AuthManagerSpecialPage::needsSubmitButton() is supposed to be doing that. It is confused by the rememberMe field in this case; not sure what to do about that.

Hmm, right. The problem: AuthManager sets the "remember me" option automatically (and internally), so you can't configure it to don't do that (and Remember me triggers a login button, as it's a form input rather than a submit value) :/

Isn't that the right thing to do, though? Even if you use GoogleLogin you still need to know what cookie lifetime the user wants.

What probably should be fixed is showing that checkbox when $wgExtendedLoginCookieExpiration is not set. That should be doable by changing getRememberUserDuration() in CookieSessionProvider and CentralAuthSessionProvider to return null instead of the normal cookie lifetime in that case (which it should be doing anyway according to its documentation). That will in effect disable RememberMeAuthenticationRequest.

Maybe we can move the "internal" fields of AuthManager into the AuthManager default config array, maybe with a key like "internal" and an array or into a separate configuration variable, so that the user can configure it (if he knows what he do) and so the config isn't overwritten, if the AuthManager config is set. In this way a user can configure what other requests should be added to a form of a specific action, e.g. login, or what fields shouldn't be there?

Edited after reading @Tgr's comment:
Even if I've the remember me checkbox, I don't need the login button, as it's still useless, so we should think about to not add the login button, if no other input field is there :)

In T141471#2499994, @Florian wrote:

Maybe we can move the "internal" fields of AuthManager into the AuthManager default config array, maybe with a key like "internal" and an array or into a separate configuration variable, so that the user can configure it (if he knows what he do) and so the config isn't overwritten, if the AuthManager config is set. In this way a user can configure what other requests should be added to a form of a specific action, e.g. login, or what fields shouldn't be there?

I'd rather not. If someone is really desperate they can always use the AuthChangeFormFields hook.

In T141471#2499994, @Florian wrote:

Even if I've the remember me checkbox, I don't need the login button, as it's still useless, so we should think about to not add the login button, if no other input field is there :)

I guess LoginSignupSpecialPage could override needsSubmitButton() and add special handling for the remember me checkbox.

Change 301431 had a related patch set uploaded (by Florianschmidtwelzow):
Special:UserLogin: Don't show login button with rememberMe checkbox only

https://gerrit.wikimedia.org/r/301431

Change 303012 had a related patch set uploaded (by Gergő Tisza):
AuthManager: do not rewrite PRIMARY_REQUIRED to REQUIRED

https://gerrit.wikimedia.org/r/303012

Change 303012 merged by jenkins-bot:
AuthManager: do not rewrite PRIMARY_REQUIRED to REQUIRED

https://gerrit.wikimedia.org/r/303012

Change 301431 merged by jenkins-bot:
Special:UserLogin: Don't show login button when not required

https://gerrit.wikimedia.org/r/301431

Change 313588 had a related patch set uploaded (by Cicalese):
Merge "AuthManager: do not rewrite PRIMARY_REQUIRED to REQUIRED" into REL1_27

https://gerrit.wikimedia.org/r/313588

Change 313596 had a related patch set uploaded (by Cicalese):
Merge "Special:UserLogin: Don't show login button when not required" into REL1_27

https://gerrit.wikimedia.org/r/313596

Change 313596 merged by jenkins-bot:
Special:UserLogin: Don't show login button when not required

https://gerrit.wikimedia.org/r/313596

Change 313588 merged by jenkins-bot:
AuthManager: do not rewrite PRIMARY_REQUIRED to REQUIRED

https://gerrit.wikimedia.org/r/313588