Properly quote autogenerated column aliases

Fix: #43878

activerecord/CHANGELOG.md

@@ -1,3 +1,19 @@
+*   Fix quoting of column aliases generated by calculation methods.
+
+    Since the alias is derived from the table name, we can't assume the result
+    is a valid identifier.
+
+    ```ruby
+    class Test < ActiveRecord::Base
+      self.table_name = '1abc'
+    end
+    Test.group(:id).count
+    # syntax error at or near "1" (ActiveRecord::StatementInvalid)
+    # LINE 1: SELECT COUNT(*) AS count_all, "1abc"."id" AS 1abc_id FROM "1...
+    ```
+
+    *Jean Boussier*
+
 *   Add `authenticate_by` when using `has_secure_password`.
 
     `authenticate_by` is intended to replace code like the following, which

activerecord/lib/active_record/relation/calculations.rb

@@ -345,12 +345,13 @@ def execute_grouped_calculation(operation, column_name, distinct) # :nodoc:
         column = aggregate_column(column_name)
         column_alias = column_alias_for("#{operation} #{column_name.to_s.downcase}")
         select_value = operation_over_aggregate_column(column, operation, distinct)
-        select_value.as(column_alias)
+        select_value.as(connection.quote_column_name(column_alias))
 
         select_values = [select_value]
         select_values += self.select_values unless having_clause.empty?
 
         select_values.concat group_columns.map { |aliaz, field|
+          aliaz = connection.quote_column_name(aliaz)
           if field.respond_to?(:as)
             field.as(aliaz)
           else

activerecord/test/cases/calculations_test.rb

@@ -12,6 +12,7 @@
 require "models/topic"
 require "models/reply"
 require "models/numeric_data"
+require "models/need_quoting"
 require "models/minivan"
 require "models/speedometer"
 require "models/ship_part"
@@ -1380,4 +1381,10 @@ def test_count_with_block_and_column_name_raises_an_error
       end
     end
   end
+
+  test "group alias is properly quoted" do
+    assert_nothing_raised do
+      NeedQuoting.group(:name).count
+    end
+  end
 end

activerecord/test/fixtures/1_need_quoting.yml

@@ -0,0 +1,2 @@
+- name: Foo
+- name: Bar

activerecord/test/models/need_quoting.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class NeedQuoting < ActiveRecord::Base
+  self.table_name = "1_need_quoting"
+end

activerecord/test/schema/schema.rb

@@ -8,6 +8,10 @@
   #                                                                     #
   # ------------------------------------------------------------------- #
 
+  create_table :"1_need_quoting", force: true do |t|
+    t.string :name
+  end
+
   create_table :accounts, force: true do |t|
     t.references :firm, index: false
     t.string  :firm_name