Specifically: narrow the type used for form statuses from string to a union of possible statuses. Change the API methods from any to use the new type.
This is a breaking change. However, as discussed in the PR, breakage seems minimal, and google3 has been prepped to land this.
Background: we uncovered these any typings in the course of design work for typed forms. They could be fixed in a non-breaking manner by piggybacking them on top of the new typed forms generics, but it would be much cleaner to fix them separately if possible.
BREAKING CHANGE:
A new type called `FormControlStatus` has been introduced, which is a union of all possible status strings for form controls. `AbstractControl.status` has been narrowed from `string` to `FormControlStatus`, and `statusChanges` has been narrowed from `Observable<any>` to `Observable<FormControlStatus>`. Most applications should consume the new types seamlessly. Any breakage caused by this change is likely due to one of the following two problems: (1) the app is comparing `AbstractControl.status` against a string which is not a valid status; or, (2) the app is using `statusChanges` events as if they were something other than strings.
PR Close#42952
Several new functionalities are possible with this change: the most requested is that callers can now check whether a control has a required validator. Other uses include incrementally changing the validators set without doing an expensive operation to reset all validators.
Closes#13461.
PR Close#42838
If the validator is bound to be `null` then no validation occurs and
attribute is not added to DOM.
For every validator type different PR will be raised as discussed in
https://github.com/angular/angular/pull/42378.
Closes#42267.
PR Close#42565
Dylan Hunn
iRealNirmal
Paul Gschwendtner