mat-error does not display properly using custom cross validation

[worthy7]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

Show form validation error text

What is the current behavior?

mat-error only shows if the Confirm Password field is kept empty.

What are the steps to reproduce?

https://stackblitz.com/edit/angular-material2-issue-59b6pg

What is the use-case or motivation for changing an existing behavior?

It's broken.

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Material 6.4.6

Is there anything else we should know?

[sty1iss]

In my case. 'min', 'max' are not work,

some answers said " using ErrorStateMatcher"
ErrorStateMatcher was not work after changed the value.

some answers said " mat-error displayed only with the 'required', 'minlength', 'maxlength' and 'pattern'"
but Validtors.email are work, so still mystery.

anyway I thought, mat-error does not work with custom validators,
I hope to this is an error, not an intended things

So I decide using the mat-hint and classes for display custom error until the fix this problem.

get customError(){
    return errors & !(errors['required'] || errors['minlength'] || errors['maxlength'] || errors['pattern'])
}

<mat-form-field  [class.mat-form-field-invalid]="customError">
<mat-hint *ngIf="customError">
    <span *ngIf="errors['customErrror']" class="mat-error">this is a custom error</span>
</mat-hint>
<mat-error *ngIf="!customError">
</mat-error>
</mat-form-field>

[manklu]

@worthy7 Since you set the error on the group, both form fields are displayed with no error.

[worthy7]

@manklu I see what you mean but I just moved it and the same thing happens.
https://stackblitz.com/edit/angular-material2-issue-59b6pg

[worthy7]

@manklu Actually I'm not sure what you mean. Can you show me a version that works?

[manklu]

@worthy7 https://stackblitz.com/edit/angular-material2-issue-nk4pbz?file=app%2Fapp.component.html

[worthy7]

I don't fully understand but that works so it's not a bug

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