Revert "FEATURE: enforce_canonical_emails site setting"

This reverts commit 6f9177e2ed.

We decided on a completely different approach to the problem.

Instead we will let blocked emails be treated as canonical.

app/models/user_email.rb

@@ -15,27 +15,12 @@ class UserEmail < ActiveRecord::Base
   validate :user_id_not_changed, if: :primary
   validate :unique_email
 
-  before_save :save_canonical
-
   scope :secondary, -> { where(primary: false) }
 
-  def self.canonical(email)
-    name, domain = email.split('@', 2)
-    name = name.gsub(/\+.*/, '')
-    if ['gmail.com', 'googlemail.com'].include?(domain.downcase)
-      name = name.gsub('.', '')
-    end
-    "#{name}@#{domain}".downcase
-  end
+  self.ignored_columns = ['canonical_email']
 
   private
 
-  def save_canonical
-    if SiteSetting.enforce_canonical_emails && self.will_save_change_to_email?
-      self.canonical_email = UserEmail.canonical(self.email)
-    end
-  end
-
   def strip_downcase_email
     if self.email
       self.email = self.email.strip
@@ -49,14 +34,8 @@ class UserEmail < ActiveRecord::Base
   end
 
   def unique_email
-    if self.will_save_change_to_email?
-      exists = self.class.where("lower(email) = ?", email).exists?
-      exists ||= SiteSetting.enforce_canonical_emails &&
-        self.class.where("canonical_email = ?", UserEmail.canonical(email)).exists?
-
-      if exists
-        self.errors.add(:email, :taken)
-      end
+    if self.will_save_change_to_email? && self.class.where("lower(email) = ?", email).exists?
+      self.errors.add(:email, :taken)
     end
   end
 
@@ -73,17 +52,15 @@ end
 #
 # Table name: user_emails
 #
-#  id              :integer          not null, primary key
-#  user_id         :integer          not null
-#  email           :string(513)      not null
-#  primary         :boolean          default(FALSE), not null
-#  created_at      :datetime         not null
-#  updated_at      :datetime         not null
-#  canonical_email :string
+#  id         :integer          not null, primary key
+#  user_id    :integer          not null
+#  email      :string(513)      not null
+#  primary    :boolean          default(FALSE), not null
+#  created_at :datetime         not null
+#  updated_at :datetime         not null
 #
 # Indexes
 #
-#  index_user_emails_on_canonical_email      (canonical_email) WHERE (canonical_email IS NOT NULL)
 #  index_user_emails_on_email                (lower((email)::text)) UNIQUE
 #  index_user_emails_on_user_id              (user_id)
 #  index_user_emails_on_user_id_and_primary  (user_id,primary) UNIQUE WHERE "primary"

config/locales/server.en.yml

@@ -1586,7 +1586,6 @@ en:
     allow_index_in_robots_txt: "Specify in robots.txt that this site is allowed to be indexed by web search engines. In exceptional cases you can permanently <a href='%{base_path}/admin/customize/robots'>override robots.txt</a>."
     email_domains_blacklist: "A pipe-delimited list of email domains that users are not allowed to register accounts with. Example: mailinator.com|trashmail.net"
     email_domains_whitelist: "A pipe-delimited list of email domains that users MUST register accounts with. WARNING: Users with email domains other than those listed will not be allowed!"
-    enforce_canonical_emails: "Prior to creating users strip email to canonical form ensuring uniqueness. Setting will only take effect on new account registrations. When set user+1@domain.com will not be allowed to register if user+2@domain.com is already registered."
     auto_approve_email_domains: "Users with email addresses from this list of domains will be automatically approved."
     hide_email_address_taken: "Don't inform users that an account exists with a given email address during signup and from the forgot password form."
     log_out_strict: "When logging out, log out ALL sessions for the user on all devices"

config/site_settings.yml

@@ -459,7 +459,6 @@ login:
   email_domains_whitelist:
     default: ""
     type: list
-  enforce_canonical_emails: false
   auto_approve_email_domains:
     default: ""
     type: list

db/migrate/20200414034210_add_canonical_email_to_user_email.rb

@@ -1,7 +0,0 @@
-# frozen_string_literal: true
-class AddCanonicalEmailToUserEmail < ActiveRecord::Migration[6.0]
-  def change
-    add_column :user_emails, :canonical_email, :string, length: 513
-    add_index :user_emails, :canonical_email, where: 'canonical_email IS NOT NULL'
-  end
-end

db/post_migrate/20200424032633_remove_canonical_email_from_user_emails.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class RemoveCanonicalEmailFromUserEmails < ActiveRecord::Migration[6.0]
+  def up
+    execute <<~SQL
+      ALTER TABLE user_emails
+      DROP COLUMN IF EXISTS canonical_email
+    SQL
+  end
+  def down
+    # nothing to do, we already nuke the migrations
+  end
+end

spec/jobs/user_email_spec.rb

@@ -672,32 +672,4 @@ describe Jobs::UserEmail do
     end
 
   end
-
-  context "canonical emails" do
-    it "correctly creates canonical emails" do
-      expect(UserEmail.canonical('s.a.m+1@gmail.com')).to eq('sam@gmail.com')
-      expect(UserEmail.canonical('sa.m+1@googlemail.com')).to eq('sam@googlemail.com')
-      expect(UserEmail.canonical('sa.m+1722@sam.com')).to eq('sa.m@sam.com')
-      expect(UserEmail.canonical('sa.m@sam.com')).to eq('sa.m@sam.com')
-    end
-
-    it "correctly bans non canonical emails" do
-
-      email = UserEmail.create!(email: 'sam@sam.com', user_id: user.id)
-      expect(email.canonical_email).to eq(nil)
-
-      email = UserEmail.create!(email: 'sam+1@sam.com', user_id: user.id)
-      expect(email.canonical_email).to eq(nil)
-
-      SiteSetting.enforce_canonical_emails = true
-
-      email = UserEmail.create!(email: 'Sam+5@sam.com', user_id: user.id)
-      expect(email.canonical_email).to eq('sam@sam.com')
-
-      expect do
-        UserEmail.create!(email: 'saM+3@sam.com', user_id: user.id)
-      end.to raise_error(ActiveRecord::RecordInvalid)
-
-    end
-  end
 end