Allow var to have multiple declarations

[imteekay]

Examples

var s = 'test';

var s1: string = 'test';

var s2 = 'test';
var s2: string = 'test';

var s3: number = 2;
var s3 = 'test';

var s4: string = 'test';
var s4: number = 2;
var s4 = 'test';

var s5 = 'test';
var s5: string = 2;

Error message

Example of an error:

Error: "Subsequent variable declarations must have the same type. Variable 's' must be of type 'string', but here has type 'number'."

Logic

!001

It doesn't have a variable declaration of s before it and it doesn't have a typename, so it should just need to return the type related to the expression 'test', which's string

var s = 'test';

!002

It doesn't have a variable declaration of s before it but it has a typename and the type of the expression, so it should compare both and return the typename

var s: string = 'test';

!003

It has a variable declaration of s before it and it has the typename and the type of the expression, so it should compare its typename with the first variable declaration type

var s = 'test';
var s: string = 'test';

!004

It has a variable declaration of s before it and it has only the type of the expression, so it should compare the expression type with the first variable declaration type

var s: number = 2;
var s = 'test';

!005

It has a variable declaration of s before it and it has the typename and the type of the expression, so it should compare its typename with the first variable declaration type. In a mismatch case, it should generate the type error. Subsequent variable declarations that follow the same type as the first one, should not generate an error

var s: string = 'test';
var s: number = 2;
var s = 'test';
``
`

### !006

It has a `typename` that matches the first variable declaration type but its expressions type mismatches its `typename`

```ts
var s = 'test';
var s: string = 2;

[imteekay]

@sandersn I finally created the PR related to that exercise we discussed a couple of weeks ago. With this exercise, I could the benefits of using some kind of "caching system" to prevent recreating types that were created before. But I tried to make it as simple as possible for now. Appreciate any feedback!

[sandersn]

Looks good. Nice clean code.

[sandersn]

interesting choice not to have an error on 2. Probably the right one, to avoid inundating the user with errors.

[imteekay]

Do you mean this?

var s4: string = 'test';
var s4: number = 2; // this has an error because it should actually be a string
var s4: string = 's'; // it doesn't produce an error because it compares only with the first var declaration

If so, I got this behavior from TS itself 😅

to avoid inundating the user with errors.

^ That makes sense to me!

[sandersn]

I meant no error on the 2 in var s4: number = 2, even though s4 actually has type string. It makes sense because of the explicit type annotation : number.