Bug in angular.FormController when nesting ng-form's

[Joel-Kornbluh]

When using $removeControl to remove a nested ng-form, the inner form still holds a reference to parentForm, (specifically those 3 methods: $setValidity, $setDirty and $setSubmitted). So, when the validity state of the nested (isolated) form changes, it will also affect the parentForm, even though it was removed.

Here is a Demo
http://plnkr.co/edit/uiUjwB?p=preview

Occurences of parentForm referenced in nested form/control
addSetValidityMethod
FormController.$setDirty
FormController.$setSubmitted

Suggested Fix
In above mentioned methods, add if(parentForm[form.$name]){/*do*/} before changing parentForm to check if it still holds a reference to the nested form/control

[shahata]

Honestly I'm not sure why those two methods are even public. :)
Those methods are very confusing as public API because the truth is you cannot just add an input control to any form control you like, the input control is pretty much bound to it's parent form forever.

The way I see it, $addControl and $removeControl should be private and instead we should expose $enableControl and $disableControl that let users ignore and un-ignore validity/dirtiness of child controls without actually removing or adding them as child controls.

But I guess this is too much of a change right now... Anyway, I'm looking into this.

[btford]

I looked at this with @IgorMinar and @tbosch and we decided that there's no reason to use these APIs to do this. It's better to just destroy/recreate the relevant forms.