[typescript-rxjs] add rxjs 7 support

[denyo]

This PR adds support for rxjs 7 (https://github.com/ReactiveX/rxjs/blob/master/CHANGELOG.md) which introduces some breaking interface changes but brings both better minification and improved performance.

Also type imports are refactored to type-only imports.

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[macjohnny]

@denyo thanks for your contribution. would there be a possibility to support RxJS 7 in a backwards compatible way? maybe introduce an option or version flag, similar to

openapi-generator/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/TypeScriptAngularClientCodegen.java

Line 121 in c4b9804

this.cliOptions.add(new CliOption(NG_VERSION, "The version of Angular. (At least 6.0.0)").defaultValue(this.ngVersion));

?

[macjohnny]

@denyo ping

[denyo]

@macjohnny I won't get the chance to make it backwards compatible.
Therefore I would suggest to change the target branch to the next major version.

[macjohnny]

@wing328 what is your opinion here? should we break the existing rxjs generator, or should we create a new rxjs7 generator?

[TiFu]

Quick question: Why does this PR affect 4,359 files? Looks like some unrelated commits have been included.

[macjohnny]

@TiFu I guess this is because of the changed target branch

[jopelle1]

Any update on this PR ? Rxjs 7 support would be very useful

[trumbitta]

@macjohnny would it possible to release this as is and let people stuck with rxjs 6 (rxjs 8 is coming) just point to an old version of the generator by themselves?

[Polm1]

Following 👀

[macjohnny]

According to https://github.com/OpenAPITools/openapi-generator#11---compatibility, we can have breaking changes only for a major release.
If an option is introduced, we can also habe it for the current minor or patch release

[macjohnny]

@denyo can you rebase onto the 6.0 branch to avoid the unrelated changes?

[jopelle1]

I opened a new PR fixing this one #11364 :

• Rebased on 6.0x
• Implemented option to switch to rxjs 7

[denyo]

@macjohnny done.

For everyone else waiting, this is the docker image built from this branch: denyo/openapi-generator-cli:6.0.0-test

[macjohnny]

I would suggest to close this PR in favor of #11364, which we could have in 5.4, and thus avoid merge conflicts in the future.
Any objections?

[denyo]

I would suggest to close this PR in favor of #11364, which we could have in 5.4, and thus avoid merge conflicts in the future. Any objections?

The only concern I have is that complexity will increase in the generator with every new version of rxjs, especially within templates, e.g. by adding a toggle or extending the flag for every version and at the same time users need to update their flags/toggles, too.

From a user's perspective I would expect to get the latest version by default and have an opt-in for older versions if I really wanna be backwards compatible. At least this is what I am used to.

However the philosophy of this project might be different.

[macjohnny]

@denyo we can remove the rxjs<7 support for the 6.0 release, which is an easy thing to do an removes the complexity in the template

[macjohnny]

since the next release will be 6.0.0, lets merge this PR