Deprecate `supports_migrations?` on connection adapters

`supports_migrations?` was added at 4160b518 to determine if schema
statements (`create_table`, `drop_table`, etc) are implemented in the
adapter. But all tested databases has been supported migrations since
a4fc93c3 at least.

6 files changed, 8 insertions, 28 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 5e3b8fd393..ef1d9f81a9 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -232,10 +232,10 @@ module ActiveRecord
         self.class::ADAPTER_NAME
       end
 
-      # Does this adapter support migrations?
-      def supports_migrations?
-        false
+      def supports_migrations? # :nodoc:
+        true
       end
+      deprecate :supports_migrations?
 
       def supports_primary_key? # :nodoc:
         true
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 21a547bab2..e3b6327dd8 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -89,11 +89,6 @@ module ActiveRecord
         /mariadb/i.match?(full_version)
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations?
-        true
-      end
-
       def supports_bulk_alter? #:nodoc:
         true
       end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 6c59bd9a15..db5530f793 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -281,11 +281,6 @@ module ActiveRecord
         NATIVE_DATABASE_TYPES
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations?
-        true
-      end
-
       def set_standard_conforming_strings
         execute("SET standard_conforming_strings = on", "SCHEMA")
       end
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 221445dd3b..285b0ec243 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -117,11 +117,6 @@ module ActiveRecord
         true
       end
 
-      # Returns true, since this connection adapter supports migrations.
-      def supports_migrations? #:nodoc:
-        true
-      end
-
       def requires_reloading?
         true
       end
diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 40f6226315..263a8a7da3 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -548,12 +548,10 @@ module ActiveRecord
       end
 
       def call(env)
-        if connection.supports_migrations?
-          mtime = ActiveRecord::Migrator.last_migration.mtime.to_i
-          if @last_check < mtime
-            ActiveRecord::Migration.check_pending!(connection)
-            @last_check = mtime
-          end
+        mtime = ActiveRecord::Migrator.last_migration.mtime.to_i
+        if @last_check < mtime
+          ActiveRecord::Migration.check_pending!(connection)
+          @last_check = mtime
         end
         @app.call(env)
       end
@@ -1098,8 +1096,6 @@ module ActiveRecord
     end
 
     def initialize(direction, migrations, target_version = nil)
-      raise StandardError.new("This database does not yet support migrations") unless Base.connection.supports_migrations?
-
       @direction         = direction
       @target_version    = target_version
       @migrated_versions = nil
diff --git a/activerecord/lib/active_record/railties/databases.rake b/activerecord/lib/active_record/railties/databases.rake
index 246d330b76..fabd326649 100644
--- a/activerecord/lib/active_record/railties/databases.rake
+++ b/activerecord/lib/active_record/railties/databases.rake
@@ -288,8 +288,7 @@ db_namespace = namespace :db do
       current_config = ActiveRecord::Tasks::DatabaseTasks.current_config
       ActiveRecord::Tasks::DatabaseTasks.structure_dump(current_config, filename)
 
-      if ActiveRecord::Base.connection.supports_migrations? &&
-          ActiveRecord::SchemaMigration.table_exists?
+      if ActiveRecord::SchemaMigration.table_exists?
         File.open(filename, "a") do |f|
           f.puts ActiveRecord::Base.connection.dump_schema_information
           f.print "\n"