

the commands for testing can be found in pom.xml in the sample folders. e.g. https://github.com/OpenAPITools/openapi-generator/blob/master/samples/client/petstore/rust/reqwest/petstore/pom.xml#L36

[siketyan]

So should I add an execution of cargo clippy to the pom.xml of rust-server sample?

[wing328]

@siketyan yes please, we'll see how that goes.

[siketyan]

Added clippy execution to the integration-test chain, could you please take a look? @jacob-pro @wing328

Actually .cargo/config under sub directories in workspace are not used at this time, so I copied one of them to the workspace root directory (samples/server/petstore/rust-server) to enforce cargo to use flags specified in the config.

Also I noticed the compilation of examples/server finishes with some 'unused-mut' warnings (this means the compilation fails with -Dwarnings flag) on macOS, so added #[allow(unused_mut)] to avoid that.

[wing328]

Travis CI tests: https://app.travis-ci.com/github/OpenAPITools/openapi-generator/builds/255780525

let's see how that goes.

[siketyan]

@wing328 ci/circleci: node0 only failed but it looks a temporary network issue. Could you please rerun the workflow?

[wing328]

for circle ci failure, we can ignore it as it's not related to this change.

travis ci tests passed.

let's give this PR a go.

[wing328]

I tested rust-server locally but got:

error: unknown lint: `clippy::derive_partial_eq_without_eq`
 --> output/multipart-v3/src/lib.rs:3:10
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::blacklisted_name)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `-D unknown-lints` implied by `-D warnings`

error: unknown lint: `clippy::derive_partial_eq_without_eq`
 --> output/no-example-v3/src/lib.rs:3:10
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::blacklisted_name)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `-D unknown-lints` implied by `-D warnings`

error: unknown lint: `clippy::derive_partial_eq_without_eq`
 --> output/ping-bearer-auth/src/lib.rs:3:10
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::blacklisted_name)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `-D unknown-lints` implied by `-D warnings`

error: unknown lint: `clippy::derive_partial_eq_without_eq`
 --> output/petstore-with-fake-endpoints-models-for-testing/src/lib.rs:3:10
  |
3 | #![allow(clippy::derive_partial_eq_without_eq, clippy::blacklisted_name)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `-D unknown-lints` implied by `-D warnings`

error: could not compile `ping-bearer-auth` due to previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `no-example-v3` due to previous error
error: could not compile `multipart-v3` due to previous error
error: could not compile `petstore-with-fake-endpoints-models-for-testing` due to previous error

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

command: mvn integration-test -f samples/server/petstore/rust-server/pom.xml

[jacob-pro]

@wing328 According to https://rust-lang.github.io/rust-clippy/master/ it looks like derive_partial_eq_without_eq was only added in Rust 1.63.0.

When I tested this I got the same error as you, but after running rustup update, those errors have gone away (although I am now getting different errors such as needless-borrow)

One thing you might want to do at a project level is define a fixed MSRV (Minimum Supported Rust Version) which we use as the standard to test these by. Because otherwise what can happen is code is passing the tests, and then you run your build system at a later date and it is now failing, because new clippy lints have been added.