TypeScript Version: 4.00-beta and Nightly

Search Terms:
"Class property inference"
"model' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer."

Code

Below are two classes that demonstrate the new Class Property Inference from Constructors in Typescript 4.

The first class calls an instance method to initialize model and the type of model is correctly inferred. LOVE IT!
The first class also demonstrates that a primitive type can be assigned from the constructor (as explained in the announcement).

The second class attempts to do the same, but without a method call. It fails with an error about it being self referencing which it isn't.

class AnimalViewModel_PASS {

    constructor()
    {
        // call a function to get a type - PASS
        this.model = this.createModel();

        // assign simple type directly in constructor - PASS
        this.qty = 10;
    }

    createModel()
    {
        return {
            animal: 'dog',
            sound: 'bark'
        };
    }

    model;  // PASS - type infered as { animal: 'dog', sound: 'bark' }
    qty;    // PASS - type infered as number
}


class AnimalViewModel_FAILS {

    constructor()
    {
        this.model = {
            animal: 'dog',
            sound: 'bark'
        };
    }

    // FAILS
    // 'model' implicitly has type 'any' because it does not have a type 
    // annotation and is referenced directly or indirectly in its own initializer.(7022)
    model;  
}

Expected behavior:
The two classes should compile and type of model should be fully inferred wherever the type is ultimately declared.

Actual behavior:
The second class AnimalViewModel_FAILS shows the following error for model property:

'model' implicitly has type 'any' because it does not have a type annotation and is referenced directly or indirectly in its own initializer.(7022)

Playground Link:
Sorry I tried, but there is no Share option on typescript playground. I looked everywhere and tried multiple versions.

Related Issues:
No related issues found