Adding legacy primary key should be compatible

Currently implicit legacy primary key is compatible, but adding explicit
legacy primary key is not compatible. It should also be fixed.

Fixes #30664.

1 files changed, 19 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/migration/compatibility.rb b/activerecord/lib/active_record/migration/compatibility.rb
index 87c1c58aff..92993d64a7 100644
--- a/activerecord/lib/active_record/migration/compatibility.rb
+++ b/activerecord/lib/active_record/migration/compatibility.rb
@@ -20,6 +20,11 @@ module ActiveRecord
 
       class V5_0 < V5_1
         module TableDefinition
+          def primary_key(name, type = :primary_key, **options)
+            type = :integer if type == :primary_key
+            super
+          end
+
           def references(*args, **options)
             super(*args, type: :integer, **options)
           end
@@ -86,6 +91,20 @@ module ActiveRecord
           end
         end
 
+        def add_column(table_name, column_name, type, options = {})
+          if type == :primary_key
+            case adapter_name
+            when "PostgreSQL"
+              type = :serial
+            when "Mysql2"
+              type = :integer
+              options[:auto_increment] = true
+            end
+            options[:primary_key] = true
+          end
+          super
+        end
+
         def add_reference(table_name, ref_name, **options)
           super(table_name, ref_name, type: :integer, **options)
         end