Fix recreating partial indexes after alter table for sqlite

activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb

@@ -452,6 +452,7 @@ def copy_table_indexes(from, to, rename = {})
               # index name can't be the same
               opts = { name: name.gsub(/(^|_)(#{from})_/, "\\1#{to}_"), internal: true }
               opts[:unique] = true if index.unique
+              opts[:where] = index.where if index.where
               add_index(to, columns, opts)
             end
           end

activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb

@@ -453,6 +453,23 @@ def test_add_column_with_custom_primary_key
         Barcode.reset_column_information
       end
 
+      def test_remove_column_preserves_partial_indexes
+        connection = Barcode.connection
+        connection.create_table :barcodes, force: true do |t|
+          t.string :code
+          t.string :region
+          t.boolean :bool_attr
+
+          t.index :code, unique: true, where: :bool_attr, name: "partial"
+        end
+        connection.remove_column :barcodes, :region
+
+        index = connection.indexes("barcodes").find { |idx| idx.name == "partial" }
+        assert_equal "bool_attr", index.where
+      ensure
+        Barcode.reset_column_information
+      end
+
       def test_supports_extensions
         assert_not @conn.supports_extensions?, "does not support extensions"
       end