Casting to an assignable type is unnecessary. I would like to propose a rule that warns against it.

For instance:

leta:string='str'asstring;

or more commonly in return statements

interfaceFoo{bar:string}functionfoo():Foo{return{bar:'str'}asFoo;}

I'm not exactly sure how to make this rule smart enough to not to be annoying. For instance, when usingArray.prototype.reduce to construct a record, I always cast the initial value of type{} toRecord<string, SOME_TYPE>. This rule would warn against it:

[1,2,3].reduce((acc,item,index)=>{acc[index]=itemreturnacc;},{}asRecord<string,number>)

Assignable types are not "the same type", so I wonder if we should limit this rule to "to cast to exactly the same types". For instance anas cast here does not seem unnecessary:

interfaceFoo{bar:string;baz?:number}functionfoo(){return{bar:'str'}asFoo}

Of course we can use reduce's generic type argument to avoid the as cast. We can also use the return type declaration to avoid as cast infoo(). Maybe I can't find a good example if this rule can become annoying oras casts are usually easy to avoid if types are assignable.

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