Consider enabling "noImplicitOverride" by default

[kitsonk]

In TypeScript 4.3, the override keyword was introduced which ensure when type checking code that a method with the override keyword is present in the base class. This helps make it more explicit when extending classes. In addition, there is the flag "noImplicitOverride" which enforces that if a method is present in a base class and the extended class that the override keyword is present in the extended class, helping ensure that users don't "accidentally" override a method unintentionally.

I am personally not sure about this, as it has a lot of potential to break existing code, but I wanted to bring it up so that we can try to consider what "version" of TypeScript we want to support in Deno. The existing behaviour allows people to opt-in to using override for the protection it offers, but essentially doesn't deliver as "safe" as code as possible.

[getspooky]

I think it's a good to enable noImplicitOverride in order to to improve code health in the repository. but as you already said it will introduce a lot of code refactoring. A good example of noImplicitOverride integration is Angular.

[David-Else]

I think it is one of the best improvements they ever made! I always hated inheritance due to not being sure if the extended class method was overriding the base class. It would be great to enable noImplicitOverride.

[sigmaSd]

for future searchers to enable this add to deno.json

{
  "compilerOptions": {
    "noImplicitOverride": true
  }
}

(take from denoland/std#1933)

[sigmaSd]

Maybe this can be considered for deno 2.0 ?

[sigmaSd]

though I just discovered this issue microsoft/TypeScript#47250 which makes this feature in my opinion partially finished

[lucacasonato]

We're doing this for Deno 2.

[dsherret]

I think this one hasn't been decided yet or implemented, so reopening.