Support is operator for enums

[artsiommiksiuk]

Clear and concise description of the problem

While migrating from open api and several schemas, I found my self repeatedly writing pattern like

model A is Core.A;
model B is Core.B;

this is done as a remapping measure, to keep for a while backward compatible schemas.

but enums require to write this

enum C { ...Core.C };

which also doesn't take into account decorators of course.

So, having the same is operator would make this process more uniform.

enum C is Code.C;

Otherwise, I don't see other language constructs allow to do so. Aliases are not creating named entries in the OpenAPI document and not even reaching AST.

Checklist

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• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[timotheeguerin]

I think this could be resolved by the declare type proposal which would work for any types instead of having individual syntax

declare C = Code.C;

[markcowl]

Will track this in the other issue