Object spread and this: spread types may only be created from object types

[sanex3339]

TypeScript Version: 2.1.4

Code

example

interface IOptions {
    option1: string;
    option2: string;
    option3: string;
}

const DEFAULT_OPTIONS_PRESET: IOptions = {
    option1: 'string1',
    option2: 'string2',
    option3: 'string3'
};

class Options implements IOptions {
    public readonly option1: string;
    public readonly option2: string;
    public readonly option3: string;

    constructor (inputOptions: IOptions) {
        this = { // The left-hand side of an assignment expression must be a variable or a property access.
            ...this, // spread types may only be created from object types
            ...DEFAULT_OPTIONS_PRESET,
            ...inputOptions 
        };

        const errors = OptionsValidator.validate(this);

        if (errors.length) {  // ...  }

        this = { // The left-hand side of an assignment expression must be a variable or a property access.
            ...this,  // spread types may only be created from object types
            ...OptionsNormalizer.normalize(this)
        };
    }
}

Expected behavior:
No errors?
With object assign code works well

constructor (inputOptions: IOptions) {
    Object.assign(this, DEFAULT_OPTIONS_PRESET, inputOptions);
}

Actual behavior:
Two errors:
The left-hand side of an assignment expression must be a variable or a property access.
Spread types may only be created from object types.

If it's a a correct behaviour please explain me it.

[timocov]

Are you sure that code with Object.assign is the same as in your code?
I guess no, because you rewrite this ref to "new" object (but it is the same as this, yeah).

[mhegazy]

this is a generic type. it refers to the type of the instance type of the class that will be new'ed later on. this could be your class Options or any decedent of it later on.
spread and rest are not supported on generics at the moment. this is tracked by #10727

[sanex3339]

Ok thank you for explanation, i will close this issue