feat(rust,client): derive Default for operation parameter structs

[PiDelport]

This makes operations with many parameters easier to work with.

• Relevant for: [BUG][RUST] Twilio OpenAPI codegen errors #10421

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@frol (2017/07) @farcaller (2017/08) @richardwhiuk (2019/07) @paladinzh (2020/05)

[wing328]

LGTM. I assume this is a backward-compatible change. Please correct me if I'm wrong.

[wing328]

Looks like this breaks the existing tests:

    Checking petstore-reqwest-async v1.0.0 (/home/travis/build/OpenAPITools/openapi-generator/samples/client/petstore/rust/reqwest/petstore-async)
    Checking rust-test-reqwest v1.0.0 (/home/travis/build/OpenAPITools/openapi-generator/samples/client/petstore/rust/reqwest/rust-test)
error[E0277]: the trait bound `Pet: Default` is not satisfied
   --> reqwest/petstore-async/src/apis/pet_api.rs:21:5
    |
18  | #[derive(Clone, Debug, Default)]
    |                        ------- in this derive macro expansion
...
21  |     pub pet: crate::models::Pet
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `Pet`
    |
note: required by `std::default::Default::default`
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `Pet: Default` is not satisfied
   --> reqwest/petstore-async/src/apis/pet_api.rs:57:5
    |
54  | #[derive(Clone, Debug, Default)]
    |                        ------- in this derive macro expansion
...
57  |     pub pet: crate::models::Pet
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `Pet`
    |
note: required by `std::default::Default::default`
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `Order: Default` is not satisfied
   --> reqwest/petstore-async/src/apis/store_api.rs:35:5
    |
32  | #[derive(Clone, Debug, Default)]
    |                        ------- in this derive macro expansion
...
35  |     pub order: crate::models::Order
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `Order`
    |
note: required by `std::default::Default::default`
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `User: Default` is not satisfied
   --> reqwest/petstore-async/src/apis/user_api.rs:21:5
    |
18  | #[derive(Clone, Debug, Default)]
    |                        ------- in this derive macro expansion
...
21  |     pub user: crate::models::User
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `User`
    |
note: required by `std::default::Default::default`
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: the trait bound `User: Default` is not satisfied
   --> reqwest/petstore-async/src/apis/user_api.rs:67:5
    |
62  | #[derive(Clone, Debug, Default)]
    |                        ------- in this derive macro expansion
...
67  |     pub user: crate::models::User
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `User`
    |
note: required by `std::default::Default::default`
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)

    Checking petstore-reqwest v1.0.0 (/home/travis/build/OpenAPITools/openapi-generator/samples/client/petstore/rust/reqwest/petstore)
For more information about this error, try `rustc --explain E0277`.

Ref: https://app.travis-ci.com/github/OpenAPITools/openapi-generator/builds/238201866

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

[PiDelport]

Ah, that makes sense, yeah: the generated models need to derive Default too. (The spec I've been testing with doesn't hit that case.)

[PiDelport]

Cool, I updated the model template (and actually tested the generated petstore samples locally, this time 😅).

[PiDelport]

LGTM. I assume this is a backward-compatible change. Please correct me if I'm wrong.

Yes, it is. 👍🏼

[wing328]

Tests passed via https://app.travis-ci.com/github/OpenAPITools/openapi-generator/builds/238302672

[Foorack]

LGTM. I assume this is a backward-compatible change. Please correct me if I'm wrong.

Seems like it wasn't. This was forgotten for Enums, so a breaking regression for us. We have had to pin Rust SDK to 5.2.0, as 5.3.0 can no longer generate the spec.

error[E0277]: the trait bound `DeveloperType: Default` is not satisfied
   --> src\models\current_user.rs:37:5
    |
12  | #[derive(Clone, Debug, PartialEq, Default, Serialize, Deserialize)]
    |                                   ------- in this derive macro expansion
...
37  |     pub developer_type: crate::models::DeveloperType,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `DeveloperType`
    |
note: required by `std::default::Default::default`
   --> C:\Users\Foorack\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\default.rs:116:5
    |
116 |     fn default() -> Self;
    |     ^^^^^^^^^^^^^^^^^^^^^
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `UserStatus: Default` is not satisfied
   --> src\models\current_user.rs:87:5
    |
12  | #[derive(Clone, Debug, PartialEq, Default, Serialize, Deserialize)]
    |                                   ------- in this derive macro expansion
...
87  |     pub status: crate::models::UserStatus,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `UserStatus`
    |
note: required by `std::default::Default::default`
   --> C:\Users\Foorack\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\default.rs:116:5
    |
116 |     fn default() -> Self;
    |     ^^^^^^^^^^^^^^^^^^^^^
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0277]: the trait bound `FavoriteType: Default` is not satisfied
   --> src\models\favorite.rs:22:5
    |
12  | #[derive(Clone, Debug, PartialEq, Default, Serialize, Deserialize)]
    |                                   ------- in this derive macro expansion
...
22  |     pub _type: crate::models::FavoriteType,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Default` is not implemented for `FavoriteType`
    |
note: required by `std::default::Default::default`
   --> C:\Users\Foorack\.rustup\toolchains\stable-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\default.rs:116:5
    |
116 |     fn default() -> Self;
    |     ^^^^^^^^^^^^^^^^^^^^^
    = note: this error originates in the derive macro `Default` (in Nightly builds, run with -Z macro-backtrace for more info)