Redirect to source

ive seen the shortcode addition

1.1

• Feature: Add shortcode [google_login] with optional attributes: [google_login button_text="Login with Google" force_display="no" redirect_to="https://example.url/page"]

but i was wondering, what link should we use (if possible, otherwise a php function) to redirect the user in the source page. For example, if he tries to login/signup while in checkout, redirect him to checkout after signup/login.

Thank you in advance